Health officials are trying to locate leftovers, said department spokeswoman Jennifer Valentine.
"In this day and age, botulism from food is fairly rare. Generally it's canned foods," said Dr. Andrew Murry of Fairfield Medical Center. "The fatality rate is usually fairly low."
At a press conference Wednesday, Murry stressed that botulism is not contagious and, in this instance, would only affect anyone who ate at the potluck.
"It is not a threat to our patients, visitors or staff or the community at large," Murry said.