Temporal, Seasonal, and Patient Demographic Trends Among Culture-Confirmed Human Salmonellosis Cases Identify Regional Differences in Salmonella Serotypes Reported in Virginia, USA From 2012 through 2022

The U.S. federal government established a national goal of reducing the salmonellosis incidence to ≤11.5 cases/100,000 persons by 2030. To assess progress toward this goal in Virginia, we used data from culture-confirmed salmonellosis cases reported to the Virginia Department of Health during 2012-2022 (N = 11,411). A Bayesian negative binomial splines model was implemented to estimate changes in incidence/100,000 persons during 2012-2022 statewide and for specific localities (for example: county or independent city). Incidence varied substantially by locality and over time. Output from modeled incidence suggests limited progress toward federal salmonellosis reduction goals in Virginia. During 2012-2022, statewide modeled incidence ranged between 11.6 (in 2022) and 12.9 (in 2018). From 2018 to 2022, there was a consistent decrease in the modeled incidence of culture-confirmed salmonellosis in Virginia. In contrast to FoodNet trends, the inclusion of culture-independent diagnostic tests in the case definition did not significantly reduce the number of culture-confirmed cases, suggesting a high rate of reflex culturing among patients in Virginia. Among 187 Salmonella serotypes reported, 64.2% of culture-confirmed infections were attributed to six serotypes: Typhimurium (including the monophasic variant, I 4,[5],12:i:-; 20.3%), Enteritidis (18.0%), Newport (10.7%), Javiana (7.7%), Bareilly (3.9%), and Braenderup (3.6%). Trends in salmonellosis attributable to specific serotypes varied substantially; modeled incidence of infections caused by some serotypes decreased substantially (e.g., S. Typhimurium/I 4,[5],12:i:-) and others increased (e.g., S. Braenderup). This may indicate that serotype-specific trends may be masking changes in salmonellosis epidemiology and contributing to the apparent overall stability in salmonellosis incidence in Virginia; efforts to meet federal goals may need to be tailored to reduce the incidence of specific serotypes that are increasing in incidence.