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Biology 103
2001 Third Web Report
On Serendip



For several years, I have had an interest in virology and the spread and characteristics of various infectious diseases. Though it makes sense not to possibly induce a state of panic by informing individuals of illnesses that are not native to the area they live in and that they are not likely to contract, I have always liked to remain informed out of my own curiosity and interest. Thus, I have decided to write about malaria.

Malaria kills more people than any communicable disease except for tuberculosis. It is caused by four species of parasitic protozoa that infect human red blood cells. Four different types of these protozoa are known: protozoa falciparum, protozoa vivax, protozoa ovale, and protozoa malariae. Protozoa falciparum is the most lethal of the four and accounts for the majority of infections. Malaria parasites are not able to survive unless they have both a mosquito and human host, however the disease cannot be hosted by any kind of mosquito, only those of the genus "anopheles".

Malaria is spread when the mosquito picks up the parasites from the blood of an infected human when it feeds. The mosquito will first recieve the malaria parasite from feeding on the blood of a person who may not neccessarily show symptoms of the disease, but has the parasites in their bloodstream. When the mosquito feeds again, these parasites will be passed on to another human being. Symptoms of malaria include fever, shivering, pain in the joints, headache, repeated vomiting, generalized convulsions, and coma. If not treated, the disease, especially that caused by protozoa falciparum, will progress to severe malaria. Severe malaria generally results in death.

Approximately 90% of of the world's malaria cases occur in sub-Saharan Africa, including in high altitude areas such as Kenya's highlands that were previously thought to have elevations too high for the transmission of the disease. Malaria, however, is not unique to Africa. There are a multitude of documented cases in Asia annually, particularly in countries such as India, Bangladesh, Vietnam, and Cambodia. Malaria has also been known to occur in portions of Iran and the Middle East. Lower altitude regions of South and Central America also have their share of annual malaria cases, but control programs set up in those regions typically keep things under control. Generally, North America, Europe, and the Carribean have been highly successful in the control and elimination of malaria, although isolated, rare cases of local transmission have occured in Haiti, Turkey, and the Dominican Republic.

Medical treatment for malaria is available and the disease is curable if promptly diagnosed and treated well. This is crucial because those who have malaria parasites available for mosquitoes to feed on are perpetuating the spread of the disease. However, if these people are treated with the appropriate drugs, the parasites disappear from their bloodstream. This helps to reduce the transmission of the disease. Unfortunately, not everyone is responsive to drug treatments for malaria and thus a variety of alternatives need to be available. Not everyone with malaria parasites in their bloodstream shows the symptoms of malaria and the disease itself is becoming resistant to some of the drugs used to treat it.

Fortunately, there are also many non-medical options in the control and treatment of malaria. Some methods have included the screening of dwellings to prevent infected misquitos from entering the home, the introduction of mosquito-eating fish to more bodies of water, and surrounding beds with incesticide-treated netting. Anything which reduces the likelyhood of mosquito presence can help.

One of the most highly successful methods for malaria control has been DDT, a compound used to treat the walls of dwellings in areas with high rates of malaria infection. DDT has been in use in malaria control programs since the 1940's and has proved generally effective. The most common use of DDT in preventing the spread of malaria is to spray the backs of chairs and walls of a dwelling with the substance to keep out adult mosquitos who enter the dwelling to feed on those who live there. Though DDT treatments are still an effective way to stop the spread of malaria, some mosquitos have become resistant to the compound and therefore more methods of prevention must be utilized.

WWW Sources

1)Malaria Foundation International

2)Malaria Fact Sheet

3)Division of Parasitic Diseases - Malaria

4)Malaria in Southern Africa

5)Roll Back Malaria