Distribution and chromosomal characterization of the Anopheles gambiae complex in Angola.

Mosquitoes of the Anopheles gambiae complex (N = 1,336) were sampled (2001-2005) across Angola to identify taxa, study inversion polymorphisms, and detect the circumsporozoite protein of Plasmodium falciparum. Anopheles gambiae s.s. was found in all sites; it was characterized as M-form in localities of the tropical dry and semi-desertic belts, whereas the S-form was predominant in comparatively more humid and less anthropized sites. Both forms were characterized by low degrees of chromosomal polymorphism based solely on the 2La inversion, a pattern usually associated with An. gambiae populations from forested, humid, and derived savanna areas. Unexpectedly, this pattern was also observed in M-form populations collected in dry/pre-desertic areas, where this form largely predominates over An. arabiensis, which was also detected in central/inland sites. Anopheles melas was found in northern coastal sites. Three of 534 An. gambiae s.s. were positive for P. falciparum CS-protein, whereas none of the 105 An. melas were positive.