Botulism: What is it and how can we prevent it?
The toxin is produced by Clostridium botulinum (C. botulinum), a type of bacterium.
All types of botulism eventually lead to paralysis, so any case of botulism is treated as a medical emergency.
In the past, it was often fatal, but antitoxins have significantly improved the outlook.
In 2015, the United States saw the biggest outbreak of botulism in 40 years. It stemmed from improperly home-canned potatoes that were shared at a potluck meal.
Botulism is a serious disease caused by the botulinum toxin.
The signs and symptoms depend on the type of botulism.
In food-borne botulism, signs and symptoms include nausea, vomiting, and diarrhea followed by constipation and abdominal distention. There may be weakness and difficulty breathing. Symptoms normally appear between 18 and 36 hours after consuming the contaminated food, but this can vary between 3 hours and 8 days.
In wound botulism, the nerves that connect the brain to the spine, known as the cranial nerves, experience the first symptoms. This then spreads to the rest of the body. The incubation period is from 4 days to 2 weeks.
Neurological signs and symptoms of adult, food-borne, and wound botulism are the same, but the symptoms of wound botulism ones may take longer to appear.
The patient may experience double or blurred vision, the eyelids may droop, there will be facial weakness, a dry mouth, dysphagia, or difficulty swallowing, and speech slurring. Muscles will become weak.
Next, paralysis will set in. Without treatment, the patient's breathing muscles will eventually become paralyzed, resulting in respiratory failure and death.
The patient remains conscious during this process.
In infant botulism, signs and symptoms may include:
- poor feeding
- bad temper
- excessive drooling when feeding
- sagging eyelids
- flat facial expression
- lethargy and listlessness
- respiratory difficulties
- slow or improper reflexes
- weak crying weakly
- floppiness and poor muscle tone
- no gag reflex
- unfocused eyes
- weak sucking
The incubation period for infant botulism varies from 3 days to 30 days.
The botulinum toxin, a poison produced by the bacterium Clostridium botulinum (C. botulinum), is common in soil and exists in untreated water. It can survive in these environments as a resistant spore.
C. botulinum produces spores that can survive in poorly preserved or canned foods. Here, they produce a toxin. When consumed, even minimal amounts of the toxin can cause severe poisoning.
There are several types of botulism.
Foodborne botulism is caused by consuming foods containing the botulinum toxin.
Wound botulism can occur if the organism enters an open wound and produces toxins within the wound. Injection drug users are at risk for this type of botulism.
Infant botulism happens when an infant consumes the bacteria or their spores, and these grow in the gut. Infant botulism in the U.S. mostly comes from eating honey or corn syrup. The bacterium may also occur naturally in the stool of an infant.
Adult intestinal colonization is a rare form of botulism that occurs when the bacterium colonizes the digestive tract of an adult.
To reduce the risk of wound botulism, people are advised to seek urgent medical attention for any infected wounds and also to avoid injecting street drugs.
To ensure food safety, it is important to practice good food hygiene.
The toxin can thrive in improperly canned food.
- Follow any instructions carefully when canning food at home, or avoid canning food at home
- Boil home-processed foods for at least 10 minutes before eating, even if no signs of food spoilage are evident
- Do not taste canned food items to see if they are still good. Throw away any cans that are bulging, leaking, or appear damaged
- Keep potatoes that have been baked in foil hot until eaten
- Not give honey or corn syrup to infants under 12 months of age
- Ensure all foods are well-cooked
- Keep oils infused with garlic or herbs in a refrigerator
Boiling can destroy both the vegetative, or non-spore, form of the bacterium, and the toxin it produces.
However, while boiling for 10 minutes can kill the toxin, to destroy the spore form requires heating to at least 248 degrees Fahrenheit, or 120 degrees Celsius, under pressure, for at least 30 minutes in an autoclave or a pressure cooker.
This is because the spores are highly resistant to harsh environments, and they can remain viable even after several hours of normal boiling. The spores can be killed by very high temperatures such as those used in commercial canning.
The World Health Organization's (WHO) "Five keys to safer food" stresses the importance of:
- keeping clean
- separating raw and cooked food
- cooking thoroughly
- keeping food at safe temperatures
- using safe water and raw materials
This is important when people are traveling, especially to countries where access to clean water, hygiene, and refrigeration facilities may be limited.
Botulism cannot always be prevented. The toxin may be present in house dust, even after cleaning. Parents should be aware of any signs that a child is sick, and take early action as appropriate.
The most commonly tainted foods are:
- home-canned vegetables
- cured pork and ham
- raw or smoked fish
- corn syrup
For example, Home-canned foods and fermented fish and aquatic game from Alaska can be sources of the toxin.
Botulism does not grow in acidic foods with a pH of 4.5 or less.
Diagnosis of infant botulism is confirmed after testing a stool or specimen of enema. If the doctor suspects botulism, treatment with an anti-toxin should begin immediately, without waiting for test results to come back.
A lab can confirm the presence of botulism.
If the patient's history and physical examination suggest botulism, a doctor may consider it, but as other conditions share similar symptoms, a test will be needed to rule these out. Conditions with similar symptoms to botulism include stroke, myasthenia gravis, and Guillain-Barre syndrome.
Diagnostic tests may include:
- a brain scan
- cerebrospinal fluid examination
- edrophonium chloride test for myasthenia gravis
If the toxin is identified in the food, stomach, vomit, feces, or intestinal contents, a definitive diagnosis can be made.
In very acute cases the toxin might be detected in the blood.
Patients with botulism will need to be hospitalized.
Infants will be given Botulism Immune Globulin Intravenous-Human, also known as BIG-V or BabyBIG.
Those with respiratory problems will be on a ventilator, and they may need the ventilator for weeks or months, as well as intensive nursing. Over time, the paralysis may improve.
A patient with suspected botulism will immediately be given injections of antitoxins, even before diagnostic test results have returned.
If the infection results from a wound, the wound needs to be treated surgically. The area around the wound is removed, in a process known as debridement. Antibiotics may also be prescribed to prevent any secondary infection.
In most cases, infant botulism has no long-term effects. According to the NIH, fewer than 1 percent of infant cases in the U.S. are fatal. About 50 years ago, half of all patients with botulism died, compared to between 3 percent and 5 percent today.
Respiratory failure caused by botulism can result in death.
Patients with severe symptoms may need a breathing machine and sometimes intensive medical and nursing care for several months. Fatigue and shortness of breath may linger for many years.
Other illnesses may develop as a result of the patient's condition, and these are sometimes fatal.
A person who experiences paralysis may recover from botulism with the help of antitoxins, antibodies that can neutralize the toxin, but antitoxins will not cure any paralysis that has already occurred.