Trypanosomiasis

Abstract

Nervous system infections caused by the flagellate protozoan trypanosomes include American trypanosomiasis or Chagas disease, caused by the intracellular Trypanosoma cruzi, transmitted by many species of triatomine bugs, and human African trypanosomiasis (HAT), also called sleeping sickness, caused by the extracellular Trypasonoma brucei, inoculated through bites of tsetse flies (genus Glossina). During its chronic phase T. cruzi infection attacks mainly the autonomic nervous system, with heart and gastrointestinal tract denervation. Chagas disease, which is highly invalidating, remains a public health issue in Latin America despite recent progress in vector control. In HAT, the first, haemolymphatic stage evolves into the second, meningoencephalitic stage, targeting the central nervous system when parasites cross the blood-brain barrier. HAT, which has two forms caused by T. brucei gambiense and rhodesiense, respectively, has a focal distribution in sub-Saharan Africa, mostly in resource-poor and politically unstable settings. Both forms of HAT are fatal if left untreated and drugs currently available to cure the second stage are very toxic. Despite the recent decline in the number of reported new HAT cases, diagnostic progress in HAT staging and therapy are urgently needed. Both Chagas disease and HAT are included in the group of “neglected tropical diseases” which have long been absent from the public health agenda in wealthy countries. Both these diseases pose intriguing problems on mechanisms by which parasite-derived molecules and host immune response interact with nervous system cells. It is time for clinical and basic neuroscience to be at the forefront in the fight against these diseases.