Some observations on filariasis in Western Samoa after mass administration of diethylcarbamazine.

An extremely efficient diethylcarbamazine administration campaign to eradicate Wuchereria bancrofti has been carried out in Western Samoa. The use of the membrane-filtration technique has shown that a large number of people exhibit extremely low microfilarial densities, often with less than 10 in 1 ml of venous blood. It was found that one of these low level microfilaria carriers readily infected the local vector Aedes polynesiensis and that development took place to the infective stage. It was estimated that 497 infective larvae of W. bancrofti will enter the human population of Western Samoa daily from these vectors. Resumption of filariasis transmission is possible and surveillance of the human and mosquito populations should be continued for a number of years and control measures taken quickly if further transmission occurs.