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13.1.2 Botulism. What is it?


This article is from the Food Preserving FAQ, by Eric Decker ericnospam@getcomputing.com with numerous contributions by others.

13.1.2 Botulism. What is it?

The word from the FDA, courtesy of Henry Hilbreath, aka souris..

Food and Drug Administration Foodborne Pathogenic
Microorganisms and Natural Toxins 1992

1. Name of the organism: Clostridium botulinum
Clostridium botulinum is an anaerobic, Gram-positive, spore-forming
rod that produces a potent neurotoxin. The spores are heat-resistant and can
survive in foods that are incorrectly or minimally processed. Seven types (A,
B, C, D, E, F and G) of botulism are recognized, based on the antigenic
specificity of the toxin produced by each strain. Types A, B, E and F cause
human botulism. Types C and D cause most cases of botulism in animals.
Animals most commonly affected are wild fowl and poultry, cattle, horses and
some species of fish. Although type G has been isolated from soil in
Argentina, no outbreaks involving it have been recognized.

Foodborne botulism (as distinct from wound botulism and infant
botulism) is a severe type of food poisoning caused by the ingestion of foods
containing the potent neurotoxin formed during growth of the organism. The
toxin is heat labile and can be destroyed if heated at 80C for 10 minutes or
longer. The incidence of the disease is low, but the disease is of
considerable concern because of its high mortality rate if not treated
immediately and properly. Most of the 10 to 30 outbreaks that are reported
annually in the United States are associated with inadequately processed,
home-canned foods, but occasionally commercially produced foods have been
involved in outbreaks. Sausages, meat products, canned vegetables and seafood
products have been the most frequent vehicles for human botulism.

The organism and its spores are widely distributed in nature. They
occur in both cultivated and forest soils, bottom sediments of streams,
lakes, and coastal waters, and in the intestinal tracts of fish and mammals,
and in the gills and viscera of crabs and other shellfish.

2. Name of the Disease:
Four types of botulism are recognized: foodborne, infant, wound, and a
form of botulism whose classification is as yet undetermined. Certain foods
have been reported as sources of spores in cases of infant botulism and the
undetermined category; wound botulism is not related to foods.

Foodborne botulism is the name of the disease (actually a food-borne
intoxication) caused by the consumption of foods containing the neurotoxin
produced by C. botulinum.

Infant botulism, first recognized in 1976, affects infants under 12
months of age. This type of botulism is thought to be caused by the ingestion
of C. botulinum spores which colonize and produce toxin in the intestinal
tract of infants (toxico infectious botulism). Honey is the only implicated
food source for C. botulinum spores. The number of confirmed infant botulism
cases has increased significantly as a result of greater awareness by health
officials since its recognition in 1976. It is now internationally
recognized, with cases being reported in more countries.

Wound botulism is the rarest form of botulism. The illness results
when C. botulinum by itself or with other microorganisms infects a wound and
produces toxins which reach other parts of the body via the blood stream.
Foods are not involved in this type of botulism.

Undetermined category of botulism involves adult cases in which a specific food
or wound source cannot be identified. It has been suggested
that some cases of botulism assigned to this category might result from
intestinal colonization in adults, with in vivo production of toxin. Reports
in the medical literature suggest the existence of a form of botulism similar
to infant botulism, but occurring in adults. In these cases, the
patients had surgical alterations of the gastrointestinal tract and/or
antibiotic therapy. It is proposed that these procedures may have altered the
normal gut flora and allowed C. botulinum to colonize the intestinal tract.

3. Nature of the Disease:
Infective dose - a very small amount (a few nanograms) of toxin can
cause illness. Onset of symptoms in foodborne botulism is usually 18 to 36 hours
after ingestion of the food containing the toxin, although cases have varied
from 4 hours to 8 days. Early signs of intoxication consist of marked
lassitude, weakness and vertigo, usually followed by double vision and
progressive difficulty in speaking and swallowing. Difficulty in breathing,
weakness of other muscles, abdominal distention, and constipation may also be
common symptoms.

Clinical symptoms of infant botulism consist of constipation that
occurs after a period of normal development. This is followed by poor
feeding, lethargy, weakness, pooled oral secretions, and wail or altered
cry. Loss of head control is striking. Recommended treatment is primarily
supportive care. Antimicrobial therapy is not recommended. Infant botulism
is diagnosed by demonstrating botulinal toxins and the organism in the
infants' stools.

4. Diagnosis of Human Illness:
Although botulism can be diagnosed by clinical symptoms alone,
differentiation from other diseases may be difficult. The most direct and
effective way to confirm the clinical diagnosis of botulism in the laboratory
is to demonstrate the presence of toxin in the serum or feces of the patient
or in the food which the patient consumed. Currently, the most sensitive
and widely used method for detecting toxin is the mouse neutralization test.
This test takes 48 hours. Culturing of specimens takes 5-7 days.

5. Associated Foods:
The types of foods involved in botulism vary according to food
preservation and eating habits in different regions. Any food that is
conducive to outgrowth and toxin production, that when processed allows
spore survival, and is not subsequently heated before consumption can be
associated with botulism. Almost any type of food that is not very acidic
(pH above 4.6) can support growth and toxin production by C. botulinum.
Botulinal toxin has been demonstrated in a considerable variety of foods,
such as canned corn, peppers, green beans, soups, beets, asparagus, mushrooms,
ripe olives, spinach, tuna fish, chicken and chicken livers and liver pate,
and luncheon meats, ham, sausage, stuffed eggplant, lobster, and smoked and
salted fish.

6. Frequency:
The incidence of the disease is low, but the mortality rate is high
if not treated immediately and properly. There are generally between 10 to
30 outbreaks a year in the United States. Some cases of botulism may go
undiagnosed because symptoms are transient or mild, or misdiagnosed as
Guillain-Barre syndrome.

7. The Usual Course of Disease and Complications:
Botulinum toxin causes flaccid paralysis by blocking motor nerve
terminals at the myoneural junction. The flaccid paralysis progresses
symmetrically downward, usually starting with the eyes and face, to the throat,
chest and extremities. When the diaphragm and chest muscles become fully
involved, respiration is inhibited and death from asphyxia results.
Recommended treatment for foodborne botulism includes early administration of
botulinal antitoxin (available from CDC) and intensive supportive care
mechanical breathing assistance).

8. Target Populations:
All people are believed to be susceptible to the foodborne intoxication.

9. Food Analysis
Since botulism is foodborne and results from ingestion of the toxin of
C. botulinum, determination of the source of an outbreak is based on
detection and identification of toxin in the food involved. The most widely
accepted method is the injection of extracts of the food into passively
immunized mice (mouse neutralization test). The test takes 48 hours. This
analysis is followed by culturing all suspect food in an enrichment medium
for the detection and isolation of the causative organism. This test takes
7 days.

10. Recent Outbreaks:

In the last 10 years, two separate outbreaks of botulism have occurred
involving commercially canned salmon. Restaurant foods such as sauteed
onions, chopped bottled garlic, potato salad made from baked potatoes and
baked potatoes themselves have been responsible for a number of outbreaks.
[Root crops, pattern?--LEB] Also, smoked fish, both hot and cold-smoke
(e.g., Kapchunka) have caused outbreaks of type E botulism.
In October and November, 1987, 8 cases of type E botulism occurred, 2
in New York City and 6 in Israel. All 8 patients had consumed Kapchunka, an
uneviscerated, dry-salted, air-dried, whole whitefish. The product was made
in New York City and some of it was transported by individuals to Israel.
All 8 patients with botulism developed symptoms within 36 hours of consuming
the Kapchunka. One female died, 2 required breathing assistance, 3 were
treated therapeutically with antitoxin, and 3 recovered spontaneously. The
Kapchunka involved in this outbreak contained high levels of type E botulinal
toxin despite salt levels that exceeded those sufficient to inhibit C.
botulinum type E outgrowth. One possible explanation was that the fish
contained low salt levels when air-dried at room temperature, became toxic,
and then were re-brined. Regulations were published to prohibit the
processing, distribution and sale of Kapchunka and Kapchunka-type products
in the United States.

Most recently, a bottled chopped garlic-in-oil mix was responsible
for three cases of botulism in Kingston, N.Y. Two men and a woman were
hospitalized with botulism after consuming a chopped garlic-in-oil mix that
had been used in a spread for garlic bread. The bottled chopped garlic relied
solely on refrigeration to ensure safety and did not contain any additional
antibotulinal additives or barriers. The FDA has ordered companies to stop
making the product and to withdraw from the market any garlic-in-oil mix
which does not include microbial inhibitors or acidifying agents and does
not require refrigeration for safety. Since botulism is a life-threatening
disease, FDA always initiates a Class I recall.

The botulism outbreak associated with salted fish mentioned above is reported
in greater detail in Mortality and Morbidity Weekly Report (MMWR) 36(49):
1987 Dec 18. A botulism type B outbreak in Italy associated with eggplant in
oil is reported in MMWR 44(2):1995 Jan 20.

An incident of foodborne botulism in Oklahoma is reported in MMWR 44(11):
1995 Mar 24. [Traced to a 3 day-old pot of beef stew left sitting at room
temperature on the stove burner. Yikes!--LEB

In the late 1900's a MD in northern Canada was found guilty in the death of a
young woman. Autopsy showed she died of botulism. The doctor misdiagnosed the
problem and the patient died a couple of days later. Botulism is sneaky, deadly
and not seem much anymore. Be VERY careful in your canning as the doctor
treating you or your family just might make an error based on a lack of
experience with said toxin. - ED.


Botulism poisoning is due to ingesting toxin(s) produced by the anaerobic
bacterium _Clostridium botulinum_. There are seven isoforms of botulism
toxins (Types A-G). Botulism toxins are colorless, odorless, and
tasteless, but highly potent neurotoxins. To explain the physiology of
the toxin a little farther, you might remember that nerve impulses are
electrical signals (charge gradient that runs along the length of an axon),
while the connection between muscles and nerves are mediated by chemical
signals. The end of an axon releases synaptic vesicles filled with
chemical neurotransmitters. These synaptic vesicles travel a short
distance to the synaptic plate on muscle cells, then bind and release
neurotransmitters. Current research indicates that botulism toxins bind
and cleave several proteins on the outside of synaptic vesicles. Those
vesicles cannot then bind to the next synaptic plate and unload the
neurotransmitter. Thus, the connection between nerve and muscle
impulses is cut biochemically, at the place where the chemical signal is
delivered. Muscle control is lost, especially fine facial muscles.

Symptoms of botulism toxin poisoning usually occur within 12-36 hrs after
ingestion. They include muscle weakness, slurred speech, blurred vision
(all fine muscle movements); followed by an inability to hold up the head.
Death occurs by respiratory failure.

If you recognize these symptoms after trying a canned food, call 911
immediately. Whoever is able should reclose the jar, wrap well, put in
a ziploc bag, close, bring to the hospital. Wash your hands carefully
after this procedure! [Other food poisoning symptoms are listed below in
question IV.5--LEB

Treatment for botulism is straightforward. Often the antisera to the
toxin is given, and the victim is placed on a respirator. Survival
depends on the amount of toxin ingested, and how quickly the victim got
treatment. Recovery is quite slow, taking months. The United States
case/fatality rate has dropped in recent years, but the *number of cases*
in the US increases slightly in proportion to the popularity of home
canning. Interesting cultural comparison: botulism cases in Europe tend
to come from cured meats, from Japan from salted fish, from the US from
canned vegetables.


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