The Ohio outbreak of swine flu that has sickened 15 people — 14 in Butler County and one in Clark County — is in its early stages but is being closely monitered by the Centers for Disease Control and Prevention.

Because flu viruses mutate rapidly, the CDC is tracking the H3N2 virus and working with county fair officials across the U.S. as well as state health and agriculture officials this summer to track flu-like symptoms in both humans and swine. If the strain mutates, it could change to make people sicker, or it could become a milder infection. It could also change in a way that makes it more contagious.

The 15 people infected in the region had contact with infected swine at the Butler County Fair and the Ohio State Fair.

The same strain has sickened people Hawaii and Indiana this year. Last year, it infected people in Maine, Pennsylvania, Utah and West Virginia.

So far, none of the people who’ve taken ill have required hospitalization, Bresee said.

Concerns about swine flu shouldn’t stop people from enjoying county fairs this summer, said Dr. Joe Bresee, a medical epidemiologist in the CDC’s influenza division.

He said people should remember to wash their hands frequently and cover their coughs and sneezes.

“It is safe to go to the fair,” Bresee said. “We’re not recommending people don’t go to fairs. We’re just recommending that people do commonsense measures to prevent infection.”

Health officials’ best advice is for fair-goers to wash their hands and use hand sanitizer after visiting livestock barns and to avoid contact with sick pigs, he said.

“Long-term, I think it’s probably the fried Twinkies that will get you,” he said.

Officials with the Champaign County Fair, which closes Friday in Urbana, are in daily contact with the CDC and state health officials, said Tom Tullis, vice president of the fair. They’ve also worked with the Ohio Department of Agriculture to make sure there’s plenty of hand sanitizer in all of the livestock barns and signs up reminding fair-goers to wash their hands and avoid eating in the barns.

“One of our staff veterinarians goes through the buildings three times a day, and anything that has a temperature, he’ll ask the committee to take that animal off the grounds,” Tullis said.

Every year, state veterinarians randomly test swine for signs of infection, he said.

Workers with Public Health - Dayton & Montgomery County are working with organizers of the Montgomery County Fair to bring them up to speed on the swine flu outbreak, said health department spokesman Bill Wharton. The fair opens Aug. 29 in Dayton.

Flu viruses are usually species-specific; human flu viruses infect people and swine flu viruses infect pigs. Sometimes, though, a swine influenza A virus can infect people. When flu spreads from pigs to people, it’s believed to spread the same way seasonal flu spreads from person to person. An infected pig might cough or sneeze, and a nearby human could breathe in the virus, or come in contact with a surface the or object the virus has touched, then put their hands to their mouths, nose or eyes.

As flu viruses mutate, they may pick up genes from other flu strains. H3N2v contains a gene from the H1N1 flu strain that caused the 2009-2010 flu pandemic.

So far this summer, the H3N2v flu strain is only spreading from infected pigs to people. Last year, there were a few cases in which the same strain spread from person to person. The CDC is monitoring how the strain is spreading both because it’s a new strain and because summer isn’t the typical season for flu in the Northern Hemisphere.

It’s too soon to say whether the H3N2v flu will spread from person to person this year, he said.

“I think this virus can do that. The question is whether this virus can do it efficiently or not,” he said. “Last year, we didn’t see much person-to-person spread, and we didn’t see ongoing spread that kept the outbreak going.”