EPIDEMIOLOGY OF SUBPERIODIC WUCHERERIA-BANCROFTI INFECTION IN THE NICOBAR ISLANDS, INDIA

Diurnally subperiodic filariasis due to Wuchereria bancrofti has been reported from tribal populations in the Nancowry group of islands in t he Andaman and Nicobar Islands, India. This was confirmed in a survey carried out during the monsoon season in 1993. Microfilariae were dete cted in the peripheral blood throughout a 24 h period with a peak at 1 8:00. The microfilaria (mf) rate ranged from 1 . 2% to 18 . 7%, with a low disease rate (mean=1 . 9%). Incidence of mf was low in children l ess than 10 years old (3 . 5%), but increased with increasing age. Cul ex (Culex) quinquefasciatus was present at a very low density. Aedes ( Finlaya) niveus and Aedes (Stegomyia) malayensis were the only species commonly biting man. The former was incriminated as a vector, and fou nd naturally infected with W. bancrofti (infection and infectivity rat es 1 . 1% and 0 . 9% respectively). After experimental feeding on dono rs? W. bancrofti developed to L3 stage larvae in A. niveus but failed to develop in A. malayensis and A. aegypti.