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Avian Colibacillosis, Coliform Infection

Colibacillosis, otherwise known as Escherichia coli infection or avian pathogenic Escherichia coli (APEC), is a common, infectious bacterial disease affecting young chicks less than or equal to 1 week of age. Colibacillosis most frequently occurs during cold weather spells when young chicks become chilled. It can also occur as a result of fecal contamination of eggs that are placed in an incubator to hatch.

About E. coli

E. coli is a normal inhabitant in the digestive system of chickens; however, it can become an opportunistic bacteria and cause disease in it's host when their immune system is compromised or stressed.

Clinical Presentation

E. coli causes a variety of disease manifestations in chickens including: airsacculitis, cellulitis, coligranuloma, egg peritonitis, enteritis, omphalitis, osteomyelitis, pericarditis, perohepatitis, salpingitis, septicemia, and synovitis. E. coli infections often occur concurrently with other bacteria, fungi, protozoa, and viruses. The most common co-infections documented to occur with E. coli include:
  • Chronic respiratory disease (CRD): Chronic respiratory disease (CRD), also known collectively as mycoplasma gallisepticum (MG) infection, is considered to be one of the major pathogens that cause respiratory disease in poultry. It tends to develop slowly in flocks and associated with progressive and chronic respiratory signs. Chickens with chronic respiratory disease often show clinical signs associated with the respiratory system, which include mild tracheitis, sinusitis, airsacculitis and conjunctivitis.
  • Swollen head syndrome (SHS): Swollen head syndrome (SHS) is an acute, highly contagious upper respiratory tract infection of poultry. SHS is caused by infection with the avian metapneumovirus (AMPV), a type of pneumovirus which is classified into four subtypes (A, B, C, and D).
The most common manifestations of E. coli infections in chickens include:
  • Cellulitis: Cellulitis is a bacterial skin infection resulting in inflammation of the subcutaneous tissue of birds, typically seen in the lower abdomen and upper legs.
  • Colisepticemia: Septicemia, also known as blood poisoning, occurs when an Escherichia coli infection has invaded the chicken's bloodstream. Once in the bloodstream, the infection quickly spreads throughout the body. It is a serious, life-threatening condition which is associated with acute onset of very generalized clinical signs of sickness, such as listlessness, depression, weakness, loss of appetite, and sudden death.
  • Omphalitis: Omphalitis, also known as yolk sac infection, is an infectious, non-contagious, common condition affecting the naval of newly hatched chicks. It is caused by invasion by several bacterial, with one of the most common being Escherichia coli.
  • Egg peritonitis: Egg peritonitis is considered to be an emergency condition for hens. It is the inflammation of the hen's peritoneum, which is the thin tissue lining the inner wall of the abdomen. It is usually the secondary result of hens silently suffering from salpingitis. Affected hens may have a history of egg binding, usually within the past six months.
  • Coligranuloma: A rare form of colibacillosis that occurs sporadically as a chronic infection in adult birds worldwide, resulting in decreased egg production, fertility, and hatchability.
Clinical signs of colibacillosis are usually nonspecific and vary depending on the manifestation of the infection. The severity varies depending on the age of the bird, duration of infection, management conditions, and concurrent diseases present. E. coli strains are often resistant to many commonly sold antibiotics for chickens, including cephradine, tetracyclines, chloramphenicol, amino-glycosides, beta-lactam antibiotics, and sulfonamides.

E. coli is transmitted to chickens through ingestion, inhalation, or secondary to fecal contamination of eggs hatched in an incubator.

Clinical Signs

Ruffled feathers
Reduced appetite
Poor growth
Pasted vent with semisolid cheesy material
Decreased water consumption
Droopy head
Respiratory distress
Reduced egg production
Poor condition


  • History
  • Clinical signs
  • Bacterial culture
  • Necropsy


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Apramycin0.5 g/L added to drinking water dailyK Marx
Clostridium butyricum probiotic2 × 10(7) cfu C. butyricum/kg of diet for 28 daysL Zhang et al., 2016
Mannan-oligosaccharides (MOS)0.05% MOS in dietR Jahanian et al., 2015


  • Probiotics
  • Biosecurity
  • Feeding a balanced diet with good quality protein

Scientific References

Good Overviews

Age Range

All ages are susceptible, but young birds are more commonly and severely affected.

Risk Factors

  • Dry, dusty conditions
  • Contaminated environment
  • Unsanitary living conditions
  • Overcrowding
  • Feed/water restriction
  • Abrupt feed changes
  • Poor ventilation
  • Temperature extremes
  • Concurrent secondary infection
  • History of previous trauma
  • Nutrient deficiency or unbalanced diet
  • Exposure to mycotoxins
  • Stress