training module for medical officers primary health centre - NVBDCP

microgametes fertilizes the macrogamete. The resulting zygote is at first motionless, but within 18-24hours, becomes a motile ookinete, which penetrates the stomach wall of the mosquito and develops intoan oocyst on the outer surface of the stomach. The oocyst further develops into numerous sporozoites,when the oocyst ruptures and releases the sporozoites into the body cavity of the mosquito. Many ofthe sporozoites migrate to the salivary glands and the mosquito becomes infective to man. The periodrequired for the development of the parasite from the gametocyte stage to sporozoite stage is about 10-20 days depending on atmospheric temperature and humidity. This period is known as the “extrinsicincubation period”. The sporozoites (the infective stage of Plasmodium) are injected with saliva whenthe mosquito next feeds.In falciparum malaria, there may be involvement of the brain and coma in addition to life threateningcomplications including kidney or liver failure. With early and effective treatment, the case fatality ratesin P.falciparum malaria can be brought down from above 5% to close to zero. Malaria cases can beclassified according to the parasite species causing them and according to the severity of the disease,as either uncomplicated or severe malaria. It should be understood that severe vivax malaria is veryrare.Sporogony time at 20 - 21ºC P.vivax 14 - 16days (no development below 15 ºC) P.falciparum 18 - 20days (no development below 17 ºC)Temperature over 32-34 ºC inactivates the parasite13