Malaria is a devastating public health menace, killing over one million peo
ple every year and infecting about half a billion. Here it is shown that th
e protozoan Plasmodium gallinaceum, a close relative of the human malaria p
arasite Plasmodium falciparum, can develop in the fruit fly Drosophila mela
nogaster. Plasmodium gallinaceum ookinetes injected into the fly developed
into sporozoites infectious to the vertebrate host with similar kinetics as
seen in the mosquito host Aedes aegypti. In the fly, a component of the in
sect's innate immune system, the macrophage, can destroy Plasmodia. These e
xperiments suggest that Drosophila can be used as a surrogate mosquito for
defining the genetic pathways involved in both vector competence and part o
f the parasite sexual cycle.