Sleeping sickness is caused by parasites transmitted by infected tsetse flies and is endemic in 36 sub-Saharan African countries. The people most exposed to the tsetse fly and to the disease live in rural areas and depend on agriculture, fishing, animal husbandry or hunting. Human African trypanosomiasis takes 2 forms, depending on the parasite involved: Trypanosoma brucei gambiense accounts for more than 98% of reported cases. Sustained control efforts have reduced the number of new cases. In 2009 the number reported dropped below 10 000 for the first time in 50 years, and in 2018 there were 977 cases recorded. Trypanosoma brucei rhodesiense is found in 13 countries in eastern and southern Africa. Nowadays, this form represents under 2% of reported cases and causes an acute infection
Major human epidemics: There have been several epidemics in Africa over the last century:
- one between 1896 and 1906, mostly in Uganda and the Congo Basin;
- one in 1920 in a number of African countries; and
- The most recent epidemic started in 1970 and lasted until the late 1990s.
Current disease distribution: The disease incidence differs from one country to another as well as in different parts of a single country.
- In the last 10 years, over 70% of reported cases occurred in the Democratic Republic of the Congo.
- Angola, Central African Republic, Chad, Congo, Gabon, Guinea, Malawi and South Sudan declared between 10 and 100 new cases in 2018.
- Countries like Benin, Botswana, Burundi, Ethiopia, Gambia, Guinea Bissau, Liberia, Mali, Mozambique, Namibia, Niger, Rwanda, Senegal, Sierra Leone, Swaziland and Togo have not reported any new cases for over a decade.
Infection and 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.
Disease management: it is made in 3 steps:
- Screening for potential infection. This involves using serological tests (only available for b.gambiense) and checking for clinical signs – especially swollen cervical lymph nodes.
- Diagnosing by establishing whether the parasite is present in body fluids.
- Staging to determine the state of disease progression. This entails clinical examination and in some cases analysis of the cerebrospinal fluid obtained by lumbar puncture. Diagnosis must be made as early as possible to avoid progressing to the neurological stage in order to elude complicated and risky treatment procedures
Drugs used in the treatment of first stage:
- Pentamidine:used for the treatment of the first stage of b. gambiense sleeping sickness.
- Suramin: used for the treatment of the first stage of b. rhodesiense. It provokes certain undesirable effects, including urinary tract and allergic reactions.
Drugs used in the treatment of second stage:
- Melarsoprol: it is used for the treatment of both gambiense and rhodesiense.
- Eflornithine:a molecule, much less toxic than melarsoprol, it is only effective against b. gambiense. It is generally used in combination with nifurtimox but can be used also as monotherapy.
- Nifurtimox:The Nifurtimox-eflornithine combination therapy
Drugs used in the treatment of both stages:
Fexinidazole is a new oral treatment for gambiense human African trypanosomiasis. This molecule is indicated as first line for first stage and non-severe second stage. It should be administered within 30 minutes after a solid meal and under supervision of trained medical staff.