IN THIS ARTICLE
Malaria is caused by protozoa of the genus Plasmodium and is transmitted to humans by mosquitoes. The history of malaria shows that it was difficult to determine the disease's mode of transmission. When some cultures reviewed the facts available to them, they concluded that malaria was caused by bad air without realizing that the same swamps that created foul-smelling air also were excellent breeding grounds for mosquitoes. In 1880, the parasite was identified in an infected patient's blood.
There are several stages in the life cycle of Plasmodium, including sporozoites, merozoites, and gametocytes. The bite of an infected mosquito transmits the sporozoite stage of the organism to humans. The parasite travels into the bloodstream and eventually makes its way to the liver, where it begins to multiply by producing merozoites. The merozoites leave the liver and enter red blood cells to reproduce. Soon, young parasites burst out in search of new red blood cells to infect.
Sometimes, the reproducing Plasmodia will create a form known as a gametocyte in the human bloodstream. If a mosquito takes a blood meal when gametocytes are present, the parasite begins to reproduce in the insect and create sporozoites that are infectious to people, completing the life cycle.
There are five species of Plasmodium that infect humans:
Is Malaria Contagious?
Fortunately, malaria is not contagious except in rare situations; it is not spread directly from person to person with the following exceptions. A few cases have occurred in other countries through blood transfusion, intravenous drug abuse with shared needles, or organ transplantation. An infected mother can spread malaria through the placenta to her unborn child. Except for these rare situations, transmission only occurs when a person is bitten by an infected mosquito. The infected person is not contagious to other individuals, and there is no need to isolate or quarantine the person to protect others from direct transmission. However, depending on the local public-health situation, an infected traveler returning home may be asked to stay indoors until well. Some areas may have mosquitoes that are able to transmit malaria, and transmission of malaria from a returning traveler by local mosquitoes has been reported. Public-health authorities may increase mosquito-control measures in the area, as well, to reduce this risk.
Medically Reviewed by a Doctor on 5/1/2015
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