A growing number of people have come down with a flue that they caught from pigs at state or county fairs.
The Ohio Department of Health said on Wednesday that there were now 30 lab-confirmed cases in the state, double the number from the previous day.
The patients range in age from 6 months to 36 years old, but most are children who exhibited swine at fairs.
Only one patient was hospitalized as a precaution. That person was treated and released.
Though the Ohio State Fair ended, dozens of county fairs are underway across the state.
State Veterinarian Tony Forshey planned to visit as many as he can, to make sure pigs do not have influenza. He is working with county veterinarians.
"We've not had much flu issues at any of our fairs in the past. This year's an exceptional year," Forshey said.
The virus is known as H3N2.
Ted Wymyslo, the director of the Ohio Department of Health, said that the illness is mild, and that many victims do not realize that they have had the flu.
The big increase in cases did not surprise him.
"Once we increase everyone's awareness to look for these type things, yes, certainly we'll always get more reports," he said.
The bug is passed from pig to person, not person to person.
Joe Bresee of the Centers for Disease Control, which is investigating the outbreak, said that he was concerned that the virus could mutate because it carries the M gene, which makes influenza easier to transmit from person to person.
"I think what we're looking really going to be looking for is evidence that the virus has made the change to be transmitting efficiently in humans. So far we haven't seen that," Bresee said.
On Friday, state health directors are expected to take part in a conference call to alert them to the outbreak.
"All of the directors of health in the country will be coming together and discussing this. I'll be one of the people that will be leading the discussion because of the number of cases that we've seen here in Ohio," Wymyslo said.
He stressed that people cannot catch this flu by eating pork, but added that everyone who visits a swine barn should not carry food to drink inside, and should wash hands well when they leave.
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