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University of Iowa News Release

Release: March 18, 2003

UHL Preparing For Surveillance Of Insect-borne Illnesses

Summer is still a few months away, but University Hygienic Laboratory (UHL) specialists already have begun preparation for the surveillance of tick- and mosquito-borne illnesses in Iowa in 2003.

On March 11, UHL staff collected blood samples from nearly 100 Iowa Department of Natural Resources employees at the DNR annual meeting at Springbrook State Park near Guthrie Center.

UHL scientists will use the samples to perform tests to detect the presence of antibodies for a variety of tick-borne illnesses, such as Lyme disease and ehrlichiosis. They also will look for antibodies for the mosquito-borne West Nile virus, which infected 54 Iowans last year, killing two. The presence of antibodies in their blood means DNR employees were exposed to these infectious agents.

DNR personnel spend much of their time outdoors across Iowa, in areas where ticks and mosquitoes are most prevalent. UHL staff will try to determine if these persons are at higher risk of contracting tick-borne or mosquito-borne illnesses than those who spend less time outside.

"We did a similar study five years ago with the DNR," said Tom Gahan, a public health microbiologist at the UHL. "Our conclusions were that DNR employees are fairly tick-conscious. As a group they do a good job of checking for and removing ticks before the ticks become firmly attached to the skin and then transmit infection."

"It will be interesting for us to determine what their exposure was to West Nile virus last summer and fall," said Lucy DesJardin, Ph.D., who heads the units conducting this study.

The presence of antibodies for West Nile virus indicates a past exposure, not that a person has or will contract an illness, DesJardin noted. In fact, most people do not develop symptoms, or may experience a brief flu-like illness, from the virus. Those people who do have the illness typically show symptoms within two weeks of a bite from an infected mosquito. Severe infections and death occur in less than 1 percent of those infected with West Nile virus, and are most likely to occur in the elderly and those with weakened immune systems.

Experts expect at least as much West Nile virus activity in Iowa this year as last year, said Mary Gilchrist, Ph.D., director of the UHL.

"Since West Nile virus was identified in New York in 1999, it has steadily moved west and it will continue to spread," Gilchrist said. "If the spring is wet, we believe that more birds and mosquitoes will be identified with West Nile virus in Iowa, which will increase the chance that Iowans become infected."

Gilchrist stressed, however, that the chance of becoming sick from West Nile virus is still relatively low. The virus is not spread from person to person, and it can best be prevented through mosquito control – eliminating standing water around the home to minimize mosquito breeding, and wearing long-sleeved shirts and pants and using insect repellent to avoid mosquito bites.

West Nile virus was first identified in Iowa in September 2001, isolated from a dead crow found in the eastern part of the state. The first confirmed human case in Iowa was detected in August 2002; the first human death from the virus was reported in October 2002.

Following the first confirmed human case of West Nile virus last year, the UHL was inundated with calls and blood samples until at least late September, DesJardin said, adding that UHL staff anticipate as many or more samples this year.

"Last year we tested about 1,500 patient samples for West Nile, and 500 of these samples were tested for four other mosquito-borne viruses that are occasionally found in Iowa. It certainly kept us busy," she said.

STORY SOURCE: University of Iowa Health Science Relations, 5135 Westlawn, Iowa City, Iowa 52242-1178

CONTACT(S): David Pedersen, (319) 335-8032, david-pedersen@uiowa.edu