The chemotherapy of rodent malaria, VIII

Antimalarial drugs and the mosquito transmission of Plasmodium

It is well-known that whenever possible, the treatment of patients with malaria should include measures to prevent them transmitting the infection to others. This is particularly important for P. falciparum, where the gametocytes can survive for a much longer period than the asexual stages. Not all antimalarials are gametocytocidal or sporontocidal and those that are may have particular disadvantages or lose their effectiveness because of resistance. Even drugs that have no obvious gametocytocidal or sporontocidal activity may have other effects. These include the possibility of increasing transmission, either by affecting the parasite within an individual host or by selection for parasite strains with increased potential for infecting the mosquito vector. This review summarises the available information on the properties of antimalarials in relation to mosquito transmission and highlights the need for more attention to be paid to this aspect of drug action.

Plasmodium berghei: inhibition of the sporogonous cycle by alpha-difluoromethylornithine

alpha-Difluoromethylornithine (DFMO), an enzyme inhibitor of ornithine decarboxylase, inhibits the sporogonous cycle of the malaria parasite Plasmodium berghei in the mosquito vector Anopheles stephensi. DFMO was administered to the mosquitoes dissolved either in the sugar solution at their disposal in the cages or through blood meals taken from treated mice. The mice subsequently bitten by mosquitoes treated with DFMO by both routes of administration did not contract malaria.