What Is Malaria?

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Malaria is an infection caused by a parasite that almost always is transmitted by mosquitoes. It's rare in the United States, where only about 1,700 cases are reported each year, according to the Centers for Disease Control and Prevention (CDC). By contrast, the World Health Organization reports that there are more than 200 million cases of malaria around the globe annually, and more than 400,000 deaths.

When someone in the United States comes down with malaria, it's usually because they were infected while visiting a region of the world where the disease is still common. The CDC says that approximately half of all travelers who contract malaria are immigrants who had visited friends and family in their country of origin.

It's always a good idea to be aware of the symptoms, complications, and other aspects of any potential illness. So, if you're traveling to a country where malaria is commonplace, you'll want to take certain precautions, such as packing plenty of insect repellent and possibly getting a vaccination before you leave.

Malaria Prevention Tips
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Malaria Symptoms

Most symptoms of malaria are the result of toxins that the parasite produces when it invades red blood cells. These toxins can cause anemia and, in many cases, blockages in small blood vessels throughout the body.

There are different species of parasites that can cause malaria. Interestingly, when it comes to symptoms the type of parasite doesn't matter as much as the life-cycle stage it's in.

The most common symptoms of malaria include a headache, fatigue, gastrointestinal problems (upset stomach, nausea, vomiting, and diarrhea), and muscle aches. Malaria is also characterized by cycles of fever that last from six to 24 hours, alternating with chills, shaking, and sweating. These cyclic symptoms usually are the ones that are likely to tip off a doctor that a patient may have malaria.

If malaria goes untreated, systems of the body other than the circulatory systems can be affected. This can cause less common symptoms such as coughing, shortness of breath, and low blood sugar (hypoglycemia).

Malaria can cause serious complications in as many as 60 percent of people who become infected, especially those with immune system deficiencies. Women who are pregnant are also especially susceptible to malaria and may have babies with birth defects or a malarial infection.

Possible Complications

Complications that are associated with malaria include:

  • Anemia
  • Thrombocytopenia, a condition in which a low blood platelet count interferes with normal clotting of blood
  • Kidney problems
  • Cerebral malaria (This isn't common but can be devastating or even fatal.)
  • Coma, loss of consciousness, or death


There are four species of the Plasmodium parasite, the specific organism that causes malaria. The most common way to become infected is by being bitten by a female Anopheles mosquito that would have picked up the parasite by biting another person who's infected.

Once the infective form of a Plasmodium parasite enters the body, it hunkers down in the liver, reproduces, and then enters the red blood cells. At this point, symptoms of malaria will begin to appear.

Besides direct infection from a mosquito bite, it's possible for malaria to be transmitted via a blood transfusion, though it's very rare in the United States. Babies sometimes acquire the parasite from their mothers before birth. People with immune system deficiencies, including women who are pregnant, are more likely to develop malaria after being bitten. 

Malaria is rare in the United States but is an ongoing problem in certain parts of the world with a tropical climate and a lot of still water where mosquitoes thrive. Not only are people who live in these regions at high risk, visitors are as well.


Diagnosing malaria can be tricky. The initial symptoms often are so vague and general that flu seems more likely than a parasitic infection. In addition, the lengthy incubation period means that characteristic symptoms of malaria may not appear for weeks or months after the mosquito bite took place. 

Once malaria is suspected, it can be diagnosed by examining a drop of blood under a microscope for the presence of malaria parasites. A non-invasive test such as computerized tomography (CT) or magnetic resonance imaging (MRI) of the brain is sometimes used if there's a possibility malaria has spread to the brain.

And because some of the symptoms of malaria are similar to those of certain other conditions, diagnostic tests may be necessary to definitively differentiate malaria from illness such as viral or bacterial infections, sepsis (a body-wide bacterial infection of the bloodstream), and even a sickle cell anemia crisis


Malaria is treated with a combination of home remedies and over-the-counter (OTC) drugs for managing symptoms and prescription medications. To alleviate symptoms such as fever, fatigue, and headache, taking steps such as getting plenty of fluids, eating well, managing your body temperature with blankets if you're chilled or ice packs if you're feverish, resting, and taking OTC pain relievers and anti-fever medications can help.

Malaria Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Man


Prevention is another key aspect of managing malaria and, in some ways, even more important. If you can manage to avoid the infection altogether, there'll be no need for treatment.

What You Can Do

Here are some steps to take if you're planning to be in a country where there's a risk of malaria—typically a tropical region where there is a lot of standing water, the preferred breeding ground for mosquitoes:

  • Pack protection—this means ample amounts of an effective bug spray that contains the insect repellent DEET.
  • Keep covered—Long sleeves and long pants can deter mosquitoes. If you're going to be sleeping where mosquitoes might gather at night, use a mosquito net.
  • Get immunized—The shot you get will depend on where you're going to different regions harbor different species of mosquitos.

A hesitation people often have about taking preventive (prophylactic) medications for malaria are the side effects. Of particular concern are hallucinations and other psychiatric symptoms which most often are associated with mefloquine.

Other malaria drugs have also been linked to side effects. Doxycycline, which is sold under several brand names including Acticlate and Vibramycin, can make skin especially sensitive and prone to sunburn and also cause gastrointestinal problems, for example.

Often side effects from malaria drugs can be avoided by taking other medications to prevent them. Given the seriousness of malaria, taking every precaution you can if you're going to travel somewhere that the infection is a risk is well worth it.

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4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. About Malaria

  2. World Health Organization. World malaria report 2018

  3. Malaria. Frequently Asked Questions (FAQs)

  4. Centers for Disease Control and Prevention. Malaria Transmission in the United States

Additional Reading
  • Medline Plus . "Mefloquine." Mar 15, 2016.
  • Tan, Kathrine R, Magill, Alan J, Parise, Monica E, and Arguin, Paul M. "Doxycycline for Malaria Chemoprophylaxis and Treatment: Report from the CDC Expert Meeting on Malaria Chemoprophylaxis." Am J Trop Med Hyg. Par 5, 2011; 84(4): 517-531. DOI: 10.4269/ajtmh.2011.10-0285.