Lake County residents are being warned to pay particular attention to ticks as the reported number of Lyme disease cases this year has reached a record level.
So far, 20 cases of the disease, characterized by a bull's-eye rash and flu-like symptoms, have been reported to the Lake County Health Department, compared with the old record of 19 in 2011.
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That news, coupled with a report Monday by the Centers for Disease Control and Prevention saying the occurrence of Lyme disease is significantly underreported, has prompted local health officials to issue a public call for attention.
"We have never had this high a number of people with Lyme disease in Lake County, ever," said Leslie Piotrowski, spokeswoman for the health department. "It is a serious illness. We really want people to be aware of ticks and avoid getting bitten."
Lyme disease is caused by bacteria transmitted to humans through the bite of an infected deer tick. Not all deer ticks carry the bacteria. But you don't have to be in deep woods in other geographic areas to encounter them.
"They can be in your own backyard," Piotrowski said. "Now we know, people are getting Lyme disease from ticks in Lake County."
Most reported cases don't present a history of traveling outside Illinois, according to Victor Plotkin, epidemiologist with the health department. The cases are not concentrated in specific locations.
"It is spread through Lake County. It's not limited to one particular area," Plotkin said.
As of late July, the Cook County Department of Public Health reported 22 cases of Lyme disease in suburban Cook County, not including Evanston, Skokie, Oak Park and Stickney townships. That's up from 13 cases in 2012 and four cases in 2011, said spokesman Sean McDermott.
"We've seen a slight uptick in what we've seen in past years," McDermott said.
The DuPage County Health Department reported similar numbers, with 24 cases of Lyme disease so far this year. That compares to 27 cases in 2012 and 32 in 2011, said spokesman David W. Hass.
Symptoms of Lyme disease can include bull's-eye rashes or lesions around the bite site accompanied by fever, fatigue, headache, and muscle or joint aches, generally seven days or more after the bite. Lyme disease is a "reportable condition" in Illinois, and health care providers are supposed to forward the information to the local health department within seven days.
More than 30,000 Lyme disease cases are reported to the CDC each year, but it is suspected the true number of cases is 10 times that. One reason it may be unreported is some people may experience only the flu-like symptoms and not the rash, according to the health department. Lyme disease cannot be transmitted person to person.
"We also want people to be aware of the symptoms," Piotrowski said. "You really should see your health care provider" if you have been bitten by a tick and experience those symptoms in seven to 14 days, she said.
Lyme disease can be treated with antibiotics. But if untreated, some patients may develop arthritis, including episodes of swelling and pain in the large joints; abnormalities such as aseptic meningitis, facial palsy or encephalitis; and, in rare cases, inflammation of tissues surrounding the heart or an enlarged heart, according to the CDC.
The likelihood of contracting Lyme disease is small if a deer tick is attached for less than 36 hours, but deer tick nymphs, which are about the size of a pencil point, can carry the disease, according to the health department.
Preventive measures include keeping grass mowed around the home and playground equipment, minimizing wood piles that small animals that can carry ticks are attracted to and applying insect repellent containing 30 percent of less of DEET to clothes or exposed skin.
Public health officials also recommend steering clear of high grass and bushes where ticks collect and avoid brushing against plants outdoors, and walking in the center of paths through parks and forest preserves. Lastly, McDermott recommends people check themselves for ticks after they leave parks or forest preserves and after they return home, place their clothes in a dryer set on high to kill any ticks that may be attached to the material.
• Daily Herald Staff writer Barbara Vitello contributed to this report.