COLUMBUS, Ohio (Reuters) - People flocking to agricultural fairs across the United States were warned on Friday to be cautious around pigs after reports this week of nearly a dozen swine flu cases linked to attendance at fairs where sick pigs were present.
Ten new cases of influenza A (H3N2) variant were reported in Ohio and one in Indiana associated with attendance at agricultural fairs. Another case was reported from Hawaii.
"All of this week's reported cases occurred in people who had direct or indirect contact with swine prior to their illness," the Centers for Disease Control and Prevention in Atlanta said in a statement.
The reports had veterinarians at the Ohio and Indiana state fairs testing the animals for infections. Two hogs tested positive and were sent home from the Ohio State Fair, which ends on Sunday. No swine were found to be infected at the Indiana State Fair, which started on Friday and runs through August 19.
Missouri, Iowa and Illinois state fairs start next week. Minnesota's fair starts later in August.
In Butler County, Ohio, 10 human cases have been confirmed and 10 more people are being tested, said Patricia Burg, director of the county's health department. There have been no hospitalizations so far.
The hogs exhibition remained open Friday at the Ohio State Fair in Columbus, where veterinarians were checking the remaining animals as the fair winds down, said Erica Pitchford, spokeswoman for the Ohio agriculture department.
The focus on people was mainly on exhibitors who spend more time in the area than the general public, she said.
"The chances of the virus infecting anyone walking through the barn is very low," Pitchford said.
Swine influenza A viruses rarely infect humans, but can be spread when people are standing near an infected pig which coughs or sneezes. Humans also can get the virus by touching an infected pig or a surface that has been infected, and then touching their own mouth or nose.
The CDC officially has 29 U.S. reported human cases of influenza A variant H3N2 infections since July 2011. Ohio led with 10 cases, Indiana had 7, Iowa 3, Pennsylvania 3, Maine 2, West Virginia 2, Utah 1 and Hawaii 1.
Nineteen cases were associated with fairs where swine were present. Three people with high risk conditions have been hospitalized, but all have recovered.
Health officials in Indiana said on Friday they had confirmed 11 cases statewide of influenza A variant infections, all linked to swine, some of which were exhibited at local fairs, since July 2012.
"As Hoosiers visit fairs around the state this summer, they should take extra care to practice thorough hand washing and avoid eating when around animals," said Dr. Greg Larkin, Indiana's state health commissioner.
In Wisconsin, the state fair opened Thursday and agriculture officials are monitoring the situation, but have not considered canceling events involving swine, said Brian Bolan, the fair's director of agriculture and youth programs.
Dr. John Schiltz, Iowa's state veterinarian, said on Friday that livestock are examined first on the farm by private veterinarians and then at the fair where a veterinarian is available 24 hours a day to examine animals that show signs of illness.
"People are very conscientious and take the proper precautions to make sure their animals are healthy when they come in," Schiltz said.
Children under 5 and adults over 65, pregnant women, and people with chronic medical conditions such as asthma, diabetes or heart disease, are at high risk for serious complications from influenza and should consider avoiding exposure to pigs and swine barns this summer, the CDC said.
Reporting by Allen Bernard in Columbus, Brendan O'Brien in Milwaukee, Kay Henderson in Des Moines, Kevin Murphy in Kansas City and David Dawson in New York; writing by David Bailey; Editing by Bob Burgdorfer