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Sleeping sickness

Sleeping sickness is an infection caused by tiny parasites carried by certain flies. It results in swelling of the brain.


Sleeping sickness is caused by two types of parasites Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense. T b rhodesiense causes the more severe form of the illness.

Tsetse flies carry the infection. When an infected fly bites you, the infection spreads through your bloodstream.

Risk factors include living in parts of Africa where the disease is found and being bitten by tsetse flies. The disease does not occur in the United States, but travelers who have visited or lived in Africa can get infected.


General symptoms include:

  • Mood changes, anxiety
  • Fever, sweating
  • Headache
  • Weakness
  • Insomnia at night
  • Sleepiness during the day (may be uncontrollable)
  • Swollen lymph nodes all over the body
  • Swollen, red, painful nodule at site of the fly bite

Exams and Tests

Diagnosis is often based on a physical examination and detailed information about the symptoms. If the health care provider suspects sleeping sickness, you'll be asked about recent travel. Blood tests will be ordered to confirm the diagnosis.

Tests include the following:


Medicines used to treat this disorder include:

  • Eflornithine (for T b gambiense only)
  • Melarsoprol
  • Pentamidine (for T b gambiense only)
  • Suramin (Antrypol)

Some people may receive a combination of these medicines.

Outlook (Prognosis)

Without treatment, death can occur within 6 months from cardiac failure or from T b rhodesiense infection itself.

T b gambiense infection causes sleeping sickness disease and gets worse quickly, often over a few weeks. The disease needs to be treated immediately.

Possible Complications

Complications include:

  • Injury related to falling asleep while driving or during other activities
  • Gradual damage to the nervous system
  • Uncontrollable sleep as the disease gets worse
  • Coma

When to Contact a Medical Professional

See your provider right away if you have symptoms, especially if you've traveled to places where the disease is common. It is important to begin treatment as soon as possible.


Pentamidine injections protect against T b gambiense, but not against T b rhodesiense. Because this medicine is toxic, using it for prevention is not recommended.

Insect control measures can help prevent the spread of sleeping sickness in high-risk areas.

Alternative Names

Parasite infection - human African trypanosomiasis


Kirchhoff LV. Agents of African trypanosomiasis (sleeping sickness). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 277.

Petri WA. African sleeping sickness. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 325.

Review Date 12/4/2022

Updated by: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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