Malaria is a life-threatening disease caused by a parasite that’s carried by certain mosquitoes in warm climates.

The parasites that cause malaria attack your red blood cells, typically causing a high fever, shaking chills, and other symptoms that may develop into life-threatening complications.

Malaria is a major threat to human health worldwide and a leading cause of illness and death in many developing countries, especially in young children.Pregnant women are also more vulnerable to the disease.

Most cases of malaria occur in sub-Saharan Africa and South Asia, but the disease also affects several other areas of the world, including Latin America, Southeast Asia, and Oceania.

Causes and Risk Factors of Malaria

Malaria occurs when parasitic protozoa of the genus Plasmodium get into your bloodstream.

Usually, malaria gains access into your blood from the saliva of a female Anopheles mosquito after the insect feeds on someone else with the disease.

In rare cases, malaria can also be transmitted from a mother to her child during pregnancy, from a blood transfusion or organ transplant, or from shared needles.

Parasites That Cause Malaria

There are five species of parasites known to cause malaria in humans.Some are more dangerous than others, but all can potentially cause severe disease and death:

P. falciparum This species is found in tropical and subtropical regions worldwide, but it’s especially common in Africa.

Falciparum malaria is the deadliest form of malaria because it multiplies rapidly, rupturing red blood cells. These damaged cells can clog small blood vessels, including in your brain.

P. vivax This species is found mostly in Asia, Latin America, and some parts of Africa.

P. vivax has a dormant stage in the liver. As a result, it can invade your blood up to two years after the infecting mosquito bite, making you sick again.

These delayed infections (relapses) can also reintroduce malaria to areas of the world where it was previously eliminated.

P. ovale This species is found mostly in Africa and the islands of the western Pacific. Like P. vivax, it can also remain dormant in your liver and cause relapses months or years later.

P. malariae This species is found worldwide. If untreated, it can cause a chronic lifelong infection or serious complications like nephrotic syndrome, a serious kidney disease.

P. knowlesi This species is found throughout Southeast Asia in macaque monkeys. It can also infect humans and progress rapidly to severe infection.

Malaria Risk Factors

There hasn’t been ongoing transmission of malaria in the United States since the early 1950s. The disease was effectively eliminated through a combination of water management, insecticides, and other treatment and prevention efforts.

But there are numerous cases each year of travelers leaving the United States, becoming infected, and returning to the country.

Occasionally, a small outbreak of malaria occurs in the United States, when local mosquitoes spread the disease from an infected traveler. So far, these episodes have been contained effectively, without malaria posing an ongoing threat.

The main risk factors for malaria in travelers include aspects of the destination and certain traits of the traveler.

Destination-related risk factors include:

Geographic region Areas of the world where malaria is endemic (circulates widely) tend to be tropical, subtropical, or at low elevations.

This is because warm temperatures are needed for the parasite to mature within mosquitoes.

The Centers for Disease Control and Prevention has a table of malaria information by country to see if your travel destination has endemic malaria.

In general, your risk is higher if you travel to sub-Saharan Africa than most areas of Asia or the Americas.

Type of accommodation Lodging that has window screens or air conditioning poses a lower malaria risk than open-air or tented accommodations.

You’re also at greater risk if your itinerary includes outdoor dining or entertainment, especially in the evening.

Season Hotter and wetter times of the year tend to be associated with greater malaria transmission.

One reason for this is that rainfall can create collections of water, encouraging the breeding of mosquitoes that transmit malaria.


Plan Announced to Eliminate Malaria Worldwide in a Generation

It’s possible that during cooler times of the year, you won’t need to take as many preventive measures if you travel to certain areas where malaria is endemic.

Risk factors related to the type of traveler include:

Pregnancy If possible, travel to an area with malaria transmission should be delayed until after giving birth. If delaying the trip isn’t possible, it’s essential to take a drug to help prevent malaria.

Malaria during pregnancy raises the risk of miscarriage, premature birth, and low birth weight, reducing the chances of the baby’s survival.

Visiting friends and relatives People who are originally from an endemic region but have moved, and then go back to visit, are the group at highest risk for malaria in the United States.

A lot of these people don’t know that they need to take medicine to prevent malaria. Some may believe they have immunity from growing up in a malaria-prone area, but any such immunity is only temporary and is quickly lost when someone moves away.

People who visit friends and relatives, as opposed to tourists or business travelers, are also likely to spend more time in the destination country and to stay in private residences rather than hotels.

Duration of Malaria

Malaria can be frustratingly difficult to recognize, in part due to how long it can take to cause symptoms. That’s because the parasite that causes malaria travels to your liver, where it can lie dormant for as long as a year.

More typically, this incubation period, defined as the time after infection occurs but before clinical symptoms develop, usually lasts from 7 to 30 days, depending on the type of parasite.

Taking a preventive drug before you travel to an area with malaria can also lengthen the incubation period and delay the appearance of symptoms by weeks or even months.

Once you develop symptoms, you’ll probably experience “attacks” of malaria that last 6 to 10 hours. These attacks may occur every two to three days, but they don’t always follow this rule.Malaria can be persistent if it isn’t properly or successfully treated. That means it can cause bouts of recurrent symptoms for years, especially if it’s a mild form of the disease.

There are medications that can help prevent illness if you become infected, but none of these drugs is 100 percent effective.

Preventing mosquito bites is crucial to preventing malaria. Anopheles mosquitoes bite between dusk and dawn and sometimes like to live inside houses.

Ways to help prevent bites from Anopheles mosquitoes include:
  • Avoid outdoor exposure between dusk and dawn
  • Wear clothing that minimizes exposed skin
  • Wear insect repellent on your skin that contains DEET
  • Sleep under a bed net treated with an insecticide (such as permethrin)
  • Wear clothing treated with permethrin or spray clothing with permethrin spray (available at outdoor supply stores)
  • Stay in well-screened or air-conditioned rooms
These measures can also help prevent many other illnesses spread by mosquitoes, ticks, and sand flies.

Research and Statistics: How Many People Get Malaria?

Almost half the world’s population lives in areas where malaria is a concern, according to the World Health Organization (WHO).

Between 2010 and 2016, worldwide efforts successfully reduced the prevalence of malaria by 18 percent. The largest regional decline, 48 percent, occurred in South Asia and Southeast Asia.

But the WHO estimates that in 2016, there were still 216 million cases of malaria, leading to 445,000 deaths.

In a troubling development, malaria cases started to go up again from 2014 to 2016, with the greatest rise seen in Latin America.

In 2016, 91 percent of the world’s deaths from malaria occurred in sub-Saharan Africa, with most of the remaining 9 percent occurring in Asia and Latin America.There are about 2,000 cases of malaria each year in the United States, according to the CDC.Almost all of them occur in people who recently traveled to a country where malaria is transmitted.

Resources We Love

Malaria can be a confusing and scary disease. The following organizations and websites offer information and support that may help you understand and deal with a new diagnosis, as well as how to take the necessary precautions to protect yourself.

Centers for Disease Control and Prevention — Malaria

This online portal can connect you to information on nearly every aspect of the disease, from facts and statistics to information for travelers. You can dive into details about how malaria is diagnosed and treated, or read about prevention efforts around the world.

World Health Organization — Global Malaria Programme

This online resource links to information on various aspects of the WHO’s efforts to fight malaria, from controlling mosquitoes to diagnostic testing and new treatment strategies to disrupt transmission of the disease.

National Institute of Allergy and Infectious Diseases — Malaria

This division of the U.S. National Institutes of Health focuses on disease research, including developing a vaccine for malaria and other diseases spread by mosquitoes.

MedlinePlus — Malaria

This web page links to information on a number of different topics, including choosing a drug to help prevent malaria, spotting counterfeit drugs, and diagnostic tests for the disease.

Additional reporting by Erin Archer Kelser, RN.

Editorial Sources and Fact-Checking

  1. Malaria. Centers for Disease Control and Prevention. August 20, 2020.
  2. Malaria. Mayo Clinic. December 13, 2018.
  3. Key Points: World Malaria Report 2017. World Health Organization. November 29, 2017.


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