1

PREVALENCE AND SOCIODEMOGRAPHIC CHARACTERISTICS OF

HEPATITIS B SURFACE ANTIGENAEMIA AMONG CHILDREN AGED 0

TO 59 MONTHS IN OSHIMILI SOUTH LOCAL GOVERNMENT AREA OF

DELTA STATE

THIS DISSERTATION IS SUBMITTED IN PART FULFILMENT OF THE

REQUIREMENT FOR THE AWARD OF THE FELLOWSHIP OF THE

NATIONAL POSTGRADUATE MEDICAL COLLEGE OF NIGERIA IN THE

FACULTY OF PAEDIATRICS

DR NWAFOR IFEOMA OGOMA

MBBS (AWKA), 2008.

MAY 2016

2

DECLARATION

I hereby declare that this Dissertation is original and that, to the best of my knowledge and belief, it has neither been presented to any other College for a Fellowship nor has it been submitted elsewhere for publication.

Signature ……………………

Dr. Nwafor, Ifeoma Ogoma

Date …………………………

3

ATTESTATION

We certify that the study reported in this dissertation was done by the candidate under our supervision. We have also supervised the writing of the dissertation.

PROFESSOR OKOLO SELINA, N

JOS UNIVERSITY TEACHING HOSPITAL, JOS, PLATEAU STATE

SIGNATURE AND DATE……………………

DR ADENIRAN KAYODE

CONSULTANT PAEDIATRICIAN

FEDERAL MEDICAL CENTER, ASABA, DELTA STATE

SIGNATURE AND DATE…………………..

DR EZEONWU BERTILLA

CONSULTANT PAEDIATRICIAN

FEDERAL MEDICAL CENTER, ASABA, DELTA STATE

SIGNATURE AND DATE………………….. 4

TABLE OF CONTENTS

Title Page

Title page………………………………………………………………………i

Declaration…………………………………………………………………….ii

Attestation…………………………………………………………………… iii

Table of contents…………………………………………………………….. iv

Dedication…………………………………………………………………… vi

Acknowledgement……………………………………………………………vii

List of tables………………………………………………………………….viii

List of figures………………………………………………………………...ix

List of abbreviations………………………………………………………….x

Summary………………………………………………………………………xii

Introduction… ………………………………………………………………...1

Justification and relevance of the study………………………………………3

Literature review………………………………………………………………5

Study aims and objectives…………………………………………………….29

Subjects and methods ………………………………………………………...30 5

Results………………………………………………………………………...42

Discussion……………………………………………………………………..52

Conclusion…………………………………………………………………….57

Recommendations…………………………………………………………….58

Line of future research………………………………………………………..59

References…………………………………………………………………….60

Appendices……………………………………………………………………75

6

DEDICATION

I dedicate this work to God Almighty, to my family and my mentors.

7

ACKNOWLEDGEMENT

I am thankful to God for giving me the grace to finish this work.

I would like to express my sincere gratitude to Prof. Okolo Selina for the continuous encouragement, inspiration, and support throughout my residency training and throughout the period of this study. I could not have imagined having a better advisor and mentor.

I am grateful to my supervisors; Dr Ezeonwu Bertilla and Dr Adeniran Kayode for their excellent guidance, patience, and the time they took in supervising my study. I have learnt a great deal from you, and I will forever be grateful.

Thanks to Doctors Okoye and Idolor and to Sister Vira Ononye for their assistance during the actual study.

To all the study participants, I say thank you. Without your consent, the study would not have been concluded.

I would also like to thank Dr Okike for his invaluable input and for always pushing me to be a better doctor. Thanks to Dr Abonyi and Dr Opara for their encouragement.

Thanks to my peers; Dr Bamidele and Dr Ayodele for their insightful comments, criticism and humour.

I am grateful to my mother for helping to care for my son, and for her encouragement during the times when balancing motherhood and academic pursuits was overwhelming.

Finally, thanks to my husband and my son.

8

LIST OF TABLES

Table Title Page

I Total number of households and under-five children in selected wards……33

II Sampling fraction for households and under-five children in each ward…..35

III Sample size for each age cohort in each chosen ward………………………36

IV Age, gender and socioeconomic class distribution of the study subjects…...42

V Risk factors for HBsAg among the study subjects…………………………45

VI Relationship between the sociodemographic characteristics of the

study population and HBsAg positivity…………………………………..48

VII Relationship between nutritional status of the subjects and HBsAg

seropositivity………………………………………………………………..51

9

LIST OF FIGURES

Figure Title Page

1 Serologic response to acute hepatitis B Virus…………………….6

2 Schematic representation of the hepatitis B virus genome………..7

3 Acute HBV infection……………………………………………..11

4 Chronic HBV infection (HBeAg positive)……………………….12

5 Chronic HBV infection (HBeAg positive)……………………….12

6 Immunochromatographic test kit for HBsAg assay ……………..25

7 Immunochromatographic test kit for HBsAg assay……………...40

8 Pie chart showing prevalence of HBsAg among the

study population…………………………………………………..43

9 Bar chart showing the relationship between places of delivery

of the subjects and risk of HBsAg seropositivity…………………47

10 Bar chart showing the relationship between HBsAg and the

immunization status of the study subjects……………………….49

11 Hepatitis B vaccination rates among the study participants……...50

10

LIST OF ABBREVIATIONS

HBV………………………………Hepatitis B Virus

HB………………………………...Hepatitis B

WHO……………………………...World Health Organization

HCC…………………………….. .Hepatocellular Carcinoma

HbsAg…………………………….Hepatitis B Surface Antigen

HIV……………………………….Human Immunodeficiency Virus

DNA………………………………Deoxyribonucleic Acid

HBcAg……………………………Hepatitis B Core Antigen nm…………………………………nanometer

HBeAg……………………………Hepatitis Be Antigen

AntiHBs/HBsAb………………….Anti Hepatitis B Surface Antibody

HBeAb/antiHBe…………………..Hepatitis Be Antibody

IgM………………………………..Immunoglobulin M

IgG………………………………..Immunoglobulin G

HBcAb/ antiHBc………………….Hepatitis B Core Antibody

HLA………………………………Human Leukocyte Antigen 11

CD…………………………………Cluster of Differentiation

IFN………………………………..Interferon

IL………………………………….Interleukin

SES………………………………..Socioeconomic Status

ELISA…………………………….Enzyme Linked Immunosorbent Assay

HRP……………………………….Horseradish Peroxidase

HBIG……………………………..Hepatitis B Immunoglobulin G

LGA………………………………Local Government Area

HH……………………………….. Households

ARV……………………………… Antiretroviral

SCA……………………………….Sickle cell anaemia

ALT……………………………….Alanine aminotransferase

AST……………………………….Aspartate aminotransferase

PCR……………………………… Polymerase chain reaction

12

SUMMARY

Hepatitis B virus (HBV) infection is a serious public health problem in sub-Saharan Africa.

Children who acquire HBV infection early in childhood, especially before the age of five years, have a high risk of progression to chronicity and eventually, to liver cirrhosis and hepatocellular carcinoma later in adulthood. High prevalence rates of hepatitis B surface antigenaemia have been documented among Nigerian children.

This study is aimed at determining the prevalence, sociodemographic characteristics and risk factors of hepatitis B surface antigenaemia in children aged 0 to 59 months in Oshimili south local government area of Delta state. It will also ascertain any relationship between HBsAg seropositivity, sociodemographic characteristics, malnutrition, and the immunization status of the study subjects.

This was a cross-sectional descriptive study carried out over a four month period (February-

May, 2015). One hundred and fifty-three under-five children drawn from four of the eleven wards in Oshimili south LGA were enrolled into the study after an informed written consent was obtained from caregivers. Information on sociodemographic characteristics, hepatitis B vaccination status, history of surgeries, circumcision, blood transfusion, sharing of sharps and injection needles, history of scarification marks, and maternal past history of hepatitis B infection were obtained using a standardized questionnaire. The subjects with weight for height

Z-score of ≤ 2SD below the mean for age were taken to be malnourished. Blood samples collected from all the subjects and their respective mothers were tested for HBsAg using CTK

Biotech HBsAg test strip. Data was analyzed using SPSS Windows Version 23 and a p-value of

< 0.05 was considered significant. 13

Eighty-two (53.65%) and 71 (46.4%) of the 153 subjects were males and females respectively, with a male to female ratio of 1.1: 1. Mean age of the subjects was 35.73±1.3months. Out of the

153 subjects, only 1 male neonate tested positive to HBsAg giving a prevalence rate of 0.7%.

Risk factors for HBsAg positivity found in the positive subject were maternal history of HBV infection and history of contact with a family member with jaundice. Circumcision, sharing of sharps/injection needles, past surgical history, presence of scarification marks, blood transfusion history, socioeconomic class, place of delivery and nutritional status of the study subjects were not predictors of the risk of acquiring HBV infection in the study population. One hundred and seventeen of the study subjects (76%) had received HB vaccination while 36 were unimmunized, and none of the immunized subjects was positive for HBsAg. Three (1.97%) out of the 153 mothers were positive for HBsAg of which one mother and child pair was positive. 76 (49.97%) of the mothers were not screened for HBV infection during the antenatal period.

The prevalence of HBV in children less than five years in Oshimili South LGA was very low and may be due to HB vaccination. This study also showed that vertical transmission may still play a role in transmission of HBV infection in the under-five.

This study recommends that hepatitis B screening in pregnancy should be reinforced and immunization programs strengthened, including ensuring timely administration of birth dose of hepatitis B vaccine and HBIG where the mother is positive for HBsAg. In addition, public health education about the disease should be done.

14

INTRODUCTION

Hepatitis B virus (HBV) infection has been identified worldwide as one of the commonest infectious diseases and a major public health problem.1 HBV is a DNA virus belonging to the family called Hepadnaviridae and causes acute or chronic infection.2

World Health Organization (WHO) estimated that two billion people worldwide have evidence of past or recent infection of HBV; about 400 million people are estimated to be chronically infected and are at risk of liver related disease, while about 600,000 people die each year from

HBV related liver disease or hepatocellular carcinoma (HCC).3 Infection in childhood has been shown to play a major role in the spread and long term effect of this disease. Recently, more efforts have been directed to HIV/AIDS prevention and control than HBV infection which has more devastating sequelae.

The routes of transmission are vertically from an infected mother to her child, horizontally from child to child, sexually, and contact with contaminated blood and blood products during transfusion, occupational exposures or during procedures such as circumcision, tattooing, scarifications, traditional uvulectomy, and ear piercing.4,5 In under-five children, the most important risk factor for acquisition of HBV remains perinatal exposure to an HBsAg-positive mother, and vertical transmission of HBV confers a 200- fold increased risk of HCC by adulthood.6,7

World Health Organization classified HBV endemicity according to the proportion of the adult population who are positive for hepatitis B surface antigen (HBsAg) into low (0-2%), medium

(2-7%) and high endemicity (≥8%).8 Despite the existence of safe and effective HBV vaccine,

Nigeria has remained hyper-endemic with varying prevalence rates in different segments of the 15 population; 17% in female sex workers,9 8.3% amongst pregnant women,10 7.6% in primary school children,11 8.1% in sickle cell anaemic children,12 9% in children without the human immunodeficiency virus13 (HIV), and 19% in those who had HIV.13

Very high prevalence rates of HBsAg have been documented in under-five children as reported by studies of Agbede et al14 (10%) and Sadoh et al15 (14.1%). These figures are alarming and of public health importance, knowing the consequences of HBV infection in children. HBV infection in this age group is usually asymptomatic and forms the reservoir for perpetuating the disease. This may lead to chronicity with its attendant sequelae of liver cirrhosis and hepatocellular carcinoma later in adulthood.16 It has been documented that 80-90% of infections acquired in the first year of life and 30-50% acquired between 1-4 years of age become chronic; whereas only 2-5% of infections acquired in adulthood will lead to chronicity.4 Overtime, 25% of persons infected as children develop primary liver cancer or cirrhosis as adults. Vertical transmission of HBV is said to produce a high rate of persistent infection since infants cannot readily clear the infection.17 Due to immaturity of their immune system, HBV infection in children remains in the immune tolerant phase associated with high viral replication with minimal or no liver inflammation. This immune tolerant phase may last for decades.18,19 It therefore, became pertinent to assess the current status of HBsAg in this age group in order to know the public health measures to institute where necessary.

This study was thus set out to assess the prevalence of HBsAg in under-five children in OSLGA of Delta State, and to determine the sociodemographic characteristics and risk factors for the infection among the study population.

16

JUSTIFICATION FOR THE STUDY

The clinical consequences of childhood acquisition of HBV, such as liver cirrhosis and hepatocellular carcinoma later in adulthood, make a strong case for its prevention and control.

Hepatitis B Virus infection and HIV/AIDS share similar routes of transmission, however, global efforts have recently been directed to the prevention and control of HIV/AIDS infection thus neglecting HBV infection which is 50-100 times more infectious and has more devastating sequelae. World Health Organization labeled prevention and control efforts for HBV as

“fragmented” compared with HIV, and has predicted its increasing role as a cause of death in the coming decades, emphasizing the need for timely prevention and screening strategies.20

Despite the introduction of HB vaccination into the Nigerian immunization schedule in 2004, studies have reported very high prevalence rates of HBsAg among under-five Nigerian children;

10% by Agbede et al13 and 14.1% by Sadoh et al.14

From experience, most children who present to the children emergency room of Federal Medical

Center, Asaba, have been taken to traditional healers on account of hepatomegaly or splenomegaly prior to presentation. While ‘administering’ treatment to the patients, scarification is often adopted as one of the tools of treatment and the sterility of the instruments used is difficult to ascertain, and HBV infection in under-five children is usually asymptomatic but leads to chronicity with its attendant sequelae of liver cirrhosis and HCC.21 These children continue to serve as reservoir of HBV infection. In addition, the screening of antenatal women for HBV and vaccination of newborns is not widely available especially in low resource settings in Nigeria.15

Also, vaccination rates for HBV in Nigeria are poor, and according to the World Health

Organization (WHO) estimate, only 63% of Nigerians were vaccinated against HBV in 2013.22 17

The consequences of these may be increased HBV transmission in children. With all these, one may conclude that the prevalence of HBsAg in the under-5 may be high. Thus, there is need to know what the current prevalence of HBsAg in the under-five children in Nigeria is.

Screening for HBV infection using HBsAg as a serologic marker could identify chronically infected children who may benefit from long term follow up and treatment. In addition, early identification of chronically infected children will permit the identification and vaccination of susceptible household contacts, thereby interrupting ongoing transmission. Although, studies have been carried out on HBV in other parts of the country and in those above 10 years of age10,11 there is dearth of information on the prevalence of HBV amongst under-five children in

Nigeria, and in Delta state. This study set out to assess the prevalence of HBV infection amongst under-five children in Oshimili South LGA of Delta State so as to ascertain the public health importance of HBV. It is hoped that the study will assist in assessing the adequacy of the level of control and determine the sociodemographic variables that may play a role in the public health management of the disease.

RELEVANCE OF THE STUDY

This study will provide information on the prevalence and risk factors for HbsAg in the under- five children in Oshimili South LGA of Delta State.

It will serve as a baseline reference study for future studies.

Findings may guide the implementation of an effective intervention program on HBV infection in Oshimili South LGA of Delta State.

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LITERATURE REVIEW

HISTORICAL PERSPECTIVE

HBV was first identified in 1963 by the Nobel Prize winner Dr. Baruch Blumberg. Blumberg unexpectedly identified a protein in the blood of Australian aborigines, which was later named the Australian antigen. Blumberg and his assistant, while examining serum from multi-transfused patients with conditions such as leukaemia or thalassemia compared to serum from a variety of healthy individuals from different parts of the world to identify genetic polymorphisms of serum proteins, discovered an Australian aborigine's blood sample that reacted with an antibody in the serum of an American hemophilia patient. The Australian antigen was initially thought to be associated with leukaemia and Down’s syndrome, but further observations revealed that the

Australia antigen is a component of the infectious agent for HBV. The Australian antigen was eventually confirmed to be correlated with viral hepatitis.23,24 Four years after discovering the hepatitis B virus, Drs. Blumberg and Millman developed the first hepatitis B vaccine, which was initially a heat-treated form of the virus.

CLASSIFICATION AND STRUCTURE

Hepatitis B virus is the prototype member of the Hepadnaviridae and the Orthohepadnavirus genus family and has a strong preference for infecting liver cells.2

Hepatitis B virus virions are double-shelled particles, 40 to 42 nm in diameter with an outer lipoprotein envelope that contains three related envelope glycoproteins (or surface antigens).

Within the envelope is a hexagonal viral nucleocapsid, or core2 which contains the viral genome, a relaxed circular, partially duplex DNA of 3.2 kb, and a polymerase that is responsible for the synthesis of viral DNA in infected cells.25 19

The outer envelope contains hepatitis B surface antigen (HBsAg) while the inner nucleocapsid consists of hepatitis B envelope antigen (HBeAg) and hepatitis B core antigen (HBcAg).

Hepatitis B core antigen (HBcAg) is the nucleocapsid that encloses the viral DNA.

Corresponding antibodies to each of these antigens are Hepatitis B surface antibody (anti-HBs or

HBsAb), Hepatitis B envelope antibody (anti-HBe or HBeAb) and hepatitis B core IgM and IgG antibody (anti-HBc or HBcAb). The serological markers of Hepatitis B virus are HBsAg, anti-

HBs, anti-HBc (IgM and IgG), HBeAg, anti-HBe, and HBV DNA (Figure 1). They are useful for the diagnosis of the infection, its’ stage, and to determine the severity of the infection.26

Figure 1: Serologic response to acute hepatitis B Virus 27

20

VIROLOGIC CHARACTERISTICS

The HBV genome is about 3200 nucleotides long. The virus is organized into four overlapping open reading frames; S for the surface or envelope gene; C for the core gene; X for the X gene; and P for the polymerase gene. The S and C genes have upstream regions termed preS and preC.

The preS1 and preS2 represent two of the more immunogenic portions of HBsAg. The preC–C

(precore–core) region encodes hepatitis B core antigen (HBcAg) and hepatitis B e antigen

(HBeAg). The long P gene encodes the DNA polymerase, which also serves a reverse- transcriptase function. The X gene encodes two proteins that serve as transcriptional transactivators of viral replication.28

Figure 2: Schematic representation of the hepatitis B virus genome. 24

HBV serotypes have been identified based on peptide differences in the hepatitis B surface antigen (HBsAg). The common determinant “a” and two pairs of mutually exclusive 21 determinants, d/y and w/r, enable the distinction of four major subtypes: adr, adw, ayr, and ayw.29 Genotypic variations for HBV are named from A to J6 and have been associated with geographic distribution and with the progression of hepatic disease, with C being associated with more severe liver disease.30 Genotype A is seen worldwide, but is most prevalent in Northern

Europe, North America, and South Africa. Genotypes B and C are most common in Asia and the

Pacific. Genotype D is dominant in Africa, Europe, Mediterranean countries, and India.

Genotype E is mainly found in (West) Africa. Genotype F and H are most frequent in South and

Central America. Genotype G is reported in France, Germany, and the United States; and genotype H is commonly encountered in Central and South America. Genotype I has recently been reported in Vietnam and Laos. The newest HBV genotype, genotype J, has been identified in the Ryukyu Islands in Japan.31

PATHOGENESIS AND NATURAL HISTORY OF HBV INFECTION

HBV transmission is via vertical transmission (mother-to-child through infected birth canal), sexual contact, transfusion of blood and blood products, body fluids (urine, sweat, saliva, tears), and use of contaminated needles.32,33 Child to child transmission usually happens in household settings, child day care centers and in schools probably through contact of sores and small breaks in the skin or mucus membranes with blood or skin sore secretions.34,35 Perinatal transmission may occur intrapartum or, rarely, in utero. A Chinese study reported an intrauterine infection rate of 3.7% in a sample of 402 newborn infants of HBsAg-positive mothers. In their study, a high viral load and positivity of HBeAg were factors associated with an increased risk of transmission through this route.36 HBV can reach the fetus by crossing the placental barrier; and during its passage, HBV can infect and replicate in all types of placental cells before it reaches the fetus.

The percentage of infected cells has been shown to decrease from the maternal side to the fetal 22 side of the placenta. HBV may also reach the fetus following breach in the placental barrier in situations of prolonged threatened preterm labor or threatened abortion due to increased uterine contractions and possible mixing of maternal and fetal blood.36 The overall rate of transmission of HBV from an infected HBsAg-positive mother to her neonate during the perinatal period ranges from 5-90% in the absence of immunoprophylaxis. This risk depends on whether the mother is HBeAg positive; those who are HBeAg positive have a transmission rate of 70-90%, whereas those negative for HBeAg have a rate of transmission less than 10%.37

HBV is non cytopathic and causes a spectrum of liver diseases ranging from acute hepatitis

(including fulminant hepatic failure) to chronic hepatitis, cirrhosis, and hepatocellular carcinoma.18 The mechanism of injury after infection of the hepatocytes by HBV is not clearly established. Some evidence indicates that human leukocyte antigen (HLA) class I–restricted CD8 cells recognize HBV peptide fragments derived from intracellular processing and presentation on the hepatocyte surface by class I molecules. This process leads to direct cell killing by the CD8 cytotoxic T lymphocyte.38 Cytokines such as interleukin (IL)-2 and interferon gamma (IFN-g) are secreted and contribute to liver cell injury as well as to recovery from disease.

CLINICAL COURSE

The clinical course of an HBV infection is in four stages and is present in some form in all infected patients. The first stage is the immune tolerance phase characterized by an asymptomatic incubation period which varies from 4 to 26 weeks, the presence of HBeAg and large quantities of HBV DNA in serum signaling the period of active viral replication. The host is highly infectious, and an important source of horizontal infection in the family. During this stage, there is active viral replication with minimal or no hepatic inflammation, and the 23 aminotransferase levels are usually normal, or mildly elevated. Due to T cell immune tolerance to HBeAg and HBcAg, liver damage in this stage is absent or minimal despite high levels of

HBV DNA. When liver injury does occur in primary infection, alanine aminotransferase levels do not increase until after viral infection is well established, reflecting the time required to generate the T-cell–mediated immune response that triggers liver injury. In this stage also,

HBeAg and high HBV DNA levels in blood can persist for years after primary infection.39,40,41

Stage 2 is the inflammatory (Immune Active) stage and is characterized by acute disease lasting from a few weeks to 6 months. Levels of HBV DNA decline in stage 2. In patients with chronic disease, stage 2 may persist for 10 or more years, leading to cirrhosis and its complications.

Stage 3 is the low replication stage (Inactive Carrier State) and is marked by clearance of the bulk of virus-infected cells, and the end of active viral replication. In this stage, HBeAg disappears despite the presence of circulating HBsAg, and antibody to HBeAg becomes detectable. Aminotransferase levels become normal. A marked decrease in viral DNA is seen, although many patients remain positive for HBV DNA as detected by PCR. However, patients remain positive for HBsAg, presumably because of the integration of the S gene into the host’s hepatocyte genome.

In stage 4, HBsAg has been cleared and the presence of antibody to HBsAg signals the development of full immunity to the virus.39

The serologic markers associated with HBV infection are:

1. HBsAg—appears before the onset of symptoms and can be detected from 2 to 12 weeks after infection with HBV. It declines in most cases after 3 to 6 weeks. It is a lipoprotein polypeptide 24 which constitutes the external envelope of the HBV. The detection of HBsAg in human serum or plasma indicates an ongoing HBV infection.

2. HBeAg—presence in the serum indicates active viral replication and the individual is of high infectivity.

3. Anti-HBc IgM—becomes detectable in the serum shortly after the onset of symptoms, along with the elevation of serum transaminases and HBsAg and HBeAg. Anti-HBc IgM represents the first sign of an immune response after infection by the HBV and is replaced by anti-HBc IgG over ensuing months. It serves as a serologic marker for a present or past HBV infection, as well as potentially contaminated blood. Thus, anti-HBc is a serologic marker for contact with HBV.

4. Anti-HBe—becomes detectable in sera soon after the decline of HBeAg. It indicates the peak of acute disease and suggests that the disease is near remission, with titers declining after 20 weeks13. Seroconversion to anti-HBe correlates with reduced infectivity and in an acute infection; it suggests the progression towards infection resolution.42

5. Anti-HBs—its presence signifies immunity and complete resolution of infection.18,42

Figures 3, 4 and 5 below illustrate the serological profiles of acute and chronic HBV infections.

25

Figure 3: Acute HBV infection42

Figure 4: chronic HBV infection42 (HBeAg positive)

Figure 5: Chronic HBV infection42 (HBeAg negative)

90% to 95% of HBV infections in adults undergo spontaneous remission, with persistence of anti-HBc IgG and anti-HBs detectable in serum for a long period. In 3% of cases, active infection may persist with poor outcome such as cirrhosis, HCC, and increased risk of death while 5-10% of infection may become chronic. 26

Persistence of HBsAg in the blood for more than six months is considered to be chronic HBV infection.30 Chronic infection is characterized by the presence of HBsAg, HBeAg, HBV DNA and total anti-HBc in serum. HBsAg may be present in asymptomatic carriers without active viral replication and liver damage.18

The risk of becoming a chronic carrier is inversely proportional to age at infection. It ranges from 80%–90% among infants infected during the first year, 30-50% among children infected between one and five years and <5% among adults.21 Acute infections in neonates are often asymptomatic, but the majority become chronically infected.43,44 Vertical transmission of HBV is said to produce a high rate of persistent infection since infants cannot readily clear the infection.17

EPIDEMIOLOGY

High prevalence of hepatitis B virus (HBV) infection has been documented worldwide with estimated 350 million chronic carriers3 and four million acute clinical cases per year.45 WHO classified HBV endemicity according to the proportion of the adult population who are positive for hepatitis B surface antigen (HBsAg) into low (0-2%), medium (2-7%) and high endemicity

(≥8%)8. In North Western Europe, North America, and Australia, prevalence of chronic infection is less than 1% and sexual contact or needle sharing among injection-drug users are the main routes of transmission. The Mediterranean countries, Eastern and Southern Europe, the Middle

East, Japan, and part of South America are areas with intermediate HBV endemicity (prevalence of chronic infection 1-8%) and household, sexual and perinatal transmissions, as well as nosocomial infection are the major sources of infection.46 27

Sub-Saharan Africa, the Pacific and Asia47 are areas of HBV high endemicity with transmission mainly vertical (from an infected mother) or during early childhood46 and an estimated 45% of the world’s population live in these areas of high chronic HBV prevalence. In sub-Saharan

Africa, carrier rates range from 9-20%48 and most HBV infections acquired at childhood.45,46

The reason for this is not far-fetched as the risk factors for HBV infection, such as scarification marks, sharing of sharps, lack of HB vaccination, abound in these developing countries. More so, the health seeking behaviour of the people, low level of medical technology as well as lack of medical insurance impact on the prevalence in these developing countries as opposed to the developed countries with intermediate and low prevalence rates.

Other less frequent sources of infection include household contact, hemodialysis, and receipt of organs.49

Varying seroprevalence rates have been documented in Nigeria in different segments of the population.9,10,11,12 High prevalence rates have been documented by several studies in pregnant women.10,50,51,52,53 Earlier studies by Mbaawuaga et al52 in Makurdi in 2008 using ELISA test kit and Jatau et al50 in Kaduna in 2009 using a rapid diagnostic test kit reported prevalence rates of

11% and 13.3% respectively. Mbaawuaga et al52 stated that the high prevalence rate found in their study may be because of high prevalence of sexually transmitted infections in the area studied. Contrary to their findings later studies51,53 have documented lower prevalence rates in pregnant women. Onwuakor and co-workers51 had screened 350 antenatal women in Abia state in 2013 using a rapid test kit and documented a prevalence rate of 7.1% while Oluboyo et al,53 using ELISA test kit, reported 6% prevalence among 100 antenatal women in Anambra state in

2014. Both study areas are in the same geographic region thus, there may be overlap in the risk factors for HBV infection between the two areas. This slight decline in prevalence among 28 pregnant women may be due to improved awareness of HB infection; however, these findings still classify Nigeria as an endemic country for HBV infection. This emphasizes the need for routine screening for HBsAg in pregnancy in order to prevent vertical transmission of HBV.

Forbi et al9 reported a HBsAg prevalence of 17% among female sex workers in Nigeria. It is not surprising that prevalence is high in this group as sexual contact is a major route of transmission and most of these females may not use protection.

Amongst health care workers, different HBsAg prevalence rates have been reported. In 2003,

Ajayi and co-workers54 reported a prevalence rate of 4.3% amongst 420 health care workers in

Ido Ekiti. Of the positive subjects in their study, prevalence was highest among the ward attendants followed by nurses while no physician was found positive. In contrast, in AkwaIbom,

Ndako et al55 in 2014 reported a prevalence of 17% among 188 health care workers studied. The highest prevalence was among nurses (6.9%) followed by ward attendants (3.2%), while prevalence among physicians was 1.6%. The reason for these differences is unclear. Higher prevalence in health workers may be due to high risk of accidental needle-stick injuries and close proximity to infected blood and body fluids.56,57

A study58 in 2008 involving 150 students from a university in Uyo reported a seroprevalence of

HBV infection of 4.7%. This is contrary to the findings of a similar study59 in 2009 in Zaria involving 200 students of a university which documented a higher prevalence of HBsAg of

12.5%. Reason for this higher prevalence obtained in the study in Zaria was stated to be due to close personal contact as more than six students stay in a room in the hostel of the campus.

Additionally, one third of their study participants were reported to have no knowledge HBV infection. 29

Varying HBsAg seroprevalence rates have also been reported among prospective blood donors in

Nigeria; 20% in Benue state,60 5.9% in Oyo state,61 4.8% in Lagos state62 and 20.8% in Plateau state.63 Adekeye et al63 recruited 245 subjects and recorded a HBsAg prevalence rate of 20.8% with highest prevalence recorded among students. This high prevalence obtained was attributed to negative social behavior associated with the youth such as sexual activity with multiple partners, intravenous drug use and tattooing. Similarly, Alao et al60 recruited 2,500 subjects between 2006 and 2008 and reported an HBsAg seroprevalence rate of 20%. Reason for this high prevalence was stated to possibly be due to high prevalence rate of HIV in Benue state, and both

HIV and HBV share similar routes of transmission. In contrast to the findings of these studies, a lower prevalence rate of 5.9% and 4.8% were reported by Afolabi et al61 in 2010 and Adejare et al62 in 2011 respectively. The wide differences in the HBsAg seroprevalence rate among prospective blood donors in different parts of the country may be due to the differences in geographical locations, the period of time the studies were carried out, differences in sexual behavior, use of drugs, and immunization practices.62

Bukbuk et al64 in 2005 documented a high prevalence rate of 44.7% among 150 primary school children in Borno state using enzyme immunoassay. This contrasts with the prevalence of 9.7% reported by Ndako et al65 in primary school children in North central in 2010. Both studies were carried out in rural communities. While the study by Bukbuk et al64 was done just a year after introduction of HB vaccination into the Nigerian immunization schedule in 2004, that by Ndako et al65 was done 6 years post introduction of HB vaccination into the Nigerian immunization schedule and the role of HB vaccination may account for the difference in the prevalence rate between the two studies. These prevalence rates are however, high and may be attributable to shared risk factors such as scarification, tattooing, tribal marks which abound more in the rural 30 areas. More so, the health-seeking behaviour in rural communities is far different from the urban population with majority of rural dwellers patronizing traditional healers.66

Hepatitis B surface antigen prevalence has been found to be high among children with HIV. A retrospective study, by Ejeliogu et al67 between 2008 and 2012, of 452 HIV infected children aged 2 months to 15 years in Jos, Plateau State, documented a prevalence of 12.8%. The study participants had not been on antiretroviral therapy prior to HBsAg assay. This finding is higher than the 5.8% prevalence reported by Nwolisa et al13 in Owerri in 2012 among 139 HIV infected

Nigerian children aged 18 months to 17 years of which seventy-seven patients of their subjects were on antiretroviral (ARV) therapy. Assay for HBsAg in the study by Ejeliogu et al67 was with enzyme immunoassay whereas Nwolisa et al13 utilized a rapid diagnostic test kit. The effect of

ARV and possibly, the increased uptake of Hepatitis B vaccine may account for the differences in the prevalence rates between the two studies.

Among children admitted into the children emergency room of Benin Teaching Hospital a prevalence of 13.9% was reported by Sadoh et al.15 This is in contrast to the study by Uleanya et al68 which documented a prevalence of 4.3% among children seen at the out-patient clinic of

University of Nigeria Teaching Hospital, Enugu. Both studies had used ELISA to assay for

HBsAg. The difference in the prevalence may be due to the study population; Sadoh et al15 studied sick children on admission whereas Uleanya et al68 studied children with minor illnesses seen in the out-patient clinic.

In 2005, Emechebe et al12 studied 221 sickle cell anaemic children aged 6 months to 18 years in

Enugu and reported a prevalence rate of 8.1%. In contrast, a higher prevalence rate of 17.3% was reported by Jibrin et al69 among 300 SCA children aged 6 months to 15 years in Sokoto in 2014. 31

Both studies had evaluated similar risk factors for HBV infection such as transfusions and scarification marks and had used ELISA to assay for HBsAg. Both studies did not report the sensitivity of the kits used. Possibly, the difference in the sensitivity of the test kit used and, the geographical locations may have accounted for this wide disparity in the prevalence rates between the two studies. In addition, variation in the vaccination programs of the geographic areas may also have contributed to this difference.

Donbraye et al70 in 2008 in Osun, reported an overall prevalence of 13.9% among 144 children aged 21days to 13 years. In contrast, Uleanya et al68 had recruited 140 children aged 18 months to 15 years in Enugu in 2010 and reported a prevalence rate of 4.3%. Both studies were hospital- based and had utilized ELISA as a screening tool. Donbraye et al70 had stated their kit sensitivity to be 100% while that of Uleanya et al68 was not stated. Majority of the subjects in the work of

Uleanya et al68 had received HB vaccination while the vaccination status of the subjects of the study by Donbraye et al70 was not stated. The study by Donbraye et al70 was done 4 years post- introduction of HB vaccination into the Nigerian immunization schedule while for Uleanya et al,68 their study was done 6 years post-introduction of HB vaccination into the Nigerian immunization schedule These disparities may be attributable to possibly an improved uptake of

HB vaccination between 2008 and 2010, or to the difference in test kit sensitivity.

Agbede et al14 in 2007 in Ilorin, had recruited 70 children aged 1-5 years and their mothers and found a seroprevalence rate of 10% among the children. 57% of their positive subjects equally had their mothers’ positive. In contrast, Uleanya et al68 in their study in 2010 observed a prevalence of 2% in those aged 1-5 years. The seropositivity of their subjects’ mothers was not determined. Vertical transmission still plays a major role in the acquisition of HBV in childhood in endemic countries such as our country Nigeria. 32

Prevalence of HBsAg has been found to be lower in the vaccinated population than the unvaccinated.65,71,72 Among vaccinated children aged 1 – 4 years, Odusanya et al71 documented a prevalence of HBsAg of 1.3% compared to 4.6% in age- matched non-vaccinated control.

Similarly, Uleanya et al68 found zero prevalence in all vaccinated under-five children recruited in their study, and Ndako et al65 documented a prevalence of 2.2% and 7.5% in the vaccinated and unvaccinated primary school aged children respectively. This is expected as vaccination has been shown to be very effective in prevention of HBV. Contrary to their findings, Sadoh et al15 reported a prevalence of 15.4% among fully immunized children and 10.3% among those who had incomplete or no hepatitis B vaccination. They had concluded that the reason for this disparity could be due to the lower number of unvaccinated children compared to the vaccinated ones studied, or that those who claimed to be completely immunized may not have been immunized at all or were incompletely immunized.

Several studies have found prevalence to be higher with increasing age.64,65,68 In the study by

Uleanya et al,68 children aged 6 – 8 years had a higher prevalence rate. Similarly, Ndako et al65 studied children aged 4 – 17 years and noted higher prevalence in those above 7 years of age.

Horizontal transmission may account for this higher prevalence in those older than five years as most of them are either in schools already or visit day care centers.

Most studies have shown HBsAg prevalence to be higher among males than females.64,65,72,73,74

Ndako et al65 reported prevalence rate of 6.1% among males and 3.6% among the female children recruited in their study. Similar observation was reported by Angyo et al73 in Jos,

Nigeria, and Xiaofeng et al74 in China. The immunosuppressive effects of androgens on the immune system75 have been documented as the reason why males are more susceptible to bacterial, viral and parasitic infections than females. In contrast, both Donbraye et al70 and 33

Uleanya et al68 reported a higher prevalence of HBsAg among females in their study. The reason for this disparity is not obvious.

Childhood acquisition of infection is associated with 25% increased risk of death from HBV- related liver cancer or cirrhosis.45,76 The rate of chronicity is much higher among neonates and children.77 An Infant who acquires HBV perinatally has up to a 90% risk of developing HBV infection78 and approximately 10% of such infants suffer from chronic hepatitis B infection.79

RISK FACTORS

Risk factors associated with HBV infection include; blood transfusion, infants born to infected mothers, use of contaminated needle, intravenous drug abuse, ear piercing and tattooing, sexually active heterosexuals or homosexuals, infants/children in highly endemic areas, health care workers, haemodialysis patients, visitors to highly endemic regions,80 history of contact with someone with hepatitis,5 and positive family history of HBV infection.65,81 However, most studies in Nigeria found cultural practices such as ear piercing, scarifications and circumcision not to influence the transmission of the virus in children.10,11,12,73 The reason for this may be that health care providers now use new or sterilized sharp objects for clients. In addition, Odusanya et al71 noted in their study that blood transfusion did not increase the risk of HBV infection. The reason may be that blood banks routinely screen for HBV prior to transfusion.

Studies have documented hepatitis B virus infection to be associated with low socioeconomic status.12,81,15,68 Iman et al,81 in Egypt, documented a higher prevalence of 1.1% among children from low socioeconomic class compared to 0.4% in those from middle and upper socioeconomic classes. Higher prevalence among lower socioeconomic classes may be due to high level of poverty and unemployment, low-quality health care services, poor health behaviors, and weak 34 management of health systems in the public sector.82 Similarly, Emechebe et al12 reported

HBsAg prevalence rates of 6.5%, 7.8% and 9.5% among subjects from upper, middle and lower socioeconomic class respectively. However, these studies agreed that socioeconomic status is not a significant risk factor for HBsAg seropositivity possibly due to equal exposure to shared risk factors for HBV among the social classes.

Xiaofeng et al74 noted a lower prevalence of HBsAg among children born in hospital compared to those born in smaller township hospitals or at home. Infants born in hospitals are more likely to receive a birth dose of HBV vaccine than those born at home, and infants of those mothers found to be HbsAg positive may also be given HBIG. This may account for the lower prevalence in those born in the hospitals.

Different studies have evaluated the role of cesarean section in preventing HBV vertical transmission.83,84 A retrospective study of 546 children aged 1–7 years born to HBsAg positive mothers, 285 delivered by emergency caesarean section and 261 delivered vaginally, in the

People’s Republic of China showed a similar prevalence between the two groups. All the children had received both the hepatitis B vaccine and HBIG.83 In contrast, a meta-analysis of four randomized controlled trials that enrolled a total of 789 pregnant women showed that elective cesarean section done before labor or the rupture of membranes was associated with a lower rate of transmission (10.5%) compared with vaginal delivery (28%).84 However, the authors concluded that their finding should be interpreted with caution majorly due to diversity in HBIG administrations as some of the studies were done when HBV prophylaxis was not yet standard of care and majority of the children may not have received HBIG. Cesarean section may lower the risk of maternal to child transmission of HBV infection due to its minimization of the infant’s exposure to HBV-contaminated blood or fluid during delivery. Additionally, cesarean 35 section was often performed before the onset of uterine contraction, which may tear the placenta and result in microperfusion of maternal blood into the fetus.85

MALNUTRITION AND HBsAg POSITIVITY

Fewer studies have reviewed the effect of malnutrition on HBsAg seroprevalence. Iman et al81 found prevalence to be higher in normal weighted children than underweight children though this association was not found to be significant. They had studied 3,458 well-nourished children compared to 142 underweight children and this may have accounted for this finding.

Chronic infections and chronic liver diseases are known to lead to malnutrition through different mechanisms; Reduced calorie intake, malabsorption, elevation of inflammatory cytokines.86 In

Germany, Gerner and co-workers87 in studying growth abnormalities in children with chronic hepatitis b or c infection found affected children to have compromised height compared to non- affected children and this they attributed to high transaminase levels. Similarly, the study by

Tugba et al88 involving 43 children with a mean age of 10.81±3.23 years found a malnutrition rate of 25.6% in children with HBsAg positivity. They also noted that weight and height standard deviation scores of their study subjects decreased as alanine transaminase and aspartate transaminase levels (AST) increased while the body mass index decreased as AST and α-feto protein values increased.

CLINICAL FEATURES

Acute hepatitis B infection is self-limiting. Outcome may range from acute hepatitis (which may lead to cirrhosis), to fulminant hepatitis with massive hepatic necrosis, and an asymptomatic subclinical infection (With or without progression of the disease), or be a gateway to infection by hepatitis Delta virus.2 36

Features of acute infection in children may include fatigue, poor appetite, nausea, vomiting, diarrhea, abdominal pain, low-grade fever, jaundice, dark urine, and light stool color, liver tenderness, and possibly hepatomegaly or splenomegaly.89 Jaundice is present in 25% of cases.6

Chronic HBV infection may be asymptomatic (the HBV surface antigen carrier state), or present with features of cirrhosis or hepatocellular carcinoma or both. Some extrahepatic manifestations of HBV infection include serum sickness, polyarteritis nodosa, essential mixed cryoglobulinemia, membranous glomerulonephritis, and aplastic anemia.90

DIAGNOSIS OF HBV INFECTION

Diagnosis may be clinical, from symptoms and signs of the infection, or laboratory. Real-time

Polymerase Chain Reaction (PCR) technology, based on continuous quantitative monitoring during the exponential phase of the PCR reaction assays are the standard for direct determination of hepatitis B virus DNA.91 However, ELISAs (enzyme linked immunosorbent assays) are the most widely used HBsAg screening tests for screening large numbers of specimens on a daily basis, as is the case in blood transfusion services. ELISAs have specificity and sensitivity of

100%. The HBsAg ELISA Test kit uses polystyrene microwell strips pre-coated with monoclonal antibodies specific to HBsAg. The serum or plasma sample is added together with a second antibody, the HRP Conjugate, (horseradish peroxidase), and are allowed to react over a

10 minute incubation period. The enzyme-substrate reaction is terminated by the addition of sulfuric acid solution. The color change is measured spectrophotometrically. Only those wells containing HBsAg and antibody-conjugate will exhibit a change in color. The intensity of this color change is proportional to the concentration of HBsAg in the sample.47 37

Due to limitations such as high cost and time taking nature several simple, rapid screening tests have been developed including agglutination, immunofiltration (flow through) and immunochromatographic (lateral flow) membrane tests. For this study, rapid, immunochromatographic test kit was used which has been shown to have sensitivity ranging between 99-100% and specificity ranging between 99-99.4%.42,92,93 In its evaluation of performance of some commercially available rapid test kits for HBsAg assay, World Health

Organization42 documented sensitivity ranging between 95.5% and 99.4% with kit specificity of

99 - 100%. Maity et al92 in their comparism of ELISA and rapid test kits for diagnosis of Human

Immunodeficiency Virus, Hepatitis C virus and HBsAg found the performance of HBsAg rapid kits to be equally good as compared to ELISA with specificity of 100% for most of the kits evaluated. Similarly, Ansari et al94 evaluated 6 rapid diagnostic test kit against polymerase chain reaction (specificity and sensitivity of 100%) for the detection of HBsAg and reported sensitivity and specificity the of rapid test kits ranging between 98.3 – 99.2%.

The immunochromatographic strips are pre-coated with anti-hepatitis B surface antibodies (anti-

HBs) on the test line region. During the experiment, the serum migrates on the membrane chromatographically by capillary action and the labeled HBsAg – antibody dye conjugate binds to HBsAg in the serum forming an antibody-antigen complex. This complex binds to the immobilized antibody in the positive reaction zone to produce a burgundy color band when the concentration of HBsAg is above certain detection threshold. A positive specimen will produce two colour bands in both the test line and the control area whereas a negative specimen will produce a single distinct colour band in the control area (Figure 6). 38

Figure 6: Immunochromatographic test for HBsAg assay42

TREATMENT OF HBV INFECTION

Four drugs have been approved by the U.S. Food and Drug Administration for treatment of chronic hepatitis B; Lamivudine may be used starting at 3 years of age, Adefovir is labeled for those aged 12 years and older, and Entecavir for age 16 years and older. Recombinant interferon alpha (IFN-α) is approved for use in children as young as 12 months of age. No antiviral drugs are approved for treatment of children under the age of 1 year. Treatment is not usually required in this age group.95 IFN-α has immunomodulatory and antiviral effects and is given to children at a dose of 6 mU/m2, thrice weekly for 4-6months.46 Lamivudine, a cytosine analogue, acts as a nucleoside reverse transcriptase inhibitor and inhibits HBV replication.79 Adefovir and Entecavir are nucleotide analogue which inhibit viral polymerase.46

COMPLICATIONS OF HEPATITIS B VIRUS INFECTION

Hepatitis B virus is the leading cause of cirrhosis and primary liver cancer.96 Studies have documented causal relationship between HBV and hepatocellular carcinoma.80

A Kenyan study documented HbsAg seropositivity of 75% in hepatocellular carcinoma biopsies thus confirming strong associations of HBsAg with HCC.97

Hepatocellular carcinoma is the fifth most frequent cancer, and is said to be responsible for

300,000 to 500,000 deaths annually.98,99,100 Other complications of HBV infection include 39 fulminant hepatic failure, glomerulonephritis, polyarteritis nodosa, Gianotti-Crosti syndrome, aplastic anaemia and essential mixed cryoglobulinemia.90

PREVENTION

Protection can be passive or active. Passive protection is by the use of hepatitis B immune globulin (HBIG) which provides temporary protection of 3 to 6 months and is indicated only in certain post-exposure settings. Active protection is by the use of hepatitis B vaccine which provides long-term protection against HBV infection, and is recommended for both pre-exposure and post-exposure prophylaxis.101

The recommended series of 3 intramuscular doses (at birth, 6 weeks, and 14 weeks) of hepatitis

B vaccine induces a protective antibody response, with 90% to 95% efficacy in preventing HBV infection and its chronic sequelae.102 Administration of both hepatitis B immunoglobulin (HBIG) and hepatitis B vaccination to HBsAg-positive mothers within 12 hours of delivery has been shown to effectively reduce the risk of HBV perinatal transmission from 70-90% to approximately 5-15% than administration of HBIG alone.103,104 Anti-HBs ≥ 10 IU/L following vaccination is considered to be protective against HBV infection.105 This seroprotective value is attained by 95-100% of healthy children after receiving the three doses of HBV vaccine, and the protective antibodies are long-lasting persisting for at least 15-20 years.106,107

HBV vaccination has been available since 1982 and in 1992, the WHO recommended that childhood HBV vaccination be included in national immunization programs.4 Nigeria had included the hepatitis B vaccine in its schedule in 1995 but the vaccine only became widely available in 2004.108,109 The Nigerian hepatitis B immunization schedule for infants prescribes the receipt of a birth dose, a second dose at six weeks, a third dose at 10 weeks and a fourth dose 40 at 14 weeks of life. Initially, a monovalent HBV vaccine was utilized in providing three doses of

HBV immunization starting at birth,110 however, a pentavalent vaccine comprising DPT

(Diphtheria, Pertussis, Tetanus), HBV and HiB (Haemophilus influenza type b) was introduced to replace the trivalent DPT and monovalent HBV in 2012.111 The pentavalent vaccine is administered as three doses; at the age of six weeks, ten weeks and fourteen weeks.

Several studies globally have documented significant decline in the prevalence of HBsAg after the introduction of hepatitis B vaccination programs.74,112,113 Xiaofeng et al74 in China found reduced prevalence of HBsAg among all vaccinated children with the lowest prevalence of 0.3% in children aged 0-4 years as opposed to prevalence of 9.7% prior to the introduction of HBV vaccination program. This was explained by the possibility that children aged 0-4 might have more access to the hepatitis B vaccine and a better hepatitis B vaccine service than children aged five years and above. Goldstein et al112 documented similar decline in the incidence of acute hepatitis B in United States, particularly among persons in younger age group. Similarly, studies by Iman et al81 in Egypt and Odusanya et al71,72 in Nigeria both showed a lower prevalence in vaccinated children compared to unvaccinated children. The study by Odusanya et al72 in 2011 involved 449 vaccinated children aged 6-8 years and 373 unvaccinated age- matched controls and it found a prevalence rate of 11.8% in the unvaccinated controls and a prevalence of 2% in the vaccinated children. 61% of the vaccinated subjects were noted to have protective antibodies

> 10IU/ml.

Guidelines have been established for postexposure prophylaxis following occupational exposures to HBV. Recommendations include initiation of the hepatitis B vaccine series to any susceptible, unvaccinated person who sustains an occupational blood or body fluid exposure. HBIG may also 41 be given in addition. A booster dose only is administered if the patient had been previously vaccinated.113

Other preventive measures include compliance with universal precautions in the health care setting, 'safe sex' practices, and harm reduction programs for illicit drug users, and routine screening of blood donors.80

42

STUDY AIMS AND OBJECTIVES

AIM:

To determine the seroprevalence and sociodemographic characteristics of hepatitis B surface antigenaemia among children aged 0 to 59 months in Oshimili South LGA of Delta state.

OBJECTIVES:

1. To determine: the seroprevalence rate of hepatitis B surface antigenaemia among

children aged 0 – 59 months in Oshimili South LGA.

2. To determine: the risk factors for hepatitis B surface antigenaemia in the study

population.

3. To determine: any association between HBsAg positivity and sociodemographic

characteristics of the study population.

4. To ascertain: any association between HBsAg and malnutrition among the study

population.

5. To ascertain: any association between HBsAg and HB immunization status of the

subjects.

43

SUBJECTS AND METHODS

STUDY AREA

This study was carried out in four selected wards in Oshimili south local government area (LGA) of Delta state. Oshimili south LGA comprises Asaba town, the capital of Delta state, and the headquarters of the LGA, Oko, and Okwe. The LGA occupies an area of about 500 square kilometers, with an average tropical temperature of 90 degrees farinheight during the dry season and fertile rainfall of 6 cubic inches during the rainy season. The total population estimate by

2015 according to the 2006 national census figure is 198,635. Twenty percent (39,727) of this population are children aged less than 5years.114

Asaba town is situated along the bank of the River Niger, whose many tributaries make up the

Niger Delta. The Niger Bridge links Asaba with Onitsha in Anambra State. The natives are mainly Ibo speaking though other tribes such as Itsekiri, Urhobo, Isoko, Ijaw, Hausa, Yoruba,

Benin, and Kwale are also resident in the town. Most of the inhabitants are farmers and fishermen; others are traders and civil servants. Vegetation is rainforest. The local government area has 11 wards namely; Ogbele, Anala/Amakom, Okwe, Umuezei, Umuaji, Umuonaje,

Umuagu, Ugbomata, Cable point, Akwuebulu, and West-end.

STUDY DESIGN

This was a cross-sectional, descriptive study carried out between February and May 2015, and involved children aged 0 to 59 months drawn from four wards of Oshimili South LGA of Delta state. In order to have a uniform interval, and also, for ease of analysis of variables, the subjects were stratified into 5 groups according to age in months; 0-11 months, 12-23 months, 24-35 months, 36-47 months and 48-59 months. 44

DETERMINATION OF SAMPLE SIZE

The minimum sample size (n) for the study was calculated using the formula below, assuming a confidence interval of 95 (1.96) and degree of accuracy of 0.05.115 n = (Zi – α) 2 (P) (1- P) (where estimated population is greater than 10,000) d2 Where:

Zi – α = 1.96 (a standard normal deviate)

P = 0.10 (reported 10% prevalence rate of hepatitis B surface antigenemia in under-five children by Agbede et al).14

d = 0.05 (proportion of sampling error tolerated)

Substituting, the minimum sample size n= (1.96)2 x 0.1 x 0.9 (0.05)2 = 139 A drop out attrition rate of 10 was estimated giving a final sample size of 153.

ETHICAL ISSUES

Ethical clearance was obtained from the Ethics committee of Federal Medical Center Asaba,

Delta state (Appendix 6), and a written permission was also obtained from the local government chairman of OSLGA (Appendix 5). A written informed consent was obtained from parents/ guardian of each participant before enrolment. Confidentiality and anonymity of the subjects were maintained by matching each subject’s questionnaire to his/her blood sample by a number code.

45

SUBJECT SELECTION

Study Population

The subjects were children aged 0 to 59 months from communities of Oshimili south LGA of

Delta state, and whose parents consented to the study.

Inclusion criteria for the study subjects

• All children aged 0 to 59 months in the chosen communities

• Subjects whose caregivers gave consent

Exclusion criteria for the study subjects

• Children older than 59 months

• Failure to obtain consent

Sampling Method

The samples were determined by proportionate multistage probability sampling method. Of the

11 wards which make up Oshimili south LGA, 8 (Umuezei, Umuonaje, Umuaji, Umuagu,

Ugbomata, Cable point, Akwuebulu, West-end) are urban (densely populated area of more than

2000 residents/square mile and the residents do not depend on natural resource-based occupation), 1 (Okwe) is peri-urban (has a mix of urban and rural activities, i.e. some residents are farmers while others work in government parastatals within the ward) and 2 (Ogbele,

Anala/Amakom) are rural (low population density area of less than 2000 residents/square mile with residents relying on agriculture or natural resource-based occupation such as fishing). This information on the characterization of the wards into urban, peri-urban and rural, and the 46 criterion for such was obtained from Oshimili Local Government Headquarters. Thirty percent116 of the wards i.e. four wards were chosen, and by proportionate sampling, Cable point and

Umuonaje (urban), Okwe (peri-urban), and Anala/Amakom (rural) were selected by ballot.

Selection of Households

The estimated total number of households (HH) in each of the four chosen wards was obtained from Oshimili South Local Government headquarters. The estimated total number of under-five children (7708) in all the four selected wards and the number of under-five children in each age strata were also obtained from the LGA headquarters. (Table 1)

Table 1: Total number of households (HH) and under-five children in selected wards

WARDS HH U5 total 0-11mo 12-23mo 24-35mo 36-47mo 48-59mo

OKWE 550 1280 156 280 330 213 301

CABLE 822 2622 175 360 550 688 849

ANALA 766 1956 138 326 391 469 632

UMUONAJE 613 1850 123 249 376 460 642

TOTAL 2751 7708 592 1215 1647 1830 2424

Desired sample size (n1) for under-five (U5) children in each ward (Table 2)

This was calculated by; total U5 in each ward X Sample size (n)

All U5 population

 Okwe, n1 = 1280 X 153 = 25 7708 47

 Cable point, n1 = 2622 X 153 = 52 7708

 Anala/Amakom, n1 = 1956 X 153 = 39 7708

 Umuonaje, n1 = 1850 X 153 = 37 7708

Calculations of the sample fraction for each ward (NH) (Table 2)

This was calculated by NH = Total number of HH in chosen ward

Desired sample size (n1) for under-five (U5) children in each ward

 NH (Okwe) = 550 = 22 25

 NH (Cable point) = 822 = 16 52

 NH (Anala/Amakom) = 760 = 20 39

 NH (Umuonaje) = 613 = 17 37 Sampling interval for the households

This was calculated by; Total number of households in each ward

Desired household sample fraction (NH) for each ward

 Okwe = 550= 25 22 An assistant was asked to choose a random number between 1 and 25 as the starting point and subsequently, every 25th household from this starting point was selected.

 Cable point = 822 = 51 16 48

An assistant was asked to choose a random number between 1 and 51 as the starting point and subsequently, every 51st household from this starting point was selected.

 Anala/Amakom = 766 = 38 20 An assistant was asked to choose a random number between 1 and 38 as the starting point and subsequently, every 38th household from this starting point was selected.

 Umuonaje = 613 = 36 17 An assistant was asked to choose a random number between 1 and 36 as the starting point and subsequently, every 36th household from this starting point was selected.

Table II: Sampling fraction for households and under-five children in each ward

Ward Desired number of Sampling interval Desired number of

households for households under-five

Okwe 22 25 25

Cable point 16 51 52

Anala/Amakom 20 38 39

Umuonaje 17 36 37

Total 825 150 153

Sample size (n2) for each age cohort in each ward (Table III)

This was calculated using cohort population X desired U5 sample size (n1) Total U5 population

Example; for age cohort 0-11 months in Okwe:

156 X 25 = 3 1280

49

Table III: Sample size for each age cohort in each chosen ward

Ward 0-11mo 12-23mo 24-35mo 36-47mo 48-59mo Total

Okwe 3 6 6 4 6 25

Cable point 3 7 11 14 17 52

Anala/ Amakom 3 6 8 9 13 39

Umuonaje 2 5 8 9 13 37

Total 11 24 33 36 49 153

A questionnaire detailing age, sex, vaccination status, and family history of HBV infection, circumcision, blood transfusion history and other sociodemographic variables was given to consenting parents. Illiterate caregivers were interviewed face-face and their questionnaires completed by the researcher. Completed questionnaire was linked to a blood sample by a number.

Socioeconomic status was determined for each child using the father’s occupation and mother’s educational level as described by Olusanya et al.117 This method places families in upper, middle and lower class. This is done using two tables.

Table A grades the father's occupation into three categories while B grades the mother's academic attainment into three categories;

A

Scores Father’s occupation

1 Professionals, Top Civil Servants, Business Executives and Politicians

2 Middle level Bureaucrats, Technicians, Skilled Artisans and well to do traders.

3 Unskilled workers and those whose income is at or below the national minimum wage

50

B

Scores Mother’s educational attainment

0 Education up to University level

1 Secondary or Tertiary below University (e.g. College of Education, School of

Nursing)

2 No schooling or up to primary level only.

Adding scores from Table A and B gave the social class.

Those with scores of 1 or 2 were classified as upper socioeconomic class while those with score of 3 were classified as middle and those with scores of 4 or 5 as low socioeconomic class.

Anthropometry

The height of those above 36months was measured using SECA 206 mechanical measuring tape

(microtoise) placed against a wall. Each child was made to stand barefoot on the horizontal platform of the height metre rule. With their feet parallel, their heels, buttocks, shoulders and back of head were made to touch the upright part of the metre. The head was held comfortably erect in the same horizontal plane as the external auditory meatus and the arms hung at the sides in a natural manner. The head piece was lowered gently, crushing the hair and making contact with the top of the head. Seca 416 Infantometer with a precision of 1mm was used to measure the recumbent length of those aged below 36 months. Both instruments have a precision of

0.1cm. Measurements were read to the nearest centimeter.

The weight of those above 24 months was measured using a Salter weighing scale (precision of

0.1kg) placed on a flat surface and read to the nearest 0.1kg. Prior to use, the accuracy of the weighing scale was ensured by placing a dumbbell with a known weight on the scale and its reading zeroed. Each child was then asked to stand on it without foot wear and with only under 51 wear on. For those less than 24 months, My Weigh MBS 2010 Digital Baby Scale with a precision of 0.01kg was used. All instruments were checked after the 50th reading for any zero error and readjustments were made.

Nutritional status was assessed using weight-for-height Z–score standard according to WHO child growth standards. Children whose weight for height was ≤ 2 SD below the mean on the Z- score chart were taken to be malnourished while those whose weight for height was above 2 SD on the Z- score chart were taken to be well-nourished.

Pre-study and study visits

Prior to the final study, visits were made to the selected wards and households. In the first week, the first visit was undertaken to identify the study area and number the households. The households for the study were then selected according to the sampling interval calculated for each ward and these were marked. In the second week, selected households were visited and the research was explained to the caregivers and consent forms were given out. The total number of under5 children in each household was noted. In order to ensure that each age cohort was fairly represented, on getting to a selected household the study participants were randomly selected according to age stratum by balloting. A maximum of two under-5 children were chosen from a family. In the third week, a date was given for the selected under-five children from the chosen households, and whom their caregivers consented to the study, to be brought to the primary health care centre for recruitment into the study. Selected participants had the study questionnaire given to their caregivers. Signed consent forms were also retrieved. Blood samples were collected from the subjects and their respective mothers, and anthropometric measurements were taken. The study questionnaires were retrieved and cross-checked for completion. Further questions from caregivers were equally answered. Two house officers were trained and recruited 52 for blood sample collection and anthropometric measurements. A community health extension worker was also recruited and her duty was to facilitate the introduction and also cross-check incomplete questionnaires.

LABORATORY INVESTIGATION

Two milliliters of venous blood was collected from the subjects and their respective mothers into plain sample bottles and conveyed in ice packs to the microbiology laboratory of Federal

Medical Centre, Asaba, Delta State. Each child-mother blood sample pair was number coded and matched to the subjects’ questionnaire. The blood samples were immediately centrifuged at

2,500 rpm for 10mins, and serum aspirated. Serum samples and test kits were stored at 2oCelsius in a refrigerator until testing. Assays were carried out within 24 hours of blood sample collection. Each test kit was equally numbered to match the code on each blood sample. Only unexpired test kits were used, and within 5 minutes of opening. Hepatitis B surface Antigen detection was done by dipping the HBsAg test strip manufactured by CTK Biotech Inc. USA, into the serum specimen for at least 10 seconds and allowing 15 minutes for reaction. This test strip is a rapid lateral flow immunochromatographic assay for the qualitative detection of

Hepatitis B surface antigen in serum or plasma, with a relative sensitivity of 100% and specificity of 99.7% as quoted by the manufacturer. The test strip consists of: 1) a burgundy colored conjugate pad containing mouse anti-HBsAg antibody conjugated with colloidal gold

(HbsAg-Ab conjugates) and a control antibody conjugated with colloidal gold; 2) a nitrocellulose membrane containing a test line (T line) and a control line (C line). The T line is pre-coated with non-conjugated HBsAg antibody, and the C line is pre-coated with a control line antibody.

HBsAg, if present in the specimen, will bind to the HbsAg-Ab conjugates. The immunocomplex is then captured on the membrane by the pre-coated non-conjugated HBsAg antibody forming a 53 burgundy colored T line. Test was defined as positive if there was presence of a burgundy colored T line and a burgundy colored control (C line). Absence of the T line was interpreted as a negative result. (Figure 7)

Figure 7: Immunochromatographic test for HBsAg assay42

All samples and test kits were brought to room temperature prior to testing. Assay was performed by the researcher alone to remove observer error. For an HBsAg-positive blood sample, a repeat testing was done to be sure of accuracy.

QUALITY CONTROL

The CTK Biotech Inc. USA on-site rapid HBsAg test kit (Lot number RS 40438) with expiry date of 2017 was used for all the subjects. The test kits were stored in the refrigerator at 2oC until usage. Each sealed test kit pouch was not opened until the assay was ready to be conducted. All reagents were brought to room temperature before testing. The testing results were read within

15 minutes after a test strip was dipped into a serum sample. Unused test device was stored unopened at 2°C. Before an assay was done each day, the ability of the test strip to detect HBsAg was assessed by testing one strip from each pack with a serum sample that was known to be positive for HBsAg.

54

DATA MANAGEMENT

The data was entered into and analyzed on spreadsheets of the software package for social science (SPSS) version 23. Variables such as age, sex, were expressed in frequency tables.

An association between categorical variables was assessed using Chi-square test at 95% confidence interval with level of statistical significance set at p-value less than 0.05.

55

RESULTS

From February to May 2015, a total of 153 children aged 0 to 59 months from OSLGA were enrolled in the study.

Age, gender and socioeconomic class distribution of the study subjects

Out of the 153 subjects, 82 (53.6%) were males and 71 (46.4%) were females with a male: female ratio of 1.1: 1. The mean age was 35.73± 16.39 months and the median age was 38 months. 87 (56.9%) of the study subjects were from the middle class (social class 2) families. (Table IV)

Table IV: Age, gender and socioeconomic class distribution of the study subjects

Variable Gender n (%) Total n (%)

Male Female

Age group (months)

0 - 11 7 (63.6) 4 (36.4) 11 (100)

12 - 23 17 (70.8) 7 (29.2) 24 (100)

24 - 35 17 (51.5) 16 (48.5) 33 (100)

36 - 47 12 (34.3) 23 (65.7) 35 (100)

48 - 59 29 (58.0) 21 (42.0) 50 (100)

Social class

Upper 21 (50) 21 (50) 42 (100)

Middle 49 (56.3) 38 (43.7) 87 (100)

Lower 12 (50) 12 (50) 24 (100)

56

Prevalence of HBsAg among the study population

Only one of the study subjects was positive for HBsAg giving 0.7% prevalence in the study population (Figure 8).

Figure 8: Prevalence of HBsAg among the study population

57

Risk factors for HBsAg among the study subjects

Risk factors for hepatitis B surface antigenaemia identified in the positive subject were maternal history of HBV infection and a contact with a family member with jaundice. Other risk factors for hepatitis B surface antigenaemia identified among the study population such as sharing of sharps, circumcision history, past history of blood transfusion and surgical history were not found to influence the risk of HBsAg seropositivity among the study subjects (Table V). 58

Table V: Risk factors for HBsAg among the study subjects

Risk factors HBsAg test χ2 p value

Positive Negative

Contact with a family member with jaundice Yes 1 4 29.79 <0.001

No 0 148

Maternal history of HBV infection Yes 1 2 50.329 <0.001

No 0 150

Subjects’ HB vaccination status Yes 0 117 3.271 0.513

No 1 35

Past history of blood transfusion in the subject Yes 0 4 0.027 0.869

No 1 148

Past surgical history Yes 0 3 0.020 0.887

No 1 149

Circumcision Yes 1 76 0.994 0.391

No 0 76

Scarification marks Yes 0 8 0.056 0.814

No 1 144

Sharps sharing Yes 0 17 0.126 0.723

No 1 134

Injection sharing Yes 0 14 0.101 0.951

No 1 138

59

Prevalence of HBsAg in relation to mother and child status

Three out of the 153 mothers of the subjects were found to be HBsAg seropositive. Out of these three, only one mother-child pair was positive (33.3%), while two (66.7%) positive mothers had no affected children.

60

Places of delivery of the subjects and risk of HBsAg seropositivity

The positive subject was delivered in a hospital where as none of the subjects delivered at home and in a maternity home was positive. However, the place of delivery did not influence the risk of HBsAg seropositivity (Figure 9).

121 90

80 8 70

23 60

50 positive

40 Negative

30

20

10 1 0 0 0 Hospital Maternity Home

P-value = 0.880, χ2 = 0.256

Figure 9: Places of delivery of the subjects and risk of HBsAg seropositivity

61

Relationship between the sociodemographic characteristics of the study population and

HBsAg positivity

The one positive subject was a male neonate. The age of the subject, the gender and the socioeconomic status were not associated with the risk of HBsAg seropositivity (Table VI).

Table VI: Relationship between the sociodemographic characteristics of the study population and HBsAg positivity

Variable Number Number Number χ2 p-value

tested N HBsAg HBsAg

positive (%) negative (%)

Age group

0 -11 11 1 (9.1) 10 (90.9)

12 – 23 24 0 (0.0) 24 (100) 5.352 0.253

24 – 35 33 0 (0.0) 33 (100)

36 – 47 35 0 (0.0) 35 (100)

48 - 59 50 0 (0.0) 50 (100)

Gender

Male 82 1 (1.2) 81 (98.8) 0.872 0.351

Female 71 0 (0.0) 71 (100)

Social class

Upper class 42 0 (0.0) 42 (100)

Middle class 87 1 (1.1) 86 (98.9) 0.764 0.683

Lower class 24 0 (0.0) 24 (100) 62

Relationship between HBsAg and HB immunization status of the study population

The positive subject did not receive any hepatitis B vaccine. None of the vaccinated children tested positive to HBsAg. A sizeable number of the subjects missed the first dose of HB vaccine while a majority did not complete the HB vaccination series (Figure 10).

90 86

80

70

60

50

40 35 Frequency 30 positive 21 20 negative 10 1 5 0 0 5 0 0 0 none 1 dose 2 doses 3 doses 4 doses Number of HB vaccine dose

P-value = 0.081, χ2 = 3.046

Figure 10: HBsAg and HB immunization status of the study population

63

Hepatitis B vaccination rates among the study participants

Majority of the study participants who were eligible for particular doses of hepatitis B vaccination were noted to have missed the doses or did not complete the vaccination series

(Figure 11).

160 147

140

117 120 111

100 89 not eligible 80 63 60 eligible, received 41 36 40 eligible, not 20 received 5 0 1 1 1 0 dose 1 dose 2 dose 3 dose 4

Figure 11: Hepatitis B vaccination rates among the study participants

64

Relationship between nutritional status of the subjects and HBsAg seropositivity

Majority of the subjects were well-nourished. Among them, one was HBsAg positive. None of the malnourished subjects (36) was positive (Table VII).

Table VII: Relationship between nutritional status of the subjects and HBsAg seropositivity

Nutritional Number tested Number χ2 p-value status positive

Well-nourished 117 1

Malnourished 36 0 0.310 0.518

Total 153 1

65

DISCUSSION

The prevalence rate of HBsAg found in this work was 0.7%. This shows low endemicity of HBV in the four wards of OSLGA studied. This finding is comparable to studies in Ibadan, Nigeria,118

Egypt81 and China74 which reported prevalence rates of 0.5%, 0.11% and 1% respectively.

However, when compared to other Nigerian studies,12,15,64,68,70 this prevalence can be said to be very low. This is not surprising because 76% of the subjects in this study had at least 2 doses of

HB vaccine. This confirms earlier documentation by Van der Sande et al119 that 2 doses of HBV vaccination is enough to protect young children in hepatitis B endemic countries.

The 0.7% found in this study is similar to the 0.5% reported in 2012 by Okonko et al118 among

184 subjects aged 1-12 years in Ibadan using a rapid immunochromatographic test kit.

Additionally, the authors documented an immunization rate of 81.1%. This study also used a rapid immunochromatographic test kit to assay for HBsAg and recorded an immunization rate of

76%. This may explain the similarity in prevalence rate between these two studies. However, when compared to the 13.9% reported by both Donbraye et al70 and Sadoh et al15 in 2011 among

144 and 150 children respectively, the finding of this study is very low. Both studies had included children older than five years in whom horizontal transmission rate of HBV is higher,120 and Sadoh et al15 had recruited only sick children who are known to have more exposure to HBV risk factors relative to healthy children. The subjects recruited in this present study were apparently healthy under-five children. This difference in the subjects studied may explain the differences between the prevalence rates obtained between this study and the studies of

Donbraye et al70 and Sadoh et al15. 66

In this study, the risk factors that were identified were maternal history of HBV infection and maternal history of jaundice. The positive subject’s mother had jaundice at the point of enrolment and was also HBsAg positive. This positivity in the subject may be a vertical transmission from the mother especially given that the subject was a neonate. Ndako et al65 had similarly found that contact with a family member diagnosed of HBV contributed significantly to

HBsAg seropositivity in their study possibly due to increased risk of horizontal transmission.

Additionally, studies have shown that the risk of perinatal infection is 5–20 percent in infants born to HBsAg-positive mothers and 70–90 percent if the mother is also HBeAg-positive.121

Other risk factors such as surgeries, scarification marks, sharing of sharps and sharing of needles were not found to contribute to hepatitis b surface antigenaemia in this study and this agrees with several studies.11,12,72 However, this is at variance with the report of David et al122 who documented that sharing of sharp instruments or personal materials and sexual contact are major risk factors associated with HBsAg seropositivity. They had recruited subjects up to twenty years of age who were already sexually active, and sexual contact is a known risk factor for HBV infection. Blood transfusion as a risk factor in this study was not significantly related to HBV infection. This agrees with the report of Uleanya et al.68 This may be attributed to the fact that most blood banks now routinely screen blood and blood products for HBV as specified by the

Nigerian national blood policy which recommends that all donor blood for transfusion should be screened for HIV, Hepatitis B and C and Syphilis.123

The sociodemographic characteristics of the study population were not found to influence the risk of HBsAg seropositivity, though the only positive subject was a male neonate from the middle socioeconomic class. Age was not found to influence the risk of HBsAg seropositivity in this work. This agrees with several reports.12,68,70 Donbraye et al70 using children aged 21days to 67

13years reported that age was not significantly associated with HBsAg seropositivity. Similarly,

Emechebe et al12 reported the same observation among sickle cell anaemic children. This finding is at variance with most other studies involving children older than 5 years12,68 which had shown higher prevalence with increasing age, and this has been explained by the possibility of increased horizontal transmission as most of these children are either attending day care centre or schools.

This study has shown that the only seropositive subject was a male, though not statistically significant. Most studies14,73,15,72 have equally reported male predominance. In their study involving 70 under-five children, Agbede et al14 documented a higher prevalence among males.

Similarly, out of the 501 subjects studied in 1995, Angyo et al73 found more males affected than females. Generally, males are more susceptible to bacterial, viral and parasitic infections due to the immunosuppressive effects of androgens on the immune system.75

Socioeconomic class was not found to be associated with HBsAg seroposivity in this study. This agrees with the reports of Emechebe et al12 and Sadoh et al15 who documented comparable

HBsAg prevalence rates between children from higher, middle and lower socioeconomic classes.

This may be because of equal exposure to risk factors for HBV among the social classes. This, however, contrasts with the work in Egypt81 which reported a higher prevalence of HBV infection among children with low socioeconomic status. This may be because the health challenges in Egypt have been reported to disproportionately affect the rural poor.82 Due to poverty and lack of insurance, people with a lower socioeconomic status may not efficiently utilize health services like vaccination and health education. In addition, poor and crowded living conditions may facilitate horizontal transmission among the rural poor.124,125 68

The positive subject had missed the birth dose of HB vaccine even though in a vertically acquired HBV infection, one or more doses of the vaccine may not prevent the disease unless

HBIG is administered concurrently with the HB vaccine within 12 hours of delivery. None of the vaccinated children was positive for the surface antigen in this study. Odusanya et al72 had similarly documented a very low prevalence rate of 1.3% among vaccinated children aged 1-

4years. Various authors68,71,72 had explained that HB vaccination is effective in preventing HBV infection. However, this finding contrasts with that of Sadoh et al15 who reported a higher prevalence rate of 15.4% among vaccinated children. The authors had concluded that this finding could be due to fewer numbers of the unvaccinated recruited or that those who claimed to be completely immunized may not have been immunized at all or were incompletely immunized. In addition, loss of vaccine potency, from possible poor storage given the erratic power supply nationwide, may also be a contributory factor. It is noteworthy that a number of the subjects (36) did not receive the birth dose of the HB vaccine while a majority (147) did not receive the fourth dose needed to complete the vaccination series. A study126 in a rural community in Nigeria reported that the reasons proffered by caregivers for failure to immunize their children were non availability of vaccines, the mother being too busy, Place of immunization too far, unaware of need for immunization, unaware of need to return for 2nd or 3rd dose, postponed until another time amongst others. The reasons for failure to immunize or to complete the vaccination series were not explored in this study.

Place of delivery did not contribute to seropositivity in this study though the one positive subject was delivered in a hospital. This finding is consistent with that of Iman et al81 who reported that place of delivery was not associated with HBsAg seropositivity. It was also noted in this study that maternal screening for HBsAg during antenatal was low as 49.97% of them were not 69 screened for HBV infection during pregnancy. It has been shown that administration of HB vaccine and HBIG to a neonate, delivered to an HBsAg positive mother, within 12 hours of delivery helps to prevent vertical transmission by up to 90 - 95%. This emphasizes the need for continued medical education for health workers and for government to make adequate budgetary allocation for the provision of the all-important HBIG for prevention of vertical transmission of

HBV infection.

This work did not show any relationship between malnutrition and HBsAg seropositivity. This contrasts with the findings of Gerner et al87 and Tugba et al.88 Both studies had documented compromised nutritional status among children with chronic HB infection. The reason for the difference in this finding may be attributable to the fact that while the above authors had evaluated the growth pattern of their subjects monitored over a long time, this present study only did on the point assessment of the nutritional status of the subjects, and thus, there is need for long term follow up of this subject.

This study has shown that the prevalence of HBsAg among under-five children in OSLGA of

Delta state is low, and sociodemographic characteristics of the study population did not influence the risk of seropositivity.

70

CONCLUSION

A very low prevalence of 0.7% of HBsAg was observed in the under-five children in OSLGA of

Delta state during the study period.

Risk factors for HBsAg positivity identified in the positive subject, though not significant, were maternal history of HBV infection and a maternal history of jaundice.

Other risk factors for HBV infection such as blood transfusion, scarification marks, sharing of sharps, surgeries, were not associated with the risk of seropositivity in the study population.

Malnutrition was not found to influence the risk of HBsAg seropositivity in this study.

Majority of the subjects were unimmunized against HBV or failed to complete the vaccination series; possibly due to missed opportunities or failure on the caregiver’s part.

Maternal screening for HBsAg in pregnancy in OSLGA was noted to be poor

71

RECOMMENDATION

It is thus recommended that hepatitis B screening in pregnancy be reinforced.

Immunization programs in the under-five children in OSLGA should be strengthened as some children did not receive any HB vaccination dose while some others did not complete the vaccination series.

The government should also make provisions for ready availability of HBIG, and at affordable costs. Also, continued medical education for health workers, and public health education should be reinforced to ensure that HB vaccination and HBIG are given as at when due.

72

LINES OF FUTURE RESEARCH

Data from this study may be used to design a larger study using a more sensitive diagnostic method such as PCR.

The effect of nutritional status on the prevalence of hepatitis B surface antigenaemia in under – five children can be undertaken.

73

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APPENDIX 1

MAP OF OSHIMILI SOUTH LOCAL GOVERNMENT AREA OF DELTA STATE

89

APPENDIX 2

Informed consent for study on the prevalence and sociodemographic variables of hepatitis b surface Antigenaemia in children aged 0 to 59months in Oshimili South local government area of Delta state.

Date

Dear Parent or Guardian:

I am a Dr Nwafor Ifeoma in the department of paediatrics, F.M.C, Asaba. I am conducting a research project on prevalence and sociodemographic variables of hepatitis B surface Antigenaemia in children aged 0 to 59 months. This study essentially is to screen your child for hepatitis B virus infection since if undetected; it carries a risk of becoming chronic, and may lead to liver disease in adult life. I request permission for your child to participate.

You will be given a questionnaire to enable me get necessary information on your child. A small amount of blood will be taken from your child. Since hepatitis B infection may be transmitted from mother to child, a small amount of blood will also be taken from the mother for hepatitis B test. Also, your child’s height and weight will be measured.

Only I (the researcher) will have access to information about your child. At the conclusion of the study, a child’s result will be disclosed to interested parents.

Participation in this study is voluntary. Your child’s participation in this study will not lead to the loss of any benefits to which he or she is otherwise entitled. You are free to end the participation at any time.

Your identity and that of your child/ward will be concealed and all information obtained in this study will remain confidential.

Should you have any questions or desire further information, please call me or email me at 08069270458 or [email protected].

Signed forms will be collected on the day of the actual study.

Sincerely

Dr Nwafor Ifeoma

90

APPENDIX 3

CONSENT FROM

I have been asked to give consent for my daughter/son to participate in this research study. I have read the foregoing information, or it has been read to me. I have had the opportunity to ask questions about it and any questions that I have asked have been answered to my satisfaction. I consent voluntarily for my child to participate as a participant in this study.

I will get a copy of this consent form now and can get information on results of the study later if I wish.

Initials of Parent or Guardian ______

Signature of Parent of Guardian______

Phone Number

Date ______

Name of Researcher______

Signature of Researcher______

Date ______

Statement by the researcher/person taking consent

I have accurately read out the information sheet to the parent of the potential participant, and to the best of my ability made sure that the person understands that the following will be done:

1. A questionnaire will be given and returned after filling.

2. A small amount of blood sample will be taken from the participant.

3. Child’s height and weight will be measured.

I confirm that the parent was given an opportunity to ask questions about the study, and all the questions asked by him/her have been answered correctly and to the best of my ability. I confirm that the individual has not been coerced into giving consent, and the consent has been given freely and voluntarily. 91

A copy of this Informed Consent Form has been provided to the parent or guardian of the participant

Name of Researcher ______

92

APPENDIX 4

PROFORMA DESIGN STUDY NUMBER

1. Date of birth ………………….Age…………….. 2. Sex: Male/Female 3. Tribe 4. Religion: Christianity/Islam/ Other 5. Place of residence………………………………….. 6. Mother’s level of education (tick) a. No formal education………. b. Primary education……… c. Secondary education……… d. Tertiary education………. 7. Father’s level of education a. No formal education………. b. Primary education………. c. Secondary education………. d. Tertiary education………. 8. Mother’s occupation…………………………………………………………………….. 9. Father’s occupation………………………......

10. Delivery place (tick) Home Hospital Maternity home 11. Mode of delivery (tick) a. Vaginal…………… b. Caesarean section………… 13. Did the mother receive Hepatitis B Vaccine? Yes/ No. How many doses if yes? …………… 14. How many times has your child received Hepatitis B Vaccine…………… 15. Has your child received blood transfusion? Yes/ No. How many times if yes? ……………… 16. Has your child had a surgical operation? Yes/ No 17. Does your child have traditional or scarification marks on any part of the body? Yes/ No 18. Has your child been circumcised? Yes/ No. At what facility was it done? ………………….. 19. Does your child use the same razor blade or hair clipper with other children? Yes/ No 20. Has your child received drug injections before? Yes/ No 21. Have you observed the same injection needle being used for your child and other children? Yes/ No 22. Is there anyone in the family who has had yellowness of the eyes and who had contact with your child? Yes/ No 23. Has the mother ever been diagnosed with hepatitis infection in the past? Yes/ No 93

Anthropometry Weight (kg)

Height/Length (cm)

Subject’s test result for hepatitis B surface antigen Positive

Negative

Mother’s test result for hepatitis B surface antigen Positive

Negative

94

95