Botulism is a rare but serious paralytic illness
caused by a nerve toxin that is produced by the bacterium Clostridium botulinum.
There are three main kinds of botulism.
- Foodborne botulism is caused by
eating foods that contain the botulism toxin.
- Wound botulism is caused by toxin
produced from a wound infected with Clostridium botulinum.
- Infant botulism is caused by consuming
the spores of the botulinum bacteria, which then grow in the intestines and release
toxin.
All forms of botulism can be fatal and are considered
medical emergencies.
1. How common is botulism?
In the United States, an average of 110 cases of
botulism are reported each year. Of these, approximately 25% are foodborne, 72%
are infant botulism, and the rest are wound botulism. Outbreaks of foodborne botulism
involving two or more persons occur most years and usually caused by eating contaminated
home- canned foods. The number of cases of foodborne and infant botulism has changed
little in recent years, but wound botulism has increased because of the use of
black-tar heroin, especially in California.
2. What are the symptoms of botulism?
The classic symptoms of botulism include double vision,
blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth,
and muscle weakness. Infants with botulism appear lethargic, feed poorly, are constipated,
and have a weak cry and poor muscle tone. These are all symptoms of the muscle paralysis
caused by the bacterial toxin. If untreated, these symptoms may progress to cause
paralysis of the arms, legs, trunk, and respiratory muscles. In foodborne botulism,
symptoms generally begin 18-36 hours after eating a contaminated food, but they
can occur as early as 6 hours or as late as 10 days.
3. How can botulism be treated?
The respiratory failure and paralysis that occur
with severe botulism may require a patient to be on a breathing machine (ventilator)
for weeks, plus intensive medical and nursing care. After several weeks, the paralysis
slowly improves. If diagnosed early, foodborne and wound botulism can be treated
with an antitoxin which blocks the action of toxin circulating in the blood. This
can prevent patients from worsening, but recovery still takes many weeks. Physicians
may try to remove contaminated food still in the gut by inducing vomiting or by
using enemas. Wounds should be treated, usually surgically, to remove the source
of the toxin-producing bacteria. Good supportive care in a hospital is the mainstay
of therapy for all forms of botulism. Currently, antitoxin is not routinely given
for treatment of infant botulism.
4. How can botulism be prevented?
Botulism can be prevented. Foodborne botulism has
often been from home-canned foods with low acid content, such as asparagus, green
beans, beets and corn. Persons who do home canning should follow strict hygienic
procedures to reduce contamination of foods. Oils infused with garlic or herbs should
be refrigerated. Potatoes which have been baked while wrapped in aluminum foil should
be kept hot until served or refrigerated. Because the botulism toxin is destroyed
by high temperatures, persons who eat home-canned foods should consider boiling
the food for 10 minutes before eating it to ensure safety. Instructions on safe
home canning can be obtained from county extension services or from the US Department
of Agriculture. Because honey can contain spores of Clostridium
botulinum and this has been a source of infection for infants, children
less than 12 months old should not be fed honey. Honey is safe for persons 1 year
of age and older. Wound botulism can be prevented by promptly seeking medical care
for infected wounds and by not using injectable street drugs.
5. How long after an aerosolized release
of botulinum toxin would symptoms begin?
Symptoms would begin 12 to 72 hours after exposure.
6. How long would aerosolized botulism contaminate
a site?
Persistence of aerosolized botulinum toxin at a site
of deliberate release is determined by atmospheric conditions and particle size
of the aerosol. Extremes of temperature and humidity will degrade the toxin, while
fine aerosols will eventually dissipate into the atmosphere. Depending on the weather,
aerosolized toxin has been estimated to decay at between less than 1% to 4% per
minute. At a decay rate of 1% per minute, substantial inactivation of toxin occurs
by two days after aerosolization.
7. How should I get rid of the botulism toxin?
After exposure to botulinum toxin, clothing and skin
should be washed with soap and water. Contaminated objects or surfaces should be
cleaned with 0.1% hypochlorite bleach solution if they cannot be avoided for the
hours to days required for natural degradation.
8. What infection control practices should
be followed when caring for someone with the botulinum toxin?
Medical personnel caring for patients with suspect
botulism should use standard precautions. Patients with suspected botulism do not
need to be isolated, but those with flaccid paralysis from suspected meningitis
require droplet precautions.
CDC Website on Botulism