Lyme-carrying ticks found beside California beaches

Disease-carrying ticks, commonly associated with wooded areas, are also abundant near beaches in Northern California, according to a study. They were not found on beaches themselves, but in the brush and vegetation beachgoers may walk through to get to the sand.

Daniel Salkeld, a research scientist at Colorado State University who led the study, said researchers wanted a “bird’s eye view” of where ticks are found in Northern California and what they are infected with, such as bacteria that causes Lyme disease and other tick-borne illnesses.

“We were looking at coastal scrub and looked at redwood forests and oak woodlands and that kind of thing because everyone tends to look at the same kinds of places,” he said. “And we found ticks pretty much wherever we looked.”

The most surprising finding, Mr Salkeld said, is that the ticks were found in coastal areas.

It was unexpected in part because western grey squirrels, known to be the region’s predominant “reservoir” animal, or source of infection for ticks, are not common in coastal areas, according to the study.

Researchers and experts who focus on Lyme disease told The Washington Post that people commonly think of Lyme-carrying ticks as being in wooded areas, such as in New England. Some said Mr Salkeld’s research, which was published Friday in the journal of Applied and Environmental Microbiology, underscores that these ticks are far more widespread than realised.

Lyme disease is transmitted through the bite of an infected blacklegged tick, according to the Centres for Disease Control and Prevention. It is not known how many people get Lyme disease, which is difficult to diagnose, but the CDC says an estimate based on health insurance records suggests that nearly 480,000 people are diagnosed and treated for it each year.

The recent study did not find that ticks are crawling around the sandy beach itself, Mr Salkeld said. Rather, they were found in the vegetation that grows near a beach or coastal trail - the “low brush, often it’s kind of prickly.” 

An official from the Bay Area Lyme Foundation, which funded the research, described the “coastal scrub” as the grassy area on sand dunes that people walk through to get to the beach, or on the bluffs at the top of a hill leading down to the beach.

“If you go to those coastal bluffs, you just get that scrub, and that’s the kind of habitat we started looking in,” Mr Salkeld said. “I don’t think we were expecting to find many ticks, but we did, and we found heaps of ticks in big numbers. And they’re infected with diseases.”

John Aucott, director of the Johns Hopkins Lyme Disease Clinical Research Centre, said it was a “good study and what it points out is, geography matters.”

Mr Aucott, who was not involved in the research, said it was notable that even within California - where habitats vary greatly across the coast - research on ticks has focused on wooded areas.

“In classic oak woodlands, there’s a fair number of studies. But nobody had looked at the chaparral, which is that scrubby stuff in the hills before it hits the ocean,” he said. He said the dearth of research in such areas may be because the known reservoir animals do not really live there.

Mr Salkeld said it’s not known what animal is infecting ticks in these coastal habitats, but it’s a question that will require further research by ecologists.

One takeaway from the research, Mr Aucott said, is that “the more we look, the more we find ticks everywhere and disease-infected ticks everywhere.” 

Eva Sapi, a University of New Haven professor and director of the school’s Lyme disease research program, called Salkeld’s study “very eye-opening” and said there should be more unconventional tick research.

“Let’s go to more beaches and other places where we think there wouldn’t be ticks, and I bet we’ll find them,” said Ms Sapi, who also was not part of the study.

Mr Aucott and Ms Sapi said that the research can help spread awareness to people who may not think to check for ticks unless they’re in the woods, and that it will help physicians and diagnosticians who are treating patients who may have been bitten by a tick.

Linda Giampa, executive director of the Bay Area Lyme Foundation, said ticks “quest” in the grasslands, “waiting for a human being or dog to come around, and they’ll hop on and hitch a ride.”

She suggested that when people come home from a wooded area or beach trail, they should put all the clothes they wore in a hot dryer for 20 minutes to kill the ticks. They should then check for ticks on their body - the ticks often latch onto underarms, the groin area, head, backs of knees or backs of ears, Ms Giampa said.

Larger adult ticks - which the CDC says are generally about the size of a sesame seed - are easier to feel, and they may seem like a mole or skin tag, Ms Giampa added. Smaller nymph ticks can be harder to detect.

“I’m not trying to ruin anyone’s vacation or outdoor time,” Mr Salkeld said, adding that people should “always be aware that ticks are around in most of the habitats in California.” 

“Just be aware and get rid of them as fast as you possibly can,” he said.

The Washington Post