Review broadens the global map for Potomac horse fever pathogen

Potomac horse fever’s footprint may be broader than many clinicians assume, according to a new systematic review in Veterinary Research Communications that maps the global distribution of Neorickettsia risticii, one of the bacteria that causes equine neorickettsiosis. The review adds to a growing body of literature suggesting the pathogen is not just a North American concern, but has been documented in multiple regions, with published evidence from countries including the United States, Canada, Brazil, and Uruguay. A companion review in Veterinary Microbiology also frames equine neorickettsiosis as a global disease ecology issue, noting that clinical cases are considered endemic in parts of the U.S. and Canada and have also been reported in South America. (deepdyve.com)

Why it matters: For veterinary professionals, the practical message is that Potomac horse fever risk assessment may need to extend beyond the traditional endemic map. The American Association of Equine Practitioners says Potomac horse fever is a non-contagious infectious disease caused by N. risticii and N. findlayensis, with cases usually occurring in summer and fall, and clinical signs that can include high fever, diarrhea, laminitis, colic, edema, and abortion. Diagnostic guidance has also evolved: a 2023 review identified PCR on blood and feces as the diagnostic test of choice, while newer assay work has shown fecal testing can generate false positives if methods are not optimized. (aaep.org)

What to watch: Expect follow-up discussion around surveillance gaps, regional vector and trematode ecology, and whether broader geographic awareness should change how equine practitioners approach seasonal diagnostics, vaccination discussions, and abortion workups. (sciencedirect.com)