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What Is Malaria?

  • Malaria is caused by parasites from the genus Plasmodium, which are spread to people through the bite of infected mosquitoes of the Anopheles species. According to the World Health Organization, there were 214 million cases of malaria in 2015 worldwide, causing 438,000 deaths. Deaths are especially common in children.
  • Approximately 1,500 to 2,000 cases are diagnosed in the U.S. each year, largely as a result of international travel or immigration.
  • The hallmark of malaria is fever. Initially, symptoms may mimic the flu. Fever may be accompanied by shaking chills and muscle aches. Anemia is common.
  • Severe cases may cause organ failure or death. Travelers are much more vulnerable to severe malaria than residents of areas where malaria is present; travelers lack the partial immunity that protects residents who are frequently exposed to malaria.
  • Malaria is diagnosed from a blood smear when the parasite is seen under the microscope. Other tests are available, but microscopy remains the cornerstone of diagnosis. Malaria is treated with specific medications. Oral medications are usually used, except in severe cases.
  • Most patients recover completely after being treated. However, infection with P. vivax or P. ovale may be associated with organisms that hide in the liver for months or years, resisting treatment. Special medications are used to help eradicate these organisms, so it is important to closely follow medical directions when taking preventive medicines. Never stop the medication early if instructed to continue taking it for a few weeks after leaving the area where malaria is present.
  • People who travel to areas with malaria should visit their physician several weeks prior to departure to ensure all preventive measures are completed before travel. The risk of malaria may be reduced by taking medications and using precautions to prevent mosquito bites, including insecticides containing DEET.
  • The history of malaria and other human diseases is interesting. The gene that causes sickle cell disease is more common in areas where malaria is common, because it offers some protection. People who have sickle cell disease (two sickle cell genes) have very abnormal hemoglobin that leads to many complications, including early death. However, people who have sickle cell trait (only one sickle cell gene) do not have the complications of sickle cell disease, but their hemoglobin is just abnormal enough to make red blood cells inhospitable to the malaria parasite. Thus, sickle cell trait provides some protection against malaria, especially during infancy and toddlerhood, until the child can produce immune defenses against malaria on its own.
Medically Reviewed by a Doctor on 11/21/2017

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Treatment Overview

Medicine can prevent malaria and is necessary to treat the disease. Several factors influence the choice of medicine, including:

  • Whether the medicine is being used to prevent or to treat malaria.
  • Your condition (such as your age or whether you are pregnant).
  • How sick you are from malaria.
  • Geographic location where you were exposed to malaria.
  • Whether the malaria parasite may be resistant to certain medications.
  • Your ability to take the preferred medicine without side effects or complications.
  • Whether you are able to take the medicine as a pill.

Malaria is rare in the United States, but it is widespread in other parts of the world. Find out about the risk for malaria before you travel internationally.


Read What Your Physician is Reading on Medscape

Malaria »

Malaria, which predominantly occurs in tropical areas, is a potentially life-threatening disease caused by infection with Plasmodium protozoa transmitted by an infective female Anopheles mosquito vector.

Read More on Medscape Reference »

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