An Overview of African Sleeping Sickness

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African trypanosomiasis, or sleeping sickness, is a neglected tropical disease caused by a parasite and spread by the tsetse fly in sub-Saharan Africa. Infections begin with mild to moderate symptoms like fever and body aches before moving on to serious neurological issues that include sleep disturbances (which give the disease its name).

How quickly the disease progresses depends on the specific subspecies responsible for the infection, though someone can be infected for months or even years before the first symptoms become apparent. Without treatment, the disease is often fatal.

While African sleeping sickness remains a serious public health issue in sub-Saharan Africa, significant progress has been made to fight infections. According to the World Health Organization (WHO), efforts to control the disease caused the number of cases to plummet by 73 percent from 2000 to 2012, and only about 2,800 cases total were reported in 2015. Most new cases (roughly 84 percent in 2015) are reported in the Democratic Republic of the Congo.

African Sleeping sickness
Verywell / Nusha Ashjaee 


The symptoms of African trypanosomiasis vary based on the stage of the untreated disease. The first stage of sleeping sickness generally involves physical symptoms like fever and body aches, while the second stage is marked by changes to a person’s mental state and neurological processes.

First Stage

After someone becomes infected with African trypanosomiasis, the parasite circulates for a while in the bloodstream, prompting symptoms similar to those of other infectious diseases. During this first stage of sleeping sickness, symptoms generally include:

  • A large sore at the site of the tsetse fly bite
  • Fever
  • Muscle and joint aches
  • Headaches 
  • Malaise
  • Rash or itchy skin
  • Enlarged lymph nodes
  • Weight loss

Second Stage

The disease enters the second stage when the parasite crosses the blood-brain barrier, infecting the central nervous system. During this stage, a person experiences mental deterioration and, without treatment, eventually death.

Signs and symptoms of the second stage of African trypanosomiasis are often more obvious than the first and can include:

  • Personality changes
  • Sleepiness during the daytime
  • Sleep disturbances at night
  • Progressively more confusion
  • Issues with balance or walking
  • Partial paralysis
  • Coma
  • Death

How quickly someone goes from stage one to stage two depends on the subspecies of the parasite.


The two primary forms of African trypanosomiasis are East African sleeping sickness, caused by Trypanosoma brucei Rhodesiense, and West African sleeping sickness, caused by Trypanosoma brucei Gambiense.

East African Sleeping Sickness

East African sleeping sickness is caused by the subspecies T. b. Rhodesiense. Infections with the subspecies result in a much faster progression from stage one to stage two than seen with West African sleeping sickness. The parasite will infect the central nervous system after only a few weeks and can become fatal within months.

East African sleeping sickness is found in 13 countries in eastern and southern Africa and makes up less than 3 percent of all reported cases of African trypanosomiasis.

West African Sleeping Sickness

T. b. Gambiense, or West African sleeping sickness, is a parasite that moves more slowly. The parasite can live in the bloodstream for a year or two before progressing to the central nervous system and prompting stage two of the disease. Untreated infections generally become fatal in about three years, though they can stretch on for as long as six or seven years.

The more common of the two subspecies, West African sleeping sickness accounts for more than 97 percent of reported cases and is found in 24 countries in western and central Africa.


The most common way the African trypanosomiasis parasite is spread is through the tsetse fly, a large, biting fly found in much of sub-Saharan Africa. When a tsetse fly bites someone who is infected, it becomes infected with the parasite itself. The fly then becomes part of the parasite's life cycle, helping it grow and multiply. After about three weeks, the newly transformed parasites make their way to the fly's salivary gland.

When the fly takes a blood meal in a human (or in some animals), it leaves behind the parasite, prompting a new infection.

On rare occasions, people can become infected in other ways, such as via:

  • Mother-to-child transmission during pregnancy
  • Sexual activity
  • Pricks with needles contaminated with the parasite (typically due to an accident in the laboratory)


Diagnosing African trypanosomiasis as early as possible is crucial, because catching the disease in stage one can make the infection easier and safer to treat. Doctors often rely on lab tests, like microscopy, to confirm an African trypanosomiasis diagnosis, but screening tests and physical exams can also be helpful in determining who should be tested and how.

Screening Tests

Certain tests can help health officials identify potential cases of African sleeping sickness out of a larger population. The card agglutination test, for example, is a tool used to detect possible T. b. gambiense cases in populations where West African sleeping sickness is common.

While these screening tests can help health officials find suspected infections in the early stages, they are not specific enough to confirm a diagnosis, and no such screening tools are available to screen for the faster-moving East African sleeping sickness. Widespread screening is also costly, which can be a significant challenge for remote areas with limited resources.

Physical Exam

Doctors rely on lab tests to make a definitive diagnosis, but knowing what signs and symptoms a person is experiencing (and how quickly they've progressed) can give a healthcare provider clues as to what stage of the disease a person might be in and possibly what subspecies is responsible for the infection. This, in turn, can help guide diagnostic procedures.

During an exam, doctors will likely ask about a person’s history of exposure.

This means asking whether the individual lives in or has visited areas where sleeping sickness is common as well as looking for clinical signs of the disease and its stage.


The current standard for diagnosing African trypanosomiasis is by looking for the parasite under a microscope using a body fluid or tissue sample. Samples are generally taken from blood, chancres (the sore that forms at the site of the fly bite), lymph nodes, or bone marrow.

The site of the sample can depend on what subspecies is suspected of causing the infection. For example, T. b. Rhodesiense is generally easy to spot in blood, whereas T. b. Gambiense is more readily spotted in samples taken from the lymph node.

Once a diagnosis is confirmed, however, it’s recommended that doctors also do a spinal tap to look for signs of the parasite in the cerebrospinal fluid. That will help healthcare providers determine the stage of the disease and, therefore, what treatment is needed.


Sleeping sickness is treatable with medications, but the specific treatment used depends on the subspecies of the parasite and the stage of the disease. Procedures needed to treat stage one disease are simpler and less toxic than those used to treat more advanced infections. 

Stage One Treatments

Two antimicrobial medications are primarily used to treat early-stage African trypanosomiasis: pentamidine and suramin.

  • Pentamidine: Pentamidine is given to those with stage one West African sleeping sickness and is administered via injection or intravenously. This medication is usually well tolerated but can cause side effects like hypoglycemia and an upset stomach.
  • Suramin: Suramin is used to treat East African sleeping sickness and is given intravenously. Side effects are common, though generally mild and temporary.
  • Fexinidazole: This new drug for West African sleeping sickness was approved in 2019. It is effective at treating both stage one and early stage two of the disease. It cannot be used in first trimester of pregnancy or in children under 6 years of age. The most common side effects are nausea, vomiting, and headache. It is given as a once-daily pill for 10 days.

Stage Two Treatments

Three medications are recommended for infections that have already crossed the blood-brain barrier: eflornithine, melarsoprol, and nifurtimox.

  • Eflornithine: Eflornithine treats those with stage two West African sleeping sickness. It’s administered intravenously four times a day for two weeks straight, which can be hard to manage in rural health settings. Due to this, it is sometimes combined with nifurtimox so that it can be given in less frequent doses.
  • Melarsoprol: Melarsoprol is the only medication available to treat East African sleeping sickness in its second stage, but it can treat West African sleeping sickness as well. While effective, melarsoprol is difficult to use and rather toxic. It’s administered intravenously, using a complicated dosing schedule, and side effects can be intense. An estimated 5 to 10 percent of the time, it can cause neurological issues or sometimes death.
  • Nifurtimox: Nifurtimox is typically used to treat American trypanosomiasis (also called Chagas disease), but it is sometimes combined with eflornithine to treat West African sleeping sickness.


There’s no vaccine or medication you can take to prevent African trypanosomiasis. The best way to protect yourself is to avoid tsetse fly bites altogether.

If you’re planning on visiting or residing in areas where African sleeping sickness is common, it is important to take precautions.

  • Ask locals if they know which areas have higher concentrations of tsetse flies and which places you should avoid.
  • Steer clear of bushes or thick vegetation during the day where the flies might be resting.
  • Cover up by wearing long sleeves, long pants, and hats made from medium-weight, neutral-colored fabrics. Flies can bite through lighter materials and are drawn to vibrant and dark colors, especially blue.
  • Check inside vehicles before getting into them. Tsetse flies like moving vehicles that kick up dust.
  • Use bug spray as directed. Insect repellants don’t appear to provide much protection from tsetse flies, but the flies aren’t the only insects that can transmit diseases. Mosquito-borne illnesses like dengue fever or malaria are also significant public health concerns for those living in regions where African trypanosomiasis can spread. 

A Word From Verywell

African sleeping sickness is a serious and potentially fatal disease, but it’s treatable—especially if diagnosed in the early stages of the disease. If you’ve recently traveled or lived in areas with African trypanosomiasis and are showing symptoms of the disease, be sure to talk to a healthcare provider right away and let them know about your travel history.

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Additional Reading

By Robyn Correll, MPH
Robyn Correll, MPH holds a master of public health degree and has over a decade of experience working in the prevention of infectious diseases.