Three bats have tested positive for rabies so far this year in DuPage County, and eight people throughout the county have been treated for the disease, according to the DuPage County Health Department.

The middle of August to late September is the prime migration period for bats, and county animal control and health officials are warning residents to exercise caution in dealing with the winged creatures because they are a primary carrier of rabies. More than 50 bats have tested positive statewide in 2008.

The Health Department did not have additional details about when or where the rabid bats were found.

Any bats found in the living area of a home — not including the attic — should be captured by police or animal control personnel for rabies testing, officials said. If residents find bats in their attics, they should contact a professional trapper.

“What’s most important to remember is that if you have a bat in your living quarters, that is considered exposure,” said Kerry Vinkler, executive director of DuPage County Animal Care and Control.

Unless a bat found in the home tests negative for rabies, the entire family will have to receive post-exposure vaccinations, Vinkler said. There is currently a shortage of the vaccine, she added.

Rabies is a virus that affects the nervous system of humans and other mammals, according to health officials. Humans get rabies after being bitten, or more rarely after being scratched, by an infected animal. Pets are also vulnerable to the disease.

No one has died of rabies in DuPage County since 1954, said Dave Hass, a spokesman for the Health Department.

Vinkler said it is important for all dogs and cats — even ones that only live indoors — to be up to date on their rabies vaccinations.

Scott Meister is an ecologist with the Forest Preserve District of DuPage County. He said there are six species of bats found in DuPage, most commonly the big brown and red varieties.

The vast majority of bats do not carry rabies, so residents shouldn’t be alarmed when they are seen flying around at night, Meister said.

“Bats are everywhere,” he said. “They’re in our forest preserves; they’re in our neighborhoods. They’ve been here forever.”

When bats are seen during the daytime or inside the living area of a home, residents should exercise caution and not try to handle them, Meister said.