Ohio, Indiana and Hawaii have confirmed or suspected cases.
Health officials in Ohio said Thursday that as many as 41 people and all but two of them children have become sick with symptoms like those of a swine flu strain.
The cases are linked to the Butler County Fair, which ended last weekend. No one required hospitalization and people were reported to have seasonal flu like symptoms. Ohio officials had said Wednesday that preliminary laboratory tests on 10 people had indicated possible H3N2 variant flu virus, whose symptoms include cough, sore throat, fever, body aches and possible nausea and diarrhea. The Centers for Disease Control and Prevention is testing specimens from those 10 to confirm the virus.
The CDC now indicates there have been five confirmed cases in Indiana in recent days. With another case recently confirmed in Hawaii, the total is now 19 cases of the swine flu strain since it first showed up about one year ago. There were four cases linked to a northwest Indiana county fair and a fifth in southern Indiana.
Health and agriculture officials are reminding fairgoers to wash their hands, and refrain from taking food and drinks into livestock barns. Pregnant women, young children, the elderly and people with weakened immune systems should be particularly careful.