Systematic review widens the map for Potomac horse fever

Potomac horse fever’s map may be broader than many clinicians assume. A new systematic review in Veterinary Research Communications pulls together scattered reports on Neorickettsia risticii, the main cause of equine neorickettsiosis, and frames the pathogen as a global surveillance issue rather than a narrowly regional one. A companion review in Veterinary Microbiology adds that clinical disease is considered endemic in multiple parts of the United States and Canada, and has also been reported in Brazil and Uruguay, while emphasizing that horses are exposed through trematode-linked aquatic life cycles rather than horse-to-horse spread. (deepdyve.com)

Why it matters: For veterinary professionals, the takeaway is practical: geographic assumptions may miss cases. The broader review literature suggests equine neorickettsiosis should stay on the differential for febrile horses with colitis, laminitis risk, or abortion history in endemic seasons, especially near waterways or irrigated pasture. Current guidance from AAEP and Merck also underscores that PCR is the preferred rapid diagnostic approach, and that vaccination may reduce disease impact but does not reliably prevent infection, likely in part because of strain diversity. (sciencedirect.com)

What to watch: Expect more discussion around true geographic range, species and strain diversity, and whether surveillance and vaccine strategy need to catch up with what the literature is now showing. (sciencedirect.com)