Bancroftian filariasis in coastal north Trinidad, West Indies: intensity of transmission by Culex quinquefasciatus

ABSTRACT

The intensity of transmission of Wuchereria bancrofti was measured in a coastal community in north Trinidad where 15 percent of the residents were microfilaraemic. The only significant vector Culex quinquefasciatus, was studied in detail to determine seasonal abundance, longevity, infection and infectivity rates. Only 2.1 percent of the indoor biting population and 7.0 percent of the indoor resting population were infected. The daily mortality rate of the vector increased with age from 27 percent at 4 days to 44 to 47 percent at 12 days and is considered to be an important factor contributing to the low infectivity rate (0.1 percent). The mean number of C. quinquefasciatus bites received by a resident of the village during the year of observation was estimated to be 17,948 of which 14 were from mosquitoes harbouring infective larvae of W. bancrofti. The results from similar studies elsewhere are outlined, but the need for standardisation of procedures is emphasised before more reliable comparisons can be made (Summary)