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Release: Immediate

University Hygienic Laboratory monitoring tick-borne diseases in Iowa

IOWA CITY, Iowa -- Warmer weather soon will have Iowans gearing up for outdoor activities such as camping, hiking and fishing. But being outdoors also means being exposed to the potential health risks associated with tick bites. Increased awareness among the public and health professionals is key to detection, say researchers at the University of Iowa Hygienic Laboratory.

Around 15 years ago, Lyme disease succeeded Rocky Mountain Spotted Fever as the most recognized tick-borne disease in Iowa. In addition, human monocytic ehrlichiosis (HME) and human granulocytic ehrlichiosis (HGE) have been identified as illnesses attributed to organisms carried by ticks. Tick-borne diseases typically begin with a low-grade fever, headache, malaise and possibly a rash. Left untreated, the symptoms may progress to serious and even life-threatening conditions. However, many cases may resolve without treatment and remain unrecognized.

"Our detection system is such that when we detect tick-borne infections we immediately report them. Overall, there has not been a lot of evidence of human disease in Iowa," says Dr. Mary Gilchrist, director of the UI Hygienic Laboratory. "However, the public and many physicians in the state are perhaps not as familiar with the more recently identified tick-borne diseases like HME and HGE. So part of our job is to make the public and health professionals aware of what's out there, which helps in our detection efforts."

In Iowa, Hygienic Laboratory research gathered from deer blood samples from 1994 and 1996 (conducted in collaboration with researchers at Iowa State University, the Iowa Department of Natural Resources and the Iowa Department of Public Health) has indicated a modest frequency of the organism that causes HME among Lone Star ticks in the southern tier of Iowa counties, especially in the southeast portion of the state. Deer serve as sentinels in tick-borne disease detection, since they typically stay within the same geographic area and receive hundreds of tick bites each year. The Lone Star tick is responsible for transmitting HME in Iowa.

HGE is transmitted by bites from the deer tick, the same tick that is responsible for transmitting Lyme disease, and is found mainly in northeastern Iowa and in counties bordering the Mississippi River. So far the HGE organism has not been prevalent in Iowa, but Gilchrist notes that it has been detected in deer samples from those counties.

As for Lyme disease, researchers know that the northeast counties of the state are the main areas for tick-borne exposure. More recent data suggests, however, a newly evolving focus of Lyme disease among the deer population in the more forested northwestern counties in Iowa, particularly around the Lake Okoboji area.

"The signal of a tick-borne infection in the deer population generally leads us to expect to see the disease in humans, too," Gilchrist says. "We already have a modest amount of tick-borne illnesses, especially Lyme disease, in Iowa. We suspect there may be a similar amount of ehrlichiosis in Iowa, but it's just not been recognized."

Part of the reason for this, Gilchrist says, is that one of the early signs of Lyme disease--a bulls eye-like ring that develops at the site of the tick bite--is not present following a bite from a tick carrying ehrlichiosis. "You don't have that kind of red flag. Ehrlichiosis produces a flu-like illness, with or without a generalized rash. People with this may think they simply have a rash due to allergy." Gilchrist notes that ehrlichiosis typically does not progress to chronic complications such as arthritis or central nervous system symptoms, as can be the case with Lyme disease, and adds that people tend to recover from the illness.

The Hygienic Laboratory has just released maps on its World Wide Web page ( that show the prevalence of the bacteria that cause Lyme disease and HME in deer in each Iowa county. Viewers can "click" a county on the maps and find a table of positive deer serology results from 1994 and 1996. The laboratory's Web page also has information on tick bite prevention and how to safely remove a tick from the skin.

Hygienic Laboratory researchers continue to accept and identify ticks submitted by the public for tick-borne diseases. The researchers also will conduct tick-borne disease surveillance among the state's deer population in 1998. For more information, call (319) 335-4500.