Lyme disease – Enviro Updates

Guy Kovner, THE PRESS DEMOCRAT

The U.S. Centers for Disease Control and Prevention recommends the following steps for preventing Lyme disease and other tick-borne infections:
– Walk in the center of trails- Use repellents that contain 20 to 30 percent DEET on exposed skin and clothing for protection that lasts up to several hours. Treat clothing and gear with products containing 0.5 percent permentrin.
– Bathe or shower as soon as possible after coming indoors, preferably within two hours.- Examine gear and pets. Ticks can ride into the home on cothing and pets, then attach to a person later.
– Tumble clothes in a dryer on high heat for up to an hour to kill remaining ticks.
– For more information, go to www.cdc.gov/lyme

Annadel State Park, the popular 5,000-acre wildland on Santa Rosa’s east flank, is a hotbed of ticks that can transmit Lyme disease, according to a Stanford University study that sampled 20 recreational areas from Sonoma County to Santa Cruz.
Researchers found six immature blacklegged ticks, also known as deer ticks, per 100 meters on trails in Annadel, the second-highest concentration of the tiny arachnids reported in the study, which was financed by the Bay Area Lyme Foundation and published in the scientific journal PLOS ONE.
The only higher concentration was 10 ticks picked up along a trail in the Windy Hill Open Space Preserve in Portola Valley.
Nearly 10 percent of the ticks from Annadel tested positive for the bacteria that causes Lyme disease, a condition that afflicts about 30,000 people a year nationwide and almost eight per year in Sonoma County.
Aside from some fine points overall, the study said nothing new about the county, which has a 10-year average of 1.41 Lyme disease cases per 100,000 people a year, seven times higher than the statewide rate, according to the Sonoma County Department of Health Services.
“I wouldn’t say it’s a big surprise,” said Dan Salkeld, a disease ecologist who was the study’s lead author, regarding the Annadel tick population. “Sonoma is a beautiful place to go and look for ticks,” he said. “Other people go there for wine; I go there for ticks.”
Neill Fogarty, the supervising ranger at Annadel, said he’s accustomed to finding the immature ticks, known as nymphs, on his body after he has walked through the park, which attracts about 150,000 hikers, runners, mountain bikers and horseback riders annually.
“I usually pick up a few of them every year,” he said.
Of all the environments sampled, the Stanford study found that deer ticks favor live oak-dominated woodlands most of all, and Annadel has plenty of oaks — including coast live oak and black oak — on the west side of the park, around Lake Ilsanjo, Fogarty said.
Read more at: Study: Annadel State Park teeming with ticks | The Press Democrat

Rob Jordan, STANFORD REPORT
The risk of acquiring Lyme disease from ticks, such as this western black-legged tick, is higher than had been assumed, according to a new Stanford study.
The San Francisco Bay Area’s broad swaths of trail-lined open space hold higher risks of tick-borne disease than previously thought, according to a new study by Stanford researchers.

The scientists collected 622 ticks (typically western black-legged ticks) from 20 sites in recreational areas from Sonoma County in the north to Santa Cruz County in the south by dragging white flannel blankets along the vegetation and leaf clutter. After bringing the ticks to a lab, the researchers extracted and analyzed their DNA.
Among other surprising discoveries, they found that a higher percentage of nymphal (young) ticks were infected with the bacteria Borrelia miyamotoi, a recently discovered human pathogen, than on the East Coast. The corkscrew-shaped bacteria produce Lyme disease-like symptoms.
Nymphal ticks are much smaller than adult ticks and thus are less likely to be discovered when they hitch themselves onto humans walking outdoors.
“Users of recreation areas in the Bay Area need to know the risk of tick-borne diseases such as Lyme is real, and not limited to other parts of the country,” said co-author Eric Lambin, the George and Setsuko Ishiyama Provostial Professor in the School of Earth, Energy & Environmental Sciences and a senior fellow at the Stanford Woods Institute for the Environment.
The research, published in PLOS ONE, found the density of non-infected ticks, infected ticks and disease risk varies widely and unpredictably among different habitats (e.g., coast live oak, redwood, grassland) and geographic areas. However, tick-borne disease risk appears to be higher in redwood forests than previously believed.
Although ticks are found in lower densities among redwoods than some other habitats, they are consistently present and harbor B. miyamotoi and Borrelia burgdorferi, which causes Lyme disease. Also, tick-borne disease exposure appears highest in coast live oak-dominated woodlands. The authors caution, however, that the statistical association is too weak to serve as a basis for targeted preventive public health policies and awareness campaigns.
Read more at: Stanford researchers find surprising level of tick-borne disease risk on local trails

Environmental Center of Sonoma County

Tag: Lyme disease

Annadel State Park teeming with ticks

Stanford researchers find surprising level of tick-borne disease risk on local trails