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Malaria Overview

Malaria: From Symptoms to Prevention
Malaria symptoms can range from none to very mild in uncomplicated disease. The flu-like symptoms are caused by toxins released when red blood cells rupture and the parasites move on to infect other cells.

In severe malaria, infections are complicated by metabolism or blood abnormalities and by serious organ failures, and may result in death. The incubation period -- the time between the onset of the infection and the appearance of symptoms -- is usually between nine and 30 days, depending on the type of parasite. In some types of infections, symptoms may not emerge for months.

Malaria Symptoms
Uncomplicated Malaria
Bouts of fever
Cerebral malaria, with abnormal behavior, impairment of consciousness, seizures, coma or other neurological abnormalities
Severe anemia
Hemoglobin in the urine
Fluid in the lungs (pulmonary edema)
Nausea and vomiting
Acute respiratory distress syndrome (ARDS)
Slight diarrhea
Blood coagulation abnormalities
Body aches
Cardiovascular collapse and shock
General malaise

Sources: CDC, Roll Back Malaria Partnership

While malaria may be suspected based on a patient's symptoms, a definitive diagnosis requires laboratory tests to identify the parasites or their components. The preferred and most reliable method for diagnosing malaria is to examine a drop of blood under a microscope. Staining of the blood and spreading the sample out as a smear on a slide allows the parasites to be easily visualized, and each of the four types has distinguishing characteristics.

Photo courtesy Dr. Mae Melvin/CDC
A photomicrograph of a blood smear showing red blood cells that contain developing P. vivax parasites, magnified 1000 times.

Rapid Diagnostic Tests (RDTs) offer an alternative when microscopy is not available. RDTs, which detect antigens derived from the parasites, most often use a cassette or dipstick and provide results in two to 10 minutes. These tests are being used in some countries, but they are not approved by the Food & Drug Administration for use in the United States. A molecular diagnosis technique, which detects parasitic genetic material, is more accurate than microscopy, but it is expensive and requires a specialized laboratory.

In areas where malaria is common, such as certain African countries, rural healthcare facilities lack microscopes and trained personnel. In these cases, workers presume that a person with a fever that does not have an obvious cause has malaria and will treat the patient for the disease.

Treatment and Prevention of Malaria
Malaria is curable if the right drugs are used for the correct period of time. Because some types of the parasites in some regions have developed resistance to the most commonly used antimalarial drug, an accurate diagnosis is essential to selecting the appropriate treatment. If you are in an area where malaria is common and you develop flu-like symptoms, immediately get tested. Timely treatment can prevent the infection from causing more harm and from spreading to other people. You can learn more about the specific drugs used to treat malaria in How Malaria Drugs Work.

bed net
Photo courtesy
Using a bed mosquito net in areas where malaria is common is one way to prevent exposure.

When traveling to areas where malaria is common, you should avoid exposure when possible, use insecticide-treated bed nets, and wear protective clothing and insect repellant. Before you travel to tropical countries, visit the CDC's Traveler's Health: Regional Malarial Information site to learn what specific prescription drugs will offer you protection from this serious disease. The CDC also provides specific guidance on protecting yourself from mosquitoes at its Traveler's Health: Mosquito and Tick Protection site.

For lots more information on malaria, mosquitos and related topics, check out the links on the following page.