Maladie du sommeil, also known as African trypanosomiasis, is a parasitic disease that poses a significant public health challenge in sub-Saharan Africa. This condition is caused by a tiny parasite and is transmitted to humans through the bite of an infected tsetse fly. Primarily affecting people in rural areas, particularly those involved in agriculture, fishing, hunting, or herding, the disease can be severe if left untreated. Without appropriate medical intervention, the illness progresses to affect the central nervous system, ultimately leading to coma and death.
Understanding the Disease
African trypanosomiasis is caused by two distinct subspecies of Trypanosoma brucei: Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. These microscopic organisms are transmitted to humans when an infected tsetse fly (genus Glossina) takes a blood meal. The parasite multiplies within the fly’s salivary glands before being injected into a new host during subsequent bites.
The two forms exhibit different characteristics and geographical distributions. Trypanosoma brucei gambiense is responsible for over 98% of reported cases and is found in western and central Africa. This form typically causes a chronic infection, with symptoms often appearing months or even years after initial infection. The disease progresses slowly, allowing a longer window for diagnosis and treatment before severe neurological involvement.
Conversely, Trypanosoma brucei rhodesiense is found in eastern and southern Africa and accounts for a smaller percentage of cases. This form causes a more acute, rapid progression. Symptoms typically emerge within weeks of infection, leading to a faster onset of severe illness. The rapid advancement of rhodesiense trypanosomiasis makes early diagnosis and intervention more challenging.
How Symptoms Progress
African trypanosomiasis progresses in two distinct stages. The initial, or hemolymphatic, stage begins when parasites circulate in the blood and lymphatic system. Early symptoms are often non-specific, making diagnosis difficult. These include intermittent fever, headaches, generalized body aches, and profound fatigue.
A characteristic early sign is a trypanosomal chancre, a painful sore at the tsetse fly bite site. As the disease advances in this stage, lymph nodes may swell, particularly in the neck, a condition known as Winterbottom’s sign. This early phase can last for several months or even years in the gambiense form, but only weeks in the more aggressive rhodesiense form.
The second, or meningoencephalic, stage occurs when parasites cross the blood-brain barrier and invade the central nervous system. This leads to the neurological symptoms that give the disease its “sleeping sickness” name. Patients experience severe sleep disturbances, including insomnia at night and overwhelming sleepiness during the day. Other neurological manifestations include confusion, personality changes, tremors, and coordination difficulties. Without treatment, neurological damage progresses, leading to seizures, coma, and death.
Controlling and Treating the Disease
Controlling African trypanosomiasis involves a dual approach focusing on preventing transmission and providing effective treatment. Preventing tsetse fly bites is a primary strategy, as there is currently no vaccine available for humans. Individuals living in or visiting affected areas are advised to wear protective clothing, such as long-sleeved shirts and trousers, which can reduce exposed skin. Insect repellents containing DEET can also offer protection against bites.
Avoiding areas heavily infested with tsetse flies, particularly during peak biting hours, is also advised. Community-level interventions include targeted tsetse fly control programs, involving insecticide-treated traps and screens to reduce fly populations. These efforts aim to break the transmission cycle between flies, animals, and humans.
Systematic screening of at-risk populations is also used for disease control, particularly for the more chronic gambiense form. Early detection through active screening campaigns allows for timely treatment before the disease progresses to the neurological stage, simplifying treatment outcomes. These screening programs involve blood tests followed by confirmation tests for positive cases.
Treatment for African trypanosomiasis depends on the disease stage and specific parasite subspecies involved. Medications used in the early stage are less toxic and easier to administer because the parasites have not yet invaded the central nervous system. Once the disease progresses to the neurological stage, treatments become more complex and often require drugs that can cross the blood-brain barrier, which historically have had more severe side effects. Recent advancements have introduced new, simpler oral medications like acoziborole, which provides a single-dose oral treatment for both stages of gambiense human African trypanosomiasis, simplifying management and improving access to care in remote areas.