Health Centres - Sleeping sickness
What is sleeping sickness?
Sleeping sickness is also known as trypanosomiasis or African sleeping sickness. It is caused by a small parasite that leads to a serious infection in the brain and the meninges (the covering of the brain and spinal cord).
The disease develops slowly and if treatment is delayed, it usually proves fatal.
These dangerous parasites are carried by the tsetse fly. Fortunately, most tsetse flies are not infected with the parasite, and often the fly's bite only causes general discomfort.
The fly and the parasite are found in Africa, in a broad belt around the Equator. Those who travel deep into areas such as the Okovango Delta in Botswana are at risk of painful bites from the tsetse fly, which are hard to differentiate from the equally painful horsefly bite.
What causes sleeping sickness?
Sleeping sickness is caused by
The flagellate reproduces in the bloodstream, and the symptoms develop gradually as the burden of parasites and their harmful effects increases. It also migrates into the central nervous system, producing the characteristic symptoms.
If the central nervous system is sufficiently affected, the patient can no longer be cured, and eventually dies, possibly from other infections that may be superimposed on the primary disease.
Long trousers, long-sleeved jackets and socks thick enough to stop the insects biting will protect you, but it may be hard to follow such advice in a hot climate.
How is sleeping sickness spread?
The tsetse fly is the host for the parasite, which is transmitted by biting. The bite is sufficiently painful for it to be noticed, but only a few of the flies carry the infection.
When the fly bites, the parasite is able to enter the bloodstream via the bite, from where it passes over into the lymph and the central nervous system.
The flagellate reproduces in the blood, and a fly that bites an infected human may therefore itself become infected, and over the course of four to six weeks this fly may infect further humans.
Where does sleeping sickness occur and how many people are affected?
The Trypanosoma parasite exists in two sub-species in Africa. The World Health Organisation (WHO) estimates that between 300,000 and 500,000 people are affected, and that the disease threatens 60 million people in the poorest underdeveloped countries in the world.
Epidemic areas, where the disease is on the increase, are Angola, the Democratic Republic of Congo, Uganda and Sudan. In several provinces in these countries, it is estimated that up to 20 per cent of the population are infected by the disease. It has a serious social and economic impact by affecting the workforce and resources, and is a major obstacle to development in these areas.
Considerable attempts have been made to control the parasite since the 1930s, and the number of infected people had been falling.
But in the last 30 years, increasing poverty and a decreasing number of surveillance programmes have had undesirable consequences, and epidemics have been seen both in known endemic areas and in areas where it had been thought that the fly and parasite had been eradicated.
Another species of Trypanosoma, called
What are the symptoms of the disease?
Symptoms of infection in the brain begin some months to two years afterwards.
The symptoms observed are confusion, reversed diurnal rhythm (ie sleeping during the day and waking at night), dementia and convulsions. The patient increasingly becomes mentally impaired, finally loses bladder control, and there may be other forms of paralysis. The patient becomes increasingly listless and difficult to wake, and finally goes into a coma.
The effect on the central nervous system results in loss of appetite and mental disturbances. The disease rarely becomes chronic (long-lasting) because the parasite also damages the kidneys and heart muscles with a fatal outcome.
What can you do to help yourself?
This parasite is more aggressive and the stages all develop more rapidly. The disease usually proves fatal within 9-12 months if it is not treated relatively quickly.
There is no vaccine or chemical prevention due to the relative toxicity of the drugs, so it is necessary to prevent bites and control the places where the tsetse fly lives in the affected areas.
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