What is Sleeping Sickness?
Sleeping sickness, also called African trypanosomiasis, is an infection caused by microscopic parasites called trypanosomes. It is transmitted by the bite of an infected tsetse fly, a blood-feeding fly found in parts of sub-Saharan Africa. Tsetse flies are mainly associated with rural woodland, savannah, forests and vegetation around waterways, rather than cities. Most tsetse flies do not carry the parasite, so the overall risk to travellers is low, but repeated bites increase the chance of infection.
There are two forms of sleeping sickness that exist, caused by two different subspecies of trypanosome, and both can be fatal without treatment. West African sleeping sickness (caused by Trypanosoma brucei gambiense) occurs mainly in West and Central Africa and usually develops slowly over months or years. The World Health Organization reports West African sleeping sickness makes up 92% of cases. East African sleeping sickness (Trypanosoma brucei rhodesiense) occurs mainly in eastern and southern Africa and progresses much more rapidly, with serious illness developing over weeks.
For Australian travellers, the risk is generally very low in urban areas but is more relevant when visiting rural regions, wildlife reserves and game parks, particularly for travellers spending prolonged periods outdoors. Safari travellers, hunters, field workers and people with frequent exposure to tsetse habitat have greater risk. The World Health Organization reports that sustained control efforts have reduced the number of new cases by 97% in the last 20 years.
FAQs
Which countries have sleeping sickness?
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The majority of cases occur in the Democratic Republic of Congo. Moderate transmission occurs in Central African Republic, South Sudan, Angola, Republic of the Congo, Gabon, and Malawi. Lower levels of transmission occur in other subsaharan countries. In all, the WHO identifies thirty-six countries which are affected.
Can I get sleeping sickness from a normal mosquito bite?
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No. Sleeping sickness is transmitted by tsetse flies, not mosquitoes. Tsetse flies bite during the day, and their bites can be quite painful. They are attracted to moving vehicles and can enter cars, safari vehicles and other transport, so being inside a vehicle does not always eliminate exposure.
Mosquito precautions provide some general insect protection but should not be relied upon for tsetse flies. Tsetse flies can bite through thin clothing, and insect repellents and permethrin-treated clothing are not particularly effective against them. Wear medium-weight, neutral-coloured clothing, including long sleeves, long trousers and socks, avoid very bright, dark or blue/black clothing, check vehicles before entering, and avoid disturbing bushes where flies may rest.
Where are Australian travellers most likely to encounter tsetse flies?
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The greatest risk is associated with rural and natural environments, including savannah, woodland, forest edges and vegetation around rivers and streams. Travellers visiting game parks or undertaking safaris are more likely to encounter tsetse flies than those staying in cities or conventional tourist areas. Risk varies considerably between countries and regions, so your itinerary is important when assessing your individual exposure.
What should I do if I am bitten by a tsetse fly?
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A tsetse bite does not mean you have sleeping sickness, as most flies are not infected. However, note the exposure and seek medical advice if you subsequently develop fever, headache, unusual tiredness, muscle or joint aches, swollen lymph nodes, a rash or a red sore at the bite site. Tell the doctor specifically that you travelled to a region where sleeping sickness occurs and that you may have been bitten by a tsetse fly.
Can sleeping sickness appear after I return to Australia?
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Yes. The timing depends on the type of infection. East African sleeping sickness usually develops within weeks, whereas West African sleeping sickness can remain relatively subtle for months or longer. A fever or unexplained illness after travel to an endemic rural area should therefore prompt medical assessment, even if the trip was some time ago. Make sure your doctor knows exactly where you travelled and whether you had tsetse-fly exposure.
Is there a vaccine for African trypanosomiasis (sleeping sickness)?
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No. There is currently no vaccine or preventive medication for sleeping sickness. Protection relies on avoiding bites from infected tsetse flies, particularly when travelling in rural areas, game parks or other known tsetse habitats.
What to Know
Symptoms of Sleeping Sickness
Early symptoms of Sleeping Sickness can resemble many other infections and may include fever, headache, tiredness, muscle and joint aches, itching, swollen lymph nodes and loss of appetite or weight. Some people develop a painful or raised red sore, called a chancre, at the site of the tsetse bite, although this is not always present or noticed. East African disease tends to cause more abrupt and severe illness, while West African disease may be mild or intermittent initially.
Without treatment, the parasite can eventually cross into the brain and central nervous system. This second stage can cause changes to the normal sleep–wake pattern, excessive daytime sleepiness, confusion, behavioural or mood changes, movement problems, sensory disturbances, seizures and eventually coma. The characteristic disturbance of sleep is why the disease is commonly called 'sleeping sickness'.
Diagnosis and treatment of Sleeping Sickness
Diagnosis of Sleeping Sickness requires identification of the parasite in a sample of blood, lymph-node fluid or another body fluid. Early infection can be difficult to confirm because the number of parasites may be low. East African infection is more readily detected in blood, while West African infection may require examination of fluid from an enlarged lymph node. A lumbar puncture, which involves collecting a small sample of fluid from around the spinal cord, is used to determine whether the infection has reached the central nervous system and therefore to establish the disease stage.
Treatment should begin as soon as the diagnosis is confirmed and depends on which parasite is responsible and whether the nervous system is involved. Treatment generally requires hospital-based care because the medicines used can have significant side effects and the disease needs careful monitoring. Follow-up may continue for two years, sometimes including repeat lumbar punctures, because infection can occasionally recur.
Prevention of Sleeping Sickness
There is no vaccine or preventive medication for African trypanosomiasis, so avoiding tsetse-fly bites is the main protection. Tsetse flies are active during the day, particularly in rural woodland, savannah and vegetation near water. Choose clothing carefully, including medium-weight, neutral-coloured items covering the arms and legs, as tsetse flies can bite through thin fabrics. Avoid bright or very dark colours, particularly blue and black, and avoid walking or standing close to dense bushes where flies may rest.
Check cars, safari vehicles and other transport for flies before entering, as tsetse flies are attracted to moving vehicles. Where local advice identifies known tsetse areas, avoid unnecessary exposure and follow guidance from experienced local guides. Insect repellent can still be used as part of your broader bite-prevention routine because it protects against other insect-borne diseases, but it provides limited protection against tsetse flies and should not create a false sense of security.
For Australian travellers returning from an endemic area, monitor for symptoms such as fever or unexplained illness. Consult a doctor and disclose your travel history, particularly if you spent time in game parks, rural areas or other tsetse habitat. Early recognition is important because sleeping sickness is treatable, but untreated infection can progress to severe neurological disease and death.