Lyme disease not prevalent, but it does occur in county
Lyme disease is a growing problem in the Northeast and upper Midwest, where swarms of suburban deer are bringing an unwelcome parasite: the deer tick, a carrier of the Lyme bacteria.
Some spots have as many as 400 deer per square mile, well above the eight-deer-per-square-mile threshold that’s considered a risk for tick-related diseases. And there are now 16,000 cases of Lyme infection a year, said a recent article in USA Weekend, a supplement in The Union on Saturdays.
“This is the middle-class pestilence of our times, and it’s really just at its early stages and growing rapidly,” the article quoted Andrew Spielman, head of the laboratory of public health entomology at the Harvard School of Public Health.
So is there reason to fear the deer here in Nevada County?
We’ve got deer, and they can carry the Western black-legged tick, which can infect humans with the Lyme disease bacteria. Six Lyme disease cases were reported last year in Nevada County, according to the California Department of Health Services.
But experts say we don’t have an exploding deer population, and our ticks don’t seem as likely to carry Lyme bacteria as do ticks in the East.
Except for a few areas where people feed deer (which is illegal), their population is steady or declining in Nevada County, said Jason Holley, the California Department of Fish and Game biologist for Nevada and Placer counties.
“It’s definitely not an explosion of deer. Our best information tells us (the deer population) is steady to slightly declining,” Holley said. However, “In some areas where people feed them, we get these high densities.”
In 2000, the Nevada County-based Sierra Foothills Lyme Disease Support Group paid to have tests for Lyme disease bacteria done on 307 Western black-legged ticks caught at the Independence Trail and Bridgeport covered bridge, both near the South Yuba River.
The tests showed Lyme bacteria in some ticks, but testing wasn’t detailed enough to show what percentage carried the bacteria.
Similar studies in Placer County showed the percentage of Western black-legged ticks with the Lyme disease bacteria ranged from a high of 12 percent to nonexistent, said Mark Miller, director of communicable disease control for Placer County.
But most samples showed about 5 to 6 percent of ticks carried the bacteria, he said.
“We certainly don’t see Lyme disease … out West to the extent that they experience it in part of the East Coast. You find much higher infectivity rates in ticks back East,” Miller said.
How to avoid tick bites
1. Stay on designated pathways and avoid grassy or brushy areas.
2. Wear light-colored clothing and tuck trouser cuffs into socks.
3. Check clothing and body frequently for ticks.
4. Apply insect repellent to clothing and exposed parts of the body.
5. Keep pets on a leash. Treat with insecticide powders or sprays labeled for tick control.
6. Carefully remove attached ticks immediately.
Source: California Department of Health Services
The Sierra Foothills Lyme Disease Support Group meets at 6:30 p.m. second Tuesdays in Sierra Nevada Memorial Hospital’s classroom A. For more information, call 432-4280 or 272-3204.
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