Nigerian Sleeping Sickness (Human African Trypanosomiasis)
Overview
Human African trypanosomiasis (HAT), commonly called sleeping sickness, is a parasitic disease transmitted by the bite of infected tsetse flies (Glossina spp.). The “Nigerian” form refers specifically to infection with the parasite Trypanosoma brucei gambiense, which is responsible for > 98 % of HAT cases in West and Central Africa. The disease progresses slowly, often over months to years, and can be fatal if untreated.
Who it affects: The disease primarily targets people living in rural, forest‑edge or savanna communities where tsetse flies breed. It is most common among men and women aged 15–45 years, the age group most likely to work outdoors (farming, hunting, fishing). Children are also affected, especially in families that spend long periods near riverbanks or game reserves.
Prevalence: According to the World Health Organization (WHO), reported cases peaked at ~ 37,000 in 1998 and have fallen dramatically due to concerted control programs. In 2023 the WHO recorded **≈ 663 new cases worldwide**, with the majority (≈ 580) from the Democratic Republic of Congo and a small but persistent number from Nigeria, Cameroon, and neighboring West‑African nations. Under‑reporting remains a challenge; the WHO estimates that the true number of infections may be up to 2–3 times higher than reported.
Although elimination as a public health problem is the goal by 2030, ongoing conflict, climate‑driven changes in fly habitats, and health‑system gaps keep HAT a concern for endemic regions.
Symptoms
HAT has two clinical stages. The first (haemolymphatic) stage reflects parasite multiplication in the blood and lymph; the second (meningo‑encephalitic) stage occurs when parasites cross the blood‑brain barrier.
Stage 1 – Haemolymphatic (early) symptoms (weeks‑months after bite)
- Fever and chills – intermittent, low‑grade.
- Headache – often dull, worsening in the afternoon.
- Generalised lymphadenopathy – painless swelling of neck, armpit or groin nodes.
- Fatigue and malaise – a sense of profound tiredness not relieved by rest.
- Joint and muscle pains – can mimic rheumatic fever.
- Weight loss – gradual, sometimes > 5 % of body weight over months.
- Itching (pruritus) – especially around bite site.
- Skin hyperpigmentation – “sun‑set” or “African” coloration of the skin, more common in chronic infection.
Stage 2 – Meningo‑encephalitic (late) symptoms (months‑years later)
- Sleep disturbances – difficulty falling asleep at night and excessive daytime sleepiness (the hallmark “sleeping sickness”).
- Behavioral changes – irritability, confusion, personality shifts.
- Neurological signs – tremor, seizures, ataxia, loss of coordination.
- Psychiatric manifestations – depression, psychosis, hallucinations.
- Motor weakness – may progress to paraplegia.
- Speech difficulties – slurred or slow speech.
- Vision problems – blurred vision, optic nerve involvement.
- Hearing loss – less common but reported.
- Enlarged spleen & liver – palpable on exam, reflecting systemic infection.
Because early symptoms are nonspecific, HAT is often mistaken for malaria, typhoid, or viral infections, leading to delayed diagnosis.
Causes and Risk Factors
Cause
The disease is caused by the protozoan parasite Trypanosoma brucei gambiense. The parasite lives in the midgut and salivary glands of the tsetse fly. When an infected fly takes a blood meal, it injects metacyclic trypomastigotes into the host’s skin, where they multiply and disseminate via the bloodstream.
Risk Factors
- Geographic exposure – living or working in endemic foci (riverine forests, savanna, agricultural fringes).
- Occupational contact – farmers, hunters, pastoralists, timber workers, and military personnel stationed in rural areas.
- Proximity to wildlife reservoirs – certain wild mammals (pseudodongo, antelopes) can harbour the parasite.
- Limited access to health services – delayed screening, lack of surveillance.
- Poor housing conditions – that allow tsetse flies easy entry (e.g., thatched roofs, unscreened windows).
- Climate change & land use – deforestation and irrigation create new fly breeding sites.
Diagnosis
Accurate diagnosis requires a combination of clinical suspicion, epidemiologic context, and laboratory testing.
Step‑wise diagnostic approach
- Screening tests
- CATT (Card Agglutination Test for Trypanosomiasis) – rapid serologic test used in field settings; positive result prompts confirmatory testing.
- RDTs (Rapid Diagnostic Tests) – newer lateral‑flow assays with comparable sensitivity.
- Parasitological confirmation
- Microscopy of lymph node aspirates, blood (thick smear), or cerebrospinal fluid (CSF) using the “mini-anion exchange centrifugation technique” (mAECT) – most sensitive for detecting live parasites.
- Polymerase Chain Reaction (PCR) – detects parasite DNA; valuable when parasite load is low.
- Staging – determining early vs. late disease
- Analysis of CSF obtained by lumbar puncture. Presence of ≥ 5 white blood cells/µL or detection of trypanosomes in CSF indicates stage 2.
- CSF protein and glucose may also be measured, but cell count is the primary staging marker.
All tests should be performed in an accredited laboratory or under the supervision of a physician experienced with HAT. In remote areas, the WHO recommends a “screen‑and‑treat” algorithm using CATT followed by immediate treatment if parasites are visualised.
Treatment Options
Treatment differs by disease stage because many drugs cannot cross the blood‑brain barrier.
Stage 1 (Haemolymphatic)
- Pentamidine isethionate (Benoît’s drug) – 4‑day intramuscular (IM) regimen (300 mg/kg total). Effective in > 95 % of cases; monitor for renal toxicity.
- Nifurtimox‑Eflornithine Combination Therapy (NECT) – increasingly used for both stages in some programs because of better tolerability; however, stage‑1 monotherapy with pentamidine remains WHO‑preferred.
Stage 2 (Meningo‑encephalitic)
- Eflornithine (DFMO) – 14‑day IV infusion (100 mg/kg every 6 h). Often combined with nifurtimox to reduce infusion time (NECT).
- Nifurtimox – oral 15 mg/kg/day in 4 divided doses for 10 days (used in combination with eflornithine).
- Fexinidazole – oral 1800 mg/day for 4 days, then 1200 mg/day for 6 days; WHO approved in 2020 for both stages in patients ≥ 6 years and ≥ 20 kg, provided they have no severe neurologic disease.
Supportive care is essential: fluid/electrolyte balance, antipyretics, analgesics, and treatment of secondary infections.
Side‑Effect Management
- Pentamidine – monitor kidney function (serum creatinine) and blood pressure.
- Eflornithine – watch for bone‑marrow suppression, liver enzyme elevation; ensure central line patency.
- Nifurtimox – can cause nausea, vomiting, neuropathy; give anti‑emetics and consider dose adjustment.
- Fexinidazole – gastrointestinal upset is common; advise food intake with doses.
Living with Nigerian Sleeping Sickness (Human African Trypanosomiasis)
Even after successful treatment, patients may face residual fatigue, mild neuro‑cognitive changes, or anxiety about recurrence. The following strategies help maintain health and quality of life.
Follow‑up schedule
- First review 3 months post‑treatment (clinical exam + CSF if stage 2).
- Subsequent visits at 6 months, 12 months, and then annually for at least 2 years.
- Any new neurological symptoms should trigger immediate re‑evaluation.
Daily management tips
- Nutrition – balanced diet rich in protein, iron, and vitamin B12 supports immune recovery.
- Hydration – especially important after pentamidine or eflornithine therapy.
- Rest & sleep hygiene – maintain regular sleep‑wake cycles; daytime naps limited to 20–30 minutes.
- Physical activity – gentle exercise (walking, stretching) improves stamina without overexertion.
- Mental health – counseling, support groups, or community health worker visits can address lingering anxiety or depression.
- Medication adherence – complete the full prescribed course even if symptoms improve.
Community health programs in endemic areas often provide free or subsidised follow‑up care; patients should be informed about these resources.
Prevention
Because there is no vaccine, prevention focuses on reducing contact with tsetse flies and controlling the vector.
Personal protective measures
- Wear long‑sleeved shirts, long trousers, and closed shoes when working in fly‑infested areas.
- Apply insect repellent containing DEET (20‑30 %) or picaridin on exposed skin.
- Use impregnated (permethrin‑treated) clothing or blankets.
- Stay in well‑screened or air‑conditioned housing; install fine‑mesh windows.
- Avoid outdoor activities at dawn and dusk when tsetse are most active.
Environmental & community interventions
- Fly‑traps – blue/black cloth traps or insecticide‑treated targets placed along riverbanks reduce local fly populations.
- Clearing vegetation near homes and livestock pens diminishes breeding sites.
- Livestock treatment – applying insecticide to cattle can create a “dead‑end” for flies (zooprophylaxis).
- Active surveillance – periodic community screening with CATT or RDTs accelerates early case detection.
Complications
If untreated or inadequately treated, HAT can lead to serious, often irreversible complications.
- Neurological deterioration – severe encephalopathy, coma, and death.
- Cardiovascular involvement – myocarditis and arrhythmias.
- Renal failure – secondary to chronic infection and drug toxicity.
- Hepatic fibrosis – due to prolonged inflammatory response.
- Psychiatric disorders – lasting depression, anxiety, or psychosis.
- Secondary infections – immunosuppression predisposes to bacterial pneumonia, skin sepsis.
Mortality rates for untreated stage 2 disease approach 100 % within 2–3 years.
When to Seek Emergency Care
Warning signs that require immediate medical attention:
- Sudden onset of severe headache combined with confusion or loss of consciousness.
- High fever (> 39 °C) that does not respond to antipyretics.
- Seizures or new‑onset tremors.
- Rapidly worsening sleepiness, inability to stay awake, or abrupt coma.
- Difficulty breathing, chest pain, or swelling of the legs (possible cardiac involvement).
- Signs of severe dehydration (dry mouth, scant urine, dizziness).
- Persistent vomiting preventing oral medication intake.
If any of these symptoms appear, go to the nearest health facility or call emergency services. Early intervention can be life‑saving.
References
- Mayo Clinic. African Trypanosomiasis (Sleeping Sickness) – Overview. Accessed April 2026.
- World Health Organization. Human African Trypanosomiasis Fact Sheet. 2023.
- Cleveland Clinic. Sleeping Sickness (African Trypanosomiasis). Updated 2024.
- National Institute of Allergy and Infectious Diseases (NIH). Human African Trypanosomiasis. 2022.
- Centers for Disease Control and Prevention. African Trypanosomiasis (Sleeping Sickness). 2023.
- Priotto G, et al. “Nifurtimox‑Eflornithine Combination Therapy for Second‑Stage African Trypanosomiasis.” N Engl J Med. 2009;361:159‑168.