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e-Medical
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The
main types & causes of food poisoning:
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Staphylococcus:
This universal bacterium causes many skin infections.
People who have staphylococcus infections and handle
food can transfer these bacteria to others. The
bacteria then breed and produce an enterotoxin
(stomach poison), which causes a temporary attack of
diarrhea and stomachache. The types of foods most
likely to carry Staph toxins are custards, cream pies,
milk, fish and processed meat.
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Mushrooms
and toadstools: Dozens of species can cause muscarine
poisoning. These poisons attack the central nervous
system, causing partial or complete paralysis in
severe cases. The mushroom Amanita phalloides and its
cousins are the deadliest of all food poisons. Even
with modern medical treatment, about 50% of cases
result in death after a few days. However, this is a
very rare occurrence.
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Fish:
Some fish, like the puffer fish, are naturally
poisonous. A poison similar to that naturally found in
the puffer fish can also occur in many edible
Caribbean and Pacific species. It's called ciguatera
poison, and it's produced by a tiny sea parasite
called a dinoflagellate, also known as "red
tide". The poison attacks the nervous system, and
can be fatal. The other kind of fish poison, called
scromboid poison, is concentrated histamine produced
by the mass death of bacteria in the fish after it was
caught. Histamine is the chemical that causes the
airways to become inflamed and blocked in asthmatics.
It has similar effects on other organs.
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Shellfish:
Clams, mussels, oysters and scallops are particularly
prone to ingesting red tide, and therefore may contain
ciguatera poison. In North America the red tide
arrives between June and October. Shellfish eaten
during those months are potentially dangerous.
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Insecticides:
There are many types of poisons found in insecticides,
including benzene-based poisons like DDT that have
effects similar to gasoline, but the most dangerous
types are the organophosphates, which are basically
nerve gas for insects, but the chemicals involved are
themselves dangerous.
These
represent a tiny fraction of the possible causes of food
poisoning. Example of other types of food poisoning
include:
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Wild
nuts, leaves, flowers and berries, underripe tubers,
botulism, cadmium from containers, lead or arsenic
from fertilizers, and acids and lead from pottery.
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Gastro-Intestinal
infections caused by eating contaminated food:
shigellosis, salmonella, infant botulism, some types
of E. coli and Clostridium perfringens are among the
foodborne diseases.
Treatment of
Food Poisoning: Click
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Most travelers are
prone to food poisoning and should be knowledgeable on the facts
and possible corrective action as to possibly prevent and treat
this acute illness. Please use the following information to assist
you and your crew on preventing food poisoning.
The human body, and
especially the gastrointestinal tract, is home to hundreds of
different types of bacteria. All of these bacteria produce various
chemicals as they go about their business of reproducing and
turning sugars to energy. Some of these chemicals are harmless and
go unnoticed. Others actually help us digest food. Some chemicals,
however, can damage or inflame our internal organs. Bacteria that
produce such chemicals are the disease-causing (pathogenic)
bacteria. In infectious diseases, it's actually these toxic
chemicals and not the bacteria themselves that make you ill.
Most cases of food
poisoning occur when people eat food containing bacterial toxins.
Contrary to popular belief, the bacteria themselves are usually
long dead or gone when this happens. If they were still there, it
wouldn't technically be food poisoning, but a foodborne
gastrointestinal infection. Salmonella and bacterial
gastroenteritis are examples of such infections.
The other kind of
food poisoning occurs when inorganic poisons or non-bacterial
organic poisons (such as poisonous toadstools) find their way into
people's stomachs. Both types are covered here, but other
illnesses caused by bacterial poisons, such as botulism, are
covered in their own sections.
Symptoms
and Complications
Many of the poisons
listed here attack the central nervous system and cause symptoms
typical of nerve poisons. Eating a red-tide-contaminated
shellfish, for example, will produce weakness or paralysis around
the mouth in a few minutes, which slowly spreads to the rest of
the body. Other neurologic signs of ciguatera poisoning include
face pain, headache, itching and odd sensations of alternating hot
and cold.
Symptoms of
mushroom poisoning also have a nervous element. Shrunken eye
pupils, tears, salivation or frothing at the mouth, sweating,
vertigo, confusion, coma, and sometimes convulsions appear within
two hours of eating a poisonous mushroom. Insecticides based on
organophosphates cause very similar symptoms. They're likely to be
milder, since it is extremely rare for really large doses of
insecticide to be eaten accidentally.
Scromboid
(histamine) fish poisoning causes the symptoms of excess
histamine. Flushing, skin rash, and pain from overstimulation of
affected organs, namely the stomach and intestines, appear within
a few minutes. Fortunately, the histamine is in the
gastrointestinal tract and not the respiratory tract, where it
could cause a serious, sometimes fatal, asthma attack. Fish
containing toxic levels of histamine, unlike fish contaminated by
red tide (ciguatera) poison, often taste unusually bitter or
spicy.
Almost all forms of
poisoning also produce nausea/vomiting, abdominal cramps and
diarrhea. This is the result of the body trying to get rid of the
offending substance. This is what most people think of when they
think of food poisoning. Staphylococcus enterotoxin poisoning
produces only these symptoms, which usually appear 2-8 hours after
eating the poison. The whole episode tends to last much less than
a day.
Diagnosis
Getting the right
diagnosis early can be vital in poisoning. Some poisons have
specific antitoxins that will cure them completely, but you can't
take the antitoxin if you don't know what the toxin is.
When people are
poisoned in groups, it's usually easier to pinpoint the cause.
Often, there's only one food that all sick the sick people ate,
and this can be studied to find the nature of the poison. Such
details may be the only clue, because you can't easily test people
for poisons the way you test them for infection.
Treatment
and Prevention
Some poisons have
specific drugs that effectively counteract their toxicity. More
often, a drug is given that's known to be effective against a
certain type of poisoning. Mushroom (muscarine) poisoning, for
example, can be countered with atropine, which is the drug that
soldiers carry in case of nerve gas attack.
Whether or not
there's an antidote, the most important part of treatment is often
evacuating the poison from the body. Emesis is the deliberate
induction of vomiting. It's usually done with ipecac syrup, but
soapy water works in a crisis. The earlier it's done, the better.
You might consider doing this yourself if you're confronted with
food poisoning far from a hospital. Only induce vomiting if you
see clear signs of dangerous poisoning (i.e., not just Staph), and
if the victim is fully conscious and not convulsing.
At hospital, the
efforts to clear the poison will continue. The techniques used are
gastric lavage, in which a tube is inserted by mouth into the
stomach and the stomach is pumped clean with liquids, Charcoal,
which when swallowed absorbs poisons faster than the lining of the
stomach does, may also be administered. People suffering from
nerve poisons, like mushrooms, botulism, and ciguatera, also need
to be watched for signs of respiratory failure and given
artificial breathing assistance if necessary. Kidney dialysis and
replacement of lost fluids and nutrients may also be required.
You can't always
prevent food poisoning. Ciguatera poison, for example, is
tasteless and can't be destroyed by cooking or even radiation. We
have yet to invent a process that could find and neutralize the
poison without destroying the fish or shellfish, so if you want to
be truly safe you'll have to stick to Atlantic fish.
Some foods are more
prone than others to infection: Green vegetables and carrots, for
example, are less likely to be toxic than fish or meat. On the
other hand, the last sizable outbreak of salmonella in Canada was
caused by cantaloupe.
The following
advice won't protect you against all types of food poisoning, but
you'll know you did your best:
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Wash your hands
thoroughly before and during cooking.
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Try to keep
different food and food types separate.
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If you're
keeping leftovers, refrigerate them immediately.
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When reheating
food, cook it thoroughly enough that the core reaches at least
75oC or 168oF. This won't remove all poisons or even kill all
bacteria, but it helps against some common kinds.
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Pay special
attention to thoroughly cooking meat and poultry.
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If you have a
skin infection like impetigo (staphylococcus), don't prepare
food for others while spots or sores are visible.
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