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Circling Disease, Listeria Monocytogenes Infection

Listeriosis is an infectious and fatal disease of animals, birds, fish, crustaceans, and humans that is caused by infection with Listeria monocytogenes. L. monocytogenes is an intracellular pathogen which has a unique ability to spread from cell to cell, allowing it to cross blood-brain intestinal and placental barriers. The organism is widespread in nature, and has been isolated from animals, humans, food sources (milk, meat and meat products, seafood, and fresh vegetables and fruits), and the environment (soil, decaying plants, water) and known for causing sporadic outbreaks worldwide.

The clinical signs of listeriosis vary, depending on the number of organisms ingested, pathogenic properties of the specific strain, and the immune condition of the bird. The most common Listeria infections are caused by three serotypes: 1/2a, 1/2b, and 4b. In chickens, listeriosis has been associated with two major forms----septicemic and encephalitic. There is a third form that occurs in humans and other animals, the abortion form, but it has not been characterized yet in chickens.
  • Encephalitic form: Sometimes referred to as "circling disease", this form is characterized by neurologic signs such as incoordination, torticollis, hyperthermia, loss of appetite, depression, and walking in circles.
  • Septicemic form: This form is characterized by diarrhea, depression, and emaciation.
Summary of documented cases in chickens
1 month oldCalifornia, USTorticollis
L. monocytogenes was isolated from the brain tissue through direct culture during necropsy1988Cooper, G.L.
8 months oldSeattle, WADecreased egg production
Loss of appetite
Isolation of L. monocytogenes serotype 4b from the lung, liver and spleen during necropsy.2013R Crespo et al
L. monocytogenes is transmitted to chickens predominately through ingestion, inhalation, or direct contact with the Listeria bacterium. L. monocytogenes has also been linked to diverse types of fresh produce such as sprouts, celery, cantaloupe, stone fruit, and apples. Contamination with L. monocytogenes is the third leading cause of food-borne illness in the United States.

Listeriosis occurs more commonly in birds living in the northern and southern latitudes and temperate climates. In northern hemispheres, listeriosis has been found to occur more frequently between December to May.

Clinical Signs

Reduced egg production
Loss of appetite
Abnormal body posture


  • History
  • Clinical signs
  • CFT
  • 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.
Enrofloxacin25 mg/kg administered IM for 5 daysR Crespo et al
Virginiamycin22 mg/kg food administered QD in feedK Marx



  • Practice good sanitary management practices
  • Develop biosecurity guidelines
  • Thoroughly wash vegetables and fruits before feeding to birds
  • Keep raw meats separate from other foods
  • Don't give soft cheeses to birds.

Scientific References

Good Overviews

Age Range

Young birds are more susceptible to infection.

Risk Factors

  • Regularly feeding birds raw vegetables and fruits that have not been thoroughly washed first
  • Feeding birds soft cheeses