WAUSAU — With a record 3,609 cases of Lyme disease in 2011, the tick-borne illness has become Wisconsin’s third-most-reported ailment, behind only chlamydia (24,254) and gonorrhea (4,761).
Diep “Zip” Hoang Johnson, an epidemiologist with the Wisconsin Department of Health Services, discussed the increase Wednesday at the annual winter meeting of the Wisconsin Chapter of the Wildlife Society. Johnson said Wisconsin recorded more than 18,000 Lyme disease cases between 2002 and 2011, more than double the 5,716 cases reported between 1990 and 2001.
One reason is that the tick responsible for Lyme disease has expanded its range. In surveys from 1981 through 2007, the blacklegged tick — commonly called deer tick — was most common in western Wisconsin.
The DHS’ Division of Public Health and the University of Wisconsin detected the tick’s eastward expansion in 2008 while inspecting nearly 800 hunter-killed deer in eastern Wisconsin. They found the tick in 18 of the 21 counties they checked.
Their research was published in the May 2013 issue of the Journal of Medical Entomology. “The results indicate that range expansion of (blacklegged ticks) is continuing and the risk of tick exposure is increasing, especially in the eastern one-third of the state,” the article reported.
Johnson also warned that Lyme disease isn’t Wisconsin’s only tick-borne disease. While the 1,906 cases reported so far from 2012 represent 75 percent of the year’s tick-related diseases, Wisconsin also had 586 cases of anaplasmosis/ehrlichiosis (two similar diseases), which accounted for 23 percent of the cases.
Blacklegged ticks spread all three diseases. These ticks are smaller than the common wood tick or “dog tick,” which doesn’t cause human-health problems. An adult female blacklegged tick, which is dark brown to reddish orange, is the largest of its species, yet measures less than 1⁄8-inch, about the size of a large sesame seed.
However, most Lyme disease victims get infected when bitten by blacklegged ticks in spring and summer during their nymph stage, when they look like poppy seeds. June and July produce the year’s most Lyme disease cases, typically combining for 60 percent of them. When including cases from May and August, the four-month period accounts for 80 percent of annual cases.
Because blacklegged tick nymphs are so small, many people never know they’ve been bitten. Further, about 20 percent of victims never develop Lyme disease’s brand: a red bull’s-eye skin rash. Only when experiencing fevers, fatigue and headaches do they realize they might have Lyme disease.
To reduce risks when outdoors, Johnson recommends using permethrin or DEET of 20 percent concentrations on light-colored clothing. Also, wear long-sleeved shirts and tuck pants inside boots when venturing off beaten paths into brush, tall grasses and other vegetation. Ticks don’t jump or fly. They simply climb aboard as we push through vegetation they inhabit.
When returning indoors, thoroughly check for ticks. Next, take a shower and scrub vigorously to wash away unseen ticks. “A shower reduces your risk by about 95 percent,” Johnson said.
Don’t panic if you find a blacklegged tick. Even if it’s a nymph, 78 percent don’t carry the Lyme bacteria. Further, they must stay attached at least 24 to 48 hours to transmit the bacteria.
Because Lyme disease is endemic in Wisconsin, the U.S. Centers for Disease Control considers a tick-caused rash larger than 5 centimeters a confirmed case of Lyme, even without a laboratory test.
Lyme disease affects all age groups, but is most prevalent in children 5 to 14, and adults 55 to 74. It’s least common in 25- to 29-year-olds and people 85 and older. Johnson thinks youngsters pick it up more often because they often roll in grass and play in brushy areas, while older people tend to spend more time outdoors gardening and landscaping.
Antibiotics are effective if used early. Adults and children 8 and older are usually cured by taking 100 mg doses of doxycycline twice daily for two weeks. In fact, Lyme disease can usually be prevented if adults take one 200 mg dose of doxycycline within 72 hours of removing a tick.
However, if you have no symptoms or no evidence of a tick bite, it’s a waste of money to insist on a laboratory test. “Screening tests do you no good,” Johnson said. “They’re a waste of time.”
Once cured, there’s no lasting immunity against Lyme disease. People can get infected more than once. Also, no vaccines for humans have been available since 2002. The first and only licensed vaccine against Lyme, LYMERix, was effective but expensive, and required a three-dose series. When many patients didn’t get the follow-up doses, and insurance companies didn’t cover it, the manufacturer ceased production.
If you find a tick attached to your skin, remove it with a tweezers or tissue pinched between your fingers. Pull it straight out, not at an angle, and flush it down the toilet. Finally, cleanse the wound in alcohol, and wash with soap and water.
Patrick Durkin is a freelance writer who covers outdoors for Press-Gazette Media. Email him at email@example.com.