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Malaria
Malaria Overview
Malaria is an infection of the blood that is carried from person to person by mosquitoes. The disease has been recognized for thousands of years and once was found almost everywhere except in the most northern areas of the world. Malaria has been wiped out in North America, Western Europe, and Russia. It remains a serious problem in much of the tropical and subtropical world, however.
Millions of people continue to be infected every year, and probably up to 1 million of them die. Although the United States is malaria-free, hundreds of cases a year are still reported here. Most of these are people who acquired the disease overseas.
Malaria Causes
Malaria is caused by protozoan of the genus Plasmodium.
- Infection begins with a bite from an infected mosquito.
- The parasite travels from the mosquito to your liver, where the parasite
begins to reproduce.
- The parasite leaves the liver and travels to the bloodstream, where it
infects red blood cells. The parasite reproduces in the red blood cells, which
destroys the cells and releases more parasites into the bloodstream.
- If another mosquito bites an infected person, that mosquito can then carry
the infection to someone else.
- There are 4 species of Plasmodium that infect humans:
- P vivax - Most common in India and Central and South America but
found worldwide. It has an incubation period of 8-13 days. Infections can
sometimes lead to life-threatening rupture of the spleen. In people treated
only with chloroquine (Aralen), this type of malaria can hide in the liver and
return later.
- P ovale - Rarely found outside Africa. This form of malaria has an
incubation period of 8-17 days and can hide in the liver of partially treated
people and return later.
- P malariae - Found worldwide but less common than the other forms.
This form of malaria has an incubation of 2-4 weeks. If untreated, the
infection can last many years.
- P falciparum - Common worldwide, this is the most life-threatening form of malaria. This parasite has an incubation period of 5-12 days. Resistance to many of the drugs used to treat or prevent malaria is becoming very common.
- P vivax - Most common in India and Central and South America but
found worldwide. It has an incubation period of 8-13 days. Infections can
sometimes lead to life-threatening rupture of the spleen. In people treated
only with chloroquine (Aralen), this type of malaria can hide in the liver and
return later.
- Although most people acquire malaria through mosquito bites, in some
foreign countries the disease can have other sources.
- Every year a handful of people are infected through blood transfusions or
organ transplants.
- IV drug users can develop malaria from sharing needles.
- Each year a few babies are born to mothers who did not know they were infected. The babies then develop malaria.
- Every year a handful of people are infected through blood transfusions or
organ transplants.
WebMD Medical Reference from eMedicineHealth



