What is botulism, and how does it kill?

A common culprit in food-borne botulism is improperly canned or fermented food.

Story highlights

  • Botulism is one of deadliest toxins on the planet
  • Botulism spores are everywhere in soil and sediment
  • Improperly home-canned foods are the most common source

(CNN)Botulism is a paralyzing nerve toxin, considered to be one of the most potent and lethal substances in the world.

It's produced by the bacterium Clostridium botulinum and sometimes by strains of Clostridium butyricum and Clostridium baratii. The rod-shaped bacteria are commonly found in soil and sediments from lakes, rivers and oceans.
    The bacteria thrive in low-oxygen conditions, such as canned foods, deep wounds and the intestinal tract, but when threatened form protective spores with a hard coating that allows the bacteria to survive for years.
    The danger is not from the spores themselves but what they produce while germinating. As the C. botulinum bacteria grow, they create eight types of neurotoxins that are so deadly, even microscopic amounts can kill.
    This deadly nerve toxin is also the source of Botox, a leading cosmetic solution for wrinkles as well as medical conditions such as migraines and excessive sweating, known as hyperhidrosis. Injecting minute, highly diluted amounts of the toxin into a muscle blocks the nerve signals that tell that muscle to contract. That temporarily weakens the muscle, thus smoothing the wrinkle or the pain the contraction causes.

    What are the symptoms of botulism?

    Because botulism toxin paralyzes muscles, early and classic signs of the illness are drooping eyelids and blurred or double vision, dry mouth, slurred speech and difficulty swallowing. If left untreated, greater paralysis of muscles of the arms, legs and trunk of the body will occur, affecting the ability to breathe.
    Babies infected with botulism will be poor feeders and seem lethargic, with a weak cry and poor muscle tone. They can also be constipated.
    Botulism does not cause fever, and those affected are usually alert and aware of their surroundings.

    How is botulism treated?

    Unless there is a clear cause, such as obviously contaminated food, doctors will first rule out other diseases that can mimic the symptoms of botulism, such as stroke and Lyme disease.
    Once botulism is confirmed, it can be treated with an antitoxin and, in some cases, antibiotics. If the antitoxin is given before paralysis is complete, it helps shorten recovery, which requires the regrowth of motor nerve endings. The patient can be hospitalized for supportive treatment, such as a ventilator, for weeks or months until the paralysis improves. In some cases, muscle weakness and shortness of breath can last years.
    Other treatment depends on the kind of botulism, of which there are five main types:
    Infant botulism
    In 2001, there were 169 cases of botulism in the United States. Among those, the vast majority -- 112 cases -- were in infants. In 2015, 141 of the 199 confirmed cases of botulism in the US were in infants.
    Although infants can be infected by swallowing contaminated soil, feeding an infant under the age of 1 honey or corn syrup is the main culprit. Their immature digestive systems cannot move C. botulinum spores through their gut quickly enough to keep the spores from germinating.
    For the same reason, babies who have less than one stool a day for more than two months are also at risk. The illness is most common in those between 6 weeks and 6 months.
    If the illness caught and treated early, most infants make a full recovery. However, antibiotics are not used in children of this age, as killing the toxin in their intestines can trigger the release of additional antitoxins. Instead, vomiting and enemas are typically used to get rid of undigested food in the gut.
    Food-borne botulism
    C. botulinum spores are commonly found on the surfaces of seafood and most fruits and vegetables. Due to today's manufacturing methods, it's rare for store-bought foods to be contaminated with botulism. The common culprit in much food-borne illness is homemade food that has not been properly canned or fermented.