FOOD BORNE INFECTIONS
AND FOOD POISONING
Raw foods such as meat, fish, milk and vegetables grown on sewage
purchased from the market are likely to be contaminated with harmful
microorganisms. These are generally destroyed during cooking or processing of
the food. Some of the microorganisms may survive due to inadequate heat
processing. Further, some of the foods if consumed in the raw state can cause
food poisoning Recent studies have shown that food grains when stored in humid
atmosphere are infected by pathogenic fungus which can cause serious illness.
Some of the important diseases caused by pathogenic bacteria
contaminating foods are discussed below:
1. Typhoid and
and vegetables grown on sewage are common carriers of typhoid and paratyphoid.
Foods kept exposed for sale are liable to be infected by typhoid and
paratyphoid bacteria as flies can transmit these bacteria from infected
material to exposed foods. The symptoms include vomiting, diarrhoea and fever.
Botulism is usually caused by consuming canned foods contaminated by
botulinum spores. The causative organism is clostridium botulinum and
it produces an endotoxin, which is highly toxic. The exotoxin can be
inactivated by heat The incubation period is 8-36 hours. The onset of the
disease is sudden. The signs and symptoms include disturbed vision, dizziness,
and sometimes headache, abdominal pain and physical exhaustion. The toxin
affects the central nervous system causing paralysis affecting speech and
swallowing. Death from respiratory or cardiac failure occurs after a few days.
3. Clostridium Perfringens Food Poisoning
This is mostly associated with consumption of
defectively processed pre cooked meat product. The causative organism is clostridium
perfringens and the symptoms are abdominal pain and diarrhoea. The
incubation period is 8 - 12 hours.
4. Salmonella Food Poisoning
The causative organism is Salmonella typhosa.
Defectively processed meat, fish and egg and raw vegetables grown on sewage are
mainly involved in transmitting the infection. The symptoms are vomiting,
diarrhoea and fever. The incubation period is 12 - 48 hours and the duration is
for 1 - 7 days.
5. Staphylococcal Food Poisoning
causative organism is staphylococcus aureus. This organism
produces an exotoxin and the poisoning is due to the presence of exotoxin in
the contaminated food. The toxin is heat stable. Pre cooked animal foods are
most commonly involved in this type of poisoning. The symptoms are vomiting,
diarrhoea and abdominal pain. The incubation period is 2 - 6 hours.
Streptococci are the causative agents for sore throat and scarlet fever.
This group causes bacillary dysentry. The symptoms are loose motions
with mucous and blood and abdominal pain. It is caused mainly from consuming
raw milk to which unclean water has been added and cooked food kept exposed.
Flies are the common carriers of this disease, transferring the bacteria from
infected material to food.
This is caused through water polluted with sewage. The viruses however
only multiply in living cells and not in food. The various diseases spread
include hepatitis, cholera and poliomyelitis.
Fungal Contamination of Foods
1. Fusarium and Cladosporium
This is caused due to the consumption of cereals and millets infected
with fusarium and cladosporium.
2. Aspergillus Flavus
This fungus can grow in moist groundnuts, soyabean, cottonseed, legumes
and cereals. It produces toxins called as aflatoxins. These can cause liver
damage and cancer.
The mode of transmission and the effects of some worm infestation is
given in the following list.
WORMS MODE OF
: Infested pork
: Through meat infested with tapeworm
latum : Through sea fish
lumbricoides (round worm) : Through people, food and water
Spiralis : Fine worm transmitted through infested pork, meat and its products
Through food infected with human feces. Generally infects the lower bowel.
Histolytica : Raw vegetables grown on sewage farms
Occuring in Some Foods
Some foods contains toxic substances which may cause serious illness
when consumed in large amounts. An important example is the legume - Lathyrus
sativus, which contains a toxin. When consumed in large amounts, the
subjects develop a crippling disease
known as lathyrism. Some varieties of mushrooms contain toxic substances
which when consumed produce serious ill effects.
Insect and Rodent
Contamination of Stored Foods
1. Insect Infestation
Insect infestation of food grains causes heavy losses and damage to the
quality of grains in storage. Taste, flavour, hygienic quality and
acceptability of the food grains are affected due to the presence of insect
excreta, insect fragments and dead insects. The content of B-Vitamins and the
nutritive value of the proteins are also lowered.
Damages caused by rodents to stored foods are as follows:
They consume large quantities of food grains.
The hygienic quality of the grain is affected by
the excreta of the rodents and also by some disease producing microorganisms
present in the food grains. They cause diseases like leptospirosis and plague.