Malaria
Anopheles freeborni photo. CDC/James Gathany
What is malaria?
Malaria is a serious mosquito-borne illness caused by a microscopic parasite that infects red blood cells. There are four primary species of malaria parasites that can infect humans:
Plasmodium falciparum, P. malariae, P. ovale, and P. vivax. There are other species of Plasmodium that infect animals. In recent years, a fifth species,
P. knowlesi, has been shown to cause human malaria in Southeast Asia. While infection with any of the malaria species can make a person very ill,
P. falciparum, the predominant strain of malaria in Africa, causes severe disease and, without treatment, death.
How is malaria spread?
Malaria parasites are spread by the bites of infected female Anopheles mosquitoes.
Where is malaria found?
Malaria is most prevalent in warmer regions of the world – typically tropical and subtropical areas, including over 100 countries in Central and South America, Hispaniola (Haiti and the Dominican Republic), Africa, the Indian subcontinent, Southeast Asia, the Middle East, and Oceania. Although risk-free for many years, and despite its more temperate climate, the Korean peninsula is again experiencing malaria along the demilitarized zone (DMZ).
Map of Malaria transmission from the CDC
How many people get malaria?
In 2016 an estimated 216 million cases of malaria occurred worldwide and 445,000 people died, mostly children in the African Region. About 1,700 cases of malaria are diagnosed in the United States each year. The vast majority of cases in the United States are in travelers and immigrants returning from countries where malaria transmission occurs, many from Sub-Saharan Africa and South Asia.
What is the malaria life cycle?
In humans, malaria parasites develop and multiply first in the liver and then in the blood, rupturing liver cells and red blood cells in the process. When a female mosquito feeds on the blood of the infected human, it picks up certain “gametocyte" forms (the male and female forms) of the blood-stage parasites. If the parasite is picked up by an Anopheles mosquito, the gametocytes will develop and multiply into sporozoites, which ultimately reside within its salivary glands. When the Anopheles mosquito feeds on another human, the sporozoites are transferred with the mosquito's saliva into the new human, and the infectious cycle starts over.
Can malaria be transmitted from person-to-person?
No. Malaria cannot be transmitted from person-to-person like a cold or the flu. You cannot get malaria through casual contact with an infected person (e.g., touching or kissing a person with the disease). Mosquito bites are the primary method of malaria transmission. Other, rare means of infection include blood transfusion, organ transplant, use of needles or syringes contaminated with blood, or congenital transmission (infected mother passing the parasite to her fetus during pregnancy).
What are the symptoms of malaria and how quickly do they appear?
Symptoms generally include the following at the onset of illness: fever, shaking chills, sweats, headache, muscle aches, exhaustion, nausea, vomiting and diarrhea. Infection with
P. falciparum, if not promptly treated, may advance to complicated (severe) malaria and lead to kidney failure, seizures, coma, acute respiratory distress condition, and death. Symptoms usually appear within 7-30 days after being bitten by an infected mosquito, but can take up to 1 year to develop.
How is malaria diagnosed and treated?
Anyone sick with flu-like symptoms suspects they may have malaria should seek immediate medical attention. Malaria is diagnosed based on symptoms, followed by laboratory confirmation. The most widely used test is microscopy. In this test, a drop of the patient’s blood is smeared across a slide, stained with a special dye, and then examined under a microscope for presence of the malaria parasites. If diagnosed early, malaria can be effectively treated with a variety of prescription drugs. Treatment should happen as early as possible to keep it from becoming life-threatening.
How long does a person remain infected with malaria?
If the correct drugs are administered for the proper length of time, malaria can be cured and all the parasites eliminated from the body. However, if the disease is improperly treated, relapses can occur and parasites can persist in the blood for years or decades.
How can malaria be prevented?
There is no vaccine for malaria. However, there are oral prescription drugs that can prevent travelers from getting sick while visiting malaria-endemic areas. Talk to you physician about preventive medications (chemoprophylaxis) for malaria. It is very important to continue to take medication for the full proscribed amount of time, even after returning home, because most malaria medications only treat the blood stage parasite. If the parasite is still in the liver stage when you stop taking the medication, you will get sick after you get home.
It is also important to protect yourself from mosquito bites by using the DoD Insect Repellent System. It incorporates insect repellent on the uniform, DEET, picaridin, or IR3535 repellent on exposed skin, a properly worn uniform, and sleeping inside a insecticide-treated bed net.
Select the image for more information on the DoD Insect Repellent System.
