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Study: Ticks at the Beach

A new study was published April 23, 2021, in Applied and Environmental Microbiology, “Examining prevalence and diversity of tick-borne pathogens in questing Ixodes pacificus ticks in California,” by Daniel Salkeld, et al. This is the first study to characterize bacteria carried by ticks in the chaparral in beach areas.

The findings were unexpected: black-legged ticks (Ixodes pacificus) infected with Borrelia burgdorferi (the bacterium that causes Lyme disease) were found in grass and scrub areas leading to the beach at equal rates to the woodland habitats in parts of northwestern California. 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.

The grey squirrel, which does not live in coastal areas, has been the main tick host and source for Lyme in northwestern California, so it was not expected to find infected ticks at the coast. It is currently unknown how the ticks are being infected, perhaps rabbits, voles and/or the white-footed mouse.

Researchers conducted tick drags of public and private areas including California State Parks (SP), County and Regional Parks, and National Parks in in Marin, Mendocino, Monterey, Napa, Santa Clara, Santa Cruz and Sonoma Counties. The prevalence of Borrelia burgdorferi, Borrelia americana, Borrelia bissettiae, Borrelia miyamotoi and Anaplasma phagocytophilum  in black-legged ticks was measured across these multiple habitats, which included woodlands and grasslands as well as coastal chaparral, which was never studied before. The collective infection rate of all the species was as high as 31% in one area. Previous research, up until this study, only tested for single species of bacteria in a specific area. Researching all the tick-borne pathogens simultaneously may be more accurate in presenting risk.

Beach goers have to be cautious, although the ticks aren’t found on the beach itself.

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

Click here for journal article

Ticks Carrying Disease Found to Be Abundant in Beach Areas, Similar to Woodlands, According to New Study  – prnewswire.com (4/23/21)

Ticks that cause Lyme disease as plentiful near beaches as in the woods – nbcnews.com (4/23/21)