Observations on the habits and control of Culex pipiens fatigans in Guyana.

Investigations in Guyana in 1961-63 showed that Wuchereria bancrofti was the only filarial parasite causing elephantiasis and that Culex pipiens fatigans was the primary vector. Mansonia titillans and Anopheles aquasalis were found to be secondary vectors.C. p. fatigans bred primarily in pit latrines and secondarily in the clean, confined water of drums and barrels near latrines. No breeding occurred in the relatively clean open water of trenches, ditches and drains.Of 21016 mosquitos collected from houses, 39.9% were found resting on walls, 34.9% on clothing and other hanging objects, and 23.4% on or under furniture. Of 15 622 female mosquitos caught, 9.6% contained W. bancrofti parasites and 0.5% contained infective larvae. The flight range was found to be about half a mile (0.8 km).Control was achieved by a combination of antimosquito (spraying with gas-oil) and antiparasitic (chemotherapy with diethylcarbamazine) measures, which reduced the average infection rates in the Buxton control area from 17.7% to 2.2%. Over the same period, breeding in drums dropped from 14%-25% to 4.7%, even though the drums were not treated or covered.