GAMETOCYTE INFECTIVITY BY DIRECT MOSQUITO FEEDS IN AN AREA OF SEASONAL MALARIA TRANSMISSION - IMPLICATIONS FOR BANCOUMANA, MALI AS A TRANSMISSION-BLOCKING VACCINE SITE

Infectivity of gametocytemic volunteers living in Bancoumana, a;villag e 60 km from Bamako, Mall, was determined by direct feeds of laborator y-reared Anopheles gambiae s. l. Gametocytemic adolescents (10-18 year s old) were as infectious to mosquitoes as younger volunteers and appe ar to be a more suitable population for testing transmission-blocking efficacy as compared with adults (> 18 years old). To begin to validat e the membrane-feeding assay, sera collected from these same volunteer s were subjected to a standard membrane-feeding assay. The data sugges t that areas with intense but seasonal transmission might be feasible sites for testing transmission-blocking vaccines because of the high g ametocytemic rates, high mosquito infectivity rates, and lack of pre-e xisting humoral-mediated transmission-blocking activity. The differenc es observed between held-based direct mosquito feeds and laboratory-ba sed membrane feeding assays suggests that caution be used in interpret ing Phase I study results in which laboratory-based membrane-feeding a ssays are used as a surrogate for vaccine efficacy.