Ohio health officials are looking into a number of cases where an Ohio potluck seems to have spread botulism among participants.

The state is looking into the outbreak after an Ohio woman was left dead and nearly 30 people were sickened. The Ohio Department of Health said Friday that at least one case had been confirmed and that an additional 26 people may have become ill with botulism since later in the week. Health officials suspect it was spread after a potluck dinner last Wednesday at Cross Pointe Free Will Baptist Church in Lancaster, Ohio.

According to local reports, upwards of 50 to 60 people are believed to have participated in the potluck dinner, including 10 children. Ohio health officials say they are investigating each case in an effort to find out whether anyone else was exposed. Outside of the 17 people already hospitalized with suspected botulism, 21 others did not appear to have any symptoms but were being watched. At least one nine-year-old has already been hospitalized with symptoms of the foodborne illness.

Health officials said they are testing 21 homemade and store-bought foods that were found at the potluck dinner, including potato salad and coleslaw. Ohio health officials say while they do not expect additional cases to arise, the situation remains “fluid.”

A botulism antitoxin arrived in the area from the CDC on Friday to treat those who are ill, said health officials. The CDC stockpiles antitoxins and disperses them as needed. The antitoxin takes upwards of 14 hours to take effect, and the hours that pass between delivery of the antitoxin and eventual recovery vary. The antitoxin is a one-time dose that takes 2 to 3 hours to administer and protects against seven types of botulism, according to the CDC. The antitoxin protects people by creating a blockade between nerve receptors and the neurotoxin itself. The earlier it is administered, the more effective it is, CDC officials explained Friday.

Botulism is a rare and serious illness. It is caused when a nerve toxin released by certain bacteria (Clostridium botulinum) enters a food source. Most often botulism is found in canned foods, canned vegetables, potato salad, and in certain types of pasta. Botulism is also found naturally in dirt and in some cases honey.

Often cases of botulism are confused with food poisoning. According to participants at the Ohio potluck, a number of people thought they had food poisoning before they realized it was botulism. The bacteria Clostridium botulinum releases the nerve toxin that causes botulism as part of its natural process. The bacteria thrives in oxygen free environments, making canned foods particularly susceptible.

Symptoms of botulism can take upwards of one day to ten days to become apparent. Symptoms include double vision or blurred vision, slurred speech, drooping eyelids, difficulty swallowing, and muscle weakness, according to the National Institutes of Health. It is not passed from person to person.

As symptoms of botulism continue they progress to life-threatening problems in the lungs. Often the antitoxin must be administered within the first 48 to 72 hours in order to protect the lungs and keep a person off a ventalatior.

Botulism, while rare, still produces around 145 cases a year in the U.S., according to the CDC. However, just 15 percent of those cases are foodborne. The rest are either related to wounds, or are found in infants.