Bacteria, Epidemiology, Infectious Diseases, Microbiology, rare infectious disease

Botulism: Symptoms, Diagnosis, Treatment, History, and Epidemiology

Author Chandana Balasubramanian , 20-Dec-2023

Botulism is a severe, potentially fatal disease caused by the ingestion or absorption of a deadly toxin produced by the bacteria Clostridium botulinum (C. botulinum). The disease is so dangerous that even the tiniest bit of the toxin can kill a person, and one pint of it can wipe out humanity. 


Although it’s rare, botulism is considered a medical emergency due to its rapid progression and severe complications, which can include paralysis and respiratory failure. 


This article explores botulism’s history, epidemiology, symptoms, treatment, prevention, and role as a bioterrorism agent.



Key milestones in the history of Botulism are:

  • Discovery of Clostridium botulinum (1895): The bacteria C.botulinum was first identified and isolated by Belgian bacteriologist Emile Pierre van Ermengem in 1895. He discovered the bacterium while investigating an outbreak of food poisoning in Belgium when people died after eating ham. Initially, the bacteria was called Bacillus botulinus (botulus is Latin for sausage). 
  • First botulism antitoxin developed (1970s): The first antitoxin against botulism was created in the 1970s by the US Army. 
  • Therapeutic uses of botulism toxin (1970s and 1980s): While botulinum toxin is highly toxic, researchers found therapeutic uses in the 1970s and 1980s. Dr. Alan B. Scott began exploring the use of botulinum toxin in the treatment of strabismus (crossed eyes). This research laid the foundation for the development of Botox, a purified and diluted form of botulinum toxin, for therapeutic and cosmetic purposes.
  • Botox approved for medical use (1989): Botox, a mild form of the botulism toxin, was approved by the FDA in 1989 to treat medical conditions like crossed eyes (strabismus) and uncontrollable blinking (blepharospasm). 
  • Botox approved by US FDA for cosmetic procedures (2002): Botox, the well-known anti-wrinkle cosmetic treatment, is a purified and dilute form of the botulism toxin. It was first approved for cosmetic procedures in 2002. 



In Europe, the countries with the largest number of botulism outbreaks are Italy and France, according to the ECDC (European Center for Disease Control).

Notable botulism outbreaks include:

  • 1919-1920: Botulism killed 18 people in the United States in New York, Michigan, and Ohio, along with a few other states.
  • 1922: The UK recorded its first case of botulism poisoning with eight deaths among people who ate duck paste at the Loch Maree Hotel in Scotland. 
  • 1977: Home-canned jalapenos from a Mexican restaurant resulted in 35 botulism cases in the United States.
  • 1994: Largest botulism outbreak in the United States, with 30 people infected and four needing ventilators for respiratory support. The culprit was a potato-based dip at a Greek restaurant. 
  • 2008-2018: France reported 82 outbreaks with 159 cases of foodborne botulism from improperly canned or preserved foods.
  • 2023: Authorities in France identified 15 cases of suspected botulism and one death during the Rugby World Cup in Bordeaux. The potential cause of poisoning is home-canned sardines.


How is it spread?

Botulism cannot spread from person to person. Instead, it typically occurs when a person eats food or substances contaminated with the botulinum toxin.

The main ways in which botulism can be contracted include:

  • Foodborne botulism: The most common source of botulism is improperly processed or preserved foods. The bacteria can grow and produce the toxin in low oxygen (anaerobic) environments, like improperly canned or vacuum-packed foods. Home-canned or homemade foods, as well as certain traditional foods and herbal-infused oils, pose a higher risk if not prepared and stored correctly.
  • Wound botulism: In rare cases, the bacteria can infect a wound, and the toxin can be produced locally. This can happen when wounds are contaminated with soil or other materials containing the bacteria. Drug users who inject drugs intravenously are at a higher risk of wound botulism.
  • Infant botulism: Infants can develop botulism when they ingest spores of the C.botulinum bacteria. This bacteria then grows and produces toxins in the baby’s immature digestive system. Babies aged 2-8 months may be at a higher risk of getting a botulism infection. 


Honey is a known source of infant botulism, and it is recommended that children under one year of age should not be given honey.


Biology of the disease

C.botulinum is deadly because it can cause irreversible nerve damage, which can be fatal. 

Once the botulism toxin enters the body (either through food or a wound), it is absorbed into the bloodstream. The toxin targets the nervous system, particularly the junctions where nerves interact with muscles. 

Usually, nerve cells release a chemical called acetylcholine at these neuromuscular junctions that stimulate muscle contractions. However, when the botulism toxin attacks, it blocks the release of acetylcholine, which leads to muscle paralysis. 

The severity of the disease is based on how many junctions are affected, whether key muscle groups are affected, and how much toxin is in circulation. For example, if muscles involved in breathing are affected, it can lead to respiratory failure.



It can take anywhere from a few hours to a few days for botulism symptoms to appear (incubation period). 

  • Foodborne botulism symptoms can appear within 12-36 hours of ingesting contaminated food.
  • Infant botulism symptoms can take longer since it takes time for the bacteria to grow in the baby’s body. It can range from a few days to a few weeks.


Botulism symptoms include:

  • Muscle weakness: Botulinum toxin affects the nerves that control muscles, leading to weakness. This weakness usually starts in the muscles of the head and face and then progresses downward.
  • Difficulty swallowing: Weakness in the muscles responsible for swallowing can lead to difficulty swallowing (dysphagia), which may contribute to drooling.
  • Dry mouth and throat: Reduced production of saliva can result in a dry mouth and throat.
  • Blurred or double vision: Botulism can affect the nerves controlling eye muscles, leading to blurred or double vision.
  • Slurred speech: Weakness in the muscles involved in speech can cause slurred or difficult-to-understand speech.
  • Breathing difficulties: In severe cases, botulism can lead to paralysis of respiratory muscles, causing breathing difficulties and respiratory failure.
  • Paralysis: As the toxin affects more muscles, generalized paralysis can occur, potentially leading to respiratory failure and death.

It is important to contact your healthcare provider immediately if you or a loved one experiences any of the symptoms of botulism or if you suspect botulism toxin poisoning.



Diagnosing botulism can be challenging because it is rare, and botulism symptoms often mimic other neurological disorders. 

However, when certain signs suddenly appear, they may raise suspicion of botulism. These include: 

  • Double vision
  • Drooping eyelids
  • Difficulty swallowing and 
  • Muscle weakness.


Botulism is diagnosed through laboratory tests. Most definitive tests include testing an infected individual’s blood, stool, or vomit.



Botulism is treated by administering an antitoxin, which neutralizes the C.botulinum toxin circulating in the bloodstream. While this antitoxin cannot reverse any nerve damage that has already occurred, it can prevent the toxin from causing more irreversible harm.

Additionally, supportive care is a critical part of treating botulism. This includes monitoring and supporting the patient’s breathing and other vital functions, such as heart rate and blood pressure. In severe cases, patients may require mechanical ventilation.



Preventing foodborne botulism

Preventing botulism is primarily about food safety. 

It’s essential to follow strict hygienic practices when preparing and storing food, especially canned and fermented foods, which provide an ideal environment for the growth of Clostridium botulinum.

Here are some ways to sterilize food containers and take precautions when preserving or fermenting foods:

  • Take extra care with low-acid foods
  • Follow safe canning practices as prescribed by the US Department of Agriculture
  • Refrigerate homemade oils
  • Refrigerate canned or pickled goods after they are opened.


Preventing wound botulism

Keep wounds clean. If you suspect or notice an infection, it’s essential to get medical attention right away. Look for signs of redness, painful swelling, warmth, pus or other fluids draining from the wound, and fever. 

Preventing infant botulism

It is extremely difficult to prevent infant botulism because the bacteria can live in the soil and dust, and even if you clean your home often, it is not possible to eliminate the toxin entirely. 

However, parents can avoid giving infants under one year of age honey or honey-derived products.

Is there a vaccine for botulism?

There is no vaccine against botulism, and the antitoxins are only helpful in treating the infection and not as preventive medicine. 


Understanding the Role of Botulism in Bioterrorism

The potential use of the botulism toxin as a biological weapon is a serious concern due to its high potency and easy production. In fact, the botulism toxin is one of the most lethal substances known to humans.

The botulism toxin can be dispersed in the air, contaminating food or water, or used in targeted attacks. The symptoms of botulism caused by bioterrorism would be the same as those caused by naturally occurring botulism, making it challenging to detect such an attack promptly.


Protecting Against the Botulism Toxin – A Public Health Perspective

From a public health perspective, protecting against the botulism toxin involves surveillance, preparedness, and response.

Regular surveillance of foodborne illnesses and unusual clusters of neurological symptoms can help detect a potential botulism outbreak or bioterrorism event.

Preparedness involves having protocols in place for rapid diagnosis and treatment of botulism, including the availability of antitoxin.

Finally, an effective response to a botulism event, natural or intentional, requires efficient communication and coordination among various healthcare and public health entities.



While botulism is rare, its potential use as a bioterrorism agent underscores the importance of awareness and preparedness. The infection is caused by the bacteria Clostridium botulinum (C. botulinum), which can cause widespread disease and devastation. There is no vaccine, and the best prevention is vigilance.


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Chandana Balasubramanian

Chandana Balasubramanian is an experienced healthcare executive who writes on the intersection of healthcare and technology. She is the President of Global Insight Advisory Network, and has a Masters degree in Biomedical Engineering from the University of Wisconsin-Madison, USA.

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