The World Health Organization has officially confirmed that Kenya can be declared free of Human Sleeping Sickness (otherwise known as Human African Trypanosomiasis) in a press release issued on 8 August 2025. This is the second Neglected Tropical Disease to have been eliminated in Kenya, following the country being declared free of Guinea Worm, Dracunculus medinensis, in 2018, and makes Kenya the tenth country to be declared free of Human Sleeping Sickness. To date, 57 countries have been confirmed as having eliminated at least one of the seventeen recognised Neglected Tropical Diseases.
Human Sleeping Sickness is caused by a Protozoan, Trypanosoma brucei, which is an extracellular parasite infecting the blood plasma and other bodily fluids of its victims (unlike other parasitic Protozoans, such as the Malaria parasite Plasmodium spp., which infect the victim's cells). Trypanosoma brucei is a zoonotic infection, which is to say infection that affects Animals as well as Humans, and is typically carried by an Animal vector. This can create a reservoir of potential infectious agents in an Animal population, making such diseases difficult to eliminate.
There are two subspecies of Trypanosoma brucei which infect humans, Trypanosoma brucei gambiense, which is found in West Africa, and Trypanosoma brucei rhodesiense, which is found in East and Southern Africa (and which was the form formerly found in Kenya). A third form, Trypanosoma brucei brucei, does not infect Humans, but can infect domestic Animals. All three known forms of Trypanosoma brucei infect a variety of Mammals (it is possible that other subspecies exist, but infect neither Humans nor domestic Animals, leading to their being overlooked), and are transferred from one host to another by the bite of the Tsetse Fly, Glossina spp.. Because of this, Humans involved in professions where they work closely with Animals, such as Animal husbandry or hunting, are particularly at risk of infection.
Because Trypanosoma brucei infections are not restricted to cells, the parasite is able to cross the blood-brain barrier with greater ease than most parasitic infections. The parasite breeds by binary fission, enabling its population within a host to increase exponentially. Once the population within the bloodstream become to high, the parasites begin to migrate within the body, frequently entering the cerebrospinal fluid and then the brain, where it caused Human Sleeping Sickness. As an Eukaryotic infection, Trypanosoma brucei is not vulnerable to antibiotics, and is typically treated with a form of chemotherapy which is also hazardous for the patient. As such, prevention of the disease is greatly preferable to treatment.
Human Sleeping Sickness was first recorded in Kenya in the early twentieth century, and has been the subject of strenuous control efforts ever since. A declaration of elimination for a disease is made at least ten years after the least recorded transmission of that disease within a country. In Kenya, the last reported case where the patient is believed to have contracted the disease within the country occurred in 2009, while the most recent reports of patients who are believed to have acquired the infection while out of the country (two patients) occurred in 2012. Despite this apparent success, Kenya has recently strengthened monitoring for Human Sleeping Sickness in counties where the disease was formerly endemic.
See also...
