Malaria

What is malaria?

Malaria is a serious, sometimes fatal, disease caused by the Plasmodium parasites P. falciparum, P. vivax, P. ovale and P. malariae. P. falciparum is the most widespread and dangerous of the malaria parasites, and is responsible for most of the severe forms of the disease and the majority of the deaths.

Where does malaria occur?

Malaria occurs in more than 100 countries and territories, primarily in Africa, Asia, and South and Central Americas. It remains a significant health problem in many parts of the world and negatively impacts social and economic development in endemic regions.

In many developing countries, malaria is a burgeoning disease due, at least in part, to the emergence of drug-resistant parasite strains, the decay in health care infrastructure, and difficulties in mosquito control. In endemic regions where transmission is high, individuals are continuously infected and gradually develop immunity to the disease. However, individuals in whom immunity has not yet developed or in whom immunity is diminished (e.g., children, pregnant women) remain highly susceptible.

How is malaria spread?

Humans contract malaria from the bite of a malaria-infected mosquito, when the parasites go from the saliva in the mosquito’s mouth into the person’s blood. The parasites then travel to the person’s liver and grow and multiply in the liver’s cells. The parasites enter the bloodstream and invade red blood cells, where they multiply again. Eventually, the red blood cells burst, freeing the parasites to attack other red blood cells. Toxins from the parasite are also released into the bloodstream, making the person feel sick and causing such symptoms as fever and anemia. Progressive malaria may also damage vital organs such as the nervous system, liver and kidney.

How many people get malaria?

The National Institute of Allergy and Infectious Diseases estimates that up to 2.7 million people die each year from malaria, most of them African children. Between 400 million and 900 million cases of acute malaria occur annually in African children alone. According to the Centers for Disease Control and Prevention, more than 1,300 new cases are reported in the United States every year in travelers returning from malaria-endemic areas.

How is malaria diagnosed?

Malaria is diagnosed by microscopically examining a blood sample for the presence of the parasites. For most people, symptoms begin 10 days to four weeks after infection, although a person may feel ill as early as eight days or as late as one year later.

Symptoms of malaria include fever and flu-like illness, including shaking chills, headache, muscle aches, and tiredness. Nausea, vomiting and diarrhea may also occur. Malaria may cause anemia and jaundice (yellow coloring of the skin and eyes) because of the loss of red blood cells. Infection with one type of malaria, P. falciparum, if not promptly treated, may cause kidney failure, seizures, mental confusion, coma and death. Two kinds of malaria (P. vivax and P. ovale) can relapse, and some parasites can rest in the liver for several months for up to four years after a person is bitten by an infected mosquito. When these parasites come out of hibernation and begin invading red blood cells, the person then becomes sick.

Can malaria be prevented?

Persons living in, and travelers to, any area of the world where malaria is transmitted may become infected. For this reason, people traveling to any of these areas should consult a health care provider four to six weeks before traveling for any necessary vaccinations and a prescription for an antimalarial drug. Mosquito and other insect bites should be prevented by using DEET insect repellent on exposed skin and flying insect spray indoors; wearing long pants and long-sleeved shirts, especially from dusk to dawn, when malaria-spreading mosquitoes tend to bite; and, if not in screened or air-conditioned housing, by sleeping under a mosquito net that has been dipped in permethrin insecticide.

How is malaria treated?

The clinical management of malaria depends on early diagnosis and immediate treatment. Malaria can be effectively treated with antimalarial drugs, including chloroquine and mefloquine. Furthermore, control of malaria transmission and prevention of disease using drugs and vector control strategies is essential. Although no vaccine yet exists for malaria, it is predicted that a successful vaccine could reduce morbidity and mortality and potentially reduce the spread of infection.

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