Malaria oocysts. Image 6 of 10. Coloured transmission electron micrograph (TEM) of malaria oocysts in a mosquito (Anopheles sp.) gut. The four oocysts (Plasmodium sp., down centre and at upper left) are on the gut wall. This parasite stage forms after a mosquito ingests infected blood from a human. Each oocyst contains sporozoites (brown), which will infect humans when the mosquito feeds. The parasites later infect human red blood cells, causing recurrent fevers, anaemia and even death. Magnification: x500 at 6x7cm size. For the complete malaria parasite life cycle, see images M210/197-206.