Human Sleeping Sickness eliminated in Kenya.

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.

A smear of blood from a patient with Human Sleeping Sickness, stained with Giemsa (a histological stain which binds to areas of DNA with high levels of adenine-thymine bonding, making it useful for identifying parasitic organisms in blood), revealing two Trypanosoma brucei ssp. parasites. Centers for Disease Control and Prevention.

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...

Sleeping Sickness no longer considered a public health threat in Côte d'Ivoire.

Côte d'Ivoire has successfully eliminated Human African Trypanosomiasis, also known as 'Sleeping Sickness', as a public health problem, becoming the second African country after Togo to be validated by the World Health Organization, according to a press release isssued on 25 March 2021.

'I dedicate this milestone to decades of hard work and the individual contribution of every single health worker who braved some of the toughest challenges in reaching populations, often in remote rural areas,' said Eugène Aka Aouele, Minister of Health and Public Hygiene of Côte d'Ivoire. 'Our challenge now is to maintain the required level of surveillance and, with the help of everyone, to achieve interruption of transmission by 2030.' 

In the 1990s, Côte d'Ivoire reported hundreds of cases of Sleeping Sickness every year. Cases have progressively declined over the last 2 decades, and in the past few years, the country has reported fewer than 10 cases per year. At this low level, Côte d'Ivoire qualifies as having eliminated the disease as a public health problem. 

This achievement is attributed to robust control and surveillance measures, active (and passive) screening of people at risk, and targeted vector control, which helped to strongly decrease the number of cases in areas of transmission. Hospitals and health centres checked patients using specific diagnostic tests, while laboratory mobile units screened people in villages. 

 

A Human African Trypanosomiasis mobile unit in Côte d’Ivoire. CT Brink/World Health Organization.

'Côte d’Ivoire’s achievement marks an important step that brings Africa closer to eliminating Sleeping Sickness,' said Matshidiso Moeti, the World Health Organization's Regional Director for Africa. 'Sustained control measures over the past two decades have brought a significant decline in cases, a positive sign that many countries will soon be crossing this landmark.'

Treatment of infected people meant that the vector, the Tsetse Fly, Glossina sp., could no longer transmit the disease to others. This had to be maintained over years in order to progressively eliminate the disease.  

 

A Tsetse Fly, Glossina sp. International Atomic Energy Agency/Wikimedia Commons.

'The result which Côte d'Ivoire has achieved after several decades of fighting against Human African Trypanosomiasis, reflects the excellent leadership of the Ministry of Health and Public Hygiene through the Directorate of the Human African Trypanosomiasis Elimination Programme” said Jean Marie Vianny Yameogo, the World Health Organization's Representative in Côte d'Ivoire.” It is also the expression of the commitment and determination of the regional and departmental health directorates, health professionals, the communities' participation in control strategies and the vitality of the partnership.'

Two other countries, Benin and Equatorial Guinea, have submitted their dossiers to the World Health Organization, requesting validation for elimination of Sleeping Sickness as a public health problem. To achieve validation for the elimination of a public health problem, a complete dossier must be submitted to present detailed information on the past and present disease incidence throughout the territory. The country must show evidence of effective, ongoing surveillance to prove that the capacity of detecting the disease is strong. The figures must be below the specific thresholds required by the World Health Organization, which means one case per 10 000 inhabitants in all districts, during a five-year period.

Under the World Health Organization’s leadership, national control programmes, bilateral cooperation agencies and nongovernmental organizations have substantially reduced cases of the disease to unprecedented low numbers, specifically less than 1000 globally, before 2020.  

Sleeping sickness is a potentially fatal disease spread by the bite of an infected Tsetse Fly, which are native to the African continent. More than 60 million people living mainly in rural parts of 36 countries across East, Central and West Africa are at risk of contracting the disease.

The World Health Organization and partners are targeting the interruption of transmission of the Trypanosoma brucei gambiense form of the disease in all endemic countries by 2030. 

 

A blood sample showing infection with Trypanosoma brucei gambiense, the causative agent for African Sleeping Sickness. Public Health Image Library/Centers for Disease Control and Prevention/Wikimedia Commons.

The main approaches to controlling Sleeping Sickness include reducing the reservoirs of infection and reducing the presence of the Tsetse Fly.

Screening of people at risk helps identify patients during the early stage of the disease. If diagnosis is made early, it is possible to avoid complicated and risky treatment procedures during the advanced stage.

Human African Trypanosomiasis is a vector-borne parasitic disease caused by infection with Protozoan parasites belonging to the genus Trypanosoma. The causative parasite is transmitted to Humans through the bite of a Tsetse Fly which has acquired the infection from Humans or Animals harbouring the Human pathogenic parasites.  

 

The life cycle of the Trypanosoma parasite, the causative agent for African Sleeping Sickness. Centers for Disease Control and Prevention.

There are two forms of the disease: one due to Trypanosoma brucei gambiense, which is found in 24 countries in West and Central Africa and accounts for more than 98% of cases; and another due to Trypanosoma brucei rhodesiense, which is found in 13 countries in East and Southern Africa and accounts for the remaining cases.

When bitten by an infected Tsetse Fly, a red sore may erupt within a few weeks. The person may experience fever, swollen lymph nodes, aching muscles and joints, headaches and irritability.  

People who become infected feel lethargic and sleepy during the day, then awake but exhausted at night. This is followed by neuropsychiatric and sensory disorders, and then a coma. Death may occur within months or even years. 

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter.