top of page

Disease Information Sheets

Human African Trypanosomiasis (Sleeping Sickness)

Sleeping sickness is caused by parasites (trypanosomes) transmitted from infected animals or people by the tsetse fly. It is found in sub-Saharan Africa where the tsetse fly is common - rural areas where there is agriculture, hunting, fishing and keeping animals. 

The disease in people takes two forms, depending on the species of trypanosome: Trypanosoma brucei gambiae (Tbg) accounts for 98% of reported cases of sleeping sickness, and causes chronic infection. It is also known as West African Trypanosomiasis and is predominantly found in west and central Africa.


Trypanosoma brucei rhodesiense (Tbr) represents the remaining 2% of reported cases, and causes an acute illness. It is also known as East African Trypanosomiasis and is found in parts of eastern and south eastern Africa. 

The tsetse fly bites during the day and is found in woodland and savannah areas. The disease can also be passed from mother to baby during pregnancy, and can also in theory be transmitted through unsafe blood transfusion.

How common is it?

Sleeping sickness threatens millions of people in 36 countries in sub-Saharan Africa. Poor, displaced and rural communities are at particular risk, not only because transmission is more likely, but also because of the poor or non-existent health care 
systems. There are now approximately 30 000 cases per year. In the last ten years, over 70% of cases occurred in the Democratic Republic of Congo (DRC). In 2012, 83% of reported cases occurred in DRC. Cases in travellers are very uncommon.

back to topic list

Download this as a PDF (free)

Countries with or at risk of HAT

Are travellers and/or expat workers at risk?

Yes - but cases are uncommon. People travelling to rural areas are at risk, for example tourists visiting game reserves or hunting, exploration geologists, development workers, people working with animals and aid workers. Not all tsetse flies carry the disease, so your risk increases with the number of times you are bitten, and therefore the longer you live or stay in an at-risk area. People in urban areas are not at risk.


What is the illness?

A tsetse fly bite is often painful and can develop into a red sore. After about one to three weeks (Tbr) or weeks to months (Tbg) the patient experiences a flu-like illness with fever, severe headaches, extreme fatigue, swollen lymph nodes and muscle aches, with or without a rash. Once the disease invades the central nervous system symptoms such as personality changes, confusion and other neurological problems develop. If left untreated the patient will die within a few months (Tbr) or years (Tbg). 


Can it be treated?

Yes. It is important that treatment is started as soon as possible, and hospitalisation is usually required. If you suspect you have sleeping sickness you should see your doctor or an infectious disease specialist for tests.


How can it be prevented?

There is no vaccine or protective medication available. Prevention relies on avoiding tsetse fly bites. Wear protective clothing - long sleeved shirts and trousers. The tsetse fly can bite through thin clothing, so more substantial material is recommended. The tsetse fly is attracted to bright or dark colours, so neutral colours are best. The tsetse fly is attracted to moving vehicles, so inspect them before you get in. Avoid bushes - the tsetse fly rests in bushes during the hottest part of the day and will bite if disturbed.

bottom of page