Botulism in Ohio foodborne illness outbreak

Ohio potluck linked to one death and others hospitalized.

An April 2015 outbreak of botulism foodborne illness in Ohio has raised concerns about the bacteria, Clostridium botulinum. Clostridium botulinum bacteria can produce heat resistant spores which enable it to survive and develop a poisonous toxin under the right conditions.

Botulism is a very serious illness. According to the Centers for Disease Control and Prevention (CDC), classic symptoms of botulism include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth and muscle weakness. These are all symptoms of the muscle paralysis caused by the bacterial toxin. If untreated, these symptoms may progress to cause paralysis of the respiratory muscles, arms, legs and trunk. In foodborne botulism, symptoms generally begin 18 to 36 hours after eating a contaminated food, but they can occur as early as six hours or as late as 10 days.

Home canned foods are of special concern for botulism. The bacteria will produce the deadly toxin under the following conditions: moist, low-acids foods, temperatures between 40 and 120 degree Fahrenheit and conditions with less than two percent oxygen. These conditions may be present in canned foods. Low-acid foods such as meat, seafood, poultry, dairy products and all vegetables have the potential to harbor the bacteria. Spores produced are heat resistant and can be destroyed by canning at a temperature of 240 degrees Fahrenheit or above for a specific amount of time. Since this temperature is above boiling temperature, it can only be reached in a pressure canner.

Foods with high acid, fruit, properly acidified tomatoes and properly pickled vegetables can be safely canned at boiling temperatures. This is because these foods contain enough acid so that the Clostridium botulinum spores will not germinate to form the vegetative cells and produce the deadly toxin.

Because tomatoes and figs have pH values (acidity) close to 4.6, borderline between what are high-acid and low-acid foods, acid in the form of lemon juice or citric acid must be added to them in order to safely can in a boiling water canner.

Botulism can be prevented by making sure home canned foods are safe. Follow current research-based canning directions such as those found at the National Center for Home Food Preservation. An online home canning course is available through Michigan State University Extension.

Other foods besides home canned foods have also been link to botulism, including baked potatoes wrapped in foil, cheese sauce, tomatoes and oils infused with garlic. When these foods are improperly handled at home, in a food service establishment or in a food processing facility, there is potential for foodborne illness.

While canning foods at home is a rewarding experience, home canned foods should never be sold or used at pot-lucks or food fundraising events. Not everyone is aware of recent research-based safe canning methods. Refusing all home-canned foods is the safest choice unless the home-canned foods came from an approved, inspected source.

For food safety information including canning and freezing foods, contact your local MSU Extension.

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