It is responsible for the death and reduced resistance in large number of persons every year, the heaviest toll being the children under 4 years of age. Due to WHO and NMEP of India, the malaria was effectively reduced but party owing to socio-economic factors and partly because of unexpected proliferation of DDT- resistant mosquitoes and drug-resistant parasites, the attempts to eradicate the infection have failed and the malaria is again on increase. About 60 species of Plasmodium are known to cause malaria in reptiles, birds and mammals. According to Jahn, there are 4 species in man, 4 in monkeys, 15 in birds, 13 in reptiles, and one or more in buffalo, antelope, squirrels, bats and frogs. Malarial parasites are found widely spread from 45S to 63° N latitudes. Their endemic home is in the tropical zone, but they also occur in many temperate countries. Species infecting the migratory birds are spread all over the world. Some avian malarial parasites are confined to cold regions only. Species infecting reptiles have a localized distribution.It is caused by P. malariae. The fever recurs every fourth day that is after 72 hours. It may last to 40 years or more in untreated persons. P. malariae is found in tropical and temperate zones. Incubation period is twenty seven to thirty seven days. Ring shaped trophozoite is one third to one half the size of the erythrocyte schizont fills the erythrocyte which is not enlarged. Haemozoin is dark brown. Erythrocyte has no Schuffner’s dots. In blood the schizont forms six to twelve merozoites. Gametocytes are found. They fill the erythrocyte which is not enlarged. It causes quartan malaria fever even 72 hours.The mosquitoes can be prevented from biting by adopting various protective measures. The houses should be built on high grounds having good drainage and away from vegetation and marshy places. In the mosquito-infected areas, the horses should be made mosquito-proof by adequate screening all the doors, windows and ventilators, etc. Light-coloured clothing may also deter some species.Mosquito nets should be used, especially during night, to keep away the mosquitoes. The cloth of mosquito net must not contain less than 100 holes in one square inch. The exposed parts of the body may be protected by the use of veils, gloves and boots, etc., or by the application of repellents, such as anti-mosquito creams (e.g., Odomos), mustard oil, and dimethyl phthalate or dimethyl carbate, etc. Application of repellents to the skin confuses the mosquito’s sensors and thus prevents it from biting.Healthy person’s inhabiting malarious regions should take small regular doses of prevention medicines as a precaution against infection through mosquito bites. A casual prophylactic drug which may kill the sporozoites before they may develop further in the body is unknown at present.