Health officials say four people who've developed flu-like illnesses all had direct contact with swine at the LaPorte County Fair in northwestern Indiana.
The Indiana State Department of Health said Tuesday that confirmed test results on patient specimens indicate the cause as a variant influenza A virus. Swine specimens have tested positive for the same virus. The department says six of the 17 human cases of variant influenza A virus identified nationwide have been in Indiana.
Health officials say flu viruses can be directly transmitted between swine and people. Human infections are most likely to occur when people are in close proximity to live infected swine, such as in barns and livestock exhibits.
Reported symptoms include cough, fever and sore throat.
The LaPorte County Fair was held July 8-14.