Chagas Disease

Chagas disease is a parasitic infection caused by the protozoa Trypanosoma cruzi, which is endemic in parts of Mexico, Central and South America (see Map). It is mainly transmitted by triatomine insect vectors, but it can also be spread through other routes, such as congenital transmission, blood transfusions, organ transplants or ingestion of infected food/drink.

After an acute influenza-like illness, infected individuals enter an asymptomatic chronic phase. While most of them remain asymptomatic their entire lives, approximately 30-40% of infected individuals will develop organ involvement over several decades (Pérez-Molina and Molina, 2018).

Chagas disease can cause cardiac and gastrointestinal complications. Cardiac involvement ranges from mild conduction abnormalities to dilated cardiomyopathy with heart failure, while gastrointestinal involvement (less frequent) ranges from achalasia/constipation to megaesophagus/megacolon.

 

SCREENING AND DIAGNOSIS

While there are no official screening recommendations for Chagas disease in Canada, children of infected mothers (who have the disease or were treated in the past) should definitely be screened due to the risk of congenital transmission. Family members of people with a history of Chagas disease should also be screened.

Moreover, it is reasonable to screen pregnant women and women of childbearing age planning a pregnancy if they are from an endemic area, given that congenital disease can be treated successfully in >90% of cases.

Screening of other asymptomatic individuals from endemic areas should also be considered, especially if they have one of the following risk factors:

  • Lived in poverty
  • Lived in a rural area
  • Lived in poor housing (mud huts, straw/palm thatch)
  • Known cases of Chagas disease in the family or in the community
  • Received a blood transfusion or an organ transplant in Latin America

In the United States, screening is recommended for all individuals who were born or have lived for prolonged periods in endemic areas.

Of note, Canadian Blood Services have already implemented selective screening of blood donors for Chagas disease.

Additionally, patients with the following symptoms/clinical findings should definitely be tested for Chagas disease if they are from an endemic area:

Cardiac:

  • Structural abnormalities (cardiomegaly, chamber enlargement, wall motion abnormality)
  • Heart failure
  • Any arrhythmia
  • ECG abnormalities (mainly right bundle branch block or left anterior fascicular block)
  • Unexplained atypical chest pain
  • History of stroke

Gastrointestinal:

  • Unexplained upper GI symptoms (dysphagia, odynophagia, regurgitation)
  • Unexplained lower GI symptoms (chronic constipation, bloating, colicky abdominal pain)
  • Signs of achalasia on imaging/endoscopy
  • Dilated esophagus or colon on imaging/endoscopy

​​Testing for Chagas disease requires special serological tests (enzyme-linked immunosorbent assays (ELISA) or immunofluorescent antibody assays (IFA)) that should be ordered by an Infectious Diseases specialist.

 

TREATMENT

All patients diagnosed with Chagas disease should be referred to an Infectious Diseases specialist. Patients with cardiac or gastrointestinal involvement should also be followed by a Cardiologist or a Gastroenterologist respectively.

Chagas disease is treated with special antitrypanosomal drugs (benznidazole and nifurtimox). This is outside the scope of these guidelines.