What are the Causes of the African Sleeping Sickness?

African sleeping sickness, or Human African Trypanosomiasis, is a parasitic disease caused by the protozoa trypanosoma. A person can be infected if he is bitten by a tsetse fly that has fed on another infected human.

Vector Information

• Tsetse flies are generally located in sub-Saharan Africa, thus limiting the illness to this region, and not all species of tsetse fly are carriers. Carrier species of tsetse flies are known to inhabit the vegetation bordering rivers and other waterways as well as forests and wooded savannas.

Causes

• Human African Trypanosomiasis can be caused by one of two organisms in the trypanosoma genus:

  • Trypanosoma brucei gambiense (T.b.g.): This parasite is native to West and Central Africa. T. brucei gambiense infection is responsible for more than 90% of the reported cases of sleeping sickness and causes a chronic infection. Many times, an infected person can be subclinical, or symptom-free for months or even years, not knowing she is infected. When the symptoms begin to manifest, the disease has often reached an advanced stage and cannot be cured.

  • Trypanosoma brucei rhodesiense (T.b.r.): This species is found in eastern and southern Africa and represents 10% or less of reported cases. The sufferer will notice the first symptoms of infection within a few months and instead of lingering, the disease advances quickly.

Transmission

• The disease is transmitted through the bite of an infected tsetse fly. The trypanosomes, or larval T. brucei, will multiply in skin tissues, blood and the lymphatic system. In time, the parasites will migrate through to the brain, infect the central nervous system and begin to cause symptoms. The most common modes of infection include:

  • Mother-to-child infection: A mother who carries the parasite can transmit the parasite to her unborn child through the placenta.
  • Mechanical transmission through the bite of a tsetse fly

  In both types of infection, a diagnosis must be made before the central nervous system is infected for treatment to be successful. Without treatment, African sleeping sickness is fatal.

Treatment

• Treatment for African sleeping sickness depends on what stage of the disease the patient is in. Drugs used to combat the parasite in areas of the body other than the central nervous system are less toxic and more easily tolerated by the patient. They are easier to give and are generally more effective than any of the treatments available for patients whose central nervous systems have been infected. This is why it is important to diagnose infection early and begin treatment as soon as possible.

Underlying Causes

• African sleeping sickness generally occurs in remote rural areas that have little access to health care. Since the disease spreads in areas of Africa that are remote and poor, most of the infected population does not receive treatment for the disease, though through the partnership of several drug manufacturers and the World Health Organization, treatments are being distributed to many more people than before.