Diurnal pattern of human-biting activity and transmission of subperiodic Wuchereria bancrofti (Filariidea: Dipetalonematidae) by Ochlerotatus niveus (Diptera: Culicidae) on the Andaman and Nicobar islands of India.

We monitored diel-landing periodicity (biting activity/cycle) of Ochlerotatus niveus and the infection/infectivity pattern through human-landing collections on Teressa Island, which is remotely located in the Nicobar district of the Andaman and Nicobar group of Islands of India, for a period of one year. The biting activity was seen throughout the day, exhibiting a bimodal peak, the first at dawn (4:00-6:00 AM) and the other towards dusk (5:00-6:00 PM). This pattern was similar during all the seasons of the year. Peak biting hours of Oc. niveus coincides with the peak appearance of microfilariae. Overall infection and infectivity rates were 2.65% and 0.5%, respectively. Perennial transmission is evident from the records of vectors with parasites (infection), including infective larvae in all months of the year, although no infective mosquitoes were recorded at a few points. The risk of transmission of filariasis based on parity status of Oc. niveus was maximal at dusk (5:00-6:00 PM) in this region. The issue of control with respect to reducing human-vector contact is discussed.