Five people were in critical condition, 15 others were ill and one has died after an outbreak of botulism, a potentially life-threatening disease caused by a neurotoxin produced by bacteria, Ohio health officials announced Tuesday. Everyone sickened by the disease had attended a church potluck on Sunday at the Cross Pointe Free Will Baptist Church in Lancaster, Ohio, about 30 miles southeast of Columbus, according to local media reports.

Some of the patients at the hospital were on ventilators. "In this day and age botulism from food is fairly rare; generally, it's canned foods," Dr. Andrew Murry of the Fairfield Medical Center, where the patients are receiving treatment, told CNN. "The fatality rate is usually fairly low." Health officials said the disease was not contagious but said anyone who attended the potluck should contact emergency personnel should they experience symptoms. The Ohio Department of Health was expected to deliver a powerful anti-toxin treatment to patients on Wednesday.

Foodborne botulism is caused by ingesting food contaminated with the bacteria Clostridium botulinum, or C. botulinum. The toxin produced by the bacteria is one of the most potent toxins known to man and results in severe food poisoning. Food that hasn’t been properly processed or was canned at home are the most common vehicles of C. botulinum, according to the Food and Drug Administration.

There are between 10 and 30 outbreaks of botulism in the U.S. every year. However, the number of cases is likely higher because symptoms are sometimes mild and go unnoticed, the FDA reports. Meat products such as sausage, and seafood and canned vegetables are the foods most frequently associated with botulism outbreaks.  

Symptoms of botulism, which include drooping eyelids, double vision, slurred speech and muscle weakness, can occur within as little as six hours or up to 10 days from exposure and typically set in within 12 to 36 hours, according to the U.S. Centers for Disease Control and Prevention