Botulism (Clostridium botulinum spp.)

C. botulinum produces a toxin that causes botulism, a rare but serious condition in humans. Clostridium botulinum is a type of bacteria that can be found in the intestines of many marine and freshwater species of fish worldwide. Though rare, outbreaks of botulism can be associated with fish, including aquatic game, canned foods, and smoked fish. Affected fish show few signs of illness, though some fish may have pale gill colorings or abdominal swelling.

A person with botulism can develop double vision, blurred vision, drooping eyelids, and paralysis, which can result in death. People are commonly exposed through the environment or contaminated food, such as smoked fish products. To protect yourself from botulism, avoid fishing in areas where there are dead fish or waterfowl and cook all fish thoroughly. Anyone who thinks they may have botulism should seek emergency medical care.


The classic symptoms of botulism include:

  • double vision,
  • blurred vision,
  • drooping eyelids,
  • slurred speech,
  • difficulty swallowing,
  • dry mouth, and
  • muscle weakness.

Infants with botulism:

  • appear lethargic,
  • feed poorly,
  • are constipated,
  • have a weak cry, and
  • have poor muscle tone.

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 6 hours or as late as 10 days.

If you or someone you know has symptoms suggestive of botulism, consult a healthcare provider or go to the emergency room.

Types of botulism

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum and sometimes by strains of Clostridium butyricum and Clostridium baratii. There are five main kinds of botulism:

  • Foodborne botulism is caused by eating foods that contain the botulinum toxin. The most frequent source is home-canned foods, prepared in an unsafe manner.
  • Wound botulism is caused by toxin produced from a wound infected with Clostridium botulinum. Injection drug users are at increased risk for wound botulism.
  • Infant botulism is caused by consuming the spores of the botulinum bacteria, which then grow in the intestines and release toxin.
  • Adult intestinal toxemia (adult intestinal colonization) botulism is a very rare kind of botulism that occurs among adults by the same route as infant botulism.
  • Iatrogenic botulism can occur from accidental overdose of botulinum toxin.

All forms of botulism can be fatal and are considered medical emergencies. Foodborne botulism is a public health emergency because many people can be poisoned by eating a contaminated food. If you or someone you know has symptoms suggestive of botulism, consult a healthcare provider or go to the emergency room.


Many cases of botulism are preventable.

 canned vegs fruits

Home Canning: Protect Yourself from Botulism

Foodborne botulism

Foodborne botulism has often been from home-canned foods with low acid content, such as asparagus, green beans, beets, and corn, and is caused by failure to follow proper canning methods. However, seemingly unlikely or unusual sources are found every decade, with the common problem of improper handling during manufacture, at retail, or by consumers; some examples are chopped garlic in oil, canned cheese sauce, chili peppers, tomatoes, carrot juice, and baked potatoes wrapped in foil. In Alaska, foodborne botulism is caused by fermented fish and other aquatic game foods.

  • People who do home canning should follow strict hygienic procedures to reduce contamination of foods, and carefully follow instructions on safe home canning including the use of pressure canners and cookers as recommended by the US Department of Agriculture in the USDA Complete Guide to Home Canning.

Other prevention tips include:

  • Keep oils infused with garlic or herbs refrigerated.
  • Keep potatoes which have been baked while wrapped in aluminum foil hot until served or refrigerated.
  • Boil home-processed, low-acid and tomato foods canned foods in a saucepan for 10 minutes before serving, even if you detect no signs of spoilage.

Wound botulism

Wound botulism can be prevented by promptly seeking medical care for infected wounds, and by not using injectable street drugs.

Infant botulism

Most infant botulism cases cannot be prevented because the bacteria that causes this disease is in soil and dust. The bacteria can be found inside homes on floors, carpet, and countertops even after cleaning.

Honey can contain the bacteria that causes infant botulism so, children younger than 12 months old should not be fed honey. Honey is safe for people 1 year of age and older.

Public health agencies work to prevent and control botulism.

Public education about botulism prevention is an ongoing activity. Information about safe canning is widely available for consumers. State health departments and CDC are knowledgeable about botulism and available to consult with physicians 24 hours a day (physicians should immediately report suspected cases of botulism to their state health department). If antitoxin is needed to treat a patient, it can be quickly delivered to a physician anywhere in the country. Suspected outbreaks of botulism are quickly investigated, and if they involve a commercial product, the appropriate control measures are coordinated among public health and regulatory agencies.

Canning at home

Protect Yourself from Botulism

Botulinum toxin is produced by the germ Clostridium botulinum. This toxin can affect your nerves, paralyze you, and even cause death. Foodborne botulism is a rare but serious illness caused by eating foods that are contaminated with a nerve toxin called botulinum toxin. Home-canned vegetables are the most common cause of foodborne botulism outbreaks in the United States. Taking even a small taste of food containing botulinum toxin can be deadly.

When in doubt, throw it out!

  • Any food that may be contaminated with botulinum toxin should be thrown out. Find out how to safely dispose of food and cans that may be contaminated.
  • Never taste the product to determine if it is safe. Do not taste or eat foods from containers that
    • are leaking,
    • have bulges or are swollen,
    • look damaged or cracked, or
    • seem abnormal in appearance.
  • When you open a jar of commercially or home-canned food, thoroughly inspect the product. Do not taste or eat foods that are discolored, moldy, or smell bad. Do not use products that spurt liquid or foam when the container is opened.

Inspect your commercial and home-canned foods

  • Don’t open or puncture any unopened cans, commercial or home-canned, if you suspect contamination.
  • Suspect contamination if
    • The container is leaking, bulging or swollen, looks damaged or cracked or seems abnormal in appearance,
    • The container spurts liquid or foam when opened, or
    • The food is discolored, moldy, or smells bad.

Safely dispose of food and cans that may be contaminated

  • Put on rubber or latex gloves before handling open containers of food that you think may be contaminated.
  • Avoid splashing the contaminated food on your skin.
  • Place the food or can in a sealable bag, and seal it shut.
  • Wrap another plastic bag around the sealable bag.
  • Tape the bags shut tightly.
  • Place bags in a trash receptacle for non-recyclable trash outside the home and out of reach of humans and pets.
  • Don’t discard the food in a sink, garbage disposal, or toilet.
  • Wash your hands with soap and running water for at least 2 minutes after handling food or containers that may be contaminated.

Use a bleach solution to wipe up spills of food that may be contaminated

  • Add ¼ cup bleach for each 2 cups of water.
  • Completely cover the spill with the bleach solution.
  • Place a layer of paper towels, 5 to 10 towels thick, on top of the bleach.
  • Let the towels sit for at least 15 minutes.
  • Wipe up any remaining liquid with new paper towels.
  • Clean the area with liquid soap and water to remove the bleach.
  • Wash your hands with soap and running water for at least 2 minutes.
  • Discard sponges, cloths, rags, paper towels, and gloves that may have come into contact with contaminated food or containers with the food.

From the Center for Disease Control and Prevention (CDC)