LACK OF MALARIA PARASITE TRANSMISSION BETWEEN APES AND HUMANS IN GABON

The International Center for Medical Research (CIRMF) is located in an area highly endemic for malaria in southeastern Gabon, where humans a nd apes (gorilla and chimpanzees) are living in the same geographic ar ea. The presence of the CIRMF primate center housing apes (59 chimpanz ees and nine gorillas in 1994) withing the city of Franceville provide d an opportunity to investigate the capability of cross-transmission o f malaria species from humans to apes. The main vector of human malari a, Anopheles gambiae, was found in the primate center and in a nearby populated area of Franceville. Despite high malaria transmission in hu mans in both Plasmodium falciparum and P. malariae (mean of 43% cumula tive prevalence in schoolchildren), none of the apes were found infect ed with plasmodia during a six-month investigation. However, low antib ody levels against sporozoite and blood stages of both P. falciparum a nd P. malariae were detected in a few chimpanzees and gorillas. These results demonstrate that only rarely would apes be bitten in the field by mosquitoes infected with human malaria parasites. In the case of i nfection proven by serology, we did not find any evidence that blood-s tage malaria parasites were able to the gametocyte stage. The absence of any established malaria transmission cycle within the primate colon y of CIRMF indicates that apes cannot be considered as animal reservoi rs for human malaria parasites in this environment.