Risk of exposure to vector-borne pathogens: what to expect in 2020

The risk of exposure to the pathogens that cause heartworm disease, Lyme disease, ehrlichiosis, and anaplasmosis continues to rise throughout the United States, particularly in areas where the pathogens are already endemic.

The 2020 forecast and supporting publications point to areas of concern where more can be done to lower the risk of exposure to companion animals. There are a multitude of reasons for the expansion of tick and mosquito vectors and their pathogens throughout the United States, and the best action veterinarians and their clients can take is to prevent companion animals from coming into contact with these vectors. Products that kill and repel mosquitoes and ticks are strongly recommended, and in the case of heartworm, chemoprophylaxis should be administered routinely.

The 2020 national forecasts for these pathogens highlight the biggest areas of concerns for veterinarians and pet owners.

Heartworm Forecast

2020 Capc Forecast Maps Heartworm
  • When we compare the 2020 heartworm forecast to the average prevalence over the past eight years, we expect the prevalence to be much higher in areas along the Mississippi river, throughout the southern portions of the Midwest, and along the Atlantic coast north into Virginia. These are endemic areas with a high prevalence and so this could represent a large burden on the health of dogs in those areas.
  • Veterinarians in states with historically low prevalence are again cautioned about the rising prevalence of heartworm infection and are encouraged to have a discussion with their clients about the changing risks. Particularly in Indiana, northern Illinois, southern Iowa, and southern Wisconsin.
  • Much of the upper Midwest and the New England region is expected to have little change, but small increases in prevalence may be seen throughout.
  • Very few regions are expected to have lower than average prevalence. These include areas around Baton Rouge in Louisiana, Atlanta in Georgia, Nashville in Tennessee and along the southwestern border of Texas. These decreases are forecasted to be very small, less than 0.5% for most spots. However, it is very important to remind clients in these areas that despite the expected decrease, the prevalence is very high, and many dogs are at risk of exposure. Year-round preventatives are strongly recommended.

The widespread increase in heartworm activity supports CAPC’s recommendation that all dogs be given heartworm preventatives year-round and tested annually for both heartworm antigens and microfilariae.

Lyme Disease Forecast

2020 Capc Forecast Maps Lyme

The tick vector of Borrelia burgdorferi, an agent of Lyme disease in dogs, is expanding its range from the northeastern and mid-Atlantic states, the upper Midwestern states, and throughout Canada. These ticks are bringing their associated pathogens along for the ride. These include Anaplasma phagocytophilum, Babesia spp., Borrelia miyamotoi, Ehrlichia muris eauclarensis, and possibly Bartonella spp. among others.

  • The seroprevalence of B. burgdorferi in dogs is expected to be higher than average from Maine all the way south to North Carolina and Tennessee. Particularly large increases are expected in an area encompassing eastern Pennsylvania, northern West Virginia, and eastern Ohio. Veterinarians throughout the Northeast and Appalachian region should reinforce their recommendations on the use of tick preventatives and may consider vaccination for high-risk patients.
  • Higher than average seroprevalence is also predicted throughout the Midwest with a hotspot expected in northwestern Minnesota.
  • Much of Indiana, Michigan, Illinois, and Iowa are also expected to have a higher risk of exposure.
  • Following last year’s trend, the coastal regions of Massachusetts, Rhode Island, Connecticut, New York, New Jersey, and Maryland are expected to see lower than average seroprevalence in 2020.

Preventing exposure to ticks is the best way to prevent infection with tick-borne pathogens. The areas highlighted above that are expected to see lower than average seroprevalence are all historically endemic for B. burgdorferi and thus the risk for exposure is still high!

Ehrlichiosis and Anaplasmosis

Forecasts are also provided for these two other important tick-borne diseases of dogs. View the Ehrlichia spp. and Anaplasma spp. forecast and learn more about the CAPC guidelines for prevention and treatment of ehrlichiosis and anaplasmosis.

2020 Anaplasma spp. forecast

2020 Ehrlichia spp. forecast

Year-round protection, annual testing

The best way to protect your patients is to advise owners of the importance of year-round prevention, even during the winter months. You can use the CAPC Parasite Prevalence Maps to support your recommendation by underscoring the risks in your area and in regions of the country your clients may travel with their pets. It is also critical to emphasize the importance of compliance and using products according to label. The use of CAPC Parasite Prevalence maps and Forecast maps are a validated tool for increasing client willingness to engage in parasite prevention. Sign up for local alerts today by visiting the CAPC Parasite Prevalence Maps and selecting "Get Updates".

Veterinary professionals and pet owners who want to monitor the activity in their county throughout the year, can also access 30-Day Parasite Forecast Maps at www.petdiseasealerts.org. These maps, developed exclusively by CAPC, provide a local forecast for every county in the continental United States on a monthly basis.

The Science behind the Forecasts

Vector-borne disease is dynamic and ever changing, driven by multiple factors that affect the development of arthropod vectors and the pathogens they carry. Leading parasitologists work in collaboration with a team of statisticians to identify regions of the country that may experience higher parasite incidence in the months ahead. Numerous factors are analyzed, including the number of positive tests and the influence of weather patterns, vegetation indices, and human population density. Using this multi-disciplinary approach, we are leveraging everyone’s expertise to focus on a single common interest: forecasting the risk of exposure to vector-borne pathogens. While these forecasts predict the potential risk of a dog testing positive, they do not necessarily reflect the occurrence of clinical disease.

To learn more about the science behind the maps, a free review can be read here and full access to all of our manuscripts describing the methodology and fidelity of our forecasts can be found here.