Malaria

Written by WebMD Editorial Contributors
Medically Reviewed by Dan Brennan, MD on July 22, 2022

Malaria is a serious and sometimes life-threatening tropical disease that is caused by a parasite and spreads through mosquitoes. It kills more than 445,000 people a year, many of them children in Africa.

Although malaria is almost wiped out in the United States, you can still get the disease when you travel to other parts of the world. The United States has about 1,700 malaria cases every year from immigrants and travelers returning from countries where malaria is more common.

These countries have climates that are hot enough for the malaria parasites and the mosquitoes that carry them to thrive. Before you travel, check the CDC’s website to see whether your destination is a hotspot for malaria. You may have to take pills before, during, and after your trip to lower your chances of getting it.

Malaria is caused by plasmodium parasites, which are carried by anophelesmosquitoes.

Only female mosquitoes spread the malaria parasites. When a mosquito bites a person who has malaria, it drinks the person’s blood, which contains the parasites. When the mosquito bites another person, it injects the parasites into that person. That’s how the disease spreads.

Once the parasites enter your body, they travel to your liver, where they multiply. They invade your red blood cells, which carry oxygen. The parasites get inside them, lay their eggs, and multiply until the red blood cell bursts. This releases more parasites into your bloodstream. As they attack more of your healthy red blood cells, this infection can make you very sick.

Malaria isn’t contagious, meaning it can’t be spread from person to person. But it can be spread in the following ways:

  • From a pregnant mother to their unborn baby
  • Sharing needles
  • Blood transfusions
  • Organ transplant

Malaria is most common in warm-weather climates. It’s found most often in:

  • Africa
  • South and Southeast Asia
  • The Middle East
  • Central and South America 
  • Oceania

There are five species of plasmodiumparasites that affect humans. Two of them are considered the most dangerous:

P. falciparum.This is the most common malaria parasite in Africa, and it causes the most malaria-related deaths in the world. P. falciparum multiplies very quickly, causing serious blood loss and clogged blood vessels.

P. vivax. This is the malaria parasite most commonly found outside of sub-Saharan Africa, especially in Asia and Latin America. This species can lie dormant, then rise up to infect your blood months or years after the mosquito bite.

Symptoms for malaria usually start about 10-15 days after the infected mosquito bite. Along with high fever, shaking chills, and sweating, they can include:

Throwing up or feeling like you're going to

Here are some things to keep in mind:

  • Because the signs are so similar to cold or flu symptoms, it might be hard to tell what you have at first.
  • Malaria symptoms don’t always show up within 2 weeks, especially if it’s a P. vivax infection.
  • People who live in areas with lots of malaria cases may become partially immune after being exposed to it throughout their lives. But this can change if they move to a place where they’re not around the parasite.

Given how quickly malaria can become life-threatening, it’s important to get medical care as quickly as possible. Young children, infants, and pregnant women have an especially high chance for severe cases of malaria.

Seek care if you get a high fever while living in or traveling to an area that has a high chance for malaria. You should still get medical help even if you see the symptoms many weeks, months, or a year after your travel.

Your doctor will ask you about your medical history and any recent travel and do a physical exam.

You’ll also get a blood test, which can tell your doctor:

  • If the parasite is in your blood
  • If certain medications will work against the parasite
  • If your body has ever made antibodies to fight off malaria 

Types of blood tests for malaria include:

Thick and thin blood smears. These are the most common and accurate malaria tests. A lab technician, doctor, or nurse will take some of your blood and send it to a lab to be stained to make any parasites show clearly. The technician spreads it on a glass slide and looks at it with a microscope. A thin blood smear, also called a blood film, is one drop of blood spread across most of the slide. A thick smear drops the blood on a small area. A normal test does two of each.

The number of malaria parasites in your blood can change each day. So your test might say you don’t have malaria even if you do. For that reason, you may need your blood drawn several times over 2 or 3 days for the best results.

Rapid diagnostic test. Also called RDT or antigen testing, this is a quick option when blood draws and smears aren't available. Blood taken from a prick on your finger is put on a test strip that changes color to show whether you have malaria or not.

This test usually can't tell which of the four common species of malaria parasites caused your infection. It also can’t tell whether the infection is minor or major. Your doctor should follow up all results with blood smears.

Molecular test. Also known as polymerase chain reaction test, it can identify the type of parasite, which helps your doctor decide which drugs to prescribe. This test is a good choice if your blood has low number of parasites or if the results of your blood smear are vague.

Antibody test. Doctors use this to find out if you've had malaria before. It looks for antibodies that show up in the blood after an infection.

Drug resistance test. Some malaria parasites are resistant to drugs. But doctors can test your blood to see if certain drugs will work.

Other blood tests. You may also have blood taken for a blood count and chemistry panel. This can tell your doctor how serious your infection is and if it's causing other problems, like anemia or kidney failure.

The treatment your doctor recommends will depend on things like:

  • The type of parasite you have
  • How bad your symptoms are
  • The geographic area where you got infected
  • Your age 
  • Whether you’re pregnant

Medications doctors use to treat malaria include:

  • Chloroquine or hydroxychloroquine. Your doctor may recommend one of these drugs if your symptoms aren’t serious and you’re in an area where the parasite hasn’t become resistant to chloroquine. 
  • Artemisinin-based combination therapy (ACT). This combines two medicines that work in different ways. They’re used to treat milder cases of malaria or as part of a treatment plan for more serious cases. 
  • Atovaquone-proguanil, artemether-lumefantrine. These combinations are other options in areas where the parasite has become resistant to chloroquine. They also can be given to children.
  • Mefloquine. This medication is another option if chloroquine can’t be used, but it’s been linked to rare but serious side effects related to your brain and is only used as a last resort.
  • Artesunate. If your symptoms are severe, your doctor may recommend this drug as treatment for the first 24 hours, then follow it with 3 days of artemisinin-based combination therapy. 

Some parasites that cause malaria have become resistant to almost all the medicines used to treat the illness, so researchers are always looking for new drugs that work.

Some people are more likely to have serious health problems if they get malaria, including:

  • Young children and infants
  • Older adults
  • People who travel from places that don’t have the vaccine
  • Pregnant women and their unborn children

These health problems can include:

In October 2021, the World Health Organization recommended RTS,S/AS01 (RTS,S), the world’s first malaria vaccine. This vaccine works against the P. falciparum malaria parasite. It can lower the rate of severe and life-threatening malaria for children in areas with moderate to high rates of the disease. If used widely, RTS,S has the potential to save tens of thousands of lives every year.

Children as young as 5 months old who are at risk for malaria will get the vaccine in four separate doses.

Experts have found that the vaccine could have major public health benefits. Models show that use of RTS,S can prevent one death for every 200 fully vaccinated children.

But the shot still isn’t as successful at disease control as most childhood vaccinations. Because of this, countries at high risk can’t rely just on the vaccine to stop the threat of malaria. But when it’s used with other prevention methods, like insecticide-treated bed nets, pesticides, and other remedies, the vaccine can greatly reduce illness and death from the disease.

Experts continue to plan long-term and sustainable methods to keep up supply of the RTS,S vaccine. This includes ways to make the vaccination more cost-effective, practical, and helpful for those most at risk.

Show Sources

SOURCES:

CDC: “Malaria: Frequently Asked Questions,” “About Malaria,” “Where Malaria Occurs,” “Malaria Information and Prophylaxis, by Country,” “Choosing a Drug To Prevent Malaria,” “Malaria’s Impact Worldwide,” “Treatment of Malaria: Guidelines for Clinicians,” "Malaria Diagnosis (United States)," "Malaria Diagnosis (U.S.) – Serology,” “Malaria Vaccine Recommended for Broader Use by WHO: “Best Thing Since Bed Nets.”

Medline Plus: “Malaria.”

World Health Organization: “Malaria,” “Q&A on RTS,S malaria vaccine.”

American Academy of Family Physicians: “Malaria.”

Medecins Sans Frontieres: “Malaria.”

Mayo Clinic: “Malaria.”

National Health Services: “Malaria.”

National Organization for Rare Disorders: “Rare Disease Database: Malaria.”

Malaria Consortium: “Artemisinin-based Combination Therapy.”

Lab Tests Line: “Malaria.”.”

Cleveland Clinic: "Malaria."

Malaria Vaccine Initiative: “RTS,S.”

Human Vaccines and Immunotherapeutics: “RTS,S/AS01 vaccine (Mosquirix™): an overview."

© 2022 WebMD, LLC. All rights reserved. View privacy policy and trust info