May 7, 2021 — Planning to hit the beach this summer? You might want to throw some bug spray into that beach bag along with your sunscreen.
For the first time, Lyme disease-carrying ticks — typically associated with woodlands in New England and other forested regions of the U.S. — have been found in abundance near beaches in Northern California, new research shows.
Daniel Salkeld, PhD, a Colorado State University research scientist who led the new study, said the findings surprised even his own team, which did not expect to discover ticks infected with Lyme disease-causing bacteria on the shoreline.
“We were a little astounded when we first found ticks in the coastal scrub — chaparral and grassland that abuts the coast — they were in abundance,” Salkeld said. “And if you’d asked at the time, I would have guessed that these ticks wouldn’t be infected with pathogens [that cause Lyme disease].
“But we did indeed find pathogens in these tick populations and that raises the question of what is the source?”
John Aucott, MD, director of the Johns Hopkins Lyme Disease Clinical Research Center, said the study is boosting new concerns about how and where Lyme disease can spread, with the prime summer beach season just weeks away.
“I was surprised by the findings,” said Aucott, an associate professor at Johns Hopkins University School of Medicine. “But I want to point out that that this was a California study. So I don’t want to extrapolate this necessarily to the East Coast. But I was a little surprised because on the West Coast we thought about Lyme more in the oak woodlands, and this really showed that when you looked, you found it in other places.”
And if that isn’t scary enough, Lyme disease forecasters are saying 2021 could be one for the record books.
This winter was one of the warmest on record, and lingering summer heat could add weeks of outdoor activity to animals that carry ticks, which thrive in hot, humid conditions.
Pests.org, which produces an annual 2021 Tick Forecast, projects the Southeastern United States won’t see more tick activity than usual this year, but adds: “Most states will experience the warmer, wetter conditions that drive tick populations — and the prospect of tick-borne diseases — skyward.”
What’s more, Aucott believes more Americans will book outdoor travel plans this summer after a year of being homebound because of the COVID-19 pandemic. Tens of millions will hit the road for beach vacations and other open-air destinations, with the loosening of travel restrictions, the rise in vaccinations, and new federal health guidelines easing mask-wearing recommendations for outdoor settings.
He noted researchers saw “a big uptick” in Lyme disease cases last summer for that same reason — “you know, people who’ve been stir crazy with COVID, wanting to get out of the house, and people taking to hiking and camping and all that.”
He added: “I’ve heard anecdotally that last summer was bad and I suspect this summer will be, too. People will have a chance to stretch their wings by getting outside. And it doesn’t have to be some big adventure, like hiking the Appalachian Trail; they just need to go to their regional park and take a hike and not take precautions.”
‘Ticks Are Always Surprising Us’
Salkeld said his research sought to provide an overview of Western black-legged tick populations in Northern California and whether they are infected with bacteria that cause Lyme disease and other illnesses.
They started by looking in typical places ticks are found — oak woodlands and redwood forests — then branched out to coastal areas.
The big surprise: Researchers found ticks almost everywhere they looked, Salkeld said. This was unexpected because Western gray squirrels, believed to be the region’s predominant source of infection for ticks, are not common in coastal areas. Now, Salkeld’s team is conducting additional studies to identify other tick carriers.
“We’ve found ticks infected with bacteria in woodland, redwood forest, coastal scrub … Now we’re really interested in understanding what animals might be the reservoir — the host that actually infects the ticks — for the disease in these other habitats,” he said. “I have uneducated guesses: Perhaps mice, wood rats, rabbits, voles.”
Salkeld’s study, funded by the Bay Area Lyme Foundation, did not find ticks on sandy beaches themselves, but in the brush, grasses, and vegetation that grow nearby.
“To be clear, we didn’t find ticks on the beach, but in the habitat on the edges of the coast,” he noted. “And colleagues and friends and members of the public have now let me know that this is probably also a concern in those coastal scrubby habitats in the eastern U.S. I’m not sure whether there are differences in the likelihood of disease being in those tick populations (compared to woodland habitats) though.”
The findings, published in the June issue of the peer-reviewed journal Applied and Environmental Microbiology, point to the need for greater awareness of the risks of tick-borne diseases among beachgoers, outdoor enthusiasts, and health care professionals, he said.
Aucott said the big takeaway is that disease-carrying ticks are in more places than once believed, not just wooded areas.
“On the East Coast, it’s pretty hard not to find an area that’s got Lyme disease, unless you live on the asphalt of inner-city Baltimore,” he noted. “Other than that, everywhere has Lyme disease. Even inner-city suburbs have woods and deer and ticks and mice. So you don’t have to be out in the county in the rural areas; even in inner suburbs