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Outbreak of Listeria monocytogenes in an urban poultry flock

Rocio Crespo1*, Michael M Garner2, Sharon G Hopkins3 and Devendra H Shah45

Author Affiliations

1 Avian Health and Food Safety Laboratory, Washington Animal Disease Diagnostic Laboratory, Washington State University, 2607 West Pioneer, Puyallup, WA 98371, USA

2 Northwest ZooPath, 654 W. Main St., Monroe, WA 98272, USA

3 Public Health–Seattle & King County, 401 5th Avenue, Ste 1100, Seattle, WA 98104, USA

4 Department of Veterinary Microbiology, Washington State University, Pullman, WA 99164-7040, USA

5 Pathology and Paul Allen School for Global Animal Health, Washington State University, Pullman, WA 99164-7040, USA

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BMC Veterinary Research 2013, 9:204  doi:10.1186/1746-6148-9-204

Published: 11 October 2013



Listeria monocytogenes infection is most commonly recognized in ruminants, including cattle, sheep, and goats; but it is rarely diagnosed in poultry. This report describes an outbreak of L. monocytogenes in a backyard poultry flock. Also, it points out the importance of collaboration between veterinarians and public health departments and the possible implications of zoonotic diseases.

Case presentation

Depression, lack of appetite, labored breathing, and increased mortality were noted for 5 months in several affected birds within the flock. The pathologic changes in the internal organs of infected birds included 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. This isolate was identified as L. monocytogenes serotype 4b by 16S rDNA sequencing and by PCR-based serotyping assay.


This is the first report describing outbreak of L. monocytogenes in backyard poultry flock in Washington State and use of molecular methods to confirm L. monocytogenes infection from formalin fixed tissues.