Lymphatic filariasis in the coastal areas of Digha, West Bengal, India

Abstract

The state of West Bengal, India, has a long coastline with the Bay of Bengal. No information exists regarding filarial epidemiology and its vector in these coastal areas. The present study was designed to assess the epidemiology of lymphatic filariasis and the role of available mosquitoes as its vector in eight coastal villages around Digha, West Bengal. Night blood samples of 4016 individuals were collected and each of them was examined clinically for any manifestations of the disease. Overall, microfilaria rate, mean microfilarial density and disease rate were 9.06%, 8.63% and 7.72%, respectively. The causative parasite was identified as Wuchereria bancrofti and Culex quinquefasciatus was incriminated as the vector responsible. Vector infection and infectivity rates were assessed to be 12.5% and 0.73%, respectively. The human blood index of human-house-frequenting vector population was 70%. Vector density, vector infection, infectivity rates and human blood index were higher in the rainy season in the study area. Overall, the filarial situation was bad and, as a measure, single-dose diethylcarbamazine citrate (6 mg/kg body weight) treatment was given to all the microfilariaemic patients. Night blood samples of the treated individuals were tested for microfilariae on days 10 and 365, which revealed interesting results.

Comparative Studies of Different Indices Related to Filarial Vector of a Rural and an Urban Area of West Bengal, India

“…A strong fall in the average load of microfilaria to average load of infective stages in those vectors shows a natural bearing in control of filarial transmission in both urban and rural area, which was also reported in some other studies [9,10,22]. However, average load of parasites per vectors was higher in urban area than in rural area (p>0.05).…”

“…Seasonal data reveal that, in both the areas infection and infectivity rates were higher in rainy season closely followed by summer season (p>0.05). This tendency was also found in some other area [9] but unlike of some other area also, where higher rates were found in summer [10]. Vector infection and infectivity rates were significantly higher in urban area than in rural area under present study (p<0.05).…”

“…quinquefasciatus was the dominant species among house frequenting mosquitoes in both urban and rural areas. MHD of vectors from both the study areas was lower than some other endemic areas of West Bengal but higher than some other area also [5,6,[8][9][10]. Comparison shows that, MHD was much higher in urban area than in rural area in all the months, seasons and overall (p<0.05).…”

“…Vector infection and infectivity rates in both the area were lower than some other areas [9,10] but higher than some other endemic areas [8]. Seasonal data reveal that, in both the areas infection and infectivity rates were higher in rainy season closely followed by summer season (p>0.05).…”

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Information about filarial vector was available from different parts of West Bengal in India [5][6][7][8][9][10]. Nevertheless, information on vector related indices from many areas is scanty.

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