This electronic thesis or dissertation has been downloaded from Explore Bristol Research, http://research-information.bristol.ac.uk Author: Weka, Rebecca Title: Helminth parasites of pigs and humans in North Central Nigeria, with a particular focus on Taenia solium General rights Access to the thesis is subject to the Creative Commons Attribution - NonCommercial-No Derivatives 4.0 International Public License. A copy of this may be found at https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode This license sets out your rights and the restrictions that apply to your access to the thesis so it is important you read this before proceeding. Take down policy Some pages of this thesis may have been removed for copyright restrictions prior to having it been deposited in Explore Bristol Research. 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HELMINTH PARASITES OF PIGS AND HUMANS IN NORTH CENTRAL NIGERIA, WITH A PARTICULAR FOCUS ON TAENIA SOLIUM A DISSERTATION SUBMITTED TO THE UNIVERSITY OF BRISTOL IN ACCORDANCE WITH THEREQUIREMENTS OF THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE FACULTY OF SCIENCE REBECCA PAUL WEKA 1 ABSTRACT The pork tapeworm Taenia solium causes neuro-cysticercosis, a parasitic zoonosis that is becoming increasingly important globally as a re-emerging disease and is typically associated with poor marginalized people in low-income countries. Various gastrointestinal parasites of pigs also present threats to human health and pig production in these countries. The study aimed to: (i) Survey existing knowledge on T. solium cysticercosis in West Africa; (ii) Determine the gastrointestinal parasites present in north central Nigeria among pigs and pig farmers, and improve understanding of risk factors for infection; (iii) Study the epidemiology of T. solium cysticercosis in pigs and humans commercial antibody-detecting enzyme-linked immune-assays (ELISAs) using crude antigen and electro-transfer blot and elucidate significant risk factors and practices associated with infection. A cross sectional survey was conducted in three pig producing states in north central Nigeria, from March 2012 to November 2013. A total of 767 and 510 faecal samples were collected from pigs, respectively before and one year after anthelmintic treatment. Blood samples from 556 pigs and 1266 humans were serologically screened for evidence of T. solium infection. Questionnaires on pig management, human behaviour and socio-demographic factors were completed to provide information on risk factors for infection. Coprological examination of the 767 pigs before and 510 after interventions indicated that 78 % and 49 %, respectively, excreted parasite eggs, and 9 parasite taxa were observed. Significant predictors of gastrointestinal parasite infection in pigs were management practices and type of feed given to pigs. Most farmers practiced a semi intensive system of management, under which the pigs find most of their food through scavenging and in the process become exposed to parasite eggs they pick up while grazing on the fields. The majority of the feed offered to pigs was kitchen waste and concentrates containing lots of fibre, favouring the development of Oesophagostomum spp. Of the 754 and 512 human faecal samples examined before and after the intervention, 8 different types of parasite ova, with a prevalence of 27 % and 15 % was obtained, respectively. Out of the 556 serum samples screened by crude antigen, 51 (9.2 %) of pigs were seropositive to porcine cysticercosis. There was a significant relationship between porcine cysticercosis and the month pigs were sampled (April and October) and the age group (5-8 months). Serum from 47 of the ELISA-positive pigs was tested by electro-transfer blot (EITB), of which 4 (8.5%) showed the presence of a band of 6 kDa, indicating active cysticercosis. Out of the 1266 human serum samples screened for T. solium antibodies using crude antigen, none were seropositive; and none of 24 samples screened by EITB, therefore no cases of active cysticercosis were identified. Results of this study indicate that conditions for transmission of gastrointestinal helminths and porcine cysticercosis are present in the study area and larger, more detailed studies should be carried out in order to underpin holistic control strategies to reduce economic loss to the farmers and the risk of zoonotic disease. 2 DECLARATION I declare that the work in this dissertation was carried out in accordance with the Regulations of the University of Bristol. This work is original except where references were cited and no part of the dissertation has been submitted for any academic award. Rebecca Paul Weka October 2019 3 ACKNOWLEDGEMENTS I wish to express my gratitude to Dr Eric Morgan for his supervision and guidance throughout the course of this work. I will like to appreciate Professor Richard Wall for his comments. I sincerely appreciate my husband Mr. Paul Weka and my children for all the support and encuragementI received from them. Thanks for always being there for me I wish to thank my mother and my siblings for every support I received from them. I sincerely wish to thank my friends whom are too numerous to mention for their advice and checking on my family in my absence. I will like to thank Dr Ifende,Dr Rimfa ,Dr Joshua Kamani and Professor Ikeh for every support rendered to me and words of advice. And I will not forget you Dr Luka Pam for all the encouragement given to me. I want to express my sincere gratitude to NVRI Vom Plateau state Nigeria for permitting me to go for studies. 4 TABLE OF CONTENTS Chapter 1: Overview of Taenia solium cysticercosis in West Africa 1.1 Introduction …………………………………………………………….. 1 1.2 Life cycle and disease ………………………………………………….. 2 1.2.1 Clinical signs in pigs ……………………………………… 4 1.2.2 Disease in humans ………………………………………… 4 1.3 Diagnosis ……………………………………………………………… 7 1.3.1 Diagnosis of porcine cysticercosis ………………………... 7 1.3.2 Diagnosis in humans ………………………………………. 7 1.4 Current status of Taenia solium infections in West Africa …………… 9 1.4.1 Human taeniasis and NCC ……………………………… 9 1.4.2 Porcine cysticercosis ……………………………………… 12 1.4.3 Economic burden of human disease ………………………. 14 1.4.4 Economic impacts of porcine cysticercosis ……………… 14 1.5 Risk factors for transmission in West Africa …………………………. 14 1.6 Treatment of Taenia solium infections ……………………………….. 17 1.7 Control ………………………………………………………………... 20 1.8 Conclusions …………………………………………………………... 27 1.9 Aims of the study …………………………………………………….. 28 5 Chapter 2: Gastrointestinal parasites of pigs under different systems of management in North Central Nigeria 2.1 Introduction ………………………………………………………….... 33 2.1.1 Economic significance of parasites in pigs in the study area 33 2.1.2 Pig parasites and management in Nigeria ………………… 34 2.2 Aims …………………………………………………………………... 36 2.3 Materials and methods ………………………………………………... 36 2.3.1 Study area …………………………………………………. 36 2.3.2 Study design, sample collection and parasite detection ……40 2.3.3 Questionnaire survey of socio-demographic information and pig husbandry practices ……………………………………………. 43 2.3.4 Ethical clearance …………………………………………. 43 2.3.5 Statistical analysis …………………………………………..44 2.4 Results ………………………………………………………………… 46 2.4.1 Animal population characteristics ........................................ 46 2.4.2 Parasite prevalence before intervention ……………………. 52 2.4.3 Prevalence of parasites before and after intervention ……… 59 2.5 Discussion ……………………………………………………………… 61 2.5.1 Gastrointestinal parasite taxa found and their regional context 61 2.5.2 Prevalence and risk factors ………………………………….. 69 2.6 Conclusions ……………………………………………………………… 75 Chapter 3: Risk factors for transmission of gastrointestinal parasites of humans in pig farming communities of North Central Nigeria 3.1 Introduction ……………………………………………………………… 78 6 3.1.1 Economic significance of gastro-intestinal parasites in humans 78 3.1.2 Prevalence among human populations in Nigeria ……………..80 3.2 Aims ……………………………………………………………………….. 83 3.3 Materials and methods …………………………………………………….. 84 3.4 Results …………………………………………………………………… 86 3.4.1 Participants enrolled in the study …………………………….. 86 3.4.2 Socio demographic data ……………………………………… 88 3.4.3 Prevalence before and after the intervention …………………. 91 3.4.4 Predictors of infection in humans before intervention ……… 92 3.4.5 Significant predictors of infection after treatment …………. 98 3.5 Discussion ……………………………………………………………… 101 3.5.1 Prevalence of gastrointestinal parasites and effects of intervention ………………………………………………………………………101 3.5.2 Risk factors for gastrointestinal parasite infection ………… 103 3.6 Conclusions ……………………………………………………………… 108 Chapter 4: Epidemiology of porcine cysticercosis in North Central Nigeria 4.1 Introduction ………………………………………………………………. 111 4.2 Aims ……………………………………………………………………… 113 4.3 Materials and methods …………………………………………………… 113 4.3.1 Study design and field survey …………………………….. 113 4.3.2 Ethical clearance …………………………………………….