Source: American Heartworm Society
The American Heartworm Society (AHS) released its latest heartworm incidence map, based on a 2026 survey of 2025 testing data, showing the disease remains widespread across the United States. Traditional high-risk regions like the Gulf Coast and Southeast continue to report the highest rates, with Texas leading the nation for the first time, followed by Louisiana, Arkansas, Mississippi, and South Carolina. New high-density “hot spots” have emerged in areas like east Texas, the Florida Panhandle, and southern Illinois. In addition, moderate increases were reported in regions previously considered lower risk, including parts of California, Colorado, Wisconsin, and Maine, as well as rising cases in several western states.
Most veterinarians (59%) reported stable infection rates, while others noted increases (19%) or decreases (22%). Experts attribute changes to factors like mosquito activity, weather events, and prevention lapses. Despite ongoing risks, heartworm disease remains თითქმის entirely preventable with consistent, year-round medication.