A Baseline Study of Rural Bancroftian Filariasis in Southern India
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RURAL BANCROFTIAN FILARIASIS IN INDIA A BASELINE STUDY OF RURAL BANCROFTIAN FILARIASIS IN SOUTHERN INDIA U Suryanarayana Murty1, B Praveen1, DVR Satya Kumar1, K Sriram1, K Madhusudhan Rao1 and KSK Sai2 1Bioinformatics Group, Biology Division, Indian Institute of Chemical Technology, Hyderabad, Andhra Pradesh; 2Ministry of Communication and Information Technology, Government of India, New Delhi, India Abstract. Night mass blood surveys were carried out for parasitological evidence of Bancroftian filariasis in 45 rural areas belonging to 9 National Filaria Control Program (NFCP) zones of East Godavari and West Godavari districts of Andhra Pradesh, India during the period 1998 to 2001. Mf prevalence range between 2.9 to 10.2%, and mf intensities in 20 mm3 blood samples ranged from 1-281. The present study explains the trend of microfilaria dynamics in the rural population, where mass drug delivery has been implemented since 1997, and anti-larivicidal and adulticidal control measures have not been adopted. INTRODUCTION mentation of mass drug delivery (MDD) in highly endemic filarial areas of India. Hence, the present Even at the completion of several decades study was taken up to understand the dynamics of fighting against filariasis, it has remained an of microfilariae in rural communities in Andhra intractable public health problem (Wayne, 2002) Pradesh, where anti-vectoral control measures and identified as the second leading cause of dis- have not been adopted. ability (WHO, 1995). India alone contributes 40% of the global disease burden (Michael et al, 1996) MATERIALS AND METHODS and annual economic loss of nearly 1.5 billion US dollars every year (Ottesen et al, 1997). Study area Bancroftian filariasis is prevalent in both urban Geography and climate. The two Godavari and rural areas. It is caused by the nematode worm districts lie between the 16.25º-18.10º latitude Wuchereria bancrofti transmitted by female Culex North and 80.75º-82.65º longitude East on the quinquefasciatus. The major prevalence is among Bay of Bengal coast of peninsular India. These the poorer sections of society and it is an impor- two districts are abundant in natural resources, tant cause of poverty (Ramaiah et al, 2000). Ru- such as monsoon rain, fertile soil, perennial riv- ral filariasis has not received mosquito control ers, for systematic crop production. These two operations (Rajagopalan et al, 1981). The exist- districts are separated by the river Godavari. ing National Filaria Control Programs (NFCP) The climate is characterized by a humid sum- caters for only 11% of the population who live in mer (46º-20ºC), winter (32º-11ºC), and mon- the endemic foci (Sharma et al, 1995) and its con- soon (June-December). The south-west mon- trol measures cannot be adopted in rural areas be- soon plays a major role in determining the cli- cause of operational problems and cost consider- mate of the state. The northeast monsoon is ations (Ramaiah et al, 1989). The 50th World responsible for about one-third of the total rain- Health Assembly (1997) recommended imple- fall in Andhra Pradesh. There was no proper wastewater disposal system in any of the study Correspondence: Dr U Suryanarayana Murty, Biology villages, and often cesspools of stagnated wa- Division, Indian Institute of Chemical Technology ter, which can facilitate favorable conditions (CSIR), Tarnaka, Hyderabad-500 007, Andhra Pradesh, for the breeding of Culex quinquefasciatus, the India. vector of Bancroftian filariasis. Tel: 91-40-719 3134; Fax: 91-40-719 3227 E-mail: [email protected]; Murty_usn@yahoo. Selection of villages. Stratified random sam- com pling methodology was applied for selection of Vol 35 No. 3 September 2004 583 SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH Table 1 Sex and NFCP unit prevalence of microfilaremia (mf) in East (E) and West (W) Godavari districts of Andhra Pradesh (AP). Name of unit Total no of persons examined Total mf carriers Total mf rate (%) Male Female Total Male Female Total Male Female Total Amalapuram 455 530 985 19 32 51 4.17 6.03 5.17 R.C. Puram 478 525 1,030 42 28 70 8.78 5.33 6.97 Mandapeta 490 520 1,010 14 16 30 2.85 3.07 2.97 Kakinada 349 457 806 15 10 25 4.29 2.18 3.10 Peddapuram 556 479 1,025 56 48 104 10.00 10.02 10.14 Pithapuram 461 557 1,018 42 44 86 9.11 7.89 8.44 Rajahmundry 474 578 1,052 21 21 42 4.43 3.63 3.99 Tanuku 503 527 1,030 52 34 86 10.33 6.45 8.34 Palakollu 479 536 1,015 32 42 74 6.68 7.83 7.29 Total 4,245 4,709 8,971 293 275 568 6.9 5.83 6.33 the villages for the entire study area. The study Table 2 was conducted from October 1999 to March Summary of the filariasis survey of <20-year- 2001 in 1,804 households of 45 rural areas in old children. East and West Godavari districts, Andhra Pradesh. Previous researchers have stated that Total villages covered 45 the study regions are endemic for filariasis Smears collected from children 3,483 (Raghavan, 1957). Number of cases recorded 215 Microfilaria rate 6.17% Parasitological studies Number of boys with mf 102 A total of 8954 blood smears was collected Microfilaria rate 2.92% from the 1,804 households of the two districts in Number of girls with mf 91 Andhra Pradesh. About 20 mm3 of blood was Microfilaria rate 2.61% collected, between 2000 and 2300 hours, from each person by finger-prick method and a smear prepared on clean glass slides (Sasa, 1976). Next morning, the blood smears were processed - they in the 9 NFCP zones is shown in Fig 1. The preva- were dehemoglobinized in tap water, fixed in lence of microfilaremia steadily increased from methanol, stained in JSB II solution, and allowed the 0-5 age group. The prevalence of microfila- to dry. The dried smears were examined for mf remia showed a rise and was stable at 11-20 and using a compound microscope. The mf status and 21-30 age groups. Then, there was a decrease the number of mf for positive individuals were among 31-40 and 41-50 age groups. The highest recorded. mf prevalence was recorded for the 51-60 age group, due to the available sample size, which RESULTS was relatively lower than the other age groups. Microfilarial densities of the two districts are rep- In East Godavari district, the microfilaremia resented in Fig 2, and the mf counts ranged from (mf) rate ranged from 2.97 to 10.14% among 7 1-281 for the entire study. The calculation of mf NFCP zones. In West Godavari district the mf rates density is generally expressed by the number of of the Tanuku and Pallakollu units were found to mf per unit volume of blood sample. Table 2 ex- be 7.29 and 8.34% respectively (Table 1). plains the dynamics of the pathogen in the chil- The age-group prevalence of microfilaremia dren. The mf rates ranged from 2.61 to 2.92%. 584 Vol 35 No. 3 September 2004 RURAL BANCROFTIAN FILARIASIS IN INDIA 100 microfilaria rates were observed 90 80 among the male community, except in 70 Mandapeta, and Kakinada. This was 60 50 because of the harvest season, when 40 most male workers spent considerable 30 time in the field. It is evident from Mf Prevalence 20 10 earlier studies that in general, the male 0 population has shown a higher mf 0 to 5 6 to 10 11 to 20 21 to30 31 to 40 41 to 50 51 to 60 Above 60 prevalence than females, due to Age Group greater exposure to mosquito bites. Amalapuram Kakinada Rajahmundry Hydrocele is the predominant sign of Mandapeta R.C.Puram Peddapuram Pithapuram Palakollu Tanuku filariasis in endemic areas of Wuchere- Fig 1–Mf prevalence by age in the nine NFCP units of East and West ria bancrofti in the Indian Sub-conti- Godavari districts of AP. nent, Southeast Asia, Africa, and Latin America (Beye and Gurian, 1960; 25 Dondero et al, 1976; Hawking, 1976; Sasa, 1976; Rajagopalan et al, 1981; 20 Ramaiah 1989; Estamble et al, 1994; Simonsen, 1995). 15 Microfilaria infection has steadily increased along with the age 10 group, and maximum prevalence was observed in the 11-30 age group, Frequency distribution (%) 5 which was similar to previous studies (Rao et al, 1980). We recorded the 0 highest mf rates in the >60 year group, 1234567891011- 21- 51- >100 Mf counts 20 50 100 which is quite uncommon. This dem- % of frequency distribution of EGDT % of frequency distribution of wGDT onstrates the persistence of parasite load in the community due to lack of Fig 2–Frequency distribution of mf counts from the rural commu- nities of Andhra Pradesh, India. awareness of the disease. The mf counts are considered an important parameter to assess the DISCUSSION transmission level in the host population (Vanamail et al, 1990) and the mf intensity is the Most of the rural areas, except Mandapeta most useful tool for understanding the transmis- (2.99%), Kakinada (3.1%), and Rajahmundry sion dynamics in filarial endemic areas (Hariston (3.99%), have shown alarming rates (above 5%) et al, 1968). The highest microfilaria count, 281, of the filarial infection. The lowest mf rates were was recorded from a 10-year-old boy from due to the impact of mass drug delivery and ac- Pithapuram, East Godavari District, followed by tive participation of the locally related control 194 from a 13-year-old girl from Tanuku, West units, ie the National Filaria Control Programs, Godavari District.