Human African Trypanosomiasis (HAT) or more commonly known as African sleeping sickness is an endemic that is responsible for posing a risk to 60 million people in 36 countries in sub-Saharan Africa( Fig 1) (Brun et al 2009). It is a vector- borne disease which is transmitted by the bite of Tsetse flies of the Glossina genus which injects the protozoan parasite of the genus trypanasoma to humans (Rodgers 2009).
The disease appears to occur in two forms which depend on the subspecies of the parasite involved which include Trypanosoma brucie (T.b) gambiense and Trypanosoma brucie (T.b) rhodesiense. The former is the more common, accounting to be the cause of more than 90% of reported cases and is seen in the Western and Central Africa. The latter causes less than 10% of the disease and prevails in the East and South Africa (Cattand et al 2001, WHO 2006).
Fig 1: Showing distribution of HAT in Sub- Saharan Africa (Brun et al 2009)
After the trypanosomes are injected into the host, the disease is said to be in the first (hemo- lymphatic) stage and as the disease spreads attacking the CNS, it is said to be in the second or meningo- encephalitic stage. T.b gambiense causes a chronic infection with the slow invasion of the CNS which lasts for several years without any major clinical signs and symptoms and T.b rhodesiense leads to an acute infection with the fast invasion of the CNS and clinical presentations are observed from a few weeks or months. Both forms are lethal without any treatment (Cattand et al 2001, Lejon et al 2005, WHO 2006).
In terms of the clinical presentations both forms of Trypanosomiasis vary considerably and many symptoms are non- specific, variable and inconstant. With chronic T.b. gambiense the most prominent symptom is gland enlargement mainly in the neck. Other symptoms in the first stage include general malaise, headache, fever,
References: ➢ Bouchet B., Legros D. & Lee E. (1998). Key indicators for the monitoring and evaluation of control programmes of human African Trypanosomiasis due to Trypanosoma brucie gambiense. Tropical Medicine & International Health, 3 (6): 478-481. ➢ Bouteille B., Oukem O., Bisser S. & Dumas M. (2003). Treatment perspectives for human African Trypanosomiasis, Fundamental & Clinical Pharmacology, 17: 171-181. ➢ Brun R., Blum J., Chappuis F. & Burri C. (2009). Human African Trypanosomiasis. The Lancet, Article in Press, Corrected Proof: 12 pages. ➢ Burri C., Nkunku S., Merolle A., Smith T., Blum J. & Brun R. (2000). Efficacy of new, concise schedule for melarosprol in treatment of sleeping sickness caused Trypanosoma brucie gambiense: a randomised trial. The Lancet, 355: 1419-1425. ➢ Cattand P., Jannin J. & Lucas P. (2001). Sleeping sickness surveillance: an essential step towards elimination. Tropical Medicine & International Health, 6 (5): 348-361. ➢ Etchegorry M.G., Helenport J.P., Pecoul H.B., Jannin J. & Legros D. (2001). Availability and affordability of treatment for Human African Trypanosomiasis. Tropical Medicine & International Health, 6 (11): 957-959. ➢ Kennedy P.G.E. (2008). The continuing problem of Human African Trypanosomiasis (Sleeping Sickness). Neurological Progress, 64: 116-127. ➢ Papadopoulos M.C., Abel P.M., Agranoff D., Sticj A., Tareli E., Bell B.A., Planche T., Loosemore A., Saadoun S., Wikins P., Krishna S. (2004). A novel and accurate diagnostic test for human African Trypanosomiasis. The Lancet, 363: 1353-1363. ➢ Rodgers J. (2009). Human African Trypanosomiasis, chemotherapy and CNS disease. Journal of Neuroimmunology, 211: 16-22. ➢ Schmid C., Nkunku S., Merolle A., Vounatsou P. & Burri. (2004). Efficacy of 10-day melarosprol schedule 2 years after treatment for late-stage gambiense sleeping sickness. The Lancet, 364: 789-790. ➢ Stich A., Abel P.M. & Krishna S. (2002). Human African Trypanosomaiasis. British Medical Journal, 325:203-206.