Chagas disease

Trypanosoma cruzi, agent de la maladie de Chagas. - © Institut Pasteur
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Chagas disease, also known as American trypanosomiasis, is a chronic infection caused by the parasite Trypanosoma cruzi. It primarily occurs in Latin America, where it represents a major public health problem, but cases have also been identified in other regions. Chagas disease is mainly transmitted by triatomine bugs, although it can also be contracted through blood/blood products and mother-to-child transmission. Early treatment can prevent complications, especially cardiac and digestive problems. Chagas disease is considered a neglected tropical disease. It was named after the Brazilian physician and scientist Carlos Chagas, who was the first to diagnose the disease in humans.

In 2025, more than 7 million people worldwide were thought to be infected with Chagas disease, according to WHO.

The disease results in more than 10,000 deaths globally every year

Update - January 2026

What are the causes?

Chagas disease is caused by the parasite Trypanosoma cruzi, which is transmitted to humans by blood-sucking insects known as triatomine bugs. The bugs hide in cracks in the walls or roofs of homes in rural areas and peripheral urban areas.

How does the disease spread?

The parasite is mainly transmitted to humans when they come into contact with the excrement of infected triatomine bugs. After biting someone, the bugs may urinate or defecate near the bite site. If the person then scratches the bite, there is a risk of contamination as the parasite in the excrement may enter the body via the skin lesion. The disease can also be transmitted through blood (during transfusions or organ transplants), from mother to child during pregnancy or childbirth, and more rarely by the consumption of food or beverages contaminated by the feces or urine of infected triatomine bugs.

What are the symptoms?

Chagas disease has two phrases: an acute phase and a chronic phase.

1-The acute phase lasts for around two months. During this phase, infected individuals may be asymptomatic or they may experience relatively mild symptoms including:

  • fever
  • headache
  • inflammation around the bite
  • sometimes swelling of the eyelids (Romaña's sign)

2-After a subsequent silent period that may last between 10 and 20 years, the chronic phase begins. During this phase:

  • 20 to 30% of people develop severe cardiac complications (heart failure and cardiac arrhythmias)
  • Around 10% of people experience digestive complications (enlargement of the colon or the esophagus)
  • Around 3% of infected individuals suffer from peripheral nervous system disorders leading to neurological symptoms

If left untreated, these complications can be fatal.

How is Chagas disease diagnosed?

Diagnosis of Chagas disease is based on blood tests to detect the presence of the parasite or Trypanosoma cruzi antibodies:

  • During the acute phase, the parasite can be directly detected in the blood, for example using a molecular method like PCR.
  • In the chronic phase, several serological assays (ELISA assays) are needed to confirm infection, as by this stage it is difficult to detect the parasite directly. These tests, generally performed in specialist laboratories, are crucial to confirm diagnosis in at-risk individuals or those from endemic areas.

What treatments are available?

Chagas disease can be cured if an antiparasitic treatment is administered early, during the acute phase. Two antiparasitic drugs are recommended for Chagas disease:

  • benznidazole
  • nifurtimox.

The two drugs can also slow disease progression in patients in the chronic phase.

The aim of the treatment is to eliminate the parasite or limit its effects. Treatment needs to be tailored to the individual patient as it may cause side effects that require medical supervision.

There is currently no preventive or curative vaccine for Chagas disease.

How can Chagas disease be prevented?

Prevention is mainly based on avoiding exposure to triatomine bugs by improving housing (sealing cracks) and using insecticides and mosquito nets in endemic areas. Screening programs for blood and organ donors and for pregnant women from at-risk regions are also important to reduce transmission. Health education and access to diagnosis in at-risk populations are crucial.

How many people are affected?

WHO estimates that more than 7 million people worldwide are affected by Chagas disease, mostly in Latin America. Brazil is the largest endemic country for this parasitic infection, accounting for 40% of disease prevalence.

The risk of infection is strongly linked to socio-economic conditions.

Chagas disease has also been diagnosed in individuals living in non-endemic areas such as the United States (over 300,000 cases, mostly from Mexico), Australia, Japan and almost all Western European countries. Estimates suggest that there are nearly 50,000 people living with Chagas disease in Spain, mainly migrants from Ecuador, Argentina, Peru and Bolivia. Although regional initiatives implemented since 1990 have made a significant contribution to controlling the vector-borne infection on the American continent, 50,000 new cases are still diagnosed annually.

Chronic Chagas disease results in more than 10,000 deaths each year.

For more information, see:

the WHO information page

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