Malaria

A parasite is an organism that depends on another organism, known as a host, for food and shelter. For my paper I have chosen to research Malaria. Malaria is an infectious disease that is widespread in tropical and subtropical regions. It infects between 300 and 500 million people every year and causes between one and three million deaths annually, mostly among young children in Sub-Saharan Africa.

Malaria is one of the most common infectious diseases and an enormous public-health problem. The disease is caused by protozoan parasites of the genus Plasmodium. The most serious forms of the disease are caused by Plasmodium falciparum and Plasmodium vivax, but other related species (Plasmodium ovale and Plasmodium malariae) can also infect humans. These groups of human-pathogenic Plasmodium species are usually referred to collectively as malaria parasites.

Malaria parasites are transmitted by female Anopheles mosquitoes. Plasmodium multiplies within the red blood cells, causing symptoms that include fever, anemia, chills, flu-like illness, and, in severe cases, coma and death. Malaria transmission can be reduced by preventing mosquito bites through the use of mosquito nets and insect repellents. Mosquito control is also an effective way of reducing the burden of malaria. This is achieved by spraying insecticides inside houses and reducing the standing water where mosquitoes breed.

Unfortunately, no vaccine is currently available to stop infection. Instead preventative drugs must be taken continuously to reduce the risk of malaria. Such prophylactic drug treatments are simply too expensive for most individuals living in widespread areas. Malaria infections are treated through the use of antimalarial drugs, such as chloroquine, although drug resistance is increasingly common.

Malaria has probably infected humans for over 50,000 years, and may have been a human pathogen for the entire history of our species. Indeed, close relatives of the human malaria parasites remain common in chimpanzees, our closest relatives. References to the unique periodic fevers of malaria are found throughout recorded history, beginning in 2700 BC in China during the Xia Dynasty. The term malaria originates from Medieval Italian: mala aria -- "bad air"; and the disease was formerly called ague or marsh fever due to its association with swamps.

Scientific studies on malaria made their first significant advance in 1880, when a French army doctor working in Algeria named Charles Louis Alphonse Laveran observed parasites inside the red blood cells of people suffering from malaria. He proposed that malaria was caused by this protozoan, the first time protozoa were identified as causing disease. For this and later discoveries, he was awarded the 1907 Nobel Prize for Physiology or Medicine. The protozoan was called Plasmodium by the Italian scientists Ettore Marchiafava and Angelo Celli. A year later, Carlos Finlay, a Cuban doctor treating patients with yellow fever in Havana, first suggested that mosquitoes were transmitting disease to humans. However, it was Britain's Sir Ronald Ross working in India who finally proved in 1898 that malaria is transmitted by mosquitoes. He did

this by showing that certain mosquito species transmit malaria to birds and isolating malaria parasites from the salivary glands of mosquitoes that had fed on infected birds. For this work Ross received the 1902 Nobel Prize in Medicine. After resigning from the Indian Medical Service, Ross worked at the newly-established Liverpool School of Tropical Medicine and directed malaria-control efforts in Egypt, Panama, Greece and Mauritius. The findings of Finlay and Ross were later confirmed by a medical board headed by Walter Reed in 1900, and its recommendations implemented by William C. Gorgas in the health measures undertaken during construction of the Panama Canal. This public-health work saved the lives of thousands of workers and helped develop the methods used in future public-health campaigns against this disease.

The first effective treatment for malaria was the bark of cinchona tree, which contains quinine. This tree grows on the slopes of the Andes, mainly in Peru. This natural