Trypanosomiasis (trih-pan-o-so-MY-uh-sis) is a disease found in Africa and the American continents that is caused by infection with a parasite * . Forms of the disease may persist for many years and have several phases, with symptoms that can vary from one stage to the next.

What Is Trypanosomiasis?

Trypanosomiasis is the name for three types of infections caused by protozoa * and spread to humans through insect bites. There are two kinds of African trypanosomiasis, East African and West African. Both of these varieties are also known as sleeping sickness. The disease can affect people living on the African continent south of the Sahara Desert. American trypanosomiasis is also called Chagas (SHAH-gus) disease. It occurs only on the American continents, from Mexico to Argentina.

What Causes Trypanosomiasis?

Lifecycle of African Trypanosomiasis. During a blood meal on the mammalian host, an infected bloodsucking tsetse fly (genus Glossina) injects metacyclic trypomastigotes into skin tissue.

Lifecycle of African Trypanosomiasis. During a blood meal on the mammalian host, an infected bloodsucking tsetse fly (genus Glossina) injects metacyclic trypomastigotes into skin tissue. The parasites enter the lymphatic system and pass into the bloodstream and are carried to other sites throughout the body (lymph, spinal fluid, etc.), and continue to replicate. The trypomastigote reproduces asexually.
Mark Giles/Science Source.

Reduviid (rih-DO-vee-id) bugs (also called assassin, cone-nose, or kissing bugs) carry the Trypanosoma cruzi (trih-pan-o-SO-mah KROO-zee) protozoa that cause the American variety of trypanosomiasis, or Chagas disease, named for the Brazilian physician Carlos Chagas (1879–1934) who discovered it in 1909. These bugs hide during the day in the cracks in mud and adobe homes. At night they crawl across sleeping people and bite them, usually on the face but sometimes on the arms, legs, or trunk. They also leave behind their feces * , which contain the protozoa. Without knowing it, people can rub the infected feces into the bite, a cut or open sore, or even into their noses, mouths, or eyes.

How Common Is Trypanosomiasis?

Is Trypanosomiasis Contagious?

People cannot catch any form of trypanosomiasis in the same way that they catch a cold or the flu from other people. Only the tsetse fly spreads the African varieties, and the reduviid bug spreads Chagas disease. Rarely, a mother infected with the West African variety of trypanosomiasis or with Chagas disease can pass the illness to her unborn child. People who receive a transfusion * of blood or an organ transplant from an infected person may also contract the disease; this form of transmission tends to happen more often with Chagas disease than with the African types.

What Are the Symptoms of the Disease?

African trypanosomiasis

People who contract the African varieties of trypanosomiasis may start sleeping more, although this usually does not happen until the later stages of the disease. Sleeping sickness may start with the appearance of a sore called a chancre (SHANG-ker) at the spot where the person received the tsetse fly bite. Later symptoms include fever, extreme tiredness, severe headaches, rashes, itching, joint pain, and swelling of the hands and feet. The lymph nodes * on the back of the neck may become swollen as well. These signs typically appear two to four weeks after infection with East African trypanosomiasis.

Other symptoms can follow quickly, as the protozoa cross the bloodbrain barrier * and start affecting a patient's mental functions. The later stages of sleeping sickness may bring mental confusion, changes in personality, problems with walking and talking, weight loss, and seizures * . The spleen and liver may become enlarged. Sleeping sickness gets its name from the later part of the disease, when the sick person has nighttime insomnia * but sleeps for long periods during the day. If the person does not receive treatment, the heart muscles may become inflamed or weakened, causing death from heart failure.

The early symptoms in West African trypanosomiasis are similar but may take longer to appear. Months or years may pass before an infected person becomes sick, and the disease develops more slowly, although it can still cause death if it is left untreated. The gap between infection and the start of symptoms can make this form of sleeping sickness difficult to diagnose.

Chagas disease * phase of Chagas disease. They may become constipated and experience trouble swallowing. The heart may become enlarged, and patients may have altered heart rhythms or heart failure leading to death.

Global Warming

The bite of an insect can transmit bacteria, protozoa, or even worms into a person's bloodstream, leading to a variety of illnesses. Trypanosomiasis is just one example of a tropical insectborne disease. A few others, along with the insects that spread them, are:

These diseases are common to the tropics because the hot and often rainy climate makes the tropics an ideal breeding ground for insects. Greenpeace, among other organizations dedicated to protecting the environment, has warned that global warming could create new breeding grounds for insects throughout the world. At the same time, rising temperatures could raise insect reproductive rates, increasing their numbers.

How Do Doctors Diagnose Trypanosomiasis?

Because all types of trypanosomiasis are rare in the United States, it is important for people who have any symptoms of the disease to let their doctor know right away if they have been traveling in areas where the disease is common. To diagnose sleeping sickness or Chagas disease, a doctor orders blood tests to look for protozoa or antibodies * to the organism. In cases in which the doctor suspects sleeping sickness, a sample drawn from fluid surrounding the brain and spinal cord or tissue from swollen lymph nodes may be examined for evidence of the disease. If a patient has a suspiciouslooking skin lesion * , a biopsy * is performed to test for T. cruzi protozoa.

Can Trypanosomiasis Be Treated Successfully?

There are medications available to treat all types of the disease. Doctors recommend that people with trypanosomiasis receive treatment as soon as possible. Treatment is given in a hospital. After leaving the hospital, patients are typically watched closely by a doctor for at least two years to see whether they show any signs that they still have the infection.

What Happens to People with Trypanosomiasis?

East African sleeping sickness can move through the body quickly, progressing in just weeks or months to the most serious phase of illness. West African sleeping sickness takes longer to develop. People may not reach the critical phase for months or even years. People who do not receive treatment for African trypanosomiasis can die from heart failure, and those who wait to start treatment may have permanent brain damage. Long-term complications of Chagas disease, which may not appear for 20 or more years after infection, include damage to the digestive and nervous systems, heart problems, and sudden death.

Can Trypanosomiasis Be Prevented?

There is no vaccine or medication that can prevent any form of the disease, so it is wise for people who travel in areas where the disease is common to take precautions. In Africa, precautions include wearing clothes of thick material, with long sleeves and long pants. Neutral colors, such as tan, are best because tsetse flies are attracted to dark and bright colors. Doctors recommend that travelers to Africa sleep under netting and avoid riding in the backs of open trucks because dust from moving vehicles attracts the flies. It is also advisable not to walk through brush. In areas where Chagas disease is found, it is a good idea for people to avoid sleeping in mud, adobe, or thatch houses; to sleep under netting; and to use insect repellent.

See also Chagas Disease • Parasitic Diseases: Overview • Travel-Related Infections: Overview


Books and Articles

Magez, Stefan, and Magdalena Radwanska. Trypanosomes and Trypanosomiasis. New York: Springer Publishing Company, 2013.


Centers for Disease Control and Prevention. “Parasites: African Trypanosomiasis (Also Known as Sleeping Sickness).” (accessed March 1, 2016).

MedlinePlus. “Chagas Disease.” U.S. National Library of Medicine. (accessed March 1, 2016).

World Health Organization. “Trypanosomiasis, African.” (accessed March 1, 2016).


Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30329-4027. Toll-free: 800-232-4636. Website: (accessed March 1, 2016).

World Health Organization. Avenue Appia 20, CH 1211 Geneva 27, Switzerland. Telephone: 41 22 791 2111. Website: (accessed March 1, 2016).

* parasite (PAIR-uh-site) is an organism such as a protozoan (one-celled animals), worm, or insect that must live on or inside a human or other organism to survive. An animal or plant harboring a parasite is called its host. A parasite lives at the expense of the host and may cause illness.

* protozoa (pro-tuh-ZOH-uh) are single-celled microorganisms (tiny organisms), some of which are capable of causing disease in humans.

* feces (FEE-seez) is the excreted waste from the gastrointestinal tract.

* transfusion (trans-FYOO-zhun) is a procedure in which blood or certain parts of blood, such as specific cells, is given to a person who needs it due to illness or blood loss.

* lymph nodes (LIMF) are small, bean-shaped masses of tissue containing immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.

* blood-brain barrier is a biological shield in the body that helps prevent germs or other potentially harmful materials in the blood from entering the brain and spinal cord.

* seizures (SEE-zhurs) are sudden bursts of disorganized electrical activity that interrupt the normal functioning of the brain, often leading to uncontrolled movements in the body and sometimes a temporary change in consciousness.

* insomnia is an abnormal inability to get adequate sleep.

* chronic (KRAH-nik) means lasting a long time or recurring frequently.

* antibodies (AN-tih-bah-deez) are protein molecules produced by the body's immune system to help fight specific infections caused by microorganisms, such as bacteria and viruses.

* lesion (LEE-zhun) is a general term referring to a sore or a damaged or irregular area of tissue.

* biopsy (BI-op-see) is a test in which a small sample of skin or other body tissue is removed and examined for signs of disease.

  This information is not a tool for self-diagnosis or a substitute for professional care.