Campylobacter jejuni

• Widespread on farms - hyperendemic
• Carried as commensals in intestines of cattle, sheep, dogs, wild birds and especially chickens
• Farm animals regularly exposed via faecal-oral route; maternal antibody protects while active immunity develops
• Animals with little exposure are very susceptible, e.g. humans, pets
• Most chicken carcasses contaminated, leading to food poisoning and enterocolitis in people from uncooked meat
• Colonisation, attachment and invasion of colonic enterocytes; toxin production
• Necrosis of colonic absorptive epithelial cells, erosion of mucosa, crypt abscesses, inflammatory infiltrate of neutrophils into mucosa causes colitis
• Enteritis and diarrhoea in susceptible dogs; treatment with enrofloxacin
• Causes abortion in ewes
• Usually asymptomatic infections in chickens and turkeys, but occasional outbreaks of avian hepatitis occur with decreased egg production, loss of condition, haemorrhage and necrosis of liver; phase contrast microscopy demonstrates curved rods in bile; in-feed dihydrostreptomycin sulphate in outbreak
• Implicated in undifferentiated neonatal calf diarrhoea, a mixed viral enteritis in calves

• An important enteropathogen of man and a number of animal species.
• The largest cause of food-poisoning in the UK.
  • Is therefore a public health issue.
• Very widely distributed on the farm- carried in the intestinal tract of:
  • Cattle
  • Sheep
  • Dogs
  • Chickens
  • Wild birds
• Widespread distribution on the farm means that it is hyperendemic.
  • All animals are regularly exposed to it by the faecal oral route.
  • Passive (colostral) protection is helpful while active immunity develops.
• There is no regular exposure in the hygienic environment of the human or pet dog.
  • These animals are much more susceptible to infection.
• The intestinal contents of the broiler chicken may be spread around the abdominal cavity at slaughter.
  • Most poultry is moderately or heavily contaminated.
    • If frozen chicken is inadequately thawed, bacteria may remain viable in the abdominal cavity.
    • Bacteria may be ingested by humans handling the raw meat.

Pathogenesis

• Bacteria colonise the gut, attach to and invade the mucosa, and produce toxin.
• Causes colitis, characterised by:
  • Necrosis of absorptive epithelial cells
  • Erosion of the mucosa
  • Crypt abscesses
  • Infiltration of inflammatory cells into the mucosa.
    • Primarily neutrophils.
• Functional flagella are important as virulence factors.
  • Non-flagellate campylobacter do not colonise in vivo, and are less invasive in vitro.
• Diagnosed by laboratory diagnosis.

Campylobacter fetus or jejuni In ewes, causes abortion storms. Transmission is oral from faeces or aborted material and leads to late abortion, premature and weak lambs. See areas of focal hepatic necrosis in foetus.