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Red Skin, Erysipelothrix Infection, St. Anthony's Fire

Erysipelas is a bacterial infection of the outer layers of the chicken's skin. It is a form of cellulitis, except unlike cellulitis, almost all erysipelas is caused by Erysipelothrix rhusiopathiae or Group A beta haemolytic streptococci (Streptococcus pyogenes).

What are the clinical signs of erysipelas

Erysipelas usually occurs abruptly and predominantly affects the skin of the lower limbs of the bird. Affected birds also often have a fever.
  • It is bright red, firm and swollen. It may be finely dimpled.
  • The affected skin has a very sharp, raised border.
  • It may be blistered, and in severe cases may become necrotic.
  • Bleeding into the skin may cause purpura.
  • Cellulitis does not usually exhibit such marked swelling, but shares other features with erysipelas, such as pain and increased warmth of affected skin.

How chickens become infected with erysipelas

E. rhusiopathiae enters the chicken's body through breaks in the skin, such as open wounds and scratches. The organism is able to survive in the soil and decaying organic matter in the environment for long periods of time. The red poultry mite (Dermanyssus gallinae), is a potential vector of E. rhusiopathiae, and can act as reservoir hosts, allowing it to persist on the premises between flocks as a source of infection for the next flock of birds. Infection with E. rhusiopathiae has also been linked to chickens consuming fish meal.

Clinical Signs

Skin scratches
Pale combs
Crusty, swollen eyes
Abnormal gait
Diarrhea (often greenish or yellowish)
Loss of appetite
Decreased egg production
Purplish or reddish skin blotches


  • History
  • Clinical signs
  • Physical exam
  • PCR
  • Bacterial culture
  • Histopathology
  • Necropsy


PenicillinOral or intravenous penicillin is the antibiotic of first choice. 1,000,000 U/gal in drinking water for 4 or 5 days to all birds in the flock. Treatment is usually required for 10-14 days.
Supportive careCold packs and analgesics to relieve local discomfort. Wound care with saline dressings that are frequently changed.



  • Avoid the use of areas previously used by pigs, sheep, or turkeys.
  • Good management practices
  • Biosecurity

Scientific References

Age Range

Erysipelas is associated with sudden, high mortality in older flocks, often those infested with poultry red mites.

Risk Factors

  • History of recent injury
  • Getting fed fish meal
  • Red poultry mites on premises
  • Raising chickens in areas that previously contained pigs, sheep or turkeys
  • Roosters spurs were recently trimmed or dubbed
  • Breaks in the skin barrier due to insect bites, ulcers, or trauma.
  • Immune deficiency or stress