Malaria can be 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.

Signs and Symptoms of Malaria

If you become infected with a malaria-causing parasite, it typically takes between 10 days and four weeks for symptoms to appear.

But some people may develop symptoms as late as a year after infection. Symptoms of malaria are often described as flu-like and may include the following:

Fever
Shaking chills
Headache
Muscle aches
Fatigue
Profound weakness
Nausea and vomiting
Chest or abdominal pain
Cough

Some people with malaria experience cycles of “attacks,” which usually begin with shaking chills followed by a high fever, sweating, and then a return to normal body temperature. Each cycle typically lasts 6 to 10 hours.

A physical examination of someone with malaria may lead to the following findings:

High body temperature
Enlarged spleen
Mild jaundice (elevated levels of bilirubin)
Enlarged liver
Increased respiratory rate

In countries where malaria is rare, the disease may go unrecognized because its symptoms are often similar to those of other infections.

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 U.S. Centers for Disease Control and Prevention (CDC) 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.

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.

How Is Malaria Diagnosed?

It’s important to get an accurate diagnosis before starting treatment for malaria and to get the diagnosis as early as possible. Your treatment may be guided by test results from the diagnostic process.

To diagnose malaria, your doctor will ask you about your health and travel history, perform a physical examination, and order blood tests.

Different blood tests can detect:

Whether you have malaria
What kind of parasite is causing your malaria
Whether your parasite is resistant to certain drugs

In the United States and other areas where malaria is uncommon, diagnosing malaria can be difficult mostly because doctors may fail to consider malaria as a possible diagnosis and not order the right tests at the start.

Even if your doctor does order a test for malaria, it’s possible that the lab technician who examines your blood under a microscope won’t be able to recognize the malaria-causing parasite in some people, since they may not be familiar with the full range of its appearance.

Prognosis for Malaria

Malaria is a serious disease that can cause dangerous complications and may be fatal.

Factors that tend to make malaria more severe and dangerous include:

Infection with P. falciparum parasite (found in much of sub-Saharan Africa)
Being an infant or young child
Being an older adult
Being pregnant
Traveling from an area without malaria

No matter who you are, your chances of recovering fully from malaria are higher if you receive a prompt diagnosis and appropriate treatment.

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.

Preventive malaria drugs are effective if taken correctly, but sometimes people get malaria if they don’t take the pills as described — which can 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.

Treatment and Medication Options for Malaria

If you’re traveling to an area of the world where malaria is common, your doctor will most likely prescribe a preventive drug for you to take.

You may decide to choose or reject a specific medicine based on its possible side effects, dosing schedule, or safety during pregnancy.

If you develop malaria, your doctor will devise your treatment plan depending upon where you got infected, the parasite causing your malaria, and the severity of your symptoms, among other factors.

Medication Options

In general, the same drugs are used to help prevent malaria if you’re traveling to an area where it’s spread, and to treat malaria if you develop the disease.

Your doctor will recommend a specific course of drugs based on the parasite causing your malaria, how severe your condition is, your age, and whether you’re pregnant.

Commonly prescribed drugs for prevention and treatment of malaria include the following:

Artemisinin-Based Combination Therapies (ACTs) These combination medicines are each designed to fight malaria parasites in different ways.

Chloroquine This drug is preferred whenever it’s likely to be effective, but many parasites are now resistant to it.

Artesunate This intravenous medication may be used for severe malaria.

Other drugs that are less commonly used to help prevent or treat malaria include:

atovaquone and proguanil (Malarone )
doxycycline (Vibramycin) quinine and doxycycline (Monodox)
mefloquine (Lariam)
primaquine

Prevention of Malaria

After more than 30 years of research and development, the World Health Organization recommended the first vaccine for malaria in October 2021. WHO approved the new preventative treatment, known as Mosquirix, or the RTS,S/AS01 (RTS,S) vaccine, for children living in sub-Saharan Africa and other regions with moderate to high spread of the deadliest strain of the disease, which is caused by the parasite Plasmodium falciparum.

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.

Complications of Malaria

Certain people are more likely to experience severe or complicated malaria, including the following groups:

Young children
Pregnant women
People without any previous exposure to malaria parasites

When malaria is fatal, it’s usually because one or more serious complications have developed. Possible complications include:

Breathing Issues Malaria can cause fluid to accumulate in your lungs, making breathing difficult.

Organ Failure When you have malaria, your kidneys or liver can fail, or your spleen may rupture.

Brain Problems Damage to your red blood cells caused by malaria can block small blood vessels in your brain, leading to swelling and possible brain damage, also known as cerebral malaria. This condition can lead to coma or death.

Anemia Damaged red blood cells can result in inadequate circulation of oxygen and vital nutrients in your blood.

Low Blood Sugar Severe malaria can result in dangerously low blood glucose. Quinine (Qualaquin), a drug used to treat malaria, can also lead to reduced blood sugar levels. If your blood sugar drops too low, coma or death can result.

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

The WHO estimates that in 2021 there were still 247 million cases of malaria, leading to 619,000 deaths.

In 2021, about 96 percent of the world’s deaths from malaria occurred in 29 countries, with four African countries accounting for over half of all global malaria deaths.

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.

Related Conditions of Malaria

Mosquitoes are more than just a nuisance — they can carry serious and potentially fatal diseases like the Zika, chikungunya, and West Nile viruses, as well as malaria parasites.

You can reduce your risk for mosquito-borne illnesses by removing standing water that acts as their breeding ground, and by using effective repellents that contain picaridin, lemon, eucalyptus oil, or DEET.

It’s also important to put distance between yourself and mosquitoes by wearing long sleeves and pants, and staying in air-conditioned or screened areas whenever possible.

Some mosquito-borne illnesses have no specific treatment, while others — like malaria — have effective treatments that should be started as soon as possible.

Learn More About Mosquito Bites That Spread Disease

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

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

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

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

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.