484 Chapter 28
and consumers ’ growing awareness of this
disease, the outbreaks of botulism have been
decreasing in recent years. Because of botu-
lism ’ s high fatality rate, the general public
usually panics at reports of botulism.
The organism is a Gram - positive, anaero-
bic, spore - forming rod that can grow at
temperatures from 3.3 ° C to as high as 50 ° C.
Most strains will grow well at 30 ° C with
optimum temperature at 37 ° C. To control the
growth of the organism, the pH must be
below 4.6, salt content needs to be 10% or
more, and a water activity less than 0.94. The
vegetative cells of this organism are easily
killed by heat, but the spores formed by this
cell are far more resistant to heat, cold, acid
and basic chemicals, radiation, and other
forms of preservation methods. Thus, control
of botulism is geared to the destruction of the
spores. Time and temperature combinations
for canning all foods are designed to kill the
most heat - resistant spores of Clostridium
botulinum.
The spores formed by this organism can
reside in soil, water, and the environment,
and can be transmitted to foods. Foods
involved in botulism cases usually are
improperly home - canned, medium - or low -
acid foods. Information since 1899 indicates
that about 70% of the outbreaks can be traced
to improperly processed, home - canned foods
and 9% to commercially processed food,
with the other outbreaks from unknown
sources.
Symptoms develop from 18 to 96 hours
after the ingestion of toxic foods. They
include vomiting, nausea, fatigue, dizziness,
vertigo, headache, dryness of mouth, muscle
paralysis, and death by asphyxiation. Since
the toxin affects peripheral nerves, the patient
is alert until the moment of death. There are
several types of botulin toxins (types A, B,
C 1 , C 2 , D, E, F, and G). These are large
molecular weight proteins (about 1 million
dalton). The important toxins affecting
human beings are toxins A, B, E, and rarely
F. These are among the most toxic materialsLong - term chemical intoxication is also
possible from the ingestion of small amounts
of toxins in food or water over many years,
which eventually causes the person to become
ill.
There are many naturally occurring chem-
ical toxins in foods as well as unintentionally
added chemical toxins, such as pesticides and
chemical residuals from packaging materials
and the environment.
Bacterial and
Microbial Intoxication
This form of intoxication is the result of sus-
ceptible persons consuming microorganisms
in food, which then form toxic substances in
the gut. The effects can be rapid (within
hours), but usually the process is longer than
chemical intoxication (such as from cyanide
or arsenic).
Clostridium botulinum
The fi rst recorded outbreak of botulism was
in 1793, involving sausages (botulus) in
Germany. Since that time, many outbreaks
all over the world have been reported. From
1899 to 1977, there were 766 outbreaks,
involving 1,961 cases and 999 deaths. In the
United States between 1971 and 1985, three
outbreaks were recorded with 485 cases and
55 deaths. In 1990, there were 12 outbreaks,
22 cases, and 5 deaths, and in 1994 there
were 42 cases of food - borne botulism, 86
cases of infant botulism, and 11 cases of
wound botulism with no fatality. In 2002 , the
CDC (U.S. Centers for Disease and Control,
Atlanta, Georgia) reported that there were 13
outbreaks, 56 cases, and 1 death. (This infor-
mation was gathered from 1993 to 1997.)
Up - dated information, organized according
to etiology, about the number of reported
food - borne diseases, outbreaks, cases, and
deaths from all reportable food - borne disease
in the United States can be obtained at the
CDC ’ s website. Due to food professionals ’