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A B C D E F G H I J K LM N O P Q R S T U V W X Y Z 0-9
(A-Z listing includes diseases, conditions, tests and procedures)


What is malaria?

Malaria is caused by a parasite. It is passed to humans by the bite of an infected Anopheles mosquito. 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 enter the body by a mosquito bite, they disappear from the circulating blood within an hour and gather in the liver. After several days, infected red blood cells (RBCs) emerge from the liver and infect other RBCs.

More Information About Infectious Diseases from Johns Hopkins Medicine

A female mosquito with antennae, maxillary palp and labella shown under magnification.

Using Mosquito Brains to Fight Malaria

Since mosquitoes use their sense of smell to find us, understanding how different odors guide their blood-seeking behavior could help us foil their efforts.

Read more.

What causes malaria?

Malaria is caused by when you are bitten by an Anopheles mosquito that is infected by a Plasmodium species parasite. There are several different species of Plasmodium that can infect humans and cause illness. Some cause more serious problems than others do. One type in particular can be life-threatening and may cause liver and kidney failure. Another can remain dormant in the liver for many months or years.

Who is at risk for malaria?

The risk of getting malaria depends on:

  • Your destination

  • Duration of your travel

  • Place 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 similar to the flu. The following are the most common symptoms of malaria. However, each person may experience symptoms differently. Symptoms may include:

  • Fever

  • Chills

  • Headache

  • Muscle ache

  • Fatigue

  • Nausea

  • Sometimes vomiting, diarrhea, and coughing

Symptoms of malaria usually appear from 7 to 30 days after the mosquito bite. However, malaria they can develop as early as 6 to 8 days after being bitten by an infected mosquito or as late as several months after leaving an area where there is malaria.

Always consult your health care provider for a diagnosis.

How is malaria diagnosed?

In addition to a complete medical history and physical exam, diagnostic procedures for malaria may include blood tests to rule out other possible infections. Infected red blood cells from a person's blood sample can also often be seen under the microscope.

How is malaria treated?

Specific treatment for malaria will be determined by your health care provider based on:

  • Your overall health and medical history

  • Extent of the condition

  • Your tolerance for specific medications, procedures, or therapies

  • Expectations for the course of the condition

  • Your opinion or preference

Malaria can be treated effectively in its early stages, but delaying treatment can have serious consequences. Treatment for malaria will vary depending on the country where you were infected and the severity of the disease.

Treatment involves taking medications that kill the parasite in the blood.

What are the complications of malaria?

Complications of malaria are more common with falciparum malaria, which is the most potentially life-threatening. People with severe falciparum malaria may develop liver and kidney failure, convulsions, and coma.

Can malaria be prevented?

Malaria can be prevented by the use of antimalarial drugs and protection measures against mosquito bites.


When planning to travel to an area where malaria occurs, talk with your health care provider well in advance of your departure. Drugs to prevent malaria can be prescribed, but travelers from different countries may receive different recommendations. Travelers visiting only cities or rural areas where there is no risk of malaria may not need preventive drugs. An exact itinerary is necessary to determine what treatment you need.

There are several medications to prevent malaria in travelers. Determining which medication is best depends on several factors, such as your medical history and the amount of time before your scheduled departure. For treatment to be effective, you must take the medication exactly as prescribed. These medications must be started before you arrive at your destination and continued for a specific number of days or weeks after your return, depending on which medication is prescribed.

Protection from mosquitoes

Be aware that you are still at risk for malaria even with the use of protection.

To avoid mosquito bites, the CDC recommends the following:

  • Apply insect repellent to exposed skin. The recommended repellent contains 20 to 35 percent N,N-Diethyl-meta-toluamide (DEET).

  • Wear long-sleeved clothing and long pants if you are outdoors at night.

  • Use a mosquito net over the bed if your bedroom is not air-conditioned or screened. For additional protection, treat the mosquito net with the insecticide permethrin.

  • Spray an insecticide or repellent on clothing, as mosquitoes may bite through thin clothing.

  • Spray pyrethrin or a similar insecticide in your bedroom before going to bed.

Note: According to the CDC, vitamin B and ultrasound devices do not prevent mosquito bites. Important, current information about prevention and precautions is available online from the CDC.

When should I call my health care provider?

If you become ill with a fever during or after travel in a malaria risk area, seek prompt medical attention and tell your health care providers of your recent travel. Don’t assume you have the flu or some other disease without completing a lab test to determine if the symptoms are caused by malaria.

Key points about malaria

  • Malaria is a disease caused by a Plasmodium species parasite that is transmitted to humans by the bite of an infected Anopheles mosquito.

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

  • Early stages of malaria may be similar to the flu.

  • If you become ill with a fever during or after travel in a malaria risk area, seek prompt medical attention and tell your health care providers of your recent travel history.

Next steps

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

  • 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 names of new medicines, treatments, or tests, and any new instructions your provider gives you.

  • 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.

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