Sleeping Sickness

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Overview

Human African trypanosomiasis, also known as sleeping sickness, is a vector-borne parasitic disease. It is caused by infection with protozoan parasites belonging to the genus Trypanosoma. They are transmitted to humans by tsetse fly ( Glossina genus) bites which have acquired their infection from human beings or from animals harbouring human pathogenic parasites.

Tsetse flies are found just in sub-Saharan Africa though only certain species transmit the disease. For reasons that are so far unexplained, in many regions where tsetse flies are found, sleeping sickness is not. Rural populations living in regions where transmission occurs and which depend on agriculture, fishing, animal husbandry or hunting are the most exposed to the tsetse fly and therefore to the disease. The disease develops in areas ranging from a single village to an entire region. Within an infected area, the intensity of the disease can vary from one village to the next.

Symptoms

The disease is mostly transmitted through the bite of an infected tsetse fly but there are other ways in which people are infected:

Mother-to-child infection: the trypanosome can cross the placenta and infect the fetus.

Mechanical transmission through other blood-sucking insects is possible, however, it is difficult to assess its epidemiological impact.

Accidental infections have occurred in laboratories due to pricks with contaminated needles.

Transmission of the parasite through sexual contact has been reported.

In the first stage, the trypanosomes multiply in subcutaneous tissues, blood and lymph. This is also called haemo-lymphatic stage, which entails bouts of fever, headaches, enlarged lymph nodes, joint pains and itching

In the second stage the parasites cross the blood-brain barrier to infect the central nervous system. This is known as the neurological or meningo-encephalic stage. In general this is when more obvious signs and symptoms of the disease appear: changes of behaviour, confusion, sensory disturbances and poor coordination. Disturbance of the sleep cycle, which gives the disease its name, is an important feature. Without treatment, sleeping sickness is considered fatal although cases of healthy carriers have been reported.

Causes

Sleeping sickness is caused by two types of parasites Trypanosoma brucei rhodesiense and Trypanosomoa brucei gambiense. T b rhodesiense causes the more severe form of the illness. Tsetse flies carry the infection. When an infected fly bites you, the infection spreads through your bloodstream.

Risk factors

Living in Central or South America.

Residing in a house constructed before the year 2000.

Exposure to either wall constructions composed of mud and sticks or straw roofs.

Ingestion of contaminated water.

Living in a hut where reduvid bugs live in the walls.

Poverty.

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Complications

Wasting syndrome. Aspiration pneumonia. Meningoencephalitis and seizures. Stupor or coma (sleeping sickness)

Prevention

Wear long-sleeved shirts and pants of medium-weight material in neutral colors that blend with the background environment. Tsetse flies are attracted to bright or dark colors, and they can bite through lightweight clothing.

Inspect vehicles before entering. ...

Avoid bushes. ...

Use insect repellent.