Botulism Outbreak Traced to Tainted Nacho Cheese Sauce

Ten people hospitalized and one man dies after eating nacho cheese sauce

nacho cheese sauce
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On May 22, 2017, the California Department of Public Health reported that 10 people became severely ill after eating nacho cheese sauce sold by a gas station outside Sacramento, California. One man has died.

In April 2015, 29 people became very ill after eating potato salad at a church potluck.

What do these two events have in common? They were both outbreaks of foodborne botulism.

Foodborne botulism is caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. This rare illness can cause life-threatening respiratory paralysis.

Foodborne Botulism Explained

Technically, foodborne botulism isn’t an infection but rather an intoxication. The preformed toxin produced by Clostridium botulinum is absorbed in the gut and circulates by blood to the nerve-muscle junctions where it binds, thus causing paralysis.

The specific damage caused by the toxin depends on which nerves are affected. For instance, when the toxin binds to the nerves in the autonomic nervous system, heart arrhythmias and blood pressure instability result.

Damage to nerve synapses caused by the botulinum toxin is permanent, and recovery requires regrowth of synapses.

Common sources of foodborne botulism include homemade foods that have been improperly preserved, canned, or fermented. More rarely, store-bought foods or foods sold in retail settings can be a source of botulism, such as chopped garlic in oil, chili peppers, tomatoes, canned cheese sauce, carrot juice, and baked potatoes wrapped in foil.

Symptoms of Foodborne Botulism

Foodborne botulism begins between 12 and 36 hours after consumption of contaminated food.

Initially, foodborne botulism results in nausea, dry mouth and, sometimes, diarrhea. Later symptoms include dilated pupils, blurred vision, and nystagmus, or rapid and uncontrolled eye movements.

Eventually, a paralysis affecting both sides of the body spreads from the eye, laryngeal, and respiratory muscles to the trunk and extremities.

Complete paralysis of the lungs—leading to lung failure—is the worst thing that can happen in those affected with foodborne botulism and results in death in 10 to 20 percent of patients.

Unfortunately, there is no cure for botulism. Treatment is directed at symptoms and is supportive. Mechanical ventilation (i.e., breathing machine on the ICU) is the key to successful treatment, and it reduces death rates to less than 10 percent. Moreover in adults, large doses of horse Clostridium botulinum antitoxin are believed to be helpful in neutralizing circulating toxin.

Prevention of Foodborne Botulism

The best way to manage foodborne botulism is to avoid exposure to it in the first place.

Clostridium botulinum spores are found in soil in many parts of the world, including the United States. Food contaminated with the toxin demonstrates no change in taste, color, or smell. Vegetables are particularly good at harboring and supporting the growth of Clostridium botulinum.

If you can your own foods, it’s imperative that you use a pressure canner for low-acid foods and follow all specified processing times for safe home canning.

Low-acid foods include vegetables, figs, some tomatoes, meats, fish, and seafood. Do not use a boiling water canner instead of a pressure canner when home-canning, because a boiling water canner doesn’t eliminate spores.

For complete instructions on safe home-canning, check out the USDA Complete Guide to Home Canning.

When consuming home-canned foods low in acid, always boil the foods in a saucepan first—even if you notice no signs of spoilage. At altitudes below 1000 feet, boil for at least 10 minutes. For each additional 1000 feet of elevation, add a minute of boiling time. For instance, at an elevation of 3000 feet, boil for at least 12 minutes.

Always inspect all canned foods, including store-bought ones, for signs of contamination. Immediately discard canned foods that are leaking, swollen, bulging, damaged, or cracked. If you open a canned food and the contents spurt liquids or foam, immediately throw it out. Finally, throw out any canned container whose contents are moldy, discolored, or smelly. You can never be too safe with canned foods.

When discarding sources of possible contamination, wear gloves to avoid skin contact, double bag the cans or containers, tightly secure the bags with tape, avoid spillage, and use bleach to clean up any spills that do occur.

A Word From Verywell

Although foodborne botulism outbreaks are rare, they do happen. Be on the lookout for food sources that are possibly contaminated, especially canned food, whether they be home-canned or store-bought. Carefully dispose of any canned foods that appear contaminated.


Botulism. County of Los Angeles Public Health.

CDPH Testing Confirms Botulism Linked to Nacho Cheese Sauce Sold at Sacramento County Gas Station. California Department of Public Health.

Clostridium, Peptostreptococcus, Bacteroides, and Other Anaerobes. In: Ryan KJ, Ray C. eds. Sherris Medical Microbiology, 6e New York, NY: McGraw-Hill; 2014.

Home-Canned Foods. Protect Yourself From Botulism.

McCarty, CL, et al. Notes from the Field: Large Outbreak of Botulism Associated with a Church Potluck Meal — Ohio, 2015. Morbidity and Mortality Weekly Report. 2015; 64(29);802-803.