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What is malaria?
Malaria is a serious disease that causes a fever and other flu-like symptoms. You can get it from a bite by an infected mosquito. Malaria is rare in the United States. It is found in over 90 countries around the world, mainly in Africa, Asia, Oceania, South America, and Central America. The risk of malaria is highest in parts of Oceania and in sub-Saharan Africa.
What causes malaria?
Malaria is caused by a bite from a mosquito infected with parasites. You cannot get malaria just by being near a person who has the disease.
What are the symptoms?
Most malaria infections cause a fever and flu-like symptoms, such as chills and muscle pain. Symptoms may come and go in cycles. Some types of malaria may cause more serious problems, such as damage to the heart, lungs, kidneys, or brain. These types can be deadly.
How is malaria diagnosed?
Your doctor will order blood tests to check for malaria.
How is it treated?
Medicines usually can treat the illness. But some malaria parasites may survive because they are in your liver or they are resistant to the medicine.
How is malaria prevented?
You may be able to prevent malaria by taking medicine before, during, and after travel to an area where malaria is present. But using medicine to prevent malaria doesn't always work. This is partly due to the parasites being resistant to some medicines in some parts of the world. Using insect repellents and mosquito nets also helps prevent malaria.
A bite from a parasite-infected mosquito causes malaria. There are five parasite species that infect people. The seriousness of the infection can vary depending on the type of parasite you are exposed to. And some species of the parasite are resistant to some antimalarial medicine. Your doctor can tell you which species are in the area you are traveling to and your level of risk.
How the disease spreads
Malaria is spread when an infected Anopheles mosquito bites a person. This is the only type of mosquito that can spread malaria. The mosquito becomes infected by biting an infected person and drawing blood that contains the parasite. When that mosquito bites another person, that person becomes infected.
When symptoms appear
Malaria can begin with flu-like symptoms, and fever is the most common symptom. If you develop a fever up to one year after traveling to a country where malaria is present, see your doctor.
The time from the initial malaria infection until symptoms appear (incubation period) is usually 7 to 30 days. But with infections from some parasite species, signs of illness may not appear for many months after exposure.
The incubation period may also be longer if you are taking medicine to prevent infection. If you have some immunity due to previous infections, your symptoms may be less severe, or you may not have any symptoms.
Variation in symptoms
In regions where malaria is present, people who get infected many times may have the disease but have few or no symptoms. Also, how bad malaria symptoms are can vary depending on your age, general health, and the kind of malaria parasite that you have.
Common symptoms of malaria
In the early stages, malaria symptoms are sometimes similar to those of many other infections caused by bacteria, viruses, or parasites. Symptoms may include:
- Nausea and vomiting.
- Body aches.
- Generally feeling sick.
Symptoms may appear in cycles. The time between episodes of fever and other symptoms varies with the specific parasite infection that you have.
In rare cases, malaria can lead to impaired function of the brain or spinal cord, seizures, or loss of consciousness. The most serious types of malaria infection can be life-threatening .
There are other conditions with symptoms similar to a malaria infection. It is important that you see your doctor to find out the cause of your symptoms.
When you're bitten by a malaria-infected mosquito, the parasites that cause malaria are released into your blood and infect your liver cells. The parasite reproduces in the liver cells, which then burst open. This allows thousands of new parasites to enter the bloodstream and infect red blood cells. The parasites reproduce again in the blood cells, kill the blood cells, and then move to other uninfected blood cells. This life cycle of malaria parasites can cause symptoms to come and go.
You may recover in a week to a month (or longer) after being infected by some parasite species, even without treatment. But other species of the parasite can cause life-threatening complications .
Malaria can be a very serious disease for anyone. But it can be especially serious for a pregnant woman and her developing fetus, for young children , and for people with certain medical conditions. Medicine choices are limited for a pregnant woman or a child. Infection with some malaria parasites can lead to death for a pregnant woman and her fetus.
To find out whether malaria is a problem in the country where you will be traveling and how you can reduce your risk for getting malaria, visit the CDC website www.cdc.gov/malaria/travelers/index.html.
What Increases Your Risk
The risk for getting malaria can vary widely among regions and people. Your doctor can tell you what your level of risk might be.
Things that increase your risk for getting malaria include:
- Living or traveling in a country or region where malaria is present.
- Traveling in an area where malaria is common and:
- Not taking medicine to prevent malaria before, during, and after travel, or not taking the medicine correctly.
- Being outdoors, especially in rural areas, after the sun sets. This is when the mosquitoes that transmit malaria are most active.
- Not taking steps to protect yourself from mosquito bites.
Your risk of getting malaria depends on your age, history of exposure to malaria, and whether you are pregnant. Most adults who live in areas where malaria is common have developed partial immunity to malaria because of previous infections. But young children who live in these areas and travelers to these areas are especially at risk for malaria because they have not developed this immunity. And people who move out of areas where malaria is common may gradually lose any immunity they've developed.
Because the immune system is suppressed during pregnancy, pregnant women are more likely than nonpregnant women to develop severe malaria. Getting malaria during pregnancy increases the risk for miscarriage and stillbirth.footnote 1
Also, pregnant women, young children , older adults, and people with other health problems are more likely to have serious complications if they get malaria. And malaria is more severe in people who have had their spleen removed (splenectomy).
You can take measures to reduce the risk of malaria if you live in areas where the disease is present or if you are traveling in these areas.
When should you call your doctor?
Call a doctor immediately if you have a fever and have been in an area in the past year where malaria is present. Make sure to tell the doctor about your travel history.
Watchful waiting is not appropriate for most travelers. If you have a question about your symptoms, or if you think you may have malaria, call your doctor.
Exams and Tests
The doctor may use a blood smear to check for malaria. During this test, a sample of blood is placed on a glass slide, prepared, and looked at under a microscope.
A blood smear test can help diagnose malaria. It can also help a doctor see what type of malaria parasite you have and how many parasites are in your blood. This can help with decisions about treatment.
If the first blood smear does not show malaria, your doctor may order more tests every 12 to 24 hours.
A blood test that can diagnose malaria quickly is also available. If this rapid test points to malaria, the results are usually confirmed with a blood smear.
Other useful tests that may be done include:
- Complete blood count (CBC), to check for anemia or evidence of other possible infections. Anemia sometimes develops in people with malaria, because the parasites damage red blood cells.
- A blood glucose test, to measure the amount of a type of sugar, called glucose, in your blood.
New tests that quickly diagnose malaria are available in some parts of the world. Testing has shown that they are reliable and easy to use.
Medicine can prevent malaria and is needed to treat the disease. Several things influence the choice of medicine, including:
- Whether the medicine is being used to prevent or to treat malaria.
- Your condition (such as your age, your health, or whether you are pregnant).
- How sick you are from malaria.
- Whether the malaria parasite may be resistant to certain medicines.
- Side effects of the medicine.
Malaria is rare in the United States. But it is widespread in other parts of the world. Find out about the risk for malaria before you travel internationally. The most accurate information about malaria risk and medicine resistance in specific countries is from the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO).
If you have been in an area where malaria occurs and you develop a fever up to one year after returning, your doctor may test you for malaria. If the tests do not show malaria, you may need additional tests to make sure that you do not have a malaria infection. During treatment, tests are repeated to follow the course of the infection and to see if the treatment is working.
Your age and health condition are important factors in selecting a medicine to prevent or treat malaria. Pregnant women , children , people who are very old, people who have other health problems, and those who did not take medicine to prevent malaria infection require special consideration.
Prevention of malaria involves protecting yourself against mosquito bites and taking antimalarial medicines. But public health officials strongly recommend that young children, pregnant women, and people who have no spleen avoid traveling to areas where malaria is common.
The most current information about malaria is available from the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO). If you are planning international travel, you can learn about the risk of malaria in that geographic area and the medicines recommended to prevent infection by contacting:
- The CDC at its toll-free phone number (1-855-856-4713) or at www.cdc.gov/malaria/travelers/index.html.
- Your doctor or local health department.
Prevent mosquito bites
To prevent mosquito bites, follow these guidelines:
- Stay inside when it is dark outside, preferably in a screened or air-conditioned room.
- Wear protective clothing (long pants and long-sleeved shirts).
- Use insect repellent with DEET.
- Use bed nets (mosquito netting). Nets that are treated with an insecticide such as permethrin or deltamethrin are preferred.
- Use flying-insect spray indoors around sleeping areas.
- Avoid areas where malaria and mosquitoes are present if you are at a higher risk (for example, if you are pregnant, very young, very old, or have other health issues).
Other steps that may be helpful in reducing the risk of malaria include wearing protective clothing, using aerosol insecticides in your house, and taking certain antimalarial medicines.
Medicines to prevent malaria
The selection of medicines to prevent malaria depends on the geographic region where you may be exposed to malaria and your health condition (such as being pregnant, being elderly or young, being sick, or having immunity or resistance to malaria, or having allergies or sensitivity to the medicine).
It is very important to take preventive medicines and to follow the correct schedule for taking them. The majority of people who become infected with malaria do not take preventive malaria medicines or do not follow the correct dosing schedule.
- Medicine to prevent malaria is most effective if you take the recommended dosage exactly as prescribed and for the length of time required.
- If you are to take the medicine once a week, take it on the same day of the week each week.
- Upon returning from an area where malaria is present, continue the medicine for the recommended length of time to ensure that all parasites have been eliminated from your body. You will need to take the medicine for 1 to 4 weeks after returning.
Medicines to prevent malaria are not necessary in all parts of the world. Contact your doctor or health department to find out if you need to take medicine to prevent malaria.
Scientists are studying malaria vaccines to see whether the vaccines are effectively preventing malaria infection. But no vaccine has been approved to prevent malaria.footnote 2 Work continues on improving vaccines for preventing malaria.
If you plan to travel in remote areas where malaria is present, it is very important to take preventive medicines and to follow the correct schedule for taking them. The majority of people who become infected with malaria did not take preventive malaria medicines or did not follow the correct dosing schedule.
If you are going to areas where there is no medical care available, you can get medicine before you leave and carry it with you while you travel. Your doctor will give you instructions on how to use the medicine if you should develop malaria symptoms. This is a temporary measure until you can get medical care. Seek medical care as soon as possible (ideally within 24 hours).
The most current information about the prevention and treatment of malaria is from the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO). Contact the CDC at its toll-free phone number (1-855-856-4713) or at www.cdc.gov/malaria. Or contact WHO at www.who.int/malaria.
You can take medicines called antimalarials to prevent and treat malaria. Malaria is a very serious disease, and its presence in many regions of the world is well known. So if you are traveling to an area where malaria is present, it is important to reduce the risk of infection by taking medicine before you travel, while you are in the area, and after you return home. Which medicine you take is based on:
- The country or areas where you will be traveling.
- The type of malaria parasite in the area where you will be traveling.
- The resistance of malaria parasites to certain medicines in the area where you will be traveling.
- Your health condition (for example, whether you are pregnant, elderly or young, sick, or have immunity or resistance to malaria).
During malaria treatment, your doctor may do daily blood smears to follow the course of the infection. Most medicines for malaria are ones you take by mouth. But you might get intravenous (IV) medicines if the infection is severe.
The medicines used may change as malaria parasites develop resistance and as new medicines are developed.
Medicines to prevent malaria
A doctor or local health department can consult the CDC for specific treatment guidelines for your travel destination. Standard medicines for preventing malaria include:
- Doxycycline. (Women who are pregnant and children younger than age 9 should not take this medicine.)
- Mefloquine. Do not take mefloquine if you have a history of active or recent depression or other mental illness, seizures, or some types of heart-rhythm problems.
Medicines to treat infections
Medicines used to treat malaria include the following:
- Doxycycline with quinine
- Clindamycin with quinine
Medicines to treat resistant infections
When a malaria infection is caused by resistant strains of the malaria parasite, treatment may be more difficult. The medicine used to treat your infection will depend on the type of parasite you have.
Antimalarials to prevent recurrences
Some people have recurring flu-like symptoms for years after the initial malaria infection. Primaquine can prevent malaria relapses. But pregnant women and people with specific enzyme deficiencies can't take primaquine. Ask your doctor if primaquine is safe for you.
What to think about
- Children, pregnant women, and people with weakened immune systems have a higher risk for malaria and for severe problems from malaria. It is especially important for people in these groups to see a doctor before traveling to areas where malaria is present.
- How effective medicines are in preventing and treating malaria depends on the medicine resistance of the parasites in the geographic location where the malaria infection occurs.
- If you are going to a location where malaria is present, it is very important to take preventive medicines and to follow the correct schedule for taking them. The majority of people who become infected with malaria did not take preventive malaria medicines or did not follow the correct dosing schedule.
Exchange blood transfusions
Exchange blood transfusions may be considered for treating severe cases of malaria.
Exchange blood transfusion is the quickest way to remove parasites. This procedure involves withdrawing blood from you at the same time that donor blood is being injected. During this exchange, the amount of blood in your body stays constant. Medicine to treat the infection is also given.
- U.S. Centers for Disease Control and Prevention (2011). Guidelines for treatment of malaria in the United States. Available online: http://www.cdc.gov/malaria/resources/pdf/treatmenttable.pdf.
- Suh KN, et al. (2004). Malaria. Canadian Medical Association Journal, 170(11): 1693–1702.
Other Works Consulted
- Day N (2008). Malaria. In M Eddleston et al., eds., Oxford Handbook of Tropical Medicine, 3rd ed., pp. 31–65. Oxford: Oxford University Press.
- Freedman DO (2008). Malaria prevention in short-term travelers. New England Journal of Medicine, 359(6): 603–612.
Current as of: July 1, 2021
Author: Healthwise Staff
E. Gregory Thompson MD - Internal Medicine
Adam Husney MD - Family Medicine
Elizabeth T. Russo MD - Internal Medicine
W. David Colby IV MSc, MD, FRCPC - Infectious Disease
Current as of: July 1, 2021
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