According to the Companion Animal Parasite Council’s 2025 forecast, the deer tick is expanding its U.S. range southward and westward.
The deer tick, also known as the blacklegged tick (Ixodes scapularis), is the species responsible for transmitting Lyme disease.
The CAPC report also highlighted the geographic expansion of other disease vectors that are key to the spread of anaplasmosis, ehrlichiosis, and heartworm disease.
“In historically endemic regions, these maps [capcvet.org/maps] reinforce the importance of continued vigilance in testing and prevention,” said Dr. Rick Marrinson, a CAPC board member and past president. “Meanwhile, in areas where these diseases are emerging, veterinarians should adapt new protocols to address the real and growing threats facing pets and people in their communities.”
Key insights from the report include:
- North Dakota, northeastern South Dakota and southeastern Iowa should have a higher-than-normal risk for Lyme disease.
- Lyme disease is extending south into eastern Tennessee and northern North Carolina.
- The Southeastern United States is at the highest risk for heartworm infection, but the middle of the country, from Kansas to Maryland, is also at heightened risk.
- Forecasters expect an increasing number of ehrlichiosis seropositive dogs in Western states such as Colorado, Utah and Wyoming compared to 2024.
- The significant risk for anaplasmosis is in the Northeast and Upper Midwest, but dogs are also at increased risk for the disease in Ohio, Kentucky, Tennessee, Virginia and North Carolina.
The forecasts highlight the public health implications of vector-borne diseases.
“Because dog health helps us predict human health, our monthly, county-by-county forecasts are a crucial health tool for communities,” said Dr. Christopher Carpenter, the parasite council’s CEO. “By leveraging the power of our extensive canine surveillance data, we help veterinarians and pet owners take proactive steps to safeguard animal and human health.”