Your Guide to
Neglected Tropical Diseases

Human African trypanosomiasis is a life-threatening parasitic disease spread through tsetse fly bites. Most cases develop slowly over months to years; a few progresses rapidly within weeks. First, parasites multiply in the blood, causing fever, headache, swollen lymph nodes, and joint pain. Then, parasites invade the brain, triggering sleep disorders (giving the disease its name “sleeping sickness”), confusion, poor coordination, and personality changes. Without treatment, patients fall into coma and die. Fortunately, early diagnosis and treatment can cure the disease and prevent brain damage.

Tsetse flies, which feed on blood, are found exclusively in sub-Saharan Africa, and are the only way this disease spreads. When an infected tsetse fly bites, it injects parasites into the skin. While most tsetse flies do not carry the parasites, each bite increases the chances of encountering one that does.

There are two forms of the disease, each with different sources. The chronic form mainly spreads among humans, while the acute form is primarily transmitted from domestic cattle and wild animals. In rare cases, the disease can pass from mother to child during pregnancy or through contaminated needles. There has been one reported case of sexual transmission. However, people cannot catch sleeping sickness through routine contact with infected individuals.

Geographic scope:

• The disease is endemic in 36 sub-Saharan African countries.
• The chronic form occurs in countries across west and central Africa, while the acute form is found in countries in eastern and southern Africa.
• Uganda is the only country with both forms, occurring in separate geographic zones.

Population affected:

• Primarily affects remote rural communities who depend on agriculture, fishing, animal husbandry, or hunting.
• Approximately 70 million people are at risk at any given time.
• Without treatment, approximately 90% of cases are fatal.
• Cases have dropped dramatically, from nearly 28,000 in 1999 to less than 550 today, showcasing the power of prevention and treatment.

A major breakthrough came in 2024 when WHO approved fexinidazole as the new first-line treatment. This oral pill is taken once daily for 10 days with food and works for both forms and stages of the disease. It is approved for use in patients aged 6 and older weighing at least 20 kilograms (44 pounds). The new treatment is much safer than previous medications. When caught early, fexinidazole cures most cases. All medicines are donated free and distributed worldwide by WHO.

Prevention focuses on controlling tsetse flies through insecticide spraying and insecticide-treated screens. Mobile screening teams visit high-risk communities to detect cases early, since initial symptoms are mild and people often do not seek care. Early detection allows treatment before the parasites reach the brain. There is no vaccine currently available. In affected areas, wearing long sleeves and pants and using insect repellent help reduce the risk of infection.