The 2025 Pet Parasite Forecast from the Companion Animal Parasite Council (CAPC) highlights the growing threat of vector-borne diseases across the United States. Using data from more than 10 million diagnostic tests annually, CAPC tracks the prevalence of Lyme disease, heartworm, anaplasmosis, and ehrlichiosis. The latest forecast shows continued geographic expansion of these diseases, largely due to shifting populations of ticks and mosquitoes. Tick-borne diseases, such as Lyme and anaplasmosis, are spreading south and west, with the upper Midwest and Northeast remaining high-risk areas. Ehrlichiosis continues to be prevalent in the Southeast, with signs of expansion into the upper Midwest and New England. Heartworm risk, spread by mosquitoes, remains high in the Southeast and is growing in areas from Kansas to Maryland, as well as in several western states, including parts of New Mexico and Northern California. CAPC stresses the importance of year-round parasite prevention and regular veterinary care. Dogs are considered important indicators of human disease risk, particularly for tick-borne illnesses like Lyme disease. The findings carry public health implications, underscoring the need for continued monitoring and preventive strategies. The forecast is developed through collaboration with parasitologists and statisticians from academic institutions to better understand disease transmission and emerging patterns.
