African Trypanosomiasis Sleeping Sickness Biology Essay

African Trypanosomiasis Sleeping Sickness Biology Essay African trypanosomiasis also known as â€Å"sleeping sickness† is a wide spread parasitic disease (disease caused by organism that lives in or on another from which it obtains nourishment) that can be fatal if not treated. It is estimated by the World Health Organisation (WHO) that it has 450 000 cases each year, however in the past there have epidemics (a rapid spread or increase) such as between 1896 and 1906 where it is believed that 300 000 to 500 000 died from the disease. [1] African trypanosomiasis is common in the sub-Saharan region near rivers, lakes, in gallery forests and in Savannahs where the large brown tsetse flies are present. It occurs in these remote rural areas because the health systems are weak and because most of these areas depend on agriculture, fishing, animal husbandry or hunting so they are exposed to the tsetse flies. [2]The disease has been present in Africa for a minimum of 14 centuries with millions of people being affected by it. As you can see below (in figure 1) the distribution of trypanosomiasis in Africa comprises currently an area of 8 million km2 between 14 degrees North and 20 degrees South latitude. tryp_map.gif [Fig. 1] Distribution of human African trypanosomiasis. http://www.who.int/tdrold/dw/images/legend5.gifEpidemic http://www.who.int/tdrold/dw/images/legend6.gifHigh endemicity http://www.who.int/tdrold/dw/images/legend4.gifLow endemicity http://www.who.int/tdrold/dw/images/legend7.gifAt risk http://www.who.int/tdrold/dw/images/legend3.gifAbsence of the disease   As well as African trypanosomiasis also occurs in South America it is called the American trypanosomiasis or the Chagas disease however the organism causing that disease is different to the Tsetse flies. African trypanosomiasis is however more common than the South American version and it is estimated that around 50,000 to 70,000 people are currently infected with it and around 48,000 people died from it in 2008. [3] If, like most diseases, Afric an Trypanosomiasis is diagnosed early there is a high chance of survival. There are no effective vaccines, and the drugs used to treat this disease are often toxic and usually have many side effects. Untreated cases have a 100 percent  mortality rate. [4] The extent of African Trypanosomiasis is shown more clearly when compared to other diseases and during epidemic periods prevalence reached 50% in several villages in the Democratic Republic of Congo, Angola and Southern Sudan. Sleeping sickness was the first or second greatest cause of mortality in those communities, ahead of even HIV/AIDS. [5] There are two types of African trypanosomiasis which are common in humans. The first of the two sub species is trypanosomiasis brucei gambiense which causes a slow chronic trypanosomiasis in humans. This mostly occurs in central and western Africa, where humans are thought to be the primary target. The second is T. brucei rhodesiense and this causes a rapid onset of trypanosomiasis in huma ns and this is most common in southern and eastern Africa, where animals are the primary target. Tsetse flies are large flies which can be easily misinterpreted for a housefly but can be distinguished by various characteristics. These flies cause human sleeping sickness and animal trypanosomiasis (or nagana) as well as other diseases and its estimated it kills around 250,000 to 300,000 people a year. Tsetse flies are multivoltine (they have more than 2 generations per year) and there are 23 species of this fly existent today. Tsetse flies include all the species in the genus Glossina, which are generally placed in their own family, the Glossinidae. [6]