Doctors and officials said at a news conference Wednesday that health workers are interviewing those who attended the Sunday potluck at Cross Pointe Free Will Baptist Church in Lancaster and searching the church's trash to determine what might have caused the outbreak.
Fairfield Medical Center announced Tuesday that one woman had died of the suspected illness.
Dr. Mark Aebi with Fairfield County Health said health officials are collecting samples from the church's trash bin for leads. They're also going into homes to test samples of homemade canned items that were used for some of the dishes at the potluck.
Officials have narrowed down their search to a few items that seem suspect, Aebi said.
Dr. Andrew Murry with the Fairfield Medical Center says a botulism antitoxin was sent from the Centers for Disease Control and Prevention and distributed early Wednesday to hospitals treating the patients with suspected cases of botulism.
Symptoms include blurred or double vision, drooping eyelids, difficulty swallowing and shortness of breath.
Doctors are also confident the illness is specific to those who attended the potluck, not a communitywide outbreak.
Copyright 2015 by myFOXDetroit.com. The Associated Press and FOX News contributed to this report. Click here to read more on FOXNews.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.