Sleeping Sickness, or its scientific term – Trypanosoma Brucei need two hosts to live and reproduce. Its life cycle starts, when an infected tsetse fly bites human skin. While it is feeding on blood, metacyclic trypomastigotes are transmitted to the skin from the salivary glands of the fly. The parasites get into the bloodstream by entering lymphatic or blood vessels. They travel in different body fluids (such as blood, lymphatic or spinal fluid), transform into bloodstream trypomastigotes and multiply by binary fission. The disease can be spread by another tsetse fly that drinks the infected blood. Inside the fly the life cycle takes about three weeks. Ingested bloodstream trypomastigotes transform into procyclic trypomastigotes in the fly’s midgut and multiply. They transform into epimastigotes, migrate to the salivary glands, then transform into metacyclic trypomastigotes and multiply once again by binary fission.

The disease has been a problem in Africa since at least the 14th century, and probably for thousands of years before that. Because there was a lack of travel between indigenous people, sleeping sickness in humans had been limited to isolated pockets. This changed once Arab slave traders entered central Africa from the east, following the Congo River, bringing parasites along. Gambian sleeping sickness travelled up the Congo River, then further eastwards. In 1901 a devastating epidemic had erupted in Uganda, killing more than 250,000 people, about two-thirds of the population in the affected lake-shore areas.

More than 12000 new infections are reported to the WHO each year showing signs of declining.. However there is some good news for persons like bicycle tourists who spend many days outdoors traveling through remote areas – Less than 1 % of tsetse flies carry the parasite. Travelers should be aware of the risk of infection in  eastern and south-eastern Africa. where over 95 % of the infections occur in Malawi, Tanzania, Uganda, and Zambia and another strain of infection occurs in Angola, Central African Republic, Chad, northern Uganda, Sudan, Republic of the Congo and Democratic Republic of the Congo.

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