Bancroftian filariasis in Bagdogra town, district Darjeeling (West Bengal).

Filaria endemicity is probably gradually increasing over the years in Bagdogra town, district Darjeeling (West Bengal). Of 1511 night blood smears examined, 35 were found positive for Wuchereria bancrofti (mf rate 2.32%). The microfilaria (mf) rates for males and females were 2.84% and 1.79 % respectively. The age of these positives ranged from 5-45 years. The mf rate was highest (4.46%) in the age group of 20-29 years. All mf carriers were local residents of Bagdogra and Wuchereria bancrofti was only the infection encountered. Mean microfilaria density was 7.71 per 20 cmm. of blood, whereas Median microfilaria density (MFD50) was 21 per 20 cmm. of blood. Disease and filarial endemicity rates were 0.33% and 2.65% respectively. Ten man hour vector mosquito density ranged from 30 to 65. Out of 49 female Culex quinquefasciatus mosquitoes dissected for the presence of filaria infection, none was found positive for the infection. During 1976 survey in the same town, mf rate was 1.6% and disease rate was nil.