Characterization of an Outbreak of Infectious Coryza (Avibacterium paragallinarum) in Commercial Chickens in Central California.

In 2017, the Turlock branch of the California Animal Health & Food Safety laboratory system received a significant increase in infectious coryza (IC) necropsy cases, with a total of 54 submissions originating from commercial broilers (n = 40), commercial layers (n = 11), and backyard chickens (n = 3). Layer flocks positive for IC were distributed within the adjacent counties of Merced and Stanislaus, while broiler flocks were concentrated within Merced County. The backyard flocks were located in Alameda and Sacramento counties. The clinical and pathologic presentation was consistent with IC, although septicemic lesions were also noticed. Avibacterium paragallinarum was isolated and identified by PCR from the respiratory tract as well as from extrarespiratory sites. Polymicrobial infections involving other viral (infectious bronchitis virus, infectious bursal disease virus) and bacterial (Mycoplasma spp., Escherichia coli, Ornithobacterium rhinotracheale, Gallibacterium anatis biovar haemolytica) agents were commonly reported. Thirteen selected Av. paragallinarum isolates were successfully characterized as serovar C (Page scheme) and serovar C2 (Kume scheme). They shared a unique enterobacterial repetitive intergenic consensus (ERIC) PCR, differing from the four reference strains, and showed consistent high minimum inhibitory concentration values for tetracycline, suggesting a common origin from a single clone. Based on these results, high biosecurity standards and proper immunization of susceptible, multi-age flocks should always be implemented and adjusted as needed. The importance of backyard flocks should not be underestimated due to their unique epidemiologic role.

Caracterización de un brote de coriza infecciosa (Avibacterium paragallinarum) en pollos comerciales en la parte central de California. En el año 2017, la sede en Turlock del Sistema de Laboratorios de Salud Animal y Seguridad Alimentaria de California recibió un aumento significativo en el número de casos de necropsia por coriza infecciosa, con un total de 54 casos, incluyendo casos provenientes de pollos de engorde comerciales (n = 40), gallinas de postura comerciales (n = 11) y aves de traspatio (n = 3). Las parvadas de gallinas de postura positivas para coriza infecciosa se distribuyeron en los condados adyacentes de Merced y Stanislaus, mientras que las parvadas de pollos de engorde se concentraron en el condado de Merced. Las parvadas de traspatio estaban ubicadas en los condados de Alameda y Sacramento. La presentación clínica y patológica fue consistente con coriza infecciosa, aunque también se observaron lesiones septicémicas. Se aisló Avibacterium paragallinarum y se identificó mediante PCR en el tracto respiratorio y también de sitios extrarespiratorios. Las infecciones polimicrobianas relacionadas con otros virus (virus de la bronquitis infecciosa, virus de la enfermedad infecciosa de la bolsa) y bacterias (Mycoplasma spp., Escherichia coli, Ornithobacterium rhinotracheale, Gallibacterium anatis biovar haemolytica) fueron reportadas comúnmente. Trece aislamientos seleccionados de A. paragalinarum se caracterizaron con éxito como serovar C (esquema de Page) y serovar C2 (esquema de Kume). Estos aislamientos Compartieron por PCR un consenso intergénico repetitivo enterobacterial (ERIC) único, que difiere de las cuatro cepas de referencia y mostraron valores constantes de concentración mínima inhibitoria alta para tetraciclina, lo que sugiere un origen común de un solo clon. Con base en estos resultados, siempre se deben implementar y ajustar estándares de bioseguridad altos y la inmunización adecuada de parvadas susceptibles de edades múltiples, según sea necesario. La importancia de las parvadas de traspatio no debe subestimarse debido a su función epidemiológica especial.

Otitis and meningoencephalitis associated with infectious coryza ( Avibacterium paragallinarum) in commercial broiler chickens.

Infectious coryza, caused by Avibacterium paragallinarum, is an acute respiratory disease of poultry that can result in substantial morbidity, mortality, and economic losses. In March 2017, the Turlock branch of the California Animal Health and Food Safety laboratory system encountered an unusual clinical and pathologic presentation of infectious coryza in 6 live, 29-d-old, commercial broiler chickens that were submitted for diagnostic investigation. Antemortem evaluation revealed severe neurologic signs, including disorientation, torticollis, and opisthotonos. Swollen head-like syndrome and sinusitis were also present. Histologically, severe sinusitis, cranial osteomyelitis, otitis media and interna, and meningoencephalitis were noted, explaining the clinical signs described. A. paragallinarum was readily isolated from the upper and lower respiratory tract, brain, and cranial bones. Infectious bronchitis virus (IBV) was also detected by PCR, and IBV was isolated in embryonated chicken eggs. Based on sequencing analysis, the IBV appeared 99% homologous to strain CA1737. A synergistic effect between A. paragallinarum and IBV, resulting in exacerbation of clinical signs and increased mortality, may have occurred in this case. A. paragallinarum should be considered among the possible causes of neurologic signs in chickens. Appropriate media should be used for bacterial isolation, and the role of additional contributing factors and/or complicating agents should be investigated in cases of infectious coryza.