Skip Navigation LinksMalaria

Malaria

What is malaria?

Malaria is a serious mosquito-borne disease caused by small parasites called Plasmodium that spread from mosquito bites and infect and destroy red blood cells in people. Four different species of Plasmodium can cause disease in humans: Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale, and Plasmodium vivax.​

Where does malaria oc​cur?

Malaria occurs in many tropical and sub-tropical areas of the world, particularly sub-Saharan Africa, Southeast Asia, the Middle East, and Central and South America. It is estimated that nearly half of the world's population lives in a malaria area, and each year, millions of malaria cases occur worldwide.

Although malaria occurred naturally in parts of the United States (including California) until the mid-1900s, most malaria cases in the U.S. today are diagnosed in people who were infected while traveling in other countries where malaria is common. About 2,000 cases of malaria are reported in the United States each year.

The mosquitoes that can spread malaria (called “Anopheles") are present in California, but the parasites that cause malaria are not currently found in these mosquitoes in California. The last cases of local transmission of malaria in California were reported in 1989. About 100 cases of malaria are reported each year in California from people who were infected while traveling in other countries. ​

How do y​ou get m​alaria?

The main way people get malaria ​is from the bite of an infected Anopheles mosquito. A mosquito can become infected when it bites a person who has malaria parasites in their blood. It takes a week or more for the malaria parasites to mature in the mosquito, and then the mosquito can transmit the parasites to another person when it bites that person.​

What are t​he symptoms of malaria?

Fever is the most common early symptom of malaria. The fever tends to rise over several days and may be accompanied by headache, muscle pain, and fatigue. People with malaria also may experience intense shivering, chills, sweating, nausea, and vomiting. These symptoms can occur together or in stages (“attacks") that last for several hours and occur every 1–3 days. Symptoms usually develop within 1–4 weeks after a person is infected, though in some cases, symptoms do not appear for up to a year.

If not treated, malaria can become severe, especially from infection with Plasmodium falciparum. Severe symptoms can include kidney failure, seizures, mental confusion, coma, and can lead to death. ​

How is m​​alaria treated?

Malaria can be treated with prescription medication. The type of medicine and length of treatment depend on the type of malaria a person has, where the person was infected, their age, whether they are pregnant, and how sick they are at the start of treatment. Treatment can also prevent patients from relapsing with malaria, which can happen when a person feels sick again weeks or months after they were initially sick with malaria. ​

​​What can I do to keep from getting malaria?

At least four weeks before traveling to an area with malaria, talk with a doctor who specializes in travel medicine to get preventive medications (called “antimalarial" medications). Antimalarial medications are very effective at preventing disease, but they must be taken according to the prescribed schedule. It is important to not miss any doses while traveling in areas with malaria. Be sure to take an adequate supply of antimalarial medication to last for your entire trip.

Even if you have had malaria before, taking antimalarial medications is important when traveling to areas with malaria transmission. Previous infections do not provide protection because there are four different kinds of Plasmodium parasite that can cause malaria.

Important: While traveling in areas with malaria, prevent mosquito bites by wearing protective clothing (long pants, long-sleeved shirts) and applying EPA-registered insect repellent on clothes and exposed skin. Placing mosquito netting around your bed can help prevent being bitten while sleeping.

Page Last Updated :