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FOODBORNE ILLNESS
Introduction
• Gastrointestinal disturbances resulting from the
ingestion of food can have a variety of causes,
e.g., overeating, allergies, nutritional deficiencies,
actual poisoning by chemicals, toxic plants, or
animals, toxics produced by bacteria infestation
by animal parasites, and infection by
microorganisms.
• All food-borne diseases, are subdivided into
poisoning or the infections.
• Food poisonings can be the result of either
chemical poisoning or the ingestion of a toxicant
(intoxication).
• A bacterial food intoxication therefore
refers to food borne illnesses caused
by the presence of a bacterial toxic
formed in the food.
• A bacterial food infection refers to food
borne illnesses caused by entrance of
bacteria into the body through
ingestion of contaminated foods and
the reaction of the body to their
presence or their metabolites.
Food borne diseases
Intoxications
Infections
Salmonellois: enterotoxin and cytotox of
salmonella spp.
Staphylococcal
intoxication(staph
ylococal
enterotoxicosis):
an enterotoxin
produced by
staphylococcus
aureus.
Botulism: a
neurotoxin
produced by
Clostridium
botulinum.
Clostridium perfringens illness: an
enterotoxin released during sporulation of
clostridium perfringens type A in the
intestinal tract.
Bacillus cereus gastroenteritis: an
exoenterotoxin released during lysis of
bacillus cereus in the intestinal tract.
Enteropathogenic escherichia coli
infection: several serotypes of E. coli,
some invasive and some enterotoxigenic
Others
Yersiniosis, shigellosis, vibrio
parahaemolyticus
BACTERIA
Escherichia coli
– Infection
– Incubation: 3-4 days
– Symptoms: diarrhea, vomiting, mild fever
– Foods: unpasteurized cider
– Source: Human and bovine
intestinal tract
• E. coli is generally regarded as part of the normal
flora of the human intestinal tract and that of
many animals. Several nursery epidemics in the
1940s implicated E. coli in diarrheal disease in
infants.
• Serotypes of E. coli which have been implicated
in human diarrheal diseases or food poisoning
outbreaks have been designated enteropathogenic E. coli(EEC).
• The human disease syndromes resulting from the
ingestion of EEC have been divided into two main
groups.
• The first group consists of strains which produce
an enterotoxin and result in a cholera like or
enterotoxigenics illness in humans.
• These entero-toxigenic strains usually
produce two entero-toxins, a heat
stable(ST) and a heat labile(LT) toxin, and
are thought to be responsible for infantile
diarrheal diseases and traveler’s diarrhea.
• To experience the entero-toxigenic
illnesses , EEC serotypes capable of
elaborating the entero-toxins must be
ingested, followed by colonization in the
upper small intestine and production of the
entero-toxins.
• The second major group consists of
invasive strains which produce a cytotoxin
and result in the invasive illness, colitis, or
dysentery like syndrome. These serotypes
are non-enterotoxigenic , grow in the colon,
and invade or penetrate the epithelial cells
of colonic mucosa, resulting in the signs
and symptoms.
• The organism is relatively heat
sensitive and can readily be
destroyed at pasteurization
temperature and by the proper
cooking of foods.
• These strains can result in illness in
humans as manifested by bloody
diarrhoea and severe abdominal
pain.
BACTERIA
Salmonella enteritidis
– Infection
– Incubation: 4- 36 hours
– Symptoms: abdominal cramps, headache,
fever, nausea, diarrhea
– Foods: poultry, meat, eggs and egg products,
sliced melons
– Sources: water, soil, insects, animals, and
humans
• It is a zoonotic infection since the major
source of human illness is infectious
animals.
• Animals may suffer from salmonella
infections or become excretors as do
humans.
• They may get infected through eating
contaminated feeding meals or grazing on
contaminated land or by contact with
animal or human or bird excretors on the
farm or during slaughter or during transport.
• Organisms from infected carcass may be
transferred to other meat in the slaughter
house or during transport or in the
butcher’s shop wide spread out breaks of
salmonella occurred by distribution of
contaminated raw meat and by
contamination of cooked meats from the
raw meat.
• The transmission of salmonella is fecal oral
route by which intestinal contents from an
infected animal are ingested with food or
water.
• The transmission of disease usually takes place from
animals to humans by ingestion of food of animal origin.
• Also there may be direct transmission from human to
human , human to animals and animals to human.
• Salmonellosis is an infection resulting from the ingestion
of vegetatives cells of salmonella and is most commonly
occur in bacterial food infection.
• Salmonella are gram negative rods , non spore former
and most strain are motile and can grow both aerobically
and anaerobically , and ph range for optimum growth is
between 4.1 – 9 and temperature is 37°C . therefore they
can grow in acidic food also.
• These organisms can attain considerable numbers of
causing detectable changes in appearance , odour in
taste of food in which they grow . infection follows
consumption of such food.
• Individuals differ in their sensitivity to salmonella
infection and susceptibility varies with the species
, strains and total number of bacteria ingested.
• A temperature period which allow salmonella to
grow in food and inadequate or absent final heat
treatment are common factors contributing to
their outbreaks.
• COMMON ORGANISM CAUSING
SALMONELLA ARE :• Salmonella typhimurium
• Salmonella enteritidis
• Salmonella cholera suis
• S.newport
• INCUBATION PERIOD :- 4 to 36 hours.
• FOOD INVOLVED :- Meat , milk , poultry and
eggs. Eggs and poultry are primary carriers. They
may be undercooked allowing the salmonella or
they may cross contaminate other foods which
are consumed without further cooking.
• Cross contamination can occur through direct
contact or indirectly via contaminated kitchen
equipment and utensils , eggs ,eggs products ,
ice-cream contaminated with infected eggs shells
and raw milk are carriers.
• SYMPTOMS :- vomiting , nausea , abdominal
pain and diarrhoea which appears suddenly . it
may be proceded by headache and chills.
Mortality is low and severity and duration varies
with number of bacteria ingested .
• Symptoms persist for 2-3 days . but if
further infection occurs illness may persist
for months.
• Characteristics of illness are :Salmonellosis has been considered to be
an infection caused by the action of the
organism in the intestine.
• The organism secretes a cholera like
entero-toxin which induces increase level of
cyclic AMP and some strains produced a
heat stable entero-toxin which is supposed
to cause the gastrointestinal disturbance.
• PREVENTION :• IT does not required therapy except giving ORS
to stabilize the loss of fluids to prevent
dehydration.
• By avoiding consumption of contaminated food.
• Destruction of salmonella by heat.
• By prevention of its growth by refrigeration the
food.
• Protecting food from contamination by mice , flies
, rats or other insects.
• Cooking the food properly which is obtained from
animals sources for example meat ,sausages etc.
• Periodic inspection of food handlers and suitable
refrigeration and covering of prepared foods.
BACTERIA
Clostridium perfringens
– Infection
• Forms spores in adverse conditions
– Incubation: 8- 24 hours
– Symptoms: abdominal pain, nausea, diarrhoea
• Fever, headache, vomiting usually absent
– Foods: Stews, gravies, beans
– Sources: soil, animal and human intestinal
– tract
• Gram positive rod about 4-6 µm in length and 1 µm in width . so it is a
large ,broad with rounded ends occurs singly or in pairs has a
capsule, non motile spore former, anaerobe, grow at 37°C to 45°C
and growth quickly in cooked meat broth.
• It is sacchrolytic and mildly proteolytic.
• It grows at ph 5-9 and gets inhibited by 5 % sodium chloride. The
spores are heat resistant and are found in raw foods, soil, sewage
and feces.
Food involved:- the spores have been found in part of the samples
of most raw foods examined as well as in soil , sewage and
animals feces.
• Most commonly involved are meats that have been cooked ,
allow to cool slowly and held for some time before consumption.
• Fish paste and cold chicken also have been incriminated.
• The spores are fairly common in raw foods and are heatresistant ,and their presence in many foods may be unavoidable.
• Cooking of foods will destroy the vegetative cells and the spores
of some strain ; however germination and out growth of
surviving spores are possible in cooked foods which have been
inadequately refrigerated.
Incubation period :- 8 to 24 hours.
Symptoms :• Acute abdominal pain, diarrhoea, gas, vomiting and nausea and
vomiting are rare. the ingestion of millions of viable cells of
C.perfringens per gram of food are required for symptoms to occur.
• A toxin is released in the gut during sporulation of the cell and result
in excessive fluid accumulation in the intestinal lumen.
• The enterotoxin is relatively heat – sensitive , being inactivated at
60°C for 10 min.
Mechanism of food poisoning :-
• The spores are able to survive cooking and if cooked
meat and poultry are not cooled enough, they will
germinate. The organisms multiply between 30°C and 50°
C and produce a variety of toxins example alpha toxin,
theta toxin etc.
• prevention consists either by cooking food just prior to its
consumption or if it has to be stored by rapid and
adequate cooling
Condition needed for outbreaks are:• the food should be contaminated with Clostridium perfringens
(welchii).
• the food should be inadequately cooled and favorable temperatures
and enough time are allowed for its growth.
• Food should be consumed without reheating so that large numbers of
viable cells are ingested and
• Cells sporulate after ingestion and produce enterotoxin.
Prevention :• Adequate and quick cooling of cooked meat and other foods.
• Holding hot food above 60°C.
• Reheating of left over food.
• Good personal hygiene
BACTERIA
Bacillus cereus
– Intoxication
– Incubation: 30 min. to 6 hours (emetic) and 6
to 15 hours (diarrheal)
– Symptoms: nausea, vomiting, watery
diarrhea
– Foods: rice products, starchy foods,
casseroles, puddings, soups
– Source: soil and dust, cereal crops
• Bacillus Cereus is an aerobic, spore-bearing, motile,
gram positive rod. Spores are resistance to heat and
service considerable degree of cooking.
• Symptoms to develop large number of cells has to
ingested.
• The spores can survive cooking and germinate and
multiply rapidly when the food is held at favorable
temperatures.
• B.Cerus has been recognized as a cause of food
poisoning with increasing frequency in recent years.
• The mechanism of pathogenicity is believed to introduce
lesser of the bacterial cell in the intestinal cells and the
release of entero-toxic which appears to be a protein.
Shigellosis( Bacillary
Dysentery)
• Shigellosis are also known as bacillary dysentery caused by the
organism shigella.
• Shigella is gram negative rod, non - motile, aerobe, non- spores
former belong to the family of Entero bacteriaceal . Optimum
temperature for growth is 37°C, ph 5- 8.
• Shigella don't survive for long in acid food. It is heat sensitive and
can be destroyed at 65°C for 5 minutes.
• Shigellosis is an active infectious disease of the lower ileum and
colon. It is transmitted from man to man contacted by fecal oral
route. So , it is not, adaptive to human beings.
• Host food borne incidence or cases of shigellosis involves poor
personal hygiene amongst handlers. Specially failure to observe
hand washing requirement after using the toilet before handling
food.
• There are several types of Shigella dysentery . Shiga is name of
scientist.
Shigella dysenteriae
Shigella flaxnerei
Shigella boydii
Shigella soneii
• It may occur as primary disease or secondary to another disease . it
may be an epidemic or endemic usually acute but may be chronic.
• Shigella dysentery produce a very potent thermo liable toxic protein
which is a neuro tropic exotoxin which is responsible for intestinal
hemorrhage or loss of cut.
• The organism do not passed through the intestinal wall but remain
localized within the intestine or in cells, living in the intestinal mucosa.
Therefore the organism are not present in blood and urine but stools
contains a pure culture or Shigella. It is known as filth disease
because it is associated with poor personal hygiene as sanitation.
The number of organisms needed to cause Shigellosis is very low as
few as 10 organism of the virulent strain will produce illness.
Mode of Transmission
•
•
•
It is known as disease of four F’s as it is transmit by food , fingers , feces and
flies. so the transmission is person to person and hand to mouth. So, it
occurs through ingestion of contaminated food or water.
Flies and formites spread through feces of carriers and patients.
Factor related to its occurrence are malnutrition resistance and poor
sanitation.
INCUBATION PERIOD ;•
12-50 Hours and is range is 5 to 7 days.
SYMPTOMS:•
•
Abdominal pain, diarrhoea, high fever. Stools are composed of mucus ,
blood or pus, giving red jelly like appearance where is a burning sensation in
a rectum, dehydration electrolyte imbalance and some time vomiting may
accompany defecation. The patient may pass stool 6-7 per day.
Recovering individuals become carriers of Shigella . Complication may occur
in the form of perforation of bowls and heavy bleeding may occur. Average
illness last 5 – 6 days but the range fro 1 hours to 3 weeks.
Immunity
• The attack of Shigella imparts some degree of immunity but one can
have 2 attacks in the same season.
Prevention :• The disease is checked by sanitary measures. The feces and all
material contaminated by patient should be discarded properly or
sterilized. every secretion and excretion of the patient is its spread of
disease and the attendant should prevent its transmission.
• Attendant should not prepare food with infected hands after each
contact with the patient feces and urine.
• Sputum should be taken in tissue paper and discarded. Bed sheet
alter cloth should be sterilized. Food remains should be burnt.
Patient should not assure till repeated fecal culture have failed to
show the causative organism.
Food Involved
• Out breaks are those which are handle. The most salads
ingredients may be cleaned. But during the preparation
the salad may get contaminated by hand mixing.
• The organism can multiply quickly in moist food held at
room temperature.
• Other foods in which hands are used may also cause
shigellosis.
Enteric Fever
•
These are typhoid and paratyphoid fever. The term enteric fever is used for
these two fevers which are clinically similar. The organism for these are
Salmonella typhus and Salmonella paratyphi A and B. there is C also but C
is not prevalent in india . Paratyphi is also known as Salmonella schottmulari.
Typhoid fever:- they are motile. The ingestion through contaminated food and
water through the portal of entry and exist of the infecting organism in the
intestinal tract yet these enteric fevers involve nearly all tissues of the body.
Both the typhoid and paratyphoid organism are essentially human parasites
and are acquired almost exclusively from human sources namely patient and
barriers. These organism are spread from the feces or urine from the patient
or carrier to other person by the fecal oral root.
So the transmission is :• Water borne
• Food borne
• By contact with hand or eating, utensils or other formites.
•
Infecting those in Para typhoid fever is probably much larger than for typhoid
so that multiplication in some suitable substrates for example milk, cream,
artificial cream, takes place before ingestion and infection.
•
The pathogenic action of the organism is due to release of endo - toxin.
Salmonella typhus lives for about one week in sewage contaminated water
and may be viable in fecal matter for one to two months. Natural infection is
most often but ingestion followed by penetration through the mucus
membrane of the small intestine.
• INCUBATION PERIOD ;- 7- 14 days but appears to be related to the
•
•
•
•
doors of infection.
On reaching the small intestine the organism attach to the epithelial cells of
the intestinal villi and penetrate the lamina propria and sub mucosa .
They enter the mesenteric wall to multiply it. Then they enter the thorasic
duct and subsequently go to the blood stream. As a result there is bacteria
and organism go to the liver, gall bladder, spleen, bone marrow, lymph
nodes, lungs and kidney.
Salmonella multiply in gall bladder because bile is the good culture medium
for organism. They are discharged continuously into the intestine . The
organism invade the typhoid follicles of the small intestine.
The intestinal lesion forms an ulcer and hemorrhage or perforation may
occur. The organism liberated endo - toxin which produce toxic symptoms
such as head ache , loss of appetite, continuous fever, congestion of the
mucus membrane, there is step ladder increases in fever, skin rashes called
rose spots may appear during the second and third day. These rose spots
fade on pressures , abnormal constipation and some time nausea and
vomiting.
•
•
•
•
The rose spots are mainly on the back of the patients.
The fecal matter is yellowish green in color as loose consistency and blood
may be present.
Diarrhoea may occur during second week of infection. The organism appears
in stools during second to third week and in urine during third to fourth week.
Positive urine culture are obtained in 25 – 50 % of patients. So , the portal of
exist is via feces and urine. So , entry is from mouth.
IMMUNITY: 98% of cases who have typhoid fever renders them immune.
SPREAD OF DISEASE : The organism from the feces or urine of the carrier or
a person or a patient have reached the mouth of the victims.
CARRIERS : Typhoid carriers are of two types:Fecal carriers : the organism multiplies in the gall bladder and are excreted in
the feces. Fecal carriers are more common.
Urinary carriers : example organism passed out in the urine. Women become
more carrier than men. The most important factor in spread of typhoid is the
carrier who prepares food which is served raw carriers contaminate there
fingers with there discharges and then contaminate food with there fingers.
Prevention
Community prevention:•
•
•
•
•
•
supply of clean pasteurized milk.
Pure uncontaminated water.
Efficial disposal of sewage.
Proper sanitary control of food and eating places.
Detection and isolation of carriers specially food handlers.
Destruction of flies and vaccination.
Laboratory diagnosis :•
Different samples which have to be taken are blood culture, stool culture .
The main test then is widal test. The blood culture and widal test are most
important in diagnosing suspected culture. The stool and urine culture are
mainly used for detecting carriers and indicates stops to be a source of given
infection. Blood culture become positive in second week widal test become
positive in those cases during third week.
Para typhoid fever
•
•
•
It s a mild as compared to typhoid fever. It is a light typhoid fever. It is
characterized by sudden onset after a incubation period of 1 to 10 days with
chills, most of the same symptoms as typhoid fever but to a lesser degree.
The course of the disease is usually shorter, the average mortality rate is
lower. The only way to differentiate between typhoid and Para typhoid fever is
by isolating and identifying the causative organisms which is salmonella typhi
and salmonella schottmulari in this case.
Para typhus infection occurs almost exclusively in men while salmonella
schottmulari sometimes cause infection in lower animals.
Immunity and Treatment:•
Recovery from typhoid and paratyphoid fever is accompanied by good
regrade of immunity and artificial immunization by bacteria is effective. the
usual immunogen is a mixture of typhoid bacteria and salmonella Para typhus
A and b and salmonella schottmulari. This is TAB vaccine which is
administrated in 3 weekly doses and protects against ordinary exposure. It
should be reinforced by booster immunization at frequent intervals if there is
a likelihood of contact with infective organism. Choloramfevicol is treatment
for typhoid fever but it is not that satisfactory in Para typhoid infection
VIRUSES
Hepatitis A
– Infection
– Incubation: 10-50 days
– Symptoms: sudden fever, vomiting,
jaundice
– Foods: water (ice), shellfish, ready-toeat, fruit juices, vegetables
– Source: human intestinal/ urinary
tracts
VIRUSES
Norwalk virus
– Infection
– Incubation: 10-50 hours
– Symptoms: nausea, diarrhea,
headache, mild fever
– Foods: water, shellfish, raw vegetables
and fruits
– Source: human intestinal tract, water
VIRUSES
Rotavirus
– Infection
– Incubation: 1-3 days
– Symptoms: vomiting, diarrhea, mild fever
– Foods: ready-to-eat, water and ice
– Sources: human intestinal tract, water
FUNGI
Molds
– Usually spoil foods,
sometimes illness
– Sweet, acidic, low Aw foods
– Some produce aflatoxins
(peanuts)
– Gorgonzola, bleu, Brie,
Camembert cheeses,
mushrooms
PARASITES
Trichinella spiralis
– Roundworm
– Incubation: 2-28 days
– Symptoms: flu-like, swelling around eyes,
extreme sweating, hemorrhaging
– Foods: undercooked pork, game
– Source: domestic pigs, bear, walrus
PARASITES
Giardia lamblia
– Protozoan
– Incubation: 3-25 days
– Symptoms: fatigue, nausea, gas,
weight loss, abdominal cramps
– Foods: water, ice, raw vegetables
– Source: beavers, bears, dogs, cats,
humans