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African trypanosomiasis or sleeping sickness〔 is a parasitic disease of humans and other animals. It is caused by protozoa of the species ''Trypanosoma brucei''. There are two types that infect humans, ''Trypanosoma brucei gambiense'' (T.b.g) and ''Trypanosoma brucei rhodesiense'' (T.b.r.).〔 T.b.g causes over 98% of reported cases. Both are usually transmitted by the bite of an infected tsetse fly and are most common in rural areas.〔 Initially, in the first stage of the disease, there are fevers, headaches, itchiness, and joint pains.〔 This begins one to three weeks after the bite.〔 Weeks to months later the second stage begins with confusion, poor coordination, numbness and trouble sleeping.〔 Diagnosis is via finding the parasite in a blood smear or in the fluid of a lymph node.〔 A lumbar puncture is often needed to tell the difference between first and second stage disease.〔 Prevention of severe disease involves screening the population at risk with blood tests for T.b.g.〔 Treatment is easier when the disease is detected early and before neurological symptoms occur.〔 Treatment of the first stage is with the medications pentamidine or suramin.〔 Treatment of the second stage involves: eflornithine or a combination of nifurtimox and eflornithine for T.b.g. While melarsoprol works for both it is typically only used for T.b.r. due to serious side effects.〔 The disease occurs regularly in some regions of sub-Saharan Africa with the population at risk being about 70 million in 36 countries. As of 2010 it caused around 9,000 deaths per year, down from 34,000 in 1990. An estimated 30,000 people are currently infected with 7000 new infections in 2012.〔 More than 80% of these cases are in the Democratic Republic of the Congo.〔 Three major outbreaks have occurred in recent history: one from 1896 to 1906 primarily in Uganda and the Congo Basin and two in 1920 and 1970 in several African countries.〔 Other animals, such as cows, may carry the disease and become infected.〔 ==Signs and symptoms== African trypanosomiasis symptoms occur in two stages. The first stage, known as the haemolymphatic phase, is characterized by fever, headaches, joint pains, and itching. Fever is intermittent, with attacks lasting from a day to a week, separated by intervals of a few days to a month or longer. Invasion of the circulatory and lymphatic systems by the parasites is associated with severe swelling of lymph nodes, often to tremendous sizes. Winterbottom's sign, the tell-tale swollen lymph nodes along the back of the neck, may appear. Occasionally, a chancre (red sore) will develop at the location of the tsetse fly bite. If left untreated, the disease overcomes the host's defenses and can cause more extensive damage, broadening symptoms to include anemia, endocrine, cardiac, and kidney dysfunctions. The second, neurological phase, begins when the parasite invades the central nervous system by passing through the blood–brain barrier. Disruption of the sleep cycle is a leading symptom of this stage and is the one that gave the disease the name 'sleeping sickness.' Infected individuals experience a disorganized and fragmented 24-hour rhythm of the sleep-wake cycle, resulting in daytime sleep episodes and nighttime periods of wakefulness. Other neurological symptoms include confusion, tremor, general muscle weakness, hemiparesis and paralysis of a limb. Parkinson-like movements might arise due to non-specific movement disorders and speech disorders. Individuals may also exhibit psychiatric symptoms such as irritability, psychotic reactions, aggressive behaviour, or apathy which can sometimes dominate the clinical diagnosis. Without treatment, the disease is invariably fatal, with progressive mental deterioration leading to coma, systemic organ failure, and death. An untreated infection with ''T. b. rhodesiense'' will cause death within months whereas an untreated infection with ''T. b. gambiense'' will cause death after several years. Damage caused in the neurological phase is irreversible.〔(【引用サイトリンク】date=11 May 2008 )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「African trypanosomiasis」の詳細全文を読む スポンサード リンク
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