Causes and Risk Factors of Chagas Disease

Chagas disease is a major cause of heart disease in Latin America, caused by an infection with Trypanosoma cruzi (T. cruzi), a protozoan parasite. People get Chagas disease when their bloodstream is exposed to the organism.

chagas disease risk factors
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How Infection Spreads

Most typically, this occurs when they are bitten by a triatomine insect, which is known in Latin America as a “kissing bug.” These insects feed on the blood of vertebrates and live in areas where blood supply is plentiful, such as in peoples’ homes. When they suck the blood of an animal that is infected with T. cruzi, they are able to pass the infection on to the next animal they feed upon.

Certain species of the kissing bug are well adapted to living with humans and it is thought that most cases of Chagas disease are spread from human to human by these insects.

Kissing bugs are usually inactive during the day when it is hot, but they feed at night during cooler temperatures. Most people infected with T. cruzi acquire the infection during sleep.

Risk Factors​

Acute-Phase Chagas Disease

The risk of developing the acute-phase disease is related, first, to whether a person lives in or visits an area where the T. cruzi parasite and the kissing bugs are endemic. Essentially, this area extends from the southern United States to northern Argentina and Chile.

Houses with adobe walls or thatched roofs seem to provide an especially attractive environment for kissing bugs. People living in such homes in endemic areas are particularly prone to develop Chagas disease.

However, measures to control the population of kissing bugs have been quite successful in some areas in Latin America.

Chagas disease is much less common in cities than it is in rural areas.

Chronic-Phase Chagas Disease

In a person who has been infected with T. cruzi, several factors can increase the risk of developing chronic Chagas heart or gastrointestinal disease. These include:

  • Failure to seek medical help during the acute phase. If Chagas disease is recognized early on, treatment with antitrypanosomal drugs can eradicate the infection. Unfortunately, in the rural areas where Chagas disease now is most often found, most people with Chagas disease are never diagnosed during the acute phase.
  • Genetic factors. It now appears that in people chronically infected with T. cruzi, genetic factors have a lot of influence on whether the disease will progress to cause heart or gastrointestinal disease.
  • The integrity of the immune system. People with chronic Chagas disease are much more likely to develop heart disease or gastrointestinal problems if their immune systems are compromised, for instance, by other medical conditions such as HIV or by chemotherapy.
  • Unknown factors. These known risk factors do not appear to answer all the questions. Researchers are actively working to identify why the immune system fails in the first place to get rid of the T. cruzi infection entirely, and why some people progress to severe chronic disease while others never do.

Frequently Asked Questions

  • Is there a vaccine for Chagas disease?

    No. No vaccine for Chagas disease is yet available, As a result, the World Health Organization has designated it as one of the world’s neglected diseases.

  • What percentage of kissing bugs carry T. cruzi?

    Researchers at Texas A&M found the T. cruzi parasite in about half of the kissing bugs they tested. However, they note that this percentage, which varies by location and species, can range as low as 10% to as high as 70%.

  • Where are kissing bugs found?

    The triatomine bug is most common in Mexico, Central America, and South America, where Chagas disease is most likely to be contracted. It is also found in the southern United States, including in Texas, Arizona, Arkansas, Louisiana, Mississippi, Tennessee, Utah, and Los Angeles County. However, very few cases of contracting Chagas disease within the United States have thus far been reported.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Machado FS, Jelicks LA, Kirchhoff LV, et al. Chagas heart disease: report on recent developments. Cardiol Rev. 2012;20(2):53-65. doi:10.1097/CRD.0b013e31823efde2

  2. Díaz S, Villavicencio B, Correia N, Costa J, Haag KL. Triatomine bugs, their microbiota and Trypanosoma cruzi: asymmetric responses of bacteria to an infected blood meal. Parasit Vectors. 2016;9(1):636. doi:10.1186/s13071-016-1926-2

  3. Centers for Disease Control and Prevention. Parasites - American Trypanosomiasis (also known as Chagas Disease).

  4. Coura JR, Viñas PA, Junqueira AC. Ecoepidemiology, short history and control of Chagas disease in the endemic countries and the new challenge for non-endemic countries. Mem Inst Oswaldo Cruz. 2014;109(7):856-62. doi:10.1590/0074-0276140236

  5. Cucunubá ZM, Nouvellet P, Peterson JK, et al. Complementary Paths to Chagas Disease Elimination: The Impact of Combining Vector Control With Etiological Treatment. Clin Infect Dis. 2018;66(suppl_4):S293-S300. doi:10.1093/cid/ciy006

  6. Meymandi S, Hernandez S, Park S, Sanchez DR, Forsyth C. Treatment of Chagas Disease in the United States. Curr Treat Options Infect Dis. 2018;10(3):373-388. doi:10.1007/s40506-018-0170-z

  7. De oliveira AP, Bernardo CR, Camargo AV, et al. Genetic Susceptibility to Cardiac and Digestive Clinical Forms of Chronic Chagas Disease: Involvement of the CCR5 59029 A/G Polymorphism. PLoS ONE. 2015;10(11):e0141847. doi:10.1371/journal.pone.0141847

  8. World Health Organization. Chagas disease (also known as American trypanosomiasis).

  9. Texas Ecological Laboratory, Texas A&M University. Kissing bugs and Chagas disease in the United States. FAQ.

Additional Reading
  • Cunha-Neto E, Chevillard C. Chagas Disease Cardiomyopathy: Immunopathology And Genetics. Mediators Inflamm; 2014:683230.

  • Marin-Neto JA, Cunha-Neto E, Maciel BC, et al. Pathogenesis Of Chronic Chagas Heart Disease. Circulation; 115:1109.

  • Rassi A JR, Rassi A, Marin-Neto JA. Chagas Disease. Lancet 2010; 375:1388.

By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.