Detection of sexual stage parasites in anopheles mid gut post membrane fed with plasmodium falciparum gametocytes - Ellen Ndhlovu

Abstract

The study was conducted to detect the sexual stage parasites (oocysts) of Plasmodium falciparum (Pf) in mosquitoes post membrane feeding. The main aim was to investigate the sexual development of laboratory cultured(Pf) gametocytes in Anopheles host using membrane feeding with the ultimate goal of understanding malaria transmission. Specifically, the focus was to determine optimal feeding density and feeding duration, assessing infection success and infection rate and identifying bottlenecks to successful Pf gametocytes transfer through membrane feeding. Mosquitoes were reared in the laboratory to produce F1 generation which is parasite free and later were inoculated with cultured Pf gametocytes (stage V). The gametocytes were fed to the mosquitoes through membrane feeding. Mosquito midguts were later dissected to detect the sexual stage parasites (oocysts) using microscopy after incubation period of 9 days. Mosquito rearing and parasite culturing were successful. Successful parasite inoculation was confirmed by presence of gametocytes in the mosquitoes within 24 hours post feeding. However, oocysts were not detected in the mid gut after 9 days. The study results showed that P. falciparum infection into the Anopheles was not complete as shown by failure to detect oocysts on the midgut and sporozoites on the salivary glands. This could be due to several factors such as but not limited to parasite maturity, parasite acquisition to its host, temperature maintenance and transmission efficiency, The study concluded that gametocytes detection in the midgut has to be meticulously conducted to care for other factors that affect the viability of the parasites. However, the study successfully demonstrated the possibility of inoculating Pf gametocytes into mosquitoes through membrane feeding. It is recommended that the three novel approaches; in vitro parasite culturing of Plasmodium falciparum gametocytes, rearing of Anopheles vector and membrane feeding, being the most critical procedures for the success of the study, have to be done according to the stipulated standards of operating procedures so that required results are yielded.