The Transmission of Wuchereria Bancrofti by Anopheles Darlingi in the American Tropics

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The transmission of Wuchereria bancrofti in British Guiana is studied in relation to the infectability, the house-frequenting habits and the biting habits of the local mosquitoes.

Mosquitoes were collected from two representative localities: (a) a non-sewered suburb of Georgetown, highly infected with filariasis, in which C. fatigans is the prevailing mosquito; (b) a coastal sugar estate village, with a relatively low filarial incidence and A. darlingi as the dominant mosquito. The technique adopted for dissection is described, as this is an important point when comparative work is being undertaken. In the aggregate, 19,407 mosquitoes were dissected. Dissections were made on samples of mosquitoes collected from houses at random and from houses where there was known to be filariasis. The results of immediate dissections and of those made on mosquitoes kept alive for 7 or 12 days after capture are compared.

In both localities the relative incidence of natural infection in A. darlingi was very considerably higher than in C. fatigans.

A series of comparative infectibility experiments were undertaken with C. fatigans and A. darlingi, C. fatigans and Aedes aegypti, and A. darlingi and Aedes aegypti.

A. darlingi appears to be just as suitable a host for Wuchereria as C. fatigans, its classical vector; the specific anthropophilic feeding habits which cause A. darlingi to be the most effective malaria carrier of Equatorial America obviously also make this mosquito a particularly dangerous vector of filariasis.

Attempts to infect Aedes aegypti experimentally failed entirely, the negative role of this species in the transmission of Wuchereria being further confirmed.