Seroprevalence of Antibodies to Burkholderia pseudomallei in Mississippi Gulf Coast Residents, September 2023.

In 2022, Burkholderia pseudomallei was first identified in continental United States (U.S.) environmental samples from the Mississippi Gulf Coast following two autochthonous infections. To better understand the extent of exposure to this emerging bacterium, we tested a convenience sample of 825 residual sera samples (550 from the Mississippi Gulf Coast, 275 from the northern U.S.) from a commercial diagnostic laboratory for the presence of antibodies to B. pseudomallei, using an indirect hemagglutination assay. We estimated seroprevalence of antibodies to B. pseudomallei in Mississippi Gulf Coast residents and in controls from northern regions of the U.S. where B. pseudomallei is less likely to persist in the environment. At a titer cut-off of ≥1:40, we observed a similar seropositivity between Mississippi Gulf Coast residents (14%, 95% CI: 11%, 17%) and controls (17%, 95% CI: 13%, 18%). Similarities in seropositivity suggest environmental exposure to B. pseudomallei in the Mississippi Gulf Coast may be limited; however, a lack of accompanying illness and exposure information limits our ability to conclusively interpret these findings. These estimates can serve as a baseline of seropositivity in the U.S. for future studies and to track the spread of B. pseudomallei in the U.S. over time.