Infectivity of malarial parasites to mosquitoes: 'The interdependent roles of parasite, vector and host'

It has been possible to infect mosquitoes routinely with cultured gametocytes of Plasmodium falciparum Since 1980. This has enabled the development of a reliable bio-assay for potential transmission-blocking vaccines and research on the role of specific antibodies from the host on the parasitic stages in the mosquito midgut. After some development and fine-tuning of the assay, it became apparent that the immune responses of the human host, as well as factors from the parasite and the mosquito, determined the final outcome of the mosquito infection. The age of the mosquito, crowding of parasites inside the peritrophic membrane and the quantity and particularly the quality of the gametocytes ingested all influence the chance of successful transmission. Cytokines and/or other mediators of inflammation from the human host can also reduce transmission, probably by promoting phagocytosis of the freshly emerged gametes by leucocytes in the bloodmeal.