Malaria

malaria, infectious parasitic disease that can be either acute or chronic and is frequently recurrent. Malaria is common in Africa, Central and South America, the Mediterranean countries, Asia, and many of the Pacific islands. In the United States it was found in the South and less frequently in the northern and western parts of the country.

Plasmodium falciparum is the most deadly of all the five Plasmodium parasites that typically cause malaria in humans. All the species require both the Anopheles mosquito and humans to complete the life cycle. Sexual reproduction of the protozoans occurs in the mosquito; an immature form is then transmitted to the human via the bite of the mosquito. In a person the parasite goes to the liver, replicates, and moves into the bloodstream, where it attacks red blood cells for their hemoglobin. Some of the plasmodia become sexually mature and are transmitted back to another biting mosquito. P. knowlesi, however, is primarily transmitted from monkeys to humans via mosquitoes.

Symptoms

At the onset of malaria, bouts of chills (ague) and fever lasting several hours and occurring every three or four days are the usual symptoms. If the disease is not treated, the spleen and the liver become enlarged, anemia develops, and jaundice appears. Death may occur from general debility, anemia, or clogging of the vessels of cerebral tissues by affected red blood cells. Cerebral malaria is most commonly seen in infants, pregnant women, and nonimmune travelers to endemic areas.

Immune Response

P. falciparum creates protein knobs on the surfaces of the red blood cells it attacks. These knobs attach the cell to the lining of the blood vessel, preventing its removal to the spleen for destruction. The parasite slows detection by the immune system by changing the makeup of the knobs periodically, substituting or rearranging its 150 "var" (variability) genes, a strategy unique to malaria. A pattern of remission and relapse results as the immune system learns each new "code" only to have it again changed. Patients with malaria gradually do develop immunity that modifies the course of the disease, but this immunity has a degree of strain specificity. Some of the Plasmodium species have the ability to persist in the liver and cause a new infection years after the original one.

Treatment and Control

The bark of the cinchona and its product, quinine, have been used in the treatment of malaria for centuries. After World War II, they were largely replaced by the synthetic analog chloroquine. The use of chloroquine, in addition to the use of DDT for mosquito control, was expected to eradicate the disease, but a World Health Organization campaign (1955–69) to eradicate the disease globally (by controlling mosquitoes long enough to allow the human population to become disease free) proved unsuccessful. Despite that, spraying successfully eradicated the disease in some areas (Sardinia, Japan, and Taiwan). In the United States, the disease, which had been endemic in many SE states, was eradicated in 1951.

In the 1960s several strains of the malarial parasite developed resistance to chloroquine. This, plus the growing immunity of mosquitoes to insecticides, caused malaria to become one the of world's leading re-emerging infectious diseases, infecting some 225 million people a year and killing more than 650,000 in 2010. Those numbers may be significant underestimates. By 2010, however, it was generally agreed that the death rate was again falling due to improved malaria control in Africa.

Mefloquine may be used in areas where the disease has become highly resistant to chloroquine, but some strains are now resistant to it and other drugs. Artemisinin (derived from sweet wormwood) in combination with other drugs is now in many cases the first-line treatment in many cases, but resistance to it also has developed, in parts of SE Asia. Amodiaquine in combination with sulfadoxine and pyrimethamine has also been shown to be effective, and malarone (atovaquone and proguanil) also is used for resistant strains. The use of combinations of drugs with different modes of actions increases the effectiveness of treatment and helps reduce the development of drug resistance.

Vaccines against malaria remain experimental. Spraying is still used to control malaria-transmitting mosquitoes, and more recently the use of mosquito nets treated with a long-lasting insecticide has become widespread. Fish that feed on mosquito larvae also have been employed to control mosquitoes.

See studies by M. Humphreys (2001), S. Shah (2010), B. Shore (2010), and R. M. Packard (2011).

The Columbia Encyclopedia, 6th ed. Copyright© 2014, The Columbia University Press.

Selected full-text books and articles on this topic

Yellow Fever, Black Goddess: The Coevolution of People and Plagues
Christopher Wills.
Addison Wesley, 1996
Librarian’s tip: Discussion of malaria begins on p. 152
Health, Wealth and Population in the Early Days of the Industrial Revolution
M. C. Buer.
George Routledge & Sons, 1926
Librarian’s tip: Chap. XVI "Malaria -- General Summary"
The Anthropology of Medicine: From Culture to Method
Lola Romanucci-Ross; Daniel E. Moerman; Laurence R. Tancredi.
Bergin & Garvey, 1997 (3rd edition)
Librarian’s tip: Chap. 8 "Malaria, Medicine, and Meals: A Biobehavioral Perspective"
Medical Anthropology in Ecological Perspective
Ann McElroy; Patricia K. Townsend.
Westview Press, 1996 (3rd edition)
Librarian’s tip: "Profile: Malaria and Agriculture" begins on p. 84
Human Races
Stanley M. Garn.
Charles C Thomas, 1961
Librarian’s tip: Chap. VI "Abnormal Hemoglobins, Malaria and Race"
Coupling between Annual and ENSO Timescales in the Malaria-Climate Association in Colombia
Poveda, German; Rojas, William; Quinones, Martha L.; Velez, Ivan D.; Mantilla, Ricardo I.; Ruiz, Daniel; Zualuaga, Juan S.; Rua, Guillermo L.
Environmental Health Perspectives, Vol. 109, No. 5, May 2001
PEER-REVIEWED PERIODICAL
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
Malaria Bites Back
Garner, David.
Geographical, Vol. 72, No. 2, February 2000
Breakthroughs Put the Bite on Malaria. (Innovations)(Cover Story)
Tenenbaum, David J.
Environmental Health Perspectives, Vol. 110, No. 12, December 2002
PEER-REVIEWED PERIODICAL
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
Malaria, Mosquitoes, and DDT: The Toxic War against a Global Disease
McGinn, Anne Platt.
World Watch, Vol. 15, No. 3, May 2002
Africa's Other Deadly Plague: Malaria Kills One Child under Age 5 Every 30 Seconds. DDT Stops the Disease, but Environmentalists Still Oppose It, despite That Controlled Use Seems Harmless to Humans. (Health)
Carter, Tom.
Insight on the News, Vol. 18, No. 28, August 5, 2002
The Changing Face of Disease: Implications for Society
Nick Mascie-Taylor; Jean Peters; Stephen T. McGarvey.
Routledge, 2004
Librarian’s tip: Chap. 6 "Protecting Pregnant Women from Malaria"
Malaria Parasites May Benefit from Climate Change
Kelleher, Maria.
Alternatives Journal, Vol. 26, No. 4, Fall 2000
History of Entomology in World War II
Emory C. Cushing.
Smithsonian Institution, 1957
Librarian’s tip: Chap. III "The Fight Against Anopheles Mosquitoes and Their Allies"
Missions for Science: U.S. Technology and Medicine in America's African World
David McBride.
Rutgers University Press, 2002
Librarian’s tip: Chap. 5 "Malaria and Modernization: The Decline"
Advancing Health in Developing Countries: The Role of Social Research
Lincoln C. Chen; Arthur Kleinman; Norma C. Ware.
Auburn House, 1992
Librarian’s tip: Chap. 6 "The Malaria Transition and the Role of Social Science Research"
Masons, Tricksters and Cartographers: Comparative Studies in the Sociology of Scientific and Indigenous Knowledge
David Turnbull.
Routledge, 2003
Librarian’s tip: Chap. 5 "Making Malaria Curable: Extending a Knowledge Space to Create a Vaccine"
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