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Malaria: About

Malaria is a severe illness caused by a parasite that is spread by the bite of an infected Anopheles mosquito.

Malaria is common in some tropical and subtropical regions. Most cases of malaria in the U.S. occur in returning travelers and immigrants from countries where malaria is commonly spread. All cases of malaria reported in Wisconsin residents have occurred in people who traveled to a country with malaria.

Anyone who travels to areas where malaria is spread can get the illness, but people who spend more time outdoors are at a higher risk of being bitten by an infected mosquito. It is important to take preventive steps when traveling to areas with malaria, such as wearing protective clothing, using insect repellents, and using mosquito netting.

For more tips, please visit our Mosquito Bite Prevention page. For country-specific travel information and recommendations, visit the Centers for Disease Control and Prevention (CDC) Travelers' Health page.


Malaria is usually spread to humans through the bite of an infected mosquito.
  • Mosquitoes get infected with the parasite by feeding on infected humans.
    Contemporary bedroom with mosquito netting over bed
    • After feeding on a human that has malaria, the parasite can end up inside of the mosquito.
    • Once it has the parasite, a mosquito will spread it to other humans when it takes another blood meal.
    • The parasite multiplies in the liver and red blood cells of the infected person. If an infected person is bitten by an uninfected mosquito, they can transmit the parasite to the mosquito, continuing the cycle.
  • Malaria can also be spread through blood transfusion, organ transplant, or by sharing needles or syringes, though this is rare.
    • People who have traveled to an area where malaria is common will not be able to donate blood for one year after their return.
    • Former residents of areas with risk of malaria will not be able to donate blood for three years.
    • People who have been diagnosed with malaria cannot donate blood for three years after treatment, during which time they must have remained free of malaria symptoms.
  • Mothers can spread malaria to their unborn child before or during delivery.

Malaria is preventable. Visit our Mosquito Bite Prevention page to learn how to prevent mosquito bites.

Symptoms usually show up seven to 30 days after being bitten by an infected mosquito.

Symptoms can vary depending on which malaria parasite is causing the infection. Malaria infections can range from no symptoms or mild illness to severe illness or death. An infected person can have relapses later in life. Malaria can be cured if it is diagnosed and treated promptly and correctly. Antimalarial drugs taken by travelers to prevent malaria can delay the development of symptoms by weeks or months. If you suspect that you or your family member has malaria, it is important to visit your doctor immediately. Tell your doctor if you have traveled to an area with a risk of malaria in the last 12 months.

Mild, uncomplicated malaria signs and symptoms:

  • Fever
  • Sweats
  • Chills
  • Headache
  • Nausea and vomiting
  • Body aches
  • Low energy level

Severe, complicated malaria signs and symptoms:

  • Seizures, coma, abnormal behavior, or other nervous system problems
  • Severe anemia (destruction of the red blood cells)
  • Problems with blood clotting
  • Difficulty breathing
  • Low blood pressure
  • Acute kidney failure
  • Low blood sugar

Malaria can be treated if it is diagnosed early. Treatment varies depending on how severe the infection is, the species of malaria parasite that is causing the infection, and the part of the world in which the infection was acquired. It is important to see your doctor immediately if you suspect you may have a malaria infection. For more detailed information on treatment, please visit the CDC Malaria Treatment (United States) page.

If you are planning to travel to an area where malaria is common, you can take oral drugs to prevent infection. It is very important to talk to your doctor about prevention medications before you travel. Visit the the CDC Travelers' Health page to see if your travel destination has malaria risk.

Department of Health Services Resources

Malaria Disease Fact Sheet, P-42071 (multiple languages): Educational fact sheet for the general public on malaria covering signs and symptoms, treatment, and prevention.

CDC Resources

Mosquito Bites Are Bad: An educational activity book for kids about preventing illnesses spread by mosquitoes.

Malaria is preventable. Visit our Mosquito Bite Prevention page to learn how to protect yourself from illnesses spread by mosquitoes.

Questions about illnesses spread by mosquitoes? Contact us!
Phone: 608-267-9003 | Fax: 608-261-4976

Last revised June 15, 2022