Fifty Years of Non-pestis Yersinia Outbreaks in the United States: Patterns, Vehicles, and Surveillance Challenges,...

While non-pestis yersiniosis experienced the largest increase in reported incidence of any bacterial enteric infection in the United States during 2016-2023, yersiniosis source attribution remains poorly understood. To address this gap, we described all yersiniosis outbreaks reported to CDC during 1971-2024. Trends in annual single-etiology foodborne outbreak frequency, including before-versus-after comparisons around major changes in yersiniosis surveillance and diagnostics, were estimated using Bayesian spline regression. Of 56 outbreaks reported, 38 were single-etiology. Outbreaks were linked to foodborne (34), person-to-person (10), indeterminate (8), and waterborne (4) transmission, respectively. Pork (46%) and dairy (18%) products were the most frequently identified food vehicles. Reported contributing factors included pre-harvest contamination, cross-contamination, and inadequate time and temperature control. Outbreaks occurred across diverse exposure and preparation settings, including camps, homes, restaurants, and schools. While estimated annual outbreak frequency appeared to be higher following major surveillance and diagnostic changes, 95% credible intervals included 0 for all estimates, limiting confidence in the magnitude of these changes. Evolving diagnostic and surveillance practices may have facilitated outbreak detection, contributing to a broader understanding of yersiniosis transmission pathways, food vehicles, and exposure settings. The identification of pork and dairy as common food vehicles underscored well-established yersiniosis exposure pathways, while the diversity of exposure settings highlighted the need for prevention efforts across multiple points in the food supply chain. Strengthening prevention efforts across food, particularly the pork and dairy supply chains, is critical to reducing the yersiniosis burden in the United States.