What is Sleeping Sickness?

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.


Interesting Facts

  • Tsetse fly larva excretes a powerful toxin through pores in its skin. A single drop is powerful enough to kill a human!
  • The word ‘tsetse’ comes from Tswana (a language of Southern Africa)  which means ‘fly’
  • There are 22 different species of the tsetse fly
  • Tsetse flies feed on the blood of animals
  • Tsetse flies have been on this earth for 34 million years
  • They are primarily responsible for transmitting viruses that cause such diseases as ‘sleeping sickness’ in people and ‘nagana’ in animals
  • Tsetse flies are also known as ‘tik-tik’ flies
  • These flies are multivoltine, which means they produce many broods per year.  Tsetse flies produce about four generations yearly, and up to 31 generations total over their entire lifespan!
  • Tsetse flies look alot like regular houseflies.  However, you can tell the difference by observing their anatomy.  One way to identify them is by their wings.  The tsetse fly fold their wings completely when resting so that one wing rests directly on top of the other.
  • The tsetse fly is responsible for 250,000 – 300,000 deaths per year!!!

About the Tsetse Fly


The Female Tsetse Fly

A tsetse fly is a bloodsucking fly which is exclusively found in the African continent, south of the Sahara desert. Tsetse fly species are classified under the genus Glossina, and are slightly bigger than the common houseflies. However, they have two distinct characteristics that that usually distinguish them from houseflies. One of these characteristics is that a tsetse fly usually folds its wings completely, so that one of its wings rests directly over the other on its abdomen. It also has a long proboscis extending directly forward, which is attached to a distinct bulb at the bottom of its head.

Tsetse flies live on the blood of human beings, domestic and wild animals, and have made many areas in sub-Saharan Africa uninhabitable. It is almost unbelievable that a mere fly can wreak such havoc, but then again, a tsetse fly is no ordinary fly. It is the primary vector of trypanosomes, parasites which usually cause sleeping sickness in human beings and nagana in animals. Tsetse flies transmit these deadly parasites through biting people and animals. These diseases cause the deaths of many people and animals yearly, negatively affecting the development of the affected areas. As indicated earlier, their presence in a particular area inhibits human settlement and agricultural activity, until they have been effectively controlled.

The negative health implications resulting from tsetse fly infestation have long been a matter of concern to the World Health Organization. Tsetse flies spread diseases very fast owing to their vast numbers, and can easily wipe out herds of both domestic and wild animals in a short time. Fortunately, it can be diagnosed and treated in domestic animals such as cattle. Although the number of humans affected is lower than that of animals, the effect is equally fatal. It may come as a surprise to many people that sleeping sickness eventually leads to death of humans, since most people think that it only entails sleeping. This however is not usually the case. Initially, patients suffering from sleeping sickness contend with symptoms such as high fever and headaches, which are then followed by cardiovascular disorders. If untreated, the parasite affects a patient’s central nervous system, and may cause seizures and maniacal behavior, accompanied by excessive sleepiness. Eventually, a patient falls into a coma and dies.

Diagnosis and treatment of sleeping sickness is usually complex, requiring specialized staff. The success of treatment usually depends on the stage of the sickness; the earlier it is treated, the better. During later stages, the disease becomes difficult to treat mainly because the drugs used also have severe side effects. In view of this, people who are not diagnosed in time have few chances of survival. Worse still, there is no vaccine either for sleeping sickness or nagana.

Currently, the World Health Organization in conjunction with the affected African governments has initiated programs to reduce the proliferation of tsetse flies. It is believed that if the tsetse fly presence in Africa can be effectively reduced, its negative effects can be controlled. There are also plans underway by scientists to find ways of rendering the tsetse fly harmless, which may just end the tsetse fly menace once and for all.