The results of a primary care-based screening program for Trypanosoma cruzi in East Boston, Massachusetts

Background: This study reports the outcomes of the Strong Hearts pilot project to integrate screening for Trypanosoma cruzi into a primary care setting & facilitate referral for treatment at East Boston Neighborhood Health Center.

Methods: Continuing education about Chagas disease was offered to healthcare providers, and community-based outreach was provided. One-time screening for all patients ≤50 years old who lived in Mexico, South or Central America for ≥6 months was recommended. The initial screening test was an ELISA performed by a commercial lab and confirmatory testing was performed at the US CDC. Confirmed positives were defined as positive on both the screening & confirmatory tests. Confirmed positive patients were referred to the Pediatric & Adult Infectious Disease clinics at Boston Medical Center for further evaluation & treatment. We compared the proportion of confirmed positives by sex, age & self-reported national origin using chi-squared tests. We then used multivariable logistic regression to examine predictors of (1) confirmed positive or (2) discordant screening & confirmatory testing.

Results: 2,183 screening tests were sent; 84 (3.8%) were positive, 2,082 (95.4%) negative, and 17 (0.8%) indeterminate. Among 73 tests with confirmatory results available, 19 (26%) were positive and 54 (74%) negative. All indeterminate tests were confirmed negative. The proportion of confirmed positives increased with increasing age (p=0.014) [TABLE 1] but there were no significant differences by sex (M: 8/757, F: 11/1413, p=0.51) or national origin (p=0.79). 19 confirmed positives have been evaluated and 6 initiated benznidazole to date. 3 confirmed positives were pregnant. In multivariable models, there were no significant predictors of confirmed positive or discordant testing.

Conclusion: This pilot shows that integration of screening for Chagas disease is feasible in primary care. Though the prevalence of T. cruzi infection was higher in older age groups, there were no clear demographic predictors of a confirmed positive or discordant test. We also found a high false positive rate of the screening test, highlighting the need for improved serologic testing options.

Table 1.

Age Group (years)	Positive Cases (#)*	Total Screened (#)	Prevalence (%)
≤19	0	101	0.0
20-29	3	742	0.4
30-39	7	820	0.9
40-49	5	392	1.3
≥50	4	115	3.5