Malaria is caused by a parasite. It is passed to humans by the bite of an infected Anopheles mosquito.
What is malaria?
A parasite called Plasmodium causes malaria. A bite from an infected mosquito passes the parasite to humans. These mosquitoes are found in the tropics and subtropics in almost all countries. Nearly all cases of malaria in the U.S. occur in people who have traveled to other countries. Treatment removes the parasite from the blood.
After the parasites get into the body by a mosquito bite, they gather in the liver. After several days, infected red blood cells (RBCs) emerge from the liver. The parasites from these cells infect other RBCs.
What causes malaria?
If you are bitten by a Plasmodium-infected Anopheles mosquito, you can get malaria. Several different species of Plasmodium can infect mosquitoes. Some species cause more serious problems than others do. One species in particular (Plasmodium falciparum) can be life-threatening. It may cause liver and kidney failure along with shock. Two other species of Plasmodia can stay inactive (dormant) in the liver for many months or years, but then reactivate. Another species can stay alive in the body for many years, causing a long-term (chronic) low-level infection.
Who is at risk for malaria?
The risk of getting malaria depends on:
Your travel destination
How long your trip is
Places where you will spend the evenings and nights. Anopheles mosquitoes bite most often during nighttime hours from dusk to dawn.
What are the symptoms of malaria?
Early stages of malaria may be like the flu. These are the most common symptoms of malaria:
Chills or sweats
Extreme tiredness (fatigue)
Upset stomach (nausea)
Ill feeling (malaise)
Sometimes vomiting, diarrhea, and coughing
Symptoms of malaria often start from 7 to 30 days after the mosquito bite. Or it can develop as late as several months or years after leaving a place where there is malaria.
Always talk with your healthcare provider for a diagnosis.
How is malaria diagnosed?
Your healthcare provider will ask about your past health and do a physical exam. You may also have blood tests to rule out other possible infections. Using a microscope and other types of testing, your provider can confirm if you have malaria parasites in your blood.
How is malaria treated?
Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.
Treatment in the early stages works best. Delaying treatment can lead to serious problems. Treatment for malaria will vary depending on which species of Plasmodium you were infected with.
Treatment may include:
Antibiotics. These medicines kill the parasite in the blood.
Supportive care. You may need medicines such as acetaminophen for fever and IV (intravenous) fluids if there are complications.
What are possible complications of malaria?
Complications of malaria are more common with falciparum malaria. It is the most potentially life-threatening type of the disease. People with a severe case of this type may have:
Liver and kidney failure
Burst (ruptured) spleen
Ill effects on the baby if the infected person is pregnant
Can malaria be prevented?
You can prevent malaria by using antimalarial medicines when you may be exposed to the disease. Also take measures against mosquito bites. These include using mosquito nets when sleeping at night and insect repellent during the day.
When planning to travel to a place where malaria occurs, talk with your healthcare provider well before your trip. They can give you medicine to prevent malaria. But travelers to different countries may be given different advice. Travelers visiting cities or rural areas where there is no risk of malaria may not need preventive medicines. Give your provider an exact list of the places you will be. Your provider can then decide what treatment you need.
Several medicines can prevent malaria in travelers. Deciding which medicine is best depends on several factors. These include:
The type of malaria that is common where you are going
Your health history
The amount of time you have before your trip
For treatment to work, you must take the medicine exactly as prescribed. You must start these medicines before you arrive at your destination. And you must continue them for a certain number of days or weeks after your return. The time period depends on which medicine is prescribed.
Protection from mosquitoes
You are still at risk for malaria even when using protection.
To prevent mosquito bites, the CDC advises you:
Use insect repellent on exposed skin. Choose repellent that has 20% to 35% N,N-Diethyl-meta-toluamide (DEET).
Wear long-sleeved clothing and long pants if you are outdoors at night.
Use a mosquito net over the bed if your bedroom is not air-conditioned or screened. For more protection, treat the mosquito net with the insecticide permethrin.
Spray an insecticide or repellent on clothing. Mosquitoes may bite through thin clothing.
Spray pyrethrin or a similar insecticide in your bedroom before going to bed.
Vitamin B and ultrasound devices don't prevent mosquito bites. You can find important, current information about prevention and precautions at www.cdc.gov/malaria.
When should I call my healthcare provider?
If you become ill with a fever during or after travel in a malaria risk area, get medical care right away. Tell your healthcare providers of your recent travel. Don’t assume you have the flu or some other disease without having a lab test to find out if the symptoms are caused by malaria.
Key points about malaria
Malaria is a disease caused by a parasite. A bite from an infected mosquito passes the parasite to humans.
Nearly all cases of malaria in the U.S. are in people who have traveled to other countries.
Early symptoms of malaria may be like the flu.
If you become ill with a fever during or after travel in a malaria risk area, get medical care right away. Tell your healthcare providers of your recent travel history.
Tips to help you get the most from a visit to your healthcare provider:
Know the reason for your visit and what you want to happen.
Before your visit, write down questions you want answered.
Bring someone with you to help you ask questions and remember what your provider tells you.
At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
Ask if your condition can be treated in other ways.
Know why a test or procedure is recommended and what the results could mean.
Know what to expect if you do not take the medicine or have the test or procedure.
If you have a follow-up appointment, write down the date, time, and purpose for that visit.
Know how you can contact your provider if you have questions.
News & Publications
The purpose of this study was to quantify and describe the amount of waste generated by an Emergency Department, identify deviations from waste policy and explore areas for waste reduction.
Our publication keeps health care professionals up to date on the latest research and clinical advances from Mass General.
News and notes from the largest hospital-based research program in the United States
The Patient Gateway provides secure online access to your health information whenever you need it. Check upcoming appointments, communicate with your doctor’s office, review medications and pay medical bills—all seamlessly online 24/7.