Gametocyte infectivity by direct mosquito feeds in an area of seasonal malaria transmission: implications for Bancoumana, Mali as a transmission-blocking vaccine site

• Published in: The American journal of tropical medicine and hygiene Vol. 59; no. 3; pp. 481 - 486
• Main Authors: Toure, YT, Doumbo, O, Toure, A, Bagayoko, M, Diallo, M, Dolo, A, Vernick, KD, Keister, DB, Muratova, O, Kaslow, DC
• Format: Journal Article
• Language: English
• Published: Lawrence, KS ASTMH 01.09.1998; Allen Press
• Subjects: Adolescent; Adult; Age Distribution; Animals; Anopheles - parasitology; Anopheles gambiae; Antibodies, Protozoan - blood; Biological and medical sciences; Child; Child, Preschool; Human protozoal diseases; Humans; Infectious diseases; Insect Vectors - parasitology; Malaria; Malaria Vaccines - immunology; Malaria, Falciparum - epidemiology; Malaria, Falciparum - prevention & control; Malaria, Falciparum - transmission; Mali - epidemiology; Medical sciences; Parasitemia - epidemiology; Parasitemia - prevention & control; Parasitemia - transmission; Parasitic diseases; Plasmodium falciparum; Plasmodium falciparum - immunology; Plasmodium falciparum - pathogenicity; Prevalence; Protozoal diseases; Seasons; Tropical medicine; Mali; Africa; Human; Immunoprotection; Protozoal disease; Malaria; Insecta; Parasitosis; Infection; Immunoprophylaxis; Anopheles; Arthropoda; Infectivity; Culicidae; Invertebrata; Vector; Diptera
• ISSN: 0002-9637; 1476-1645
• DOI: 10.4269/ajtmh.1998.59.481

Infectivity of gametocytemic volunteers living in Bancoumana, a village 60 km from Bamako, Mali, was determined by direct feeds of laboratory-reared Anopheles gambiae s. l. Gametocytemic adolescents (10-18 years old) were as infectious to mosquitoes as younger volunteers and appear to be a more suitable population for testing transmission-blocking efficacy as compared with adults (> 18 years old). To begin to validate the membrane-feeding assay, sera collected from these same volunteers were subjected to a standard membrane-feeding assay. The data suggest that areas with intense but seasonal transmission might be feasible sites for testing transmission-blocking vaccines because of the high gametocytemic rates, high mosquito infectivity rates, and lack of pre-existing humoral-mediated transmission-blocking activity. The differences observed between field-based direct mosquito feeds and laboratory-based membrane feeding assays suggests that caution be used in interpreting Phase I study results in which laboratory-based membrane-feeding assays are used as a surrogate for vaccine efficacy.