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Botulism
What is it and how can
we prevent it?
Medically reviewed by Jill Seladi-Schulman, Ph.D.
Written by Stephanie Brunner
Botulism is a serious
illness caused by the botulinum toxin. The toxin causes paralysis.
Paralysis starts in
the face and spreads to the limbs. If it reaches the breathing muscles,
respiratory failure can result.
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.
Symptoms
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:
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 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.
Latrogenic
botulism
can occur through an overdose of botulism toxin, or botox. Cases of this form
of botulism have developed following therapeutic administration of botox.
Prevention
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.
Food sources
The most commonly
tainted foods are:
home-canned vegetables
cured pork and ham
raw or smoked fish
honey
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
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
electromyography
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.
Treatment
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.
Complications
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.
Jill
Seladi-Schulman,
Ph.D.Dr. Jill Seladi-Schulman is a manager for clinical trials. She specializes
in microbiology and infectious disease. In 2014, she graduated from Emory
University with her doctorate in microbiology and molecular genetics. Dr.
Seladi-Schulman has publications in peer-reviewed journals and has had her work
featured on the cover of the Journal of Virology. Dr. Seladi-Schulman is an
avid reader with interests in medical writing and communcation. She also enjoys
writing fiction for fun.
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