Areas near beaches crawling with ticks that cause Lyme disease, new research finds

Beachgoers may have felt safe from Lyme disease, but a new study suggests those heading to the shore also need to keep a careful eye out for disease-carrying ticks.

Researchers in California were surprised to find just as many adult black-legged ticks carrying Borrelia burgdorferi, the bacterium that causes Lyme, in areas of grass and scrub leading to the beach they did as in the woodland habitats in the northwestern part of the state.

“We went into new habitats and found them in numbers we didn’t expect,” said lead author Daniel Salkeld, a research scientist at Colorado State University. “A few years ago I would have said the ticks there wouldn’t have been infected because there aren’t any grey squirrels, which are the source for Lyme in California.”

People may not be looking for ticks when heading to the beach, but the tiny bugs could be hiding in coastal grasses or nearby scrub areas.

"I think they've been under our noses all along," Salkeld told NBC News. "We just haven't thought to look very closely."

Fortunately, for Californians, at least, the ticks aren’t a year-round problem. They’re only there during the rainy season, Sakeld said.

The Centers for Disease Control and Prevention estimates that around 476,000 Americans are diagnosed and treated for Lyme disease each year.

Typical symptoms include:

  • Fever

  • Headache

  • Fatigue

  • A characteristic skin rash, called erythema migrans

Most cases of Lyme can be successfully treated with a few weeks of antibiotics, according to the CDC. Untreated, the illness can spread to the joints, heart and nervous system.

To take a closer look at where the ticks might be hanging out, Sakeld and his team dragged public and private areas, including California state parks, county and regional parks and national parks in Marin, Monterey, Napa, Santa Clara, Santa Cruz and Sonoma counties for the blood-sucking bugs.

The researchers found Borrelia burgdorferi in 4.1 percent of adult ticks in coastal scrub and in 3.9 percent of adult ticks in woodland areas.

Sakeld doesn’t know yet how the ticks are being infected. The reservoir of the bacteria “could be voles or rabbits,” he said.

The findings were published Friday in the journal Applied and Environmental Microbiology.

“This is a great study,” said Laura Goodman, an assistant research professor at the Baker Institute for Animal Health at the Cornell University College of Veterinary Medicine. “There is a bias in this country where people think they are only at risk when they go into the woods. But really, prevention and vigilance should be practiced everywhere outdoors, and we should be vigilant year-round.”

Lia Gaertner, director of education and outreach at the Bay Area Lyme Foundation, offered prevention tips:

  • Stay on trails and on sand.

  • Wear light clothing and use tick repellent.

  • Check and triple check your body — up to three days later.

  • Throw clothes into hot dryer once inside.

  • Shower.

“We tell people that if they find a tick attached to themselves, they should always save it so you can send it for identification and see what type it is and if it carries disease,” Gaertner said.

While black-legged ticks are predominantly a woodland and shrubland species, they can also be found in grasslands near the coast, said Richard S. Ostfeld, a tick expert and distinguished senior scientist at the Cary Institute of Ecosystem Studies in Millbrook, New York.

While the new study was based in California, the black-legged ticks are also found in shrubby areas and coastal grasslands on the East Coast.

The good news is that ticks aren’t found on the beach itself, Ostfeld said.