How Kenya fought, beat sleeping sickness 100 years on

When sleeping sickness first emerged in Kenya in the early 1900s, it arrived as a mystery wrapped in fear.

There were many sleeping sickness patients, bitten by a tsetse fly, a very small fly carrying the parasite that steals people's consciousness.

Families watched their loved ones sleep slowly and gradually into coma, and many of them actually died. It was called sleeping sickness.

Communities lived under the shadow that they could not really fully understand, nor effectively combat.

Despite the fear and confusion, Kenya refused to surrender. More than 100 years later, what was once considered an inevitable burden has now become a conquered challenge.

Kenya has now been validated by the World Health Organisation (WHO) as having eliminated human African trypanosomiasis (HAT) or sleeping sickness as a public health problem, making it the 10^th country to reach this important milestone.

On June 16, 2025, Kenya received official validation from WHO following a rigorous external expert review.

“I congratulate the government and people of Kenya on this landmark achievement. Kenya joins the growing ranks of countries freeing their populations of human African trypanosomiasis. This is another step towards making Africa free of neglected tropical diseases,” WHO Director General Dr Tedros Adhanom Ghebreyesus said.

According to the Kenya Tsetse and Trypanosomiasis Eradication Council (KENTTEC) CEO Dr Seth Onyango, sleeping sickness was first recorded in Kenya in 1901 through the Kenya Uganda border,and by 1910, it had spread 25 miles inland along the Kuja and Migori rivers and their tributaries.

The first case was defected in Lambwe valley through human and livestock movement likely from Samia-Siaya HAT focus.

The largest outbreak in Lambwe valley in 1964 led to the first aerial spraying to control tsetse fly that spreads the disease.

“This triggered intensive control activities which included aerial and ground spraying of insecticides in the tsetse fly habitats,” Onyango said.

To combat the disease, more targeted methods were deployed, including bush clearing, use of herbicides, ground spraying with herbicides and mass treatment of livestock with trypanocides.

However, an upsurge in cases was witnessed between 1980 and 1984 in Lambwe valley, leading to sustained aerial and ground spraying.

“Despite these interventions, Lambwe Valley sleeping sickness focus remained active but with reduced incidence of below 50 cases annually up to 1988,” he said.

The country shifted from conventional tsetse fly control methods to more technologically improved tools.

These included insecticide treated, odour baited target screens being installed in Lambwe Valley and deployment of odour baited traps to trap out tsetse flies, thus leading to incidence reduction in the valley to zero.

With the WHO validation, Kenya needs to put in place various measures to ensure the gains made are not lost.

These include implementation of post elimination surveillance to ensure detection of any resurgence of cases, ensure quality health services are available for any affected individuals  and tsetse fly control must continue to suppress the vectors beyond the endemic zones.

“We must bear in mind, sleeping sickness has not been eradicated. It has been eliminated as a public health problem. This difference matters. It means it is no longer a disease that spreads from people to people in the community, but it is still there across a few individuals,” Dr Adiele Onyeze said.

Dr Onyenze is an Neglected Tropical Diseases (NTD) and strategic management expert with the WHO.

“History has taught us many lessons, some of them harsh. Some countries that have celebrated too soon realised too quickly and watched sleeping sickness return. Complacency is the enemy of elimination. Success demands real continuous vigilance.”

According to the Amref Health Africa Country Director Dr Meshack Ndirangi Wanjuki, the achievement gives immense hope showing that it is possible to relieve the suffering of the most vulnerable in society by eliminating NTDs that affect them.

He acknowledged the importance of One Health approach and strategy of integrating human health, animal health and planetary health.

This, he said, includes strong collaboration between the Ministry of Health, livestock and agricultural sectors.

He said the approach will is an essential pathway to eliminating a lot of diseases that affect humans today, especially in the age of climate change.

“We recognise and appreciate all the partners who played a role in scaling preventive chemotherapy in the control of the various neglected tropical diseases, including elephantiasis, trachoma, intestinal worms, bilharzia and river brightness,” Ndirangu said.

Health CS Adan Duale said that once endemic in six counties around Lake Victoria—Busia, Bungoma, Siaya, Homa Bay, Migori, and Narok—sleeping sickness posed a major threat to approximately seven million Kenyans.

Since 2009, no indigenous cases have been reported.

“This is a testament to our capacity to eliminate neglected tropical diseases through policy leadership, technical excellence, and community-driven action,” Duale said.

“The achievement will not only protect our people but also pave the way for renewed economic growth and prosperity,” he noted.

HAT is a vector-borne disease caused by the blood parasite Trypanosoma brucei.

It is transmitted to humans through the bites of tsetse flies that have acquired the parasites from infected humans or animals.

Rural populations dependent on agriculture, fishing, animal husbandry or hunting are most at risk of exposure.

A total of 57 countries have eliminated at least one NTD. Of these, 10 (including Kenya) have successfully eliminated HAT as a public health problem.

The other countries that have reached this milestone are Benin, Chad, Côte d’Ivoire, Equatorial Guinea, Ghana, Guinea, Rwanda, Togo and Uganda.