Role of Culex quinquefasciatus in the transmission of bancroftian filariasis in the Federal Islamic Republic of Comoros (Indian Ocean)

Abstract

In October 1988-January 1989, as a part of a malaria and filariasis control programme in Federal Islamic Republic of Comoros an entomological survey was carried out in 19 rural and urban localities of Grande Comore. Anjouan and Moheli Islands. The potential breeding places were examined and pyrethrum spray catches were made to evaluate the indoor resting densities of mosquitos. A total of 14.578 adult mosquitos potential vectors of filariasis was collected: 94.5% Culex quinquefasciatus, 3.5% Anopheles gambiae s. str. 1.9% A. funestus and 0.1% other anopheline species. A. funestus, uniformly spread in Moheli, was present only in the south-west coast of Anjouan and absent in Grande Comore. A. gambiae and Cx quinquefasciatus were present in Grande Comore. A. gambiae and Cx quinquefasciatus were present in the three islands with different densities in the villages. Only Cx quinquefasciatus specimens la maximum of 150 for each locality) were dissected to search filaria larvae being the Anopheles specimens used to evaluate the malaria transmission. The global infection rate (9.4%) and the infectivity rate (0.9%) observed in Cx quinquefasciatus are higher than indices reported in previous surveys. All the larvae in the third development instar (L3) were identified as Wuchereria bancrofti. The results suggest that in FIR of Comoros W. bancrofti is well adopted to local Cx quinquefasciatus population. Because of the presence of high mosquito density this species plays a prominent role in the transmission of lymphatic filariasis in that area. The high transmission levels calls for the implementation of a specific control program.