4 YEARS ENTOMOLOGICAL STUDY OF THE TRANSMISSION OF SEASONAL MALARIA IN SENEGAL AND THE BIONOMICS OF ANOPHELES-GAMBIAE AND ANOPHELES-ARAIBIENSIS

From 1993 to 1996, an entomological survey was conducted in the villag e of Ndiop, Senegal, as part of a research programme on malaria epidem iology and the mechanisms of protective immunity. Mosquitoes were capt ured on human bait and by indoor spraying. Species from the Anopheles gambiae complex were identified using the polymerase chain reaction, a nd Plasmodium falciparum infections were detected by enzyme-linked imm unosorbent assay for circumsporozoite protein. The vector species iden tified were A. gambiae (33.9%), A. arabiensis (63.2%), A. melas (0.3%) and A. funestus (2.5%). Similar proportions of A. gambiae (74.2%) and A. arabiensis (73.8%) contained human blood; 27.0% of A. gambiae and 28.3% of A. arabiensis had fed on cattle. The sporozoite rates were si milar for A. gambiae (3.2%) and A. arabiensis (3.7 %). The annual ento mological inoculation rates varied greatly depending on the year. Ther e were 63, 17, 37 and 7 infected bites per person per year in 1993, 19 94, 1995 and 1996 respectively. Transmission was highly seasonal, from July to October. A. arabiensis was responsible for 66% of malaria tra nsmission,A. gambiae for 31%, and A. funestus for 3%.