The Companion Animal Parasite Council (CAPC) has developed and maintains current and accurate maps on a variety of parasitic diseases, such as Lyme disease carried by Ixodes scapularis ticks, in the United States and Canada, based on data provided by IDEXX Laboratories and ANTECH Diagnostics. Using CAPC’s map strategy means you can encourage compliance among your clients and stay up to date on what your protection strategy should be based on vector-borne disease activity in your area.
The maps are a useful resource in assessing the current risks, or the forecasted risk, in the geographic area of your veterinary practice. The prevalence maps show the proportion of pets that test positive for a given infection using available assays. The forecasts represent the collective expert opinion of academic parasitologists who engage in ongoing research and data interpretation to better and monitor vector-borne disease agent transmission and changing life cycles of parasites, and are based such factors as temperature, precipitation, and population density. The CAPC Top 10 Cities report summarizes the metro areas across the U.S. that experienced the greatest percentage increase in positive heartworm disease tests during the month.
Using the maps is straightforward and easy, says Craig Prior, B.V.Sc., C.V.J., immediate past president of the CAPC. “Our maps are one of our friendliest products,” says Prior. “We are mapping heartworm for dogs; feline heartworm antibodies; feline heartworm antigens; rickettsial tickborne diseases — ehrlichia and anaplasma — Lyme; intestinal parasites — hookworms, roundworms, whipworms — and giardia. We also map feline leukemia and feline AIDS, which was done at the request of the industry and veterinarians.
The CAPC Parasite Prevalence Maps are designed to show the proportion of pets tested which test positive for a given infection using available assays. Map is courtesy of CAPC.
To use the disease prevalence maps, select the disease you want to track (Lyme disease, for example). You’ll see the total number of Lyme-positive test results veterinarians have reported in the entire United States and the total number of tests conducted.
This data is very useful to veterinarians and others trying to better understand the prevalence of parasites in a given practice area, but as with any survey, the results can be influenced by a number of factors, including the number of pets tested, the history of the pets prior to testing, the reason the pets were tested, and the assays used. Understanding each of these factors is critical to accurately interpreting the geographic distribution of these important disease agents.
Forecasting Risk for Parasitic Disease
The CAPC’s forecast maps rely on mathematical principles, past experience and related data to calculate which parts of the country will have parasite population flares or increasing parasitic disease incidence in the coming months.
“We have been doing forecasting for about 5 years on a national basis. We release these every April. Our forecasts are for heartworm, ehrlichia, anaplasma, and Lyme. If you’re doing weather forecasting, you’re going to be about 70% accurate, but our minimum accuracy is 94%,” Prior says.
The CAPC forecast maps can be used to develop a protection strategy for specific parasites and help your clients stay ahead of the risk. Map is courtesy of CAPC.
“We’re starting to do forecasting on a county basis one month in advance, so you can look at the forecast for your county for the next month for heartworm, ehrlichia, anaplasma, and Lyme, which is pretty phenomenal,” says Prior. “We are also branching out and we are going to start mapping leptospirosis and flu.”
The county maps can be emailed as a monthly update. “You put in your state and county and the parasites you want updates for,” explains Prior. “We’ll send you a monthly update on what’s happening in your backyard. Basically, it’s local, it’s timely, it’s motivating. I got a report last month in Davidson County, Tennessee, where I practice. There were something like two cases of Lyme, eight cases of ehrlichia, and six cases of heartworm. Now I’ve got something that’s local, timely, motivating — it’s happening in my county, it’s happening in my neighborhood. We get on our twitter feed, Facebook page, our Instagram account — anything that we can do to connect with and motivate our clients. We want to warn them of the risks of what’s happening in their backyard. There’s a story there and that story needs to be spread.”
Top 10 Cities Report
The CAPC Top 10 Cities report summarizes the metro areas across the United States that experienced the greatest percentage increase in positive heartworm disease tests during the month. Mosquitoes transmit the parasite that causes heartworm disease, and areas with warmer climates and stable bodies of water, such as lakes and rivers or containers of water around homes, experience higher numbers of mosquitoes that can transmit the parasite. Pets in these cities and surrounding areas may have been exposed locally or travel-related exposure may have been a contributor to these notable increases. This is why CAPC recommends year round protection of pets against heartworm disease regardless of where pets reside.
“It’s not about which state has the highest amount of heartworm prevalence in the United States,” says Prior. “We know that’s the Southeast states, like the Mississippi Delta and Texas, and places like that. What we’re looking at what is the highest increase change in prevalence for that month because that means there is something going on. This about someplace like Fargo, N.D.,or somewhere in the Midwest or Northeast, that has gone from, historically, 5 cases a month and has jumped to 20 cases. What’s going on there?”
The Impact of Moving Shelter Dogs
Prior says there are a couple of factors that impact specific metropolitan areas that historically have not seen a lot of heartworm disease in the companion animal population. “We’re now seeing massive movements of animals, especially dogs. The Northeast has a shortage of adoptable animals. Colorado has a shortage. About 4 years ago, a lot of dogs were starting to be exported to Colorado and the Northeast. And these dogs are being imported from the Southeast [many as the result of being left homeless after hurricanes].
“A lot of these rescue-stray dogs are not being tested for heartworms, and if they are, they’re not necessarily being treated for heartworm,” says Prior. “So they’re being shipped, they’re going into these neighborhoods and when they’re adopted out, and they’re then taken to a veterinarian. A huge percentage of these dogs are heartworm positive. And this dog is now in your neighborhood and is source of potential exposure and spread of heartworm. So now we’re seeing a bump in heartworm prevalence in places like Denver and the Northeast. And it’s because of this movement of dogs.
“It’s also reported that about a million dogs were imported into the U.S. last year,” Prior says. “Are these dogs being tested or treated for heartworm? We don’t know. We have no clue.”
Mosquitoes and Microclimates
Another factor is the lack of knowledge about “microclimates.” Mosquitoes can survive winters as they live in “microclimates” in the north (inside sewers, stormwater drains, crawlspaces and alleys).
“People think that it’s the middle of winter and their pet is not at risk,” says Prior. “With mosquitoes, it’s all about microclimates. It can be 30 degrees out and there can be mosquitoes everywhere. They can thrive very well and continue to spread disease. Clients need to understand that and the need for their pets to be on year-round heartworm protection.”
In producing a monthly Top 10 cities heartworm report, “we’re trying to act like an early warning — hey, there’s something going on and you need to be aware of it,” says Prior. “You need to engage your clients. If we can engage the clients, we have found that they will then go into the clinic, they will test and they will protect [their pet].”
The biggest challenge for veterinarians is education and compliance, says Prior. “Clients don’t see heartworm, so they don’t understand heartworm. They don’t understand that it’s spread my mosquitos. Or they say, ‘it’s the middle of winter, so my pet’s not at risk.’ So the challenge is getting clients to understand their pet needs to be on 12-month, year-round prevention. And [if they have heartworm], the sooner you get it treated, the less damage is done because the damage is ongoing.”
Encouraging Compliance
How can veterinarians get the message across? In some areas of the world, the heartworm is considered zoonotic,” says Prior. “So in the United States, it may in the future. A great message to your clients is ‘protect your pet and you protect your family.’” It’s a one-health message.”
The data is there to support the message. “We’ve seen a 20% increase in prevalence in heartworm over the last 5 years,” says Prior. “The latest estimates are that between 60 to 65% of clients walk out the door of the vet clinic without buying anything — not any heartworm prevention, not any flea and tick prevention. But a [Bayer study in 2015] found that 9 out of 10 clients are interested in what’s going on with parasites in their county. So it’s important that we have that conversation with every client because if 60 to 65% are walking out the door without buying anything, those pets are not protected. It’s an opportunity to do a better job. It’s protecting more pets, protecting more families, and you’re growing your market in your practice. We should be making a firm recommendation about every patient to every client.”
Get the Maps
The CAPC’s capcvet.org website is for veterinarians and other veterinarian professionals.
The CAPC’s petsandparasites.com website is primarily for consumers, written at a little lower level to make it more consumer-friendly, says Prior.
Learn More
For additional articles on heartworm, visit Today’s Veterinary Practice’s Heartworm Archives.
The Companion Animal Parasite Council (CAPC) is an independent, nonprofit organization dedicated to increasing awareness of the threat parasites present to pets and family members.