The trypanosome, a parasite responsible for sleeping sickness and transmitted by the tsetse fly, is sometimes undetectable in some individuals.
A new study carried out in the Republic of Guinea with patients and healthy carriers shows that it could be hiding in the skin. This discovery opens the way to new possibilities of diagnosis and elimination of the disease.
In sub-Saharan Africa, human African trypanosomiasis (HAT), more called sleeping sickness, has been in sharp decline for years: only a thousand cases were recorded in 2019 in the region. Yet pockets of disease remain. The reason for this is the impossibility of reliably detecting the parasite responsible for the pathology, the trypanosome. The diagnosis is in fact carried out in two stages: a serological screening, then the detection of living parasites in the blood, in the lymph nodes or in the cerebrospinal fluid. In some people, this second step is not successful: the parasites are not detected. They could be hiding elsewhere… that is, in the skin.
Healthy untreated carriers
“We had observed for several years that 90% of patients and suspects presented symptoms cut like pruritus, specifies Mariame Camara, doctor, responsible for the care of the patients within the National Program of the fight against the human African trypanosomiasis of Guinea. We therefore launched the TrypaDerm research program, in conjunction with the IRD and the Institut Pasteur, with the aim of looking for the presence of cutaneous trypanosomes. We thus performed biopsies during medical surveys in villages in Guinea: the parasite was indeed present in the skin in all confirmed cases but also in only seropositive individuals. “