News

Lyme Found in DuPage

While West Nile virus got all the press this summer, another pathogen has crept into our area with little notice. The bacterium that causes Lyme disease was found for the first time in one black-legged tick (also known as the deer tick) in DuPage County this past June. And Will County has recorded two human cases that most probably originated within its borders.

When Dr. Jeff Nelson of North Park University surveyed DuPage County for ticks this spring, he found several small populations of the black-legged tick, and one tested positive for the bacterium Borrelia burgdorferi. In a similar survey ten years ago, no ticks were found.

The Illinois Department of Public Health believes that 19 Illinois counties, including DuPage and Will, now have established populations of black-legged ticks. The department’s Web site offers a map of current distribution. Lyme disease also occurs in Wisconsin and Minnesota.

The first symptom of Lyme disease is a “bull’s-eye” rash with a central clearing that increases in size. According to Renee Thaler of the Midwest Task Force on Lyme Disease, 36 to 50 percent of those infected develop this symptom. Dr. Nelson says later symptoms can include Bell’s palsy (facial weakness) and irregular rheumatoid arthritis, most commonly affecting one knee or one shoulder. Antibiotics will successfully treat the disease if administered within the first six months.

Tom Velat, invertebrate ecologist for the Forest Preserve District of DuPage County, offers the following tips:

The nymph of a black-legged tick is about the size of a sesame seed. American dog ticks (also known as wood ticks) and are far more common and are larger than black-legged ticks.

Black-legged ticks are most active from mid-April to late June and from mid-September to the end of October.

Ticks tend to stay in the vegetation along the sides of trails frequented by mammals (including humans). Stick to the middle of a path.

Don’t count on DEET to repel the ticks, despite advertising claims.

Check for ticks after walking in the woods, and check again the next day. Removing a tick within 36 hours will prevent Lyme disease.

Put your clothing in the dryer for an hour to desiccate any ticks.

If you have symptoms of Lyme disease, consult a doctor. The initial blood test often produces a false positive, so it is important to follow a positive result with a Western blot test.

— Barbara Hill