CPH SAS 12

• Foodborne infections


  Caused by the entrance of pathogenic microorganisms contaminating food into the body, and the reaction of the body tissues to their presence; fungal, bacterial, viral or parasitic
• Bacterial foodborne infections


  • Cholera
  • Salmonellosis
  • Typhoid fever
  • Shigellosis
  • Yersiniosis
  • Escherichia coli infection
  • Campylobacteriosis
  • Vibrio parahemolyticus infection
  • Listeriosis
• Mycotic foodborne infections


  • Candida spp.
  • Sporothrix spp.
  • Wangiella spp.
• Viral foodborne infections


  • Hepatitis A
  • Norwak virus
  • Poliomyelitis virus
• Salmonellosis


  Caused by salmonella bacteria
• Salmonella enterica serotype Typhi


  The cause of Typhoid fever
• Salmonellosis


  Endotoxins first act on the vascular and nervous apparatus, resulting increased permeability and decreased tone of the vessels, upset thermal regulation, vomiting and diarrhea
• Salmonellosis


  Fecal-oral transmission
• Salmonellae grow well on food and can exist for a considerable period in feces, and on pastures
• Diagnosis of salmonellosis


  Any blood, bone marrow or stool cultures and with the Widal test (demonstration of antibodies against Salmonella antigens O- somatic and H- flagellar)
• The salmonellae are killed by temperatures attained in commercial pasteurization, they can remain alive in moist earth for one year and in dry earth for 16 months
• Factors associated with Salmonella food poisoning outbreaks

  • Consumption of inadequately cooked or thawed meat or poultry
  • Cross-contamination of food from infected food handlers
  • Presence of flies, cockroaches, rats, in the food environment that act as vectors of the disease
• Transmission of salmonellae


  1. Directly from slaughter animals to food

  2. From human excreta, and transferred to food through hands, utensils, equipment, flies etc.

  3. Food poisoning is more likely to occur if the total number of microorganisms present is high. A smaller number may have no ill effect
• Foods commonly involved in salmonellosis

  • Meat and meat products
  • Milk and milk products
  • Egg and egg product
• Control measures for salmonellosis

  • Efficient refrigeration and hygienic handling of food
  • Consumption of properly cooked meat
  • Complete thawing of frozen meats and adequate cooking
  • Heat processing of meat, milk, fish and poultry to destroy salmonella organisms in food
• Typhoid and paratyphoid fever (enteric fevers)


  Caused by Salmonella typhi and Salmonella paratyphi A, B and C respectively
• Salmonella typhi


  • Possesses capsular (vi) antigen in addition to the usual O and H antigens found in other serotypes
• Symptoms of enteric fevers

  1. Incubation period is usually 2 weeks, but might vary between 3 and 28 days for typhoid fever and between 1 and 15 days for the paratyphoid fevers

  2. Generalized septicaemic infections with a frequent, if not constant bacteraemia during the first two weeks of the disease

  3. Abdominal symptoms are severe, while fever and illness may continue for 4-6 weeks
• Campylobacteriosis

  Caused by Campylobacter jejuni and Campylobacter coli
• Campylobacter jejuni occurs in large numbers in cattle feces, and poultry as normal flora
• Disease in man caused by Campylobacter


  1. Illness characterized by diarrhoea, abdominal pain, fever, nausea, vomiting, and abdominal complaints

  2. The jejunum, ileum and colon are primarily affected resulting in acute inflammation and occasionally, abscess formation

  3. The disease is self-limiting
• Clinical signs of campylobacteriosis

  1. Incubation period ranges between 2-11 days with an average of 3-5 days

  2. Preceded by fever, followed by foul smelling watery diarrhea, which runs for 3-4 days

  3. Diarrhea may sometimes contain blood and mucus in feces

  4. Abdominal pain is associated with backache, and a high mortality

  5. The condition is self-limiting but may last for up to 10 days
• Mode of infection for campylobacteriosis

  1. Infection occurs by ingestion of campylobacter organisms in contaminated foodstuffs

  2. Foods involved includes meat from infected animals, unpasteurized milk and possibly cross contamination from these sources to foods eaten uncooked or unrefrigerated

  3. Among the meats, poultry constitutes the greatest potential source of infection to humans

  4. Carelessness in the kitchen e.g. cutting chickens with the same knife used to cut other foods without proper cleaning prior to use

  5. Pork is a major source of Campylobacter coli, contamination occurs during slaughter
• Preventive measures for campylobacteriosis

  • Thorough cooking of all foodstuffs derived from animal sources
  • Prevention of re-contamination after cooking
  • Proper refrigeration of foods
  • Recognition, control, and prevention of campylobacter infections in animals
  • Maintenance of a high standard of hygiene
• Escherichia coli foodborne infection

  E. coli strains involved fall into the following groups: Enteropathogenic E. coli (EPEC), Enterotoxigenic E. Coli (ETEC), Enteroinvasive E. coli (EIEC) and Enterohemorrhagic E. coli (EHEC)
• Illness caused by Enteroinvasive E. coli (EIEC)

  1. Characterized by watery diarrhea in most patients, fever, nausea, and abdominal cramps

  2. Bloody diarrhea may occur in fewer than 10% of patients

  3. Presence of mucus and polymorphonuclear leucocytes in stool is typical

  4. Illness is usually self-limiting, lasting for 2 to 3 days
• Illness caused by Enterohemorrhagic E. coli (EHEC)


  1. Caused by Escherichia coli serotype O157:H7

  2. Characterized by hemorrhagic colitis in humans with diarrhea, abdominal pain which may be severe and vomiting

  3. Few patients develop fever, illness lasts for 4 to 8 days, although it may extend to 13 days for severe cases

  4. Patients with complications have bloody diarrhea, acute ulcerative or ischemic colitis and submucosal edema with severe colonic inflammation
• The organism E.coli O157:H7 is heat sensitive, but resistant to freezing
• Control measures for E. coli foodborne infections

  • Proper cooking of hamburgers and other meats
  • Avoidance of cross-contamination of foods in the kitchen
  • Good personal hygiene
• Shigellosis (bacillary dysentery)


  Caused by members of the genus Shigella, including Shigella dysenteriae, Shigella flexneri, Shigella boydii and Shigella sonei
• All strains of shigella possess potent exotoxins which are carbohydrate-lipi protein complexes
• Clinical symptoms of shigellosis

  1. Illness begins 1 to 4 days after ingestion of bacteria and may last 4 to 7 days

  2. Symptoms include watery or bloody diarrhea, fever, stomach cramps, nausea or vomiting, dehydration and prostration in severe cases, and convulsions in young children

  3. The diarrhea which starts as a thin watery discharge quickly loses its fecal character to be composed of nothing but pus, mucus threads and blood
• Transmission of shigellosis


  1. Human cases and carriers are the only important sources of infection

  2. Spread is by fecal-oral route, and person-to-person transmission is common

  3. The bacteria leaves the body in stool of an infected person and infects another person through contaminated hands, food, water, or objects (toys, pens etc)

  4. Any type of food can transmit the shigella pathogens to cause disease in man

  5. Flies can spread shigella germs when they get into contact with infected stool and then contaminate drinking water or food
• Shigella organisms may remain viable in tap water for 6 months and in sea water for 2-5 months
• Cholera


  Caused by Vibrio cholera bacterium
• Cholera transmission


  1. Man is the only natural host of the cholera vibrios

  2. Spread of infection is from person-to-person, through contaminated water or foods

  3. Shrimps and other seafood can also transmit cholera
• Cholera infection


  1. Cholera vibrios are ingested in drink or food

  2. In natural infection, the dosage is usually very small

  3. The organism multiplies in the small intestine to produce a very potent enterotoxin, which stimulates a persistent outpouring of isotonic fluid by the gut mucosal cells
• Fecal-oral route


  Bacteria leaves the body in stool of an infected person and infects another person through contaminated hands, food, water, or objects
• Person-to-person transmission


  Common mode of transmission for certain foodborne diseases
• Any type of food can transmit the shigella pathogens to cause disease in man