What is malaria?

A parasite called Plasmodium causes malaria. A bite from an infected mosquito passes the parasite to humans. These mosquitoes are found in the tropics and subtropics in almost all countries. Nearly all cases of malaria in the U.S. occur in people who have traveled to other countries. Treatment removes the parasite from the blood.

After the parasites get into the body by a mosquito bite, they gather in the liver. After several days, infected red blood cells (RBCs) emerge from the liver. The parasites from these cells infect other RBCs.

What causes malaria?

If you are bitten by a Plasmodium-infected Anopheles mosquito, you can get malaria. Several different species of Plasmodium can infect mosquitoes. Some species cause more serious problems than others do. One species in particular (Plasmodium falciparum) can be life-threatening. It may cause liver and kidney failure along with shock. Two other species of Plasmodia can stay inactive (dormant) in the liver for many months or years, but then reactivate. Another species can stay alive in the body for many years, causing a long-term (chronic) low-level infection.

Who is at risk for malaria?

The risk of getting malaria depends on:

• Your travel destination

• How long your trip is

• Places where you will spend the evenings and nights. Anopheles mosquitoes bite most often during nighttime hours from dusk to dawn.

What are the symptoms of malaria?

Early stages of malaria may be like the flu. These are the most common symptoms of malaria:

• Fever

• Chills or sweats

• Headaches

• Muscle ache

• Extreme tiredness (fatigue)

• Upset stomach (nausea)

• Ill feeling (malaise)

• Sometimes vomiting, diarrhea, and coughing

Symptoms of malaria often start from 7 to 30 days after the mosquito bite. Or it can develop as late as several months or years after leaving a place where there is malaria.

Always talk with your healthcare provider for a diagnosis.

How is malaria diagnosed?

Your healthcare provider will ask about your past health and travel history and do a physical exam. You may also have blood tests to rule out other possible infections. Using a microscope and other types of testing, your provider can confirm if you have malaria parasites in your blood.

How is malaria treated?

Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.

Treatment in the early stages works best. Delaying treatment can lead to serious problems. Treatment for malaria will vary depending on which species of Plasmodium you were infected with.

Treatment may include:

• Antibiotics. These medicines kill the parasite in the blood.

• Supportive care. You may need medicines such as acetaminophen for fever and IV (intravenous) fluids if there are complications.

What are possible complications of malaria?

Complications of malaria are more common with falciparum malaria. It's the most potentially life-threatening type of the disease. People with a severe case of this type may have:

• Liver and kidney failure

• Ruptured spleen

• Convulsions

• Shock

• Coma

• Ill effects on the baby if the infected person is pregnant

• Death

Can malaria be prevented?

You can prevent malaria by using antimalarial medicines when you may be exposed to the disease. Also take measures against mosquito bites. These include using mosquito nets when sleeping at night and insect repellent during the day.

The World Health Organization has approved a malaria vaccine for use in children living in areas of the world at high risk for malaria. Over the next few years, this vaccine will be increasingly offered to children who are at the highest risk. Other malaria vaccines are in development.

When should I call my healthcare provider?

If you become ill with a fever during or after travel in a malaria risk area, get medical care right away. Tell your healthcare providers of your recent travel. Don’t assume you have the flu or some other disease without having a lab test to find out if the symptoms are caused by malaria.

Key points about malaria

• Malaria is a disease caused by a parasite. A bite from an infected mosquito passes the parasite to humans. 

• Nearly all cases of malaria in the U.S. are in people who have traveled to other countries.

• Early symptoms of malaria may be like the flu.

• If you become ill with a fever during or after travel in a malaria risk area, get medical care right away. Tell your healthcare providers of your recent travel history.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your provider if you have questions.