The efficacy of combined mefloquine-artesunate versus mefloquine-primaquine on subsequent development of Plasmodium falciparum gametocytemia.

An open randomized controlled study of mefloquine-artesunate and mefloquine-primaquine for the treatment of uncomplicated Plasmodium falciparum malaria was carried out in Kanchanaburi in the Saiyok District in western Thailand. Weekly parasite counts from thick and thin blood films were done for six weeks. The gametocyte carriage rate was calculated and compared between the two treatment groups. Gametocytes on presentation, recrudescent infection, and reinfection were the significant factors associated with subsequent development of gametocytemia. It is the increased propensity of recrudescent infections to produce gametocytes that drives drug resistance. The results of this study confirmed that the complete eradication of a sexual forms of P. falciparum by effective antimalarial treatment, but not by combination treatment with primaquine, is the most effective means to prevent subsequent gametocytemia.