Sleeping Sickness (Type 1) African Trypanosomiasis, gambiense type

What is Sleeping Sickness (Type 1)?

Human African trypanosomiasis, also known as African sleeping sickness, is a parasitic disease acquired through the bite of an infected tsetse fly. These specific parasites belong to the Trypanosoma genus.

There are two forms of human African trypanosomiasis, depending on the parasite involved:

  • Trypanosoma brucei gambiense:  This parasite is found in west and central Africa and is responsible for over 90 percent of reported cases of sleeping sickness. It causes a chronic infection where major symptoms may not emerge for months or even years. When symptoms do emerge, the patient is often already in an advanced disease stage.
  • Trypanosoma brucei rhodesiense: This parasite is found in eastern and southern Africa and causes an acute infection. Symptoms are usually seen after only a few months or weeks and develop rapidly after the parasite invades the central nervous system.

Another form of trypanosomiasis is known as American trypanosomiasis, or Chagas disease, and occurs in many Central and South American countries. The parasite involved is a different species from those causing the African form of the disease.

How do you get Sleeping Sickness (Type 1)?

African trypanosomiasis is acquired though the bite of the tsetse flies found in Sub-Saharan Africa. Only certain species of tsetse flies can transmit the disease after they have acquired the infection from humans or animals harbouring the human disease parasites. People living in rural areas are often the most exposed to the bite of the tsetse fly and those most at risk are usually farmers, hunters, and fishermen. Tsetse flies are mainly found in vegetation by rivers and lakes, in gallery-forests, and in vast stretches of wooded savannah. Different species of tsetse flies live in different habitats, but not all tsetse flies are infected with the parasites.  Thus, many areas may have tsetse flies, but sleeping sickness may not generally occur in these areas.”

Susceptibility and Resistance

Everyone is susceptible to African sleeping sickness.

Incubation Period

The incubation period for Sleeping Sickness (Type 1) is 60-365 days.

What are the Symptoms?

Bouts of fever, headaches, joint pains, and itching are characteristic symptoms of the initial stage of African sleeping sickness. Painful inflammation can also occur at the site of the tsetse fly bite. In the second stage, the parasite invades the central nervous system causing confusion, sensory disturbances, poor coordination, and disturbances of the sleep cycle which give the disease its common name. Without appropriate treatment, African sleeping sickness is fatal.

Preventative Measures

There is no vaccine currently available to prevent sleeping sickness. Tsetse flies are not affected by insect repellents and can bite through lightweight clothing. Areas of Africa with heavy infestation of tsetse flies tend to be sporadically distributed and are usually well known to local residents. Avoiding such areas is the best means of protection against sleeping sickness. Tsetse flies are attracted to movement and dark, contrasting colours. Travellers visiting areas with tsetse flies should wear clothing of wrist and ankle length that is made of medium-weight fabric in neutral colours that blend with the background environment.


Travellers who sustain tsetse fly bites and become ill with high fever or other symptoms of African sleeping sickness should seek medical attention immediately. The infection can usually be cured by an appropriate course of anti-trypanosomal therapy.

The type of treatment needed depends on the stage of the disease. The earlier the identification of the disease, the better the prospect of a cure. Drugs used in the first stage are less toxic, easier to administer, and more effective than drugs needed in the second stage.


Where Does It Commonly Occur?

This parasite is found only in rural west and central Africa.