Mosquito distribution and entomological inoculation rates in three malaria-endemic areas in Gabon

Mosquitoes were collected during 3 separate periods in 3 areas of different malaria transmission rates in the province of Moyen Ogooue, Gabon, within 1 year (July 1996-May 1997). The campus of the Alben Schweitzer Hospital (H AS) and 2 villages, Bellevue and Tchad, were investigated. A total of 19 83 6 specimens were collected: 13 122 Mansonia, 3944: Anopheles, 2755 Culex an d 15 Aedes were captured. The number of mosquitoes was 7896 and 7995 in Jul y to August and from April to May respectively, and dropped to approximatel y half in November to December. The individual species showed a different d istribution pattern in the 3 study areas. In Tchad we found the lowest numb er of mosquitoes and also the fewest Anopheles, but when we investigated th e number of Plasmodium falciparum-infected Anopheles sp. we observed the hi ghest entomological inoculation rate (EIR) there. The EIRs were 23 in HAS, 53 in Bellevue and 61 in Tchad. The method used to determine the number of infected mosquitoes was an enzyme-linked immunosorbent assay (ELISA), confi rmed by a polymerase chain reaction-based approach. The ELISA alone reveale d too many false-positive mosquitoes.