Lyme Disease Prevention

Lyme disease prevention is a One Health issue. 

When it comes to Lyme disease, Chris Adolph DVM, MS, DACVM (Parasitology), senior veterinary specialist-parasitology at Zoetis Inc., said he’ll never forget a conversation he had with friend and colleague, Dr. Rich Marconi, a Lyme disease researcher.

“He once joked with me that with Lyme disease, it’s better to be a dog than a human,” Dr. Adolph said. “With dogs, we’ve got amazing oral tick-killing products and great vaccines. But for humans, the best thing I can tell you is you better tuck your pants in your socks.” There’s not a vaccine (although the National Institutes of Health is supporting research to develop one). Sure, you can spray yourself down with repellant, but you have to repeatedly spray yourself when you’re going out into these heavy tick environments.

Lyme disease, or Lyme borreliosis, is a zoonotic disease – it affects both animals and humans. The U.S. Centers for Disease Control and Prevention (CDC) lists Lyme disease as the most commonly reported vector-borne illness in the United States. Untreated in humans, Lyme disease can produce a wide range of symptoms, depending on the stage of infection. These include fever, rash, facial paralysis, and arthritis.

The challenge for humans and their pets is that the disease can be difficult to detect because of the small size of the culprit. Indeed, Dr. Adolph said pet owners are often shocked when their dog tests positive for Lyme disease because they don’t ever remember seeing a tick.

Once the organism is in the dog, several different scenarios can play out. “Contracting Lyme disease spans a wide range of things, from owners maybe not perceiving a problem, to fatalities, and everything in between.”

The best-case scenario is the pet never gets sick and may not show outward signs that would alert the owner.

Issues that owners would begin to see outwardly include arthritis (inflammation of their joints), with visible symptoms of lameness, limping, and a swollen joint or multiple swollen joints. Sometimes those symptoms would alter pet owners and trigger a trip to the veterinary office, but not always.

The worst thing that can happen is a pet gets a syndrome from Lyme disease where the process attacks the kidneys. This is known as a Lyme nephritis or a Lyme kidney inflammation. “Labradors and Golden Retrievers seem to be particularly predisposed to this issue,” Dr. Adolph said. “This can ultimately lead to fatalities in dogs.”

Tracking ticks

According to the CDC, in the United States, most infections occur in the following endemic areas:

• Northeast and mid-Atlantic, from northeastern Virginia to Maine
• North central states, mostly in Wisconsin and Minnesota
• West Coast, particularly northern California

The CDC is not the only human health organization tracking Lyme disease and the ticks that carry it. In October 2021, the Bay Area Lyme Foundation, a nonprofit funder of innovative Lyme disease research in the U.S., announced the launch of interactive national tick maps of U.S. counties based on data published in mSphere, a multidisciplinary open-access journal of the American Society for Microbiology. The new data identify Ixodes ticks carrying disease-causing pathogens in 116 counties which were not previously identified by the Centers for Disease Control (CDC).

“The area known to harbor disease-carrying ticks continues to expand, and we hope people across the U.S. will use these interactive maps to learn more about the risks for their hometowns, their family’s residences and vacation spots,” said Linda Giampa, executive director, Bay Area Lyme Foundation. “The citizen scientists contributing to this study allowed the country’s collective tick knowledge to advance further than even the CDC could do at this time. Gaining the support of citizen scientists allowed us to collect from many counties across the country where ticks are not usually collected and tested, or they are not tested for these pathogens.”

Overall in human cases, Borrelia burgdorferi sensu lato, the bacterium that causes Lyme disease was identified in 293 U.S. counties across 29 states, and in 1,279 (14%) ticks submitted. Lyme bacteria were found in ticks in 75% of all counties in the Northeastern United States, and in 23% of ticks submitted from this region. In the Midwest, the bacteria were found in 78% of counties with more than five submitted I. scapularis ticks. In the West, Lyme bacteria were also found in ticks in 26% of the surveyed counties and, in the South, Lyme bacteria was found in ticks from 15% of the surveyed counties, where the prevalence of the bacteria among submitted ticks was 3%.

On the animal health side, the Companion Animal Parasite Council uses data collected by veterinary diagnostic tests to track the incidence of Lyme disease and other vector-borne disease.

CAPC’s 2021 forecast predicted Lyme disease to be a high threat and continue to expand southward and westward. “There is a higher-than-average seroprevalence predicted throughout eastern Kentucky, northeastern Tennessee, western Michigan and Ohio, with high-risk “hot spots” expected in northwestern and southwestern Michigan, and southern and northeastern Ohio,” CAPC said in its forecast. High risk would persist throughout the Northeast, including Wisconsin, Minnesota and the upper peninsula of Michigan. A higher-than-normal risk was expected in North Dakota, northern South Dakota, Iowa, southern Illinois, and western Kentucky. “The southward movement of Lyme is evident in the increasing risk in the Carolinas and Tennessee. Pets living in or traveling to these states are considered at high risk.”

Dr. Adolph said one of the most interesting examples where the tick population and Lyme cases in pets have exploded is the state of West Virginia. Going back to 2015, West Virginia was not thought of as Lyme disease country. Only about 5% of the dogs tested positive, or 1 in 20. Then, just a few short years later in 2018, the incidence rate shot up to almost 10%. In 2021, the incidence rate in West Virginia was almost at 15%. Dr. Adolph said that while West Virginia is one of the most notable places of rising cases, there are many other states experiencing increased incidence rates.

This speaks to the need that veterinarians should be screening all dogs for heartworm and the major tick diseases, Dr. Adolph said. “If we know a pet has it, then we can take the take the problem from there. But we can’t do anything unless we know there’s a problem.”

One Health strategies

Dogs are essentially sentinels for humans. While they can’t give their owners Lyme disease, if a dog tests positive, it’s confirming to the owner that his or her pet has been fed on by ticks, those ticks were infected with Lyme, and now the dog has the Lyme organism.

“Humans and dogs share those environments,” Dr. Adolph said. A Lyme positive case is an opportunity to confirm that the pet owner is living in a Lyme environment, and will want to do things to mitigate exposure, such as avoiding the woods, landscaping, putting up fencing to keep out or reduce the deer population in the area, etc. “You can do all of those things to help reduce the numbers of ticks, but you’re never going to get to zero,” he said. “It’s just not going to happen.”

Because people and their pets often spend time in the same environments where Lyme and other disease-transmitting ticks are found, the American Veterinary Medical Association (AVMA) and the American Academy of Pediatrics (AAP) are working together to offer advice to households with both children and pets. “People who have been diagnosed with Lyme disease should consult their veterinarian to determine their pet’s risk based on the animal’s lifestyle and possible environmental exposures,” the AVMA said on its website. “Likewise, people whose animals have been diagnosed with Lyme disease may want to consult their physician about their own or their children’s risk if they have concerns that the animals and family members might have been exposed to similar environmental risks.”

People treated with appropriate antibiotics in the early stages of Lyme disease usually recover rapidly and completely, according to the CDC. Early diagnosis and proper antibiotic treatment of Lyme disease can help prevent late Lyme disease.

For dogs, the No. 1 strategy to mitigating Lyme disease cases is diagnostics. The second-best strategy for dogs is year-round tick control. “It’s absolutely critical,” Dr. Adolph said. This is one area veterinarians may have to do some convincing with pet owners. Dr. Adolph said he’s had many conversations with pet owners who believe the myth that ticks all die off in the winter, then spontaneously generate in the spring. “That’s not how they work,” he said. “The tick that most often spreads the disease to dogs is most active in the cold weather months, so October to February. This makes it critical to maintain your-round tick control and not stop during those months. We want to get the ticks dead as quickly as possible before they can spread the pathogen. We also want to do a dual action protection protocol by vaccinating these dogs at risk.”

In regard to vaccines, the CAPC noted on its website that vaccines are available to limit Lyme borreliosis in dogs, and experimental studies testing efficacies of some of these vaccines were reported in peer-reviewed journals. “The decision to vaccinate against Lyme borreliosis should be based on a risk assessment of the individual dog that includes information about where the dog lives and how often it frequents a tick-infested area. Routine vaccination of dogs against Lyme disease is not warranted in areas of the United States where B. burgdorferi infection is not endemic.”

Vaccination against Lyme borreliosis does not replace the need for stringent tick-control programs in pets, CAPC said. “Vaccines may not protect against all strains of B. burgdorferi, and ticks harbor multiple pathogens for which vaccines are not yet available. For this reason, CAPC recommends that all pets be maintained year-round on highly effective acaricides with residual activity against ticks.”

Combination products

Veterinarians know all too well that telling pet owners they need to do year-round prevention and getting them to comply are two very different things. For years, Dr. Adolph said clients may have lapsed in compliance because they had to use multiple products for prevention. They would have a separate heartworm prevention strategy and a separate tick prevention strategy. “Sometimes they would continue the heartworm because they swatted a mosquito in their house in the dead of winter and could see the threat,” he said. “But with ticks, often they’d think maybe they could save a few bucks and wait until spring to start giving it.”

The introduction of combination products to the market has given veterinarians a new way to bridge the gap from education to actual compliance, Dr. Adolph said. Simparica Trio’s release to market has been an interesting case study in that it debuted less than a month before the country essentially shutdown because of COVID. Traditional conversations about new products had to be tabled for veterinary practices shifting to curbside care and telehealth solutions. Instead of getting to visit clinics or use in-person trainings on the new combination product, Dr. Adolph was on virtual meeting after virtual meeting. A lot of clinics saw the value in simplifying the message about parasites, and a good amount of clinics across the country took that approach right away. Then there was a segment of veterinary practices that listened, saw the value but did not have the bandwidth to sit down and educate their team on a practice protocol change right away. Those veterinary clinics have slowly integrated into offering the new preventive option for clients.

“Things like Simparica Trio make the compliance issues so much easier for clients, because we’re giving one thing every 30 days to our dogs that protects against the major health threats when it comes to parasites – heartworms, fleas and ticks,” Dr. Adolph said. “It’s like the easy button that I never had when I was in practice.”

The Companion Animal Parasite Council Recommends:

• Lyme disease in canine patients is best prevented by performing daily tick checks/avoiding tick habitats, using year-round acaricides with label claim against Ixodes spp. and, if living in or traveling to an endemic area, vaccination.
• Screening dogs for exposure to Borrelia burgdorferi due to rapid geographic expansion of endemic areas.
• In areas where Lyme disease is endemic or emerging, vaccinate dogs against Borrelia burgdorferi and reducing the risk of infection through year-round tick control and avoiding areas with ticks.
• Diagnosing Lyme disease based on a combination of clinical signs, including arthritis and renal disease, and positive serology.
• Veterinarians recognize that dogs can be sentinels for the risk of Lyme disease to people.

Source: http://capcvet.org/guidelines/lyme-disease

Image credit: istockphoto.com/Chalabala