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Listeriosis

Other Names: Circling Disease, Listeria Monocytogenes Infection

Listeriosis is a serious bacterial infection caused by Listeria monocytogenes, a gram-positive, facultatively anaerobic bacterium which is ubiquitous in the environment, especially temperate zones. L. monocytogenes has been associated with numerous outbreaks in humans and animals worldwide.

In chickens, listeriosis has been associated with two major forms of disease----septicemic and encephalitic.
  • 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.

Transmission


Infection occurs following inhalation, ingestion, or wound contamination with the Listeria bacterium. Most cases of listeriosis in humans and animals are secondary to ingestion of contaminated food and water, and the disease is particularly common in ruminants fed improperly fermented and stored silage.

Foods which are commonly associated with outbreaks include packaged mixed greens and garden salads, raw sprouts, celery, melons, deli meats, lettuce, enoki mushrooms, smoked fish, raw milk products, frozen vegetables.

Clinical Signs

Ataxia
Torticollis (wry neck)
Head tilt
Weakness
Depression
Loss of appetite
Panting
Weight loss
Listlessness
Not laying eggs
Diarrhea with yellow-white feces

Diagnosis

  • History
  • Clinical signs
  • Lab testing
  • Necropsy

Reported Cases

  • Case 1: Listerial encephalitis in a Partridge An outbreak of neurological disease was investigated in red-legged partridges between 8 and 28 days of age. Clinical signs included torticollis, head tilt and incoordination and over an initial eight day period approximately 30–40 fatalities occurred per day. No significant gross post mortem findings were detected. Histopathological examination of the brain and bacterial cultures followed by partial sequencing confirmed a diagnosis of encephalitis due to Listeria monocytogenes. Further isolates were obtained from follow-up carcasses, environmental samples and pooled tissue samples of newly imported day-old chicks prior to placement on farm. Ref

  • Case 2: Listeriosis in a Chickens Five chickens from a backyard flock of 20 eight-month-old birds started displaying clinical signs of depression, anorexia, reduced comb size, pasty butt, and panting. Most of the hens stopped laying eggs. Seven birds from the same flock had died in the previous 5 months. The flock owner occasionally fed the birds fresh garden produce that was grown on the premises. A few of the dead birds were sent to the local veterinary diagnostic lab for a necropsy. The pathologic changes in the internal organs of infected birds showed severe myocarditis, pericarditis, pneumonia, hepatitis, and splenitis. No lesions were noted in the brain. Gram-positive organisms were seen in histologic sections of the heart and spleen. Listeria monocytogenes was detected by real time PCR from formalin fixed heart and spleen, and was isolated from fresh lung, spleen, and liver. The exact source of infection for this flock is unknown. Possible sources of the Listeria infection include feces, soil, decaying plant material, feed, and water. Neither the environment where the chickens were housed nor the commercial ration or drinking water were collected or tested. The first clinical signs in the flock appeared when investigation from a multistate outbreak of listeriosis linked to whole cantaloupes was ongoing. The remaining sick birds were treated intramuscularly with 25 mg/kg of enrofloxacin for 5 days. All the birds recovered. Ref

  • Case 3: Listeriosis in a Cockatiel Listeriosis was diagnosed in a 4-yr-old female cockatiel that died after exhibiting clinical signs that included a fluffed-up appearance, weakness, and loss of weight of several days duration. Grossly, the bird was moderately emaciated, and the liver and spleen were enlarged. Microscopically, there was mild-to-moderate inflammation associated with rod-shaped, gram-positive bacteria in the liver, spleen, kidneys, adrenal glands, bone marrow, and esophagus. Listeria monocytogenes was isolated from the liver, trachea, and intestine. The isolate was identified as type 1 by agglutination with specific antisera, and it further identified as belonging to serovar group 1/2a, 3a by multiplex polymerase chain reaction assay. Listeria monocytogenes also was detected in affected tissues by immunohistochemistry. Ref

Treatment

NameSummary
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.
EnrofloxacinR Crespo et al

Support

Prevention

  • Practice good sanitary management practices
  • Develop biosecurity guidelines
  • Minimize contact between goats and chickens.
  • Don't feed chickens raw sprouts.
  • Keep chickens healthy and limit stress, since any immune compromise can increase their susceptibility to infection.

Scientific References

Age Range

Young birds are more susceptible to infection, but occurs in birds of any age.

Risk Factors

  • Keeping ruminants (cattle, goats, sheep) on the same property as chickens, since the organism is commonly found in large numbers in the feces of these animals (even healthy).
  • Feeding chickens packaged mixed greens and garden salads, raw sprouts, celery, melons, deli meats, lettuce, enoki mushrooms, smoked fish, raw milk products, or frozen vegetables.

Seasonality

WinterSpringSummerAutumn

Etiology

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