773. Screening for Chagas disease in East Boston, Massachusetts from 2017 – 2020 reveals 0.9% prevalence

Background This study reports on the results of a screening program for Chagas disease in East Boston. Methods Based at the East Boston Neighborhood Health Center, the Strong Hearts Program offers continuing medical education sessions on Chagas disease to providers in Adult Medicine, Pediatrics, Family Medicine and Obstetrics. Providers are encouraged to offer one-time screening for Chagas disease for all patients who lived in Mexico, South or Central America for ≥6 months, at their discretion. A commercial lab performs the initial screening test using the Hemagen ELISA while confirmatory testing is performed at the US CDC. For each patient, completion of screening requires a multi-step process consisting of splitting the serum sample to save a frozen aliquot for send out to CDC if the ELISA is positive/indeterminate, monitoring screening results to send the saved aliquot to the CDC if indicated, filling out the CDC requisition, shipping the serum aliquot, and monitoring the result returning from the CDC. Patients diagnosed with confirmed Chagas disease are referred to Boston Medical Center for further evaluation and treatment if indicated. Results From 3/21/2017 – 5/18/2020, 8,142 patients were screened. 423 (5.2%) patients had an initial positive test, 7,669 (94.2%) initially tested negative and 50 were indeterminate (0.6%). Among those with a positive screening result, 76 were confirmed to have T. cruzi infection for an overall prevalence of 0.93% in this population. 293 (69.3%) patients with positive screening tests had a negative (discordant) confirmatory test, 18 (4.3%) had an indeterminate test, and 36 (8.5%) had results that were unavailable or pending as of this analysis. None of the indeterminate screening tests were positive upon confirmation. Conclusion Prevalence of infection with T. cruzi was nearly 1% among patients in East Boston who had lived in Latin America. Diagnosis of Chagas was challenging due to a large number of false positive screening tests. The resource burden imposed by current screening options is itself a barrier to addressing Chagas disease. Given the significant prevalence of Chagas disease in the US, increased access to tests (i.e., two-step screening conducted through commercial laboratories) and screening assays with improved specificity are needed. Disclosures All Authors: No reported disclosures