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Life cycle

The Anopheles species of mosquito that carries malaria lays its eggs in water and needs blood to develop eggs. Once a mosquito bites an infected human, the sporozoites migrate to the salivary glands of the mosquito where they are passed on to the next human during feeding. The sporozoites travel to the liver and develop for seven to 30 days. Once they complete this asexual development, they rupture from the liver cells and invade the red blood cells of the victim. These blood-stage parasites cause the symptoms of malaria. They grow within the red cells and destroy them, releasing daughter cells (merozoites) that continue the cycle by invading other cells.

Classic attacks last six to 10 hours and occur every second or third day, depending on the strain of malaria infecting a person. As a result, symptoms tend to occur in cycles of attacks.⁴

Malaria presents with a fever; chills, which can be violent and have a sudden onset; headache; muscle aches; and fatigue. Gastrointestinal symptoms also can occur. Because the parasites multiply in the liver cells and enter the red blood cells, anemia and jaundice also may occur.⁴ Within hours, in addition to fever, the patient may develop hot, dry skin and a rapid, bounding pulse. As the patient’s temperature begins to drop, profuse sweating occurs.

This coincides with the rupture of red blood cells and may last up to 10 hours. This cycle of events may recur every several days, with frequency depending on the type of Plasmodium parasite causing the infection.⁴

“Malaria is diagnosed not by blood cultures, but by microscopic examination of a stained blood smear referred to as a ‘blood slide,’” Williams says. “This is the gold standard for diagnosing all four Plasmodium species of human malaria. The blood examination can tell you if the patient is infected, the level of infection, and which is the infecting species.”

Click here to view table.
(438K, requires Adobe Acrobat).
Reprinted with permission from The American Journal
for Nurse Practitioners 2004:8[3]: 57-58

Prevention and treatment

There are effective treatments for malaria as well as effective prophylaxis for people living in or traveling to malarious areas. Chemoprophylaxis for malaria is essential for prevention. It must be initiated several weeks before travel and must be continued several weeks after return in order to be effective.⁴

North America and Central America now are the only regions where parasites that carry malaria have not yet developed a resistance to chloroquinine. The alternative chemoprophylaxis for all other areas is mefloquine. For those unable to take mefloquine, atovaquone/proquanil (Malarone) and doxycycline can be used.

A variety of medications are available to treat malaria once a person has become infected. (See “Malaria Medications” sidebar.) Selection is based on the type of Plasmodium parasite, the likelihood of resistance in that region, as well as the severity and relapse rate of the disease.