DES MOINES, Iowa (AP) – Iowa State Fair officials are on alert but not overly worried about swine flu cases showing up at the fair as it begins Thursday. Animals have been passing a new swine flu strain on to humans. Officials say more than two dozen human cases of the new strain have been confirmed in the U.S. in the past year. Ten cases confirmed last week were linked to the Butler County Fair in southwest Ohio.

Iowa State Fair manager Gary Slater, says that the state veterinarian has been checking fairground preparations before up to 3,500 pigs start arriving today (Tuesday). Each animal must have papers from its local veterinarian, attesting to the animal’s health. Slater says any pig that appears to be sick will be sent home if necessary.