Nonenteric Lesions of Necrotic Enteritis in Commercial Chickens in California: 25 Cases (2009-2018).

Necrotic enteritis (NE) is an important enteric disease affecting a wide variety of avian species, including poultry, caused by Clostridium perfringens type G and, rarely, type C. Significant economic losses can result from elevated mortality rates and poor performance, such as decreased weight gain associated with intestinal damage and impaired absorption of nutrients. Additional losses can result from elevated condemnation at the processing plant because of a high incidence of cholangiohepatitis. Nonenteric lesions associated with NE have been rarely reported. This paper describes uncommon presentations of NE in commercial chickens received by the California Animal Health and Food Safety Laboratory (Turlock and Tulare branches) between 2009 and 2018. Overall, extraintestinal lesions associated with C. perfringens were diagnosed in 25 cases of NE involving commercial broiler chickens. The extraintestinal sites most commonly affected included liver, followed by gizzard, bursa of Fabricius, gall bladder, and spleen. The etiology of these lesions, C. perfringens, was confirmed from a combination of gross, bacteriologic, microscopic, and immunohistochemical findings. The most common predisposing factors for NE identified were coccidiosis (56%, 14/25) and immunosuppressive disease agents, including infectious bursal disease virus (16%, 4/25) and fowl adenovirus group 1 (4%, 1/25). Additionally, four cases (16%) had microscopic lesions compatible with cystic enteritis, probably of viral etiology. This study describes the incidence of extraintestinal lesions of NE in chickens, underlying the role of enteric disorders and immunosuppression as major predisposing factors for the development of NE.

Molecular epidemiology of endemic and very virulent infectious bursal disease virus genogroups in backyard chickens in California, 2009-2017.

Pathogenic strains of infectious bursal disease virus (IBDV) are associated with increased morbidity, mortality, and immunosuppression in susceptible chickens. Backyard poultry is increasing in popularity in the United States, but very little is known about the prevalence and molecular epidemiology of IBDV within these flocks. We performed a retrospective study and phylogenetic analyses of IBDV detected in backyard chickens (BYCs) submitted to the California Animal Health and Food Safety (CAHFS) diagnostic laboratory system in 2009-2017. There were 17 CAHFS autopsy cases of very virulent IBDV (vvIBDV) segment A detected by RT-rtPCR in BYC flocks from 7 counties in California from 2009-2017. During this same time period, non-vvIBDV genotypes were detected by RT-rtPCR in 16 autopsy cases originating from BYC premises in 10 counties in California. Subsequent RT-PCR and phylogenetic analysis of a segment of the hvVP2 and VP1 gene identified vvIBDV, interserotypic reassortant IBDV (vvIBDV segment A and serotype 2 segment B), and non-vvIBDV (variant/subclinical IBDV and classic IBDV) strains in BYC flocks in California.

Mycotic pododermatitis and mycotic pneumonia in commercial turkey poults in northern California.

Seven 5-week-old broad-breasted white commercial meat turkeys were submitted to the California Animal Health and Food Safety laboratory in Turlock with a history of respiratory illness. The primary diagnostic findings were mycotic pododermatitis and mycotic pneumonia. The unique feature of this case was the colonization of footpad epidermis and subcutis by fungal hyphae in commercial turkey species. No fungal cultures were undertaken at the time of the necropsy; therefore, paraffin-embedded tissue sections of lung and footpads were used to extract, amplify, and sequence mycotic DNA. A mixed population of fungi was identified in both lung and footpads by polymerase chain reaction amplification of part of the large subunit ribosomal RNA gene using broad-range fungal primers and DNA sequencing. In footpads, sequences matching Cryptococcus saitoi and Cladosporium and Cudoniella species were identified. It is believed that these fungi were opportunistic pathogens originating from the litter. The fungi identified from lungs were Aspergillus species, most closely matching Aspergillus flavus and Arxiozyma telluris (most likely a contaminant). Mycotic pododermatitis in avian species is considered a rare pathologic finding, and few documented reports are available. The on-farm prevalence of footpad lesions was estimated at 3%, and there was no associated increase in the incidence of lameness or weight depression in affected birds. Microscopically, a granulomatous inflammatory reaction associated with fungal hyphae was observed in lung parenchyma. Disruption of keratinized epidermis, encrustations, and acute inflammation were also noted in footpads invaded with fungal hyphae.