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

Staphylococcal intoxication(staphylococal enterotoxicosis): an enterotoxin produced

by staphylococcus aureus.

Botulism: a neurotoxin produced by Clostridium botulinum.

Escherichia coli

– Infection– Incubation: 3-4 days– Symptoms: diarrhea, vomiting, mild fever– Foods: unpasteurized cider– Source: Human and bovine intestinal tract

BACTERIA

• 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 entero-pathogenic 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 heat-

resistant ,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-to-

eat, fruit juices, vegetables– Source: human intestinal/ urinary

tracts

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

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