Plasmodium falciparum is the causative agent of malaria, a disease that kills 
almost one million persons each year, mainly in sub-Saharan Africa. P. 
falciparum is transmitted to the human host by the bite of an Anopheles female 
mosquito, and Anopheles gambiae sensus stricto is the most tremendous malaria 
vector in Africa, widespread throughout the afro-tropical belt. An. gambiae s.s. 
is subdivided into two distinct molecular forms, namely M and S forms. The two 
molecular forms are morphologically identical but they are distinct genetically, 
and differ by their distribution and their ecological preferences. The 
epidemiological importance of the two molecular forms in malaria transmission 
has been poorly investigated so far and gave distinct results in different 
areas. We have developed a real-time quantitative PCR (qPCR) assay, and used it 
to detect P. falciparum at the oocyst stage in wild An. gambiae s.s. mosquitoes 
experimentally infected with natural isolates of parasites. Mosquitoes were 
collected at immature stages in sympatric and allopatric breeding sites and 
further infected at the adult stage. We next measured the infection prevalence 
and intensity in female mosquitoes using the qPCR assay and correlated the 
infection success with the mosquito molecular forms. Our results revealed 
different prevalence of infection between the M and S molecular forms of An. 
gambiae s.s. in Cameroon, for both sympatric and allopatric populations of 
mosquitoes. However, no difference in the infection intensity was observed. 
Thus, the distribution of the molecular forms of An. gambiae s.s. may impact on 
the malaria epidemiology, and it will be important to monitor the efficiency of 
malaria control interventions on the two M and S forms.