Malaria (cont.)

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What is malaria?

Malaria is an infectious disease caused by a parasite, Plasmodium, which infects red blood cells. Malaria is characterized by cycles of chills, fever, pain, and sweating. Historical records suggest malaria has infected humans since the beginning of mankind. The name "mal aria" (meaning "bad air" in Italian) was first used in English in 1740 by H. Walpole when describing the disease. The term was shortened to "malaria" in the 20th century. C. Laveran in 1880 was the first to identify the parasites in human blood. In 1889, R. Ross discovered that mosquitoes transmitted malaria. Of the four common species that cause malaria, the most serious type is Plasmodium falciparum malaria. It can be life-threatening. However, the history of malaria marches on. Another relatively new species, Plasmodium knowlesi, is also a dangerous species that is typically found only in long-tailed and pigtail macaque monkeys. Like P. falciparum, P. knowlesi may be deadly to anyone infected. The other three common species of malaria (P. vivax, P. malariae, and P. ovale) are generally less serious and are usually not life-threatening. It is possible to be infected with more than one species of Plasmodium at the same time.

Currently, about 660,000 deaths per year worldwide are due to Plasmodium infections. The majority (about 86%) occur in children under 5 years of age in sub-Saharan African countries. There are about 154 to 289 million new cases per year worldwide. Most people diagnosed in the U.S. (about 1,500 people per year) obtained their infection outside of the country, usually while living or traveling through an area where malaria is endemic.

What are malaria symptoms and signs?

The symptoms characteristic of malaria include flu-like illness with fever, chills, muscle aches, and headache. Some patients develop nausea, vomiting, cough, and diarrhea. Cycles of chills, fever, and sweating that repeat every one, two, or three days are the most typical symptoms. The classical textbook hot-cold stages (rarely observed) occur over about six to nine hours with a cold stage marked by shivering and feeling cold and then followed by a hot stage when fever, headaches, vomiting, and occasionally seizures occur. Then sweating occurs and then the patient becomes afebrile but is tired or exhausted. There can sometimes be vomiting, diarrhea, coughing, and yellowing (jaundice) of the skin and whites of the eyes due to destruction of red blood cells and liver cells. Infrequently, a rash (skin lesions that are small itchy, reddish collections of papules) may occur.

People with severe P. falciparum malaria can develop bleeding problems, shock, liver or kidney failure, central nervous system problems, coma, and can die from the infection or its complications. Cerebral malaria (coma, or altered mental status or seizures) can occur with severe P. falciparum infection. It is lethal if not treated quickly; even with treatment, about 15%-20% die.

Medically Reviewed by a Doctor on 10/11/2013

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