Zebra Disease (African Trypanosomiasis) – A Comprehensive Medical Guide

Overview

African trypanosomiasis, commonly called “zebra disease” when the infection is acquired from the savanna‑type Glossina (tsetse fly) that commonly bites zebras, is a parasitic disease caused by protozoa of the genus Trypanosoma. The two species that infect humans are T. brucei gambiense (West‑ and Central‑African form) and T. brucei rhodesiense (East‑African form). Both are transmitted by the bite of infected tsetse flies (Glossina spp.).

The disease is endemic in 36 sub‑Saharan African countries, affecting an estimated ≈ 70,000 new cases per year, with the majority caused by the chronic gambiense form. While the term “zebra disease” is not used in scientific literature, it is occasionally employed in travel‑medicine circles to highlight the African savanna exposure.

Humans are accidental hosts; the parasites normally circulate among wild and domestic animals (cattle, antelopes, zebras). Occupational exposure (farmers, wildlife workers, hunters) and tourism in endemic regions increase risk.

Symptoms

The clinical picture depends on the parasite species, the stage of infection, and the host’s immune response. Symptoms are grouped into two stages: the early (haemolymphatic) stage and the late (meningo‑encephalitic) stage.

Early (Haemolymphatic) Stage – T. b. rhodesiense (acute) & T. b. gambiense (often mild)

• Fever – intermittent, often with chills.
• Headache – may be throbbing and persistent.
• Generalised lymphadenopathy – especially posterior cervical nodes (“Winterbottom’s sign”).
• Skin rash – maculopapular, sometimes pruritic.
• Joint and muscle pain – arthralgia, myalgia.
• Fatigue & malaise.
• Weight loss – especially with chronic gambiense infection.
• Hematuria or proteinuria – due to renal involvement (rare).

Late (Meningo‑Encephalitic) Stage – Central Nervous System invasion

• Sleep disturbances – “sleeping sickness” – inversion of the sleep‑wake cycle; patients may feel drowsy during the day and unable to sleep at night.
• Neuropsychiatric changes – irritability, confusion, personality changes, depression, psychosis.
• Headache (severe) and meningismus – neck stiffness.
• Coordination problems – ataxia, tremor, gait instability.
• Speech disturbances – slurred speech, dysarthria.
• Seizures – can be focal or generalized.
• Vision problems – blurred vision, optic neuritis.
• Hearing loss (rare).
• Peripheral neuropathy – numbness or tingling in extremities.

These symptoms develop weeks to months after the bite for the acute rhodesiense form, but can take years for the chronic gambiense form.

Causes and Risk Factors

Cause

The disease is caused by infection with Trypanosoma brucei parasites that are introduced into the bloodstream when an infected tsetse fly takes a blood meal. The parasite undergoes a complex life cycle, changing surface proteins (variant surface glycoprotein) to evade the immune system.

Risk Factors

• Geographic exposure – living in or traveling to rural/savanna areas of sub‑Saharan Africa where tsetse flies thrive.
• Occupational contact – farming, cattle herding, wildlife conservation, hunting, logging.
• Outdoor activities – safari tours, trekking, camping near water bodies or bush where flies rest.
• Absence of vector control – lack of insecticide‑treated traps, no cattle spraying.
• Immunocompromised state – HIV, malnutrition may increase susceptibility, though infection can occur in healthy individuals.

Diagnosis

Because early symptoms mimic malaria, typhoid, or viral infections, a high index of suspicion is crucial.

Clinical Assessment

• Travel or exposure history to endemic zones.
• Physical exam focusing on lymphadenopathy, rash, and neurological signs.

Laboratory Tests

1. Microscopic detection – thick or thin blood smears stained with Giemsa or acridine orange. Sensitivity is low in chronic disease.
2. Concentration techniques – mini‑anion exchange centrifugation technique (mAECT) improves detection to >90 %.
3. Serology – Card Agglutination Test for Trypanosomiasis (CATT) for gambiense; ELISA and rapid diagnostic tests (RDTs) are increasingly used.
4. Polymerase Chain Reaction (PCR) – detects parasite DNA; useful for low‑parasitaemia cases and species differentiation.
5. CSF analysis (lumbar puncture) – required to determine CNS involvement. Elevated white‑cell count (>5 cells/µL), increased protein, and presence of parasites confirm late stage.
6. Imaging – MRI/CT may show cerebral atrophy or diffuse hyperintensities but are not diagnostic.

Staging

Based on CSF findings: T. b. gambiense – <5 cells/µL = early stage; ≥5 cells/µL = late stage. For T. b. rhodesiense the disease progresses rapidly, and most patients present in the CNS stage.

Treatment Options

Treatment must be tailored to parasite species and disease stage. All regimens should be administered under specialist supervision because of drug toxicity.

Early‑Stage (Haemolymphatic)

• Pentamidine isethionate (for gambiense) – 4 mg/kg IV or IM once daily for 7 days. Side effects: nausea, hypotension.
• Suramin (for rhodesiense) – 1 g IV on days 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21. Monitor kidney function; can cause rash and peripheral neuropathy.

Late‑Stage (CNS) – Gambiense

• Eflornithine – 100 mg/kg IV every 6 hours for 14 days (the “DFMO” regimen). Generally well tolerated.
• Nifurtimox‑Eflornithine Combination Therapy (NECT) – eflornithine 400 mg/kg/day IV 4 times daily + nifurtimox 15 mg/kg/day orally divided three times for 10 days. NECT reduces treatment duration and hospital stay.

Late‑Stage (CNS) – Rhodesiense

• Melarsoprol – arsenical compound, 2.2 mg/kg IV daily for 3 days, then 3.6 mg/kg weekly for 3 weeks, then 5 mg/kg weekly for 4 weeks. Highly neurotoxic; can cause encephalopathic syndrome (up to 10 % mortality). Use only when alternatives unavailable.
• In some centres, fexinidazole (oral) is being studied for rhodesiense, but it is currently approved only for gambiense.

Supportive Care & Lifestyle Adjustments

• Hydration and electrolyte management.
• Antipyretics for fever.
• Physical therapy for gait and coordination deficits.
• Psychiatric support for mood or cognitive changes.

Living with Zebra disease (African Trypanosomiasis)

Even after successful therapy, some patients experience residual neurological deficits. A multidisciplinary approach helps improve quality of life.

• Follow‑up appointments – repeat CSF exams at 6‑month intervals for the first 2 years.
• Neuro‑rehabilitation – balance training, occupational therapy, speech therapy if needed.
• Medication adherence – complete the full drug course; missed doses can cause relapse.
• Nutrition – balanced diet rich in protein and vitamins supports immune recovery.
• Psychosocial support – counseling, support groups for patients and families.
• Travel advice – after cure, patients can safely return to endemic areas but should continue protective measures against tsetse bites.

Prevention

There is no vaccine; prevention relies on vector control and personal protection.

• Avoid tsetse fly habitats – dense bush, riverine vegetation, especially during sunrise and late afternoon.
• Protective clothing – long‑sleeved shirts, long trousers, and socks. Tuck trousers into boots.
• Insect repellents – DEET (20‑30 %) or picaridin applied to skin and clothing.
• Tsetse traps & targets – insecticide‑treated blue or black cloth panels deployed around settlements and livestock pens.
• Livestock treatment – pour‑on insecticides (deltamethrin) on cattle to reduce fly population.
• Prophylactic drug trials – not currently recommended outside research settings.
• Health education – community awareness campaigns by public‑health agencies (e.g., WHO “Trypanosomiasis Control Programme”).

Complications

If left untreated or inadequately treated, African trypanosomiasis can lead to life‑threatening complications:

• Severe CNS damage – irreversible sleep cycle disruption, coma, and death.
• Cardiomyopathy – due to chronic inflammation.
• Renal failure – especially in rhodesiense infection.
• Secondary infections – immunosuppression predisposes to pneumonia, malaria.
• Psychiatric disorders – chronic depression, anxiety, psychosis.
• Infertility – rare, related to gonadal involvement.

When to Seek Emergency Care

References

• World Health Organization. Human African Trypanosomiasis Fact Sheet. 2023.
• Mayo Clinic. African trypanosomiasis (sleeping sickness). Updated 2022.
• Centers for Disease Control and Prevention. Parasites – African Trypanosomiasis. Accessed May 2026.
• NIH National Institute of Allergy and Infectious Diseases. African Trypanosomiasis. 2021.
• Cleveland Clinic. African Trypanosomiasis (Sleeping Sickness). 2023.
• Peeling RW, et al. “Diagnosis of Human African Trypanosomiasis.” *Lancet Infectious Diseases*, 2020;20(8):e215‑e227.