CAPC forecasts expanding parasite risk in 2026, including Lyme disease, heartworm, ehrlichiosis, and anaplasmosis

The Companion Animal Parasite Council (CAPC) has released its 2026 Pet Parasite Forecast, warning veterinary professionals that vector-borne disease risk continues to expand geographically across the US, with implications for both animal and human health. According to CAPC, the forecast predicts continued spread of Lyme disease, ehrlichiosis, anaplasmosis, and heartworm into areas that were once considered low- or moderate-risk.¹

CAPC said its annual forecasts are designed to predict what veterinarians and diagnostic laboratories will find when testing dogs throughout the year. The organization reported that its forecasts have historically been 94% accurate when compared with nationwide diagnostic results. The data behind the projections include more than a decade of surveillance and analysis of more than 10 million veterinary diagnostic test results per disease each year.¹

Kathryn E. Reif, PhD, MSPH, an associate professor of parasitology at Auburn University, a CAPC board member, and the lead author of the forecast, said that vector-borne disease risk is shifting in response to land use changes, pet travel, wildlife movement, and climate-related warming and extreme weather. She said the forecasts are intended to help veterinarians strengthen year-round prevention, tailor vaccination strategies based on local risk, and reinforce annual testing.¹

Lyme disease remains a major focus of the 2026 forecast. CAPC said black-legged ticks continue to expand geographically, with the Upper Midwest and Northeast still representing high-risk regions. The organization projects its spread into Ohio, Kentucky, West Virginia, Tennessee, North Carolina, Indiana, Illinois, and Michigan, as well as continued westward expansion into the Northern Plains. CAPC noted that areas of higher canine Lyme risk often mirror areas where people contract Lyme disease, reinforcing the One Health connection between pets, people, and the environment.¹

Heartworm disease, transmitted by mosquitoes, remains entrenched in the Southeast, according to CAPC, with continued spread northward along the Mississippi River corridor and the Atlantic coast. The forecast also identifies persistent pockets of elevated risk in parts of the Mountain West and Northern California. CAPC said large populations of infected dogs, expanding mosquito habitats, urban development, and inconsistent preventive use are contributing to transmission.¹

The council also highlighted the expanding risk of ehrlichiosis and anaplasmosis as lone star ticks and brown dog ticks, respectively, extend their ranges. CAPC projects sustained ehrlichiosis risk across the Southeast, Southwest, and South-Central United States, as well as continued northward expansion of lone star ticks into the Upper Midwest and New England. Brown dog tick–associated risk is also expected to increase in the Southwest and Mountain West. Because some tick species can transmit pathogens year-round and brown dog ticks may live indoors, CAPC emphasized that risk is not limited to the traditional tick season.¹

“Low risk does not mean no risk,” CAPC board member Craig Prior, BVSc, CVJ, said in the release, adding that year-round prevention and annual testing are now foundational rather than optional. CAPC Executive Director Chris Carpenter, DVM, MBA, said the forecast gives veterinarians a way to anticipate risk rather than react to it.¹

Along with the annual forecast, CAPC offers 30-day parasite forecast maps and daily flea forecasts at PetDiseaseAlerts.org. The organization said these tools can help veterinarians and pet owners track local threats and tailor parasite prevention strategies accordingly.¹

Reference

CAPC 2026 Pet Parasite Forecast just released: expanding vectors, emerging hotspots and a new era of year-round risk. News release. Companion Animal Parasite Council. March 23, 2026. Accessed March 23, 2026. https://capcvet.org/about-capc/news-events/capc-2026-pet-parasite-forecast-just-released-expanding-vectors-emerging-hotspots-and-a-new-era-of-year-round-risk/