Botulism: What is it and how can we prevent it?

Botulism is a severe illness caused by the toxin botulinum. The toxin causes paralysis. Paralysis occurs in the face and extends to the limbs. If it enters the breathing muscles, it can result in a respiratory failure.

The toxin is formed by a kind of bacterium called Clostridium botulinum (C. botulinum).

Eventually all forms of botulism lead to paralysis, so every case of botulism is treated as a medical emergency.

It was always fatal in the past but the outlook has been greatly improved by antitoxins.

In 2015, the US saw the largest botulism outbreak in 40 years. It resulted from unsuitable home-canned potatoes shared at a potluck meal.

Symptoms

Botulism is a serious disease caused by the botulinum toxin.
Botulism is a serious disease caused by the botulinum toxin.

The symptoms and the signs depend on the type of botulism.

Signs and symptoms of food-borne botulism include nausea, vomiting and diarrhea accompanied by constipation and abdominal distention. There may be fatigue and respiratory problems. Symptoms usually occur between 18 and 36 hours after the infected food is eaten, but this can range from 3 hours to 8 days.

In wound botulism, the first symptoms are experienced by the nerves which connect the brain to the spine known as the cranial nerves. This then distributes to the rest of the body. The incubation period is between 4 days and 2 weeks.

Neurological signs and symptoms of adult, foodborne, and wound botulism are the same, although it can take longer to show the symptoms of wound botulism ones.

The patient may have double or blurred vision, eyelids can drop, facial weakness, dry mouth, dysphagia, or swallowing difficulties, and slurring of speech. Muscles will become weak.

Paralysis is then set in. The patient’s breathing muscles will gradually become paralyzed without treatment, leading to respiratory failure and death.

During this process the patient remains conscious.

In infant botulism, signs and symptoms may include:

  • constipation
  • 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.

Causes

The botulinum toxin, a poison produced by the Clostridium botulinum (C. botulinum) bacterium, is widespread in soil and is found in untreated water. As a resistant spore it can survive in these environments.

C. Botulinum develops spores that can live in food which is poorly preserved or canned. Here they create a toxin. Even small amounts of the toxin can cause serious poisoning when eaten.

There are various kinds of botulism.

Foodborne botulism is caused by botulinum toxin-containing foods ingested.

Botulism of wounds can occur when the organism reaches an open wound and develops toxins inside the wound. Users of injection drugs are at risk for botulism of this kind.

Infant botulism occurs when the bacteria or their spores are ingested by an infant, and these grow in the gut. Infant botulism in the United States is often caused from consuming honey or corn syrup. Even the bacterium can occur naturally in an infant’s stool.

Adult intestinal colonization is a rare type of botulism that occurs when an adult’s digestive tract is colonised by the bacterium.

Latrogenic botulism can occur through a botulism toxin, or botox, overdose. Cases of this type of botulism formed after botox therapeutic administration.

Prevention

To minimize the risk of wound botulism, it is recommended that people seek immediate medical treatment for any infected wounds and also stop injecting street drugs.

It’s essential to practice good food hygiene to ensure food safety.

The toxin can thrive in improperly canned food.
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 will kill both the bacterium’s vegetative, or non-spore, form and the toxin it generates.

However, though boiling will kill the toxin for 10 minutes, destroying the spore shape requires heating to at least 248 degrees Fahrenheit, or 120 degrees Celsius, under pressure, in an autoclave or pressure cooker for at least 30 minutes.

This is because the spores are extremely resistant to harsh environments, and even after many hours of regular boiling they will remain viable. Extremely high temperatures like those used in commercial canning will destroy the spores.

“Five Keys to Healthy Food” by the World Health Organization (WHO) emphasizes 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 crucial when traveling to countries particularly where access to clean water, hygiene and refrigeration facilities may be restricted.

Botulism can not always be prevented. In house dust the toxin can be present, even after washing. Parents should be informed of any signs of a child being ill, and take early action if possible.

Food sources

Foods most often infected are:

  • home-canned vegetables
  • cured pork and ham
  • raw or smoked fish
  • honey
  • corn syrup

For instance, Alaska home-canned foods and fermented fish and aquatic game may be sources of the toxin.

With a pH of 4.5 or less, botulism does not develop in acidic foods.

Diagnosis

Diagnosis of botulism in infants is confirmed after examining a stool or enema specimen. If the doctor suspects botulism, treatment with an anti-toxin should start immediately, without waiting to return to test results.

A laboratory will confirm botulism.
A laboratory will confirm botulism.

If botulism is indicated by the history of the patient and the physical examination, a doctor may suspect it, but since other conditions have similar symptoms, a test may be required to rule these out. Conditions with severe botulism symptoms include stroke, myasthenia gravis and syndrome of Guillain-Barre.

Diagnostic tests may include:

  • a brain scan
  • cerebrospinal fluid examination
  • electromyography
  • edrophonium chloride test for myasthenia gravis

A conclusive diagnosis may be made if the toxin is found in the food, stomach, vomit, feces or intestinal contents.

In extremely acute cases the toxin in the blood may be identified.

Treatment

Botulism patients would need to be admitted to hospital.

Infants are given Intravenous-Human Botulism Immune Globulin, also known as BIG-V or BabyBIG.

Those with respiratory problems will be on a ventilator, and they may need the ventilator as well as intensive care for weeks or months. Paralysis can improve over time.

Injections of antitoxins will be administered to a patient with suspected botulism immediately, even before diagnostic test results have returned.

If the infection occurs from a wound, surgical treatment must be performed to the wound. This removes the tissue surrounding the wound, in a process known as debridement. You may also prescribe antibiotics to avoid any secondary infection.

Complications

In most cases, there are no long-term effects of child botulism. Less than 1 percent of child cases in the U.S. are fatal according to the NIH. Half of all patients with botulism died around 50 years ago, compared with 3 to 5 percent today.

Respiratory failure caused by botulism can result in death.

For several months, patients with serious symptoms may require a breathing machine and sometimes intensive medical and nursing treatment. Fatigue and shortness of breath will last several years.

As a result of the patient’s disease, other illnesses can develop and these are often fatal.

An individual experiencing paralysis can recover from botulism by using antitoxins, anticorps that can neutralize the toxin, but antitoxins will not cure any paralysis that has already occurred.

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