CAPC study: Lyme disease spreading to regions once thought low-risk

January 19, 2019
dvm360 Staff
dvm360, dvm360 March 2019, Volume 50, Issue 3

Condition in dogs could signal increasing threat to people, researchers say.

The Companion Animal Parasite Council (CAPC) recently released a study that shows that Lyme disease is spreading to regions not previously thought to be at risk for tick-borne disease. States such as Illinois, Iowa, North Dakota, Ohio, Michigan, West Virginia and Tennessee have all seen an increase in the prevalence of Lyme disease, according to a media release discussing the study, which CAPC conducted from January 2012 to December 2016. Results from the study were recently published in Environmetrics.

“The results of this milestone study show increasing risk for Lyme disease in endemic areas and pinpoint regions in the U.S. where Lyme is spreading-areas not historically considered endemic,” says Michael Yabsley, PhD, a professor in the Department of Population Health, College of Veterinary Medicine and Warnell School of Forestry and Natural Resources at the University of Georgia. “This expanding risk of Lyme disease demands heightened vigilance in protecting both our pets and our families.”

New research from CAPC found that the prevalence of Lyme disease is trending up in areas previously thought to be at a lower risk for tick-borne diseases. (Image courtesy of CAPC)

The study was motivated by the increase in Lyme disease cases in the U.S. and, in particular, in states not traditionally considered Lyme-endemic, the release states. Results suggest that:

  • Canine prevalence rates for Lyme disease are rising.
  • Lyme prevalence rates are increasing most in areas where the pathogen has encroached recently.
  • Lyme prevalence in dogs is rising in states traditionally not considered to be of high Lyme risk, suggesting that human risk may also be increasing in these areas, including regions in Illinois, Iowa, North Dakota, Ohio, Michigan and Tennessee.
  • Significant increases in canine Lyme prevalence have been seen in some areas that are not yet reporting significant human incidence. Researchers speculate that canine prevalence is more sensitive to changes in Lyme risk and could serve as an early warning system for changes in human risk.

The study was created to investigate regional trends in the prevalence of antibodies to Borrelia burgdorferi, the disease-causing bacterium of Lyme disease, according to the release. To conduct the research, the CAPC team analyzed more than 16 million Lyme tests from domestic dogs in the U.S. over 60 months. The serologic data was provided by IDEXX Laboratories.

“CAPC research shows the risk for Lyme disease is not static. The way it's changing varies spatially across the country,” says Christopher McMahan, associate professor in the department of mathematical sciences at Clemson University, in the release.

Crucial in the fight against Lyme, Yabsley says, is year-round tick protection. Different species of ticks are active all 12 months of the year, and ticks that transmit Lyme are active at different times in the year in different regions, the release states. For instance, as you move further south, adult ticks are more active in the winter.

“I've been practicing for over 34 years in Nashville where many people don't think Lyme disease is a concern. But I've seen canine Lyme increasing in Tennessee for several years and regularly test and vaccinate for the disease,” says Craig Prior, BVSC, CVJ, a veterinarian and former owner of VCA Murphy Road Animal Hospital in Nashville, Tennessee. “Many people tend to believe that if they don't go on hikes or spend time in wooded areas, they aren't at risk for Lyme. Ticks are everywhere-including suburban and gated communities where deer, raccoons, opossum, birds and other hosts frequent back yards. That's why CAPC recommends year-round tick prevention for dogs-and cats-and regular screening to protect dogs from this debilitating disease that can be extremely hard to treat.”

On petdiseasealerts.org, CAPC now provides monthly forecasts for Lyme disease and other tick-borne diseases. It also provides access to monthly canine test results in prevalence maps, a CAPC resource available free online at petsandparasites.org. With more than 21 million canine B. burgdorferi antibody test results collected between 2012 and 2017 in dogs, these maps allow veterinarians, physicians, pet owners and travelers to assess the risk of exposure across the United States and Canada.

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