Lyme Disease Is Expanding Its Range Westward In 2014
by Susan E. Little, DVM, PhD, Cathy Lund, DVM and Emilio DeBess, DVM, MPVM
Lyme disease is a notorious vector-borne illness that can cause disease in pets and people. Because this disease is zoonotic and is responsible for a wide array of clinical signs, it is helpful to understand the risks of disease transmission throughout the country. The CAPC Parasite Forecast Maps for 2014 predict that Lyme disease is expanding its range westward from the historic focus of the northeastern United States. New England and the Pacific Coast continue to be hotspots of activity, and are likely to experience a higher number of infections. Consistently stable activity is predicted for the Mid-Atlantic States and the upper Midwest. The CAPC forecast also shows that Lyme continues to expand southward and involve more areas of Appalachia.
Dogs become infected with Borrelia burgdorferi when they are inoculated with the organism by feeding ticks. In North America, only Ixodes scapularis and Ixodes pacificus (commonly known as the Eastern and Western Black-Legged ticks, respectively) have been shown to transmit the infection to dogs. A clinical diagnosis of Lyme borreliosis usually depends on the presence of compatible clinical signs and positive serology for B. burgdorferi.
Dogs frequently travel with their owners, so even if Lyme disease isn’t a threat in your region, there is a possibility that an individual dog will test positive at your clinic. Heightened pet owner awareness of Lyme disease provides an ideal educational opportunity to discuss all vector-borne diseases and the importance of year-round protection for all pets.
In addition to the forecast, CAPC provides parasite prevalence maps available by clicking here. As a veterinarian, you can use the CAPC Prevalence Maps to monitor the activity level for parasitic diseases in any U.S. state and county. For the most up-to-date information, CAPC also offers Automatic Email Updates that can be customized to the state and county level. Because parasites are dynamic and ever-changing, CAPC will continue to provide the veterinary community with vital information about parasite prevalence that can be shared with clients.
The maps work well as an educational tool for clients who want to know more about why protecting their pets against parasites year-round is essential. The state and county forecasts are also valuable for clients who travel with their pets and need to protect them from diseases that occur in different parts of the country. 
Because ticks can be carriers of many diseases, including Lyme disease, it is imperative that veterinarians reinforce the importance of regular visits that should include parasite prevention. To prevent any type of infection or infestation, CAPC recommends year-round parasite control for dogs and cats. In addition, CAPC’s guidelines recommend regular examinations — at least annually — by a veterinarian. CAPC Guidelines for Lyme Disease can be found here.
CAPC bases its parasite forecasts on many different factors, including temperature, precipitation, humidity, ground elevation, forest cover, population density, reported human Lyme disease cases and deer strikes with cars. These factors are incorporated into an equation created by a team of statisticians that allows CAPC to predict the prevalence rate of any given disease. The forecast is also the collective expert opinion of respected parasitologists who engage in ongoing research and data interpretation to better understand and monitor disease transmission and changing parasite life cycles. Click here to learn more about the forecasts.
