By Stan Deresinski, MD, FACP, FIDSA
Clinical Professor of Medicine, Stanford University
SYNOPSIS: Chagas disease is an important public health problem in the United States. An expert panel has made a series of specific recommendations for screening for and diagnosis of Chagas disease in at-risk groups.
SOURCE: Forsyth CJ, Manne-Goehler J, Bern C, et al; U.S. Chagas Diagnostic Working Group. Recommendations for screening and diagnosis of Chagas disease in the United States. J Infect Dis 2021; Oct 8:jiab513. [Online ahead of print].
Chagas disease affects more than 300,000 people in the United States, most with chronic infection acquired during residence in Latin America. Forsyth et al reported the recommendations of an expert group, using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system, for screening and diagnosis of infection with Trypanosoma cruzi, the etiologic agent of Chagas disease. Unless otherwise stated below, all the recommendations are considered strong with low levels of evidence.
The populations targeted for screening include at least three groups:
- those who were born or resided for more than six months in endemic areas of Mexico, Central, or South America;
- first-degree relatives of individuals with a previous diagnosis of Chagas disease;
- individuals with documented exposure to triatomines (“kissing bugs”) — this recommendation is graded as conditional, low;
- travelers to endemic areas of Latin America with confirmed exposure to triatomines or with other risk factors — this recommendation is graded as conditional, low;
- consideration of screening women of childbearing age who have lived in endemic areas — this recommendation is graded as strong, moderate.
Those from endemic areas who have any of the following clinical and/or laboratory abnormalities should undergo diagnostic testing:
- those with suggestive electrocardiographic abnormalities, such as first degree atrioventricular block, premature ventricular contractions, atrial fibrillation, right bundle branch block, left anterior fascicular block, bifascicular block, low-voltage QRS complex, bradycardia, or tachyarrhythmias;
- echocardiographic evidence of regional wall abnormalities, especially those affecting basal inferolateral sites, or apical aneurysm;
- congestive heart failure;
- thromboembolic phenomena;
- megacolon or megaesophagus;
- immunosuppressed patients, including those receiving tissue, organs, or blood components from infected donors and others with epidemiological risks, including by repeated polymerase chain reaction (PCR) — no GRADE is indicated for this recommendation.
Congenital Chagas disease:
Neonates and infants (< 1 year of age) born to infected mothers should undergo screening as recommended by the Centers for Disease Control and Prevention (CDC) — this recommendation is strong, moderate.
Algorithmic test use:
To enhance diagnostic accuracy, serologic testing for chronic Chagas disease should use two distinct assays that use different antigens or different formats and, if discordant results are obtained, a third distinct test should be used as the tie breaker. In low prevalence contexts, public health laboratories and clinicians performing screening should use the most sensitive test available and follow the same recommendation regarding repeat testing. These recommendations are strong, moderate.
Initial evaluation of symptomatic or asymptomatic patients in whom Chagas disease has been confirmed: This should include an electrocardiogram (strong, high) and an echocardiogram. If the latter is not available, a chest X-ray should be performed (conditional, low).
The natural history of Chagas disease was examined recently by evaluation of a cohort of infections identified by screening of blood donors in Brazil.1 Evaluation at the time of initial screening found that approximately one in 10 already had known diagnosis of cardiomyopathy and, on follow-up almost two decades later, approximately one-half were dead, with a mortality rate of 80.9 per 1,000 person-years. Of those first found to have cardiomyopathy at screening, the mortality rate at follow-up was 15.1/1,000 person-years, while it was only 3.7/1,000 and 3.6/1,000 person-years in seropositives without cardiomyopathy and in seronegatives, respectively. New-onset cardiomyopathy was detected during the follow-up period in 12% of seropositives, occurring at a rate of 13.8/1,000 person-years, while it occurred at a rate of only 4.6 /1,000 person-years in seronegatives.
Thus, given the estimate of > 300,000 people affected in the United States, Chagas disease is a significant public health problem that must be better addressed. The recommendations of the expert panel reviewed here are an important step in this process.
- Nunes MCP, Buss LF, Silva JLP, et al. Incidence and predictors of progression to Chagas cardiomyopathy: Long-term follow-up of Trypanosoma cruzi-seropositive individuals. Circulation 2021;144:1553-1566.