Observations on Culex quinquefasciatus Say in relation to transmission of filariasis due to subperiodic Wuchereria bancrofti in Samoa.

Observations on Culex quinquefasciatus Say in Samoa during a study of the epidemiology and control of subperiodic bancroftian filariasis are reported. The man-biting rate of C. quinquefasciatus was comparable with that of Aedes (Finlaya) samoanus Gruenberg in one indicator village and lower in another. The house-frequenting behaviour of the two species was similar. Culex quinquefasciatus was active throughout the night with peak biting during midnight hours, and its survivorship, estimated by two methods, was higher than those of the main vectors, A. (Stegomyia) polynesiensis Marks and A. samoanus. Culex quinquefasciatus showed low susceptibility to subperiodic Wuchereria bancrofti, compared with the two main vectors, in laboratory feeding experiments on volunteers with three levels of microfilaraemia. This agrees with the observed very low natural infection rate, suggesting that C. quinquefasciatus is an inefficient vector of subperiodic W. bancrofti in Samoa.