One day last week my chocolate Labrador retriever developed a limp, and the following day she was unable to stand. By the time we were able to get her into the veterinarian, she could barely lift her head; we were stunned by how quickly her condition deteriorated. The veterinarian diagnosed her with Lyme disease, and gave us medication with the assurance that within 24 hours we would see marked improvement. Every step and movement was obviously painful for her, but she did improve rapidly, and continues to get better every day.
Recently, I heard an excellent presentation on Lyme disease by Diep “Zip” Hoang Johnson with the Wisconsin Department of Health Services. I was not going to attend at first; I felt I knew enough about ticks and disease. It turns out I was wrong, and I got a lot out of that talk. If you are like me, you probably have gotten a little complacent about ticks. I spray for them, I tuck my pants in my socks, I pull them off me, and I watch for the notorious bull’s-eye rash. Even though this might seem like an odd time of year for this topic, the “tick season” will be on us before you know it, and it is important to start thinking about preventative measures now.
Lyme disease is the most common of the five illnesses transmitted by ticks in Wisconsin; in 2012, 75 percent of all tick-borne illness cases recorded were Lyme disease. According to the Center for Disease Control, Wisconsin is the highest Lyme disease risk area in the Midwest; it is found mostly in the Northeast and the upper Midwest. The black-legged tick, or deer tick, is the species known to carry Lyme disease, what we refer to as the disease vector. They are less common than the larger brown American dog tick, or “wood” tick, but they are still readily found in much of Wisconsin. As their name implies, deer ticks do feed on deer, especially in the adult stage. Interestingly, deer blood can inactivate the Borrelia bacteria associated with the disease; consequently deer do not transmit it.
Deer ticks live for two years, consuming three blood meals during their life cycle. In their hatch year, the larva feed on birds and small mammals, especially white-footed mice, in mid to late summer. This is their first opportunity to pick up the Borrelia bacteria. When they reach one year old, they enter the nymph stage, and feed for the second time, but on a larger variety of hosts including humans. They feed for the third time in October, when they become adults. If you think about it, this coincides well with the flush of ticks we experience in the spring, and explains why the ticks seem to slow down in summer, followed by another flush of ticks in fall. It seems the greatest likelihood of contracting the disease is from a nymph bite in spring; most human cases appear in June and July.
The number of reported Lyme disease cases in Wisconsin has continued to increase every year. Here are some tips to reduce your chance of contracting the disease. When in the woods or field, stick to mowed or cleared trails. Tuck your pants into your socks, and shirt into your pants, and use chemical repellents like DEET or Permethrin according to directions. Check yourself thoroughly when returning home. Take a shower; this greatly reduces the likelihood of ticks latching on. Remove attached ticks within 24 hours to minimize risk of illness. Do not feed deer or birds near the house, swings or play sets; this activity brings the ticks into your yard on the bodies of birds, small mammals and deer.
Thanks to Zip Johnson and the Wisconsin Department of Health Services for all the information in this article. I could not possibly cover everything, but there is plenty more information on their website at www.dhs.wisconsin.gov.
Jeremy Holtz is a wildlife biologist with the Wisconsin DNR and writes a weekly column in the Star Journal. To contact him, call 715-365-8999.