STORY BY P.J. PEREA
PHOTOS BY ADELE HODDE

Deer hunters along the Illinois River might have experienced some rather unusual requests during visits to check stations the past few years. Researchers have been asking them to remove black-legged ticks from their harvested deer.

Dr. Uriel Kitron, Dr. Roberto Cortinas and graduate students at the University of Illinois are working on a long-term regional project to monitor the expansion of the home range of the deer tick, Ixodes scapularis, which also is known as the black-legged tick.

This tick is infamously known for its ability to harbor and transmit the bacteria responsible for the development of Lyme Disease. While most of Illinois is considered to be in the minimal or low-risk category for this disease, expansion of the deer tick's territory will increase the risk of its occurrence.

Dr. Kitron examines a recently harvested deer for ticks at a check station in Schuyler County last fall.

November 2002    17

Ticks collected at a number of check stations are tested for the presence of bacteria responsible for Lyme Disease.

Tick prevention tips • Wear light-colored clothing so you can more easily see ticks. • Wear long sleeves, buttoned at the wrist, and long pants tucked into socks. • Walk in the center of trails to avoid brushing up against dense vegetation where ticks hide. • Avoid sitting directly on the ground—use a blanket or towel. • Conduct a tick check every few hours and even more frequently when in heavily infested areas. Visually check clothing and exposed skin, and do a final, full-body tick check at the end of the day. • Use an insect repellant containing permethrin. Lightly spray clothing and avoid direct contact with skin. • Remove ticks as soon as you detect them. Do not touch them directly—use tweezers or tissue. • Do not crush the insect. Place it in a disposable container. • Examine pets after walking in a woods, and remove any attached ticks. Learn more about ticks by visiting the Center for Disease Control website: www.cdc.gov/ncidod/dvbid/lyme.

Lyme Disease was first detected in Illinois during the late 1980s in the northwest corner of the state. Since then, deer ticks have slowly expanded their range to the central part of the state. A faster expansion of the populations has been noted in the last 10 years.

"Tick densities have been increasing in counties along the southern portion of the Illinois River, where the habitat is favorable," Kitron explained.

Cortinas, a veterinarian and research assistant with the U of I Department of Veterinary Pathobiology, is developing an Illinois Lyme Disease risk assessment map. Cortinas is analyzing suitable habitats for ticks, based on soil types, bedrock and other environmental factors.

"We hope to accurately predict the spread of the black-legged tick in Illinois," Cortinas said.

For several years, he's been collecting ticks at deer check stations along the Illinois River during the first firearm deer season in areas within and outside his predicted range for the disease. Researchers have also employed a method of tick collection known as dragging. This is done by pulling a cloth over vegetation and examining ticks that grasp on to it. So far, Cortinas' range theories have held up well.

Both doctors cited two major factors in the increase of the black-legged tick in Illinois: mild winters and more deer.

Cortinas elaborated, "Deer used to be a limiting factor when they were rather sparse in Illinois, but now deer are abundant statewide. In addition, mild winters have allowed ticks to survive in far greater numbers.

"The distribution of the black-legged tick is really patchy. There are a few small areas where the risk may be high, but overall the risk of catching Lyme Disease in Illinois is relatively low compared to states like Wisconsin, where it can be a major a health issue," he concluded.

Dr. Cortinas accepts ticks for free identification. Put the tick(s) into a leak-proof container filled with rubbing alcohol along with the date and location where the tick was encountered. Send to: M. Roberto Cortinas, D.V.M, University of Illinois at Urbana-Champaign, College of Veterinary Medicine, Department of Veterinary Pathobiology, 2001 S. Lincoln Avenue, 2843 VMBSB - MC002, Urbana, IL61802.

The ongoing study will monitor the spread of the deer tick in Illinois. The cooperation of hunters is always appreciated.