The part of the parasitic cycle which takes place in the Anopheles mosquito is also very complex. The transformations and the multiplications of the parasite last from 10 to 14 days. The passage of the parasite of Man to the vector, then from the vector to Man, takes place during the bite. As the male mosquito is not a blood eater, only the female is involved in the transmission process.

The bio-ecology of the major vectors is very special: the anthropophilic and endophagous bite are high and guarantee a high Man-mosquito interaction. The result is that the vectors of malaria in tropical Africa have a remarkable aptitude for transmission: The malaria transmission rates in intertropical Africa are the highest in the world. It is mainly for this reason that the malaria endemia is so high in this area.

There can be no transmission of malaria which is acceptable in terms of public health. The only absolute way of preventing malaria is not to receive bites from infected Anopheles mosquitoes. In tropical Africa, there probably exists no locality where the absence of transmission is 100% certain. Any traveler, once he spends a fraction of a night in this part of the world, even during a simple stopover, without getting off the plane, takes the risk of being bitten by an infected Anopheles mosquito. Preventive behavior and practices may significantly reduce this risk (c.f. : chapter on the individual protection and the anti-vectoral combat), but without wiping it out completely.