A retrospective study of pigeon herpesviral infection in domestic pigeons in California (1991-2014) and literature review.

We characterized naturally occurring pigeon herpesvirus (PiHV; Columbid alphaherpesvirus 1) infection in domestic pigeons in California. We retrieved and analyzed 62 pathology reports produced between 1991 and 2014 at the California Animal Health and Food Safety Laboratory System. In 56 of the cases, the diagnosis of PiHV infection was established based on histopathology, either alone (44 cases) or combined with virus isolation (VI; 8), transmission electron microscopy (TEM; 3), or PCR (1); in the remaining 6 cases, the diagnosis was established based on VI (5 cases) or TEM (1) alone. PiHV infection affected 1 system in 34, 2 in 16, and ≥3 systems in 6 cases; data were not available for the remaining 6 cases. Most commonly affected was the digestive system (55 cases), followed by the respiratory tract (5) and lymphoid system (2). The liver (39 cases), crop (17), and esophagus (14) were the organs affected most commonly. Many affected cells often bore single eosinophilic intranuclear inclusion bodies. PiHV infection was a secondary diagnosis or incidental finding in 35 cases. Most (55) cases had 1 (21), or up to 4 (34), other concurrent infections; the most common concurrent infections were pigeon circoviral infection (26), trichomonosis (24), aspergillosis (11), and colibacillosis (10).

Health surveillance of a potential bridge host: Pathogen exposure risks posed to avian populations augmented with captive-bred pheasants.

Augmentation of wild populations with captive-bred individuals presents an inherent risk of co-introducing novel pathogens to naïve species, but it can be an important tool for supplementing small or declining populations. Game species used for human enterprise and recreation such as the ring-necked pheasant (Phasianus colchicus) are commonly raised in captivity and released onto public and private wildlands as a method of augmenting naturalized pheasant populations. This study presents findings on pathogen exposure from three sources of serological data collected in California during 2014-2017 including (a) 71 pen-reared pheasants sampled across seven game bird breeding farms, (b) six previously released pen-reared pheasants captured at two study sites where wild pheasants occurred and (c) 79 wild pheasants captured across six study sites. In both pen-reared and wild pheasants, antibodies were detected against haemorrhagic enteritis virus (HEV), infectious laryngotracheitis (ILT), infectious bursal disease virus (IBDV), paramyxovirus type 1 (PMV-1) and Pasteurella multocida (PM). Previously released pen-reared pheasants were seropositive for HEV, ILT, and PM. Generalized linear mixed models accounting for intraclass correlation within groups indicated that pen-reared pheasants were more than twice as likely to test positive for HEV antibodies. Necropsy and ancillary diagnostics were performed in addition to serological testing on 40 pen-reared pheasants sampled from five of the seven farms. Pheasants from three of these farms tested positive by PCR for Siadenovirus, the causative agent of both haemorrhagic enteritis in turkeys and marble spleen disease of pheasants, which are serologically indistinguishable. Following necropsy, owners from the five farms were surveyed regarding husbandry and biosecurity practices. Farms ranged in size from 10,000 to more than 100,000 birds, two farms raised other game bird species on premises, and two farms used some form of vaccination. Biosecurity practices varied by farm, but the largest farm implemented the strictest practices.

Case Report - A Case Report of Avian Malaria (Plasmodium spp.) in Pen-Reared Pigeons (Columbia livia).

One dead 6-week-old, male racing pigeon ( Columbia livia ) was submitted for postmortem evaluation after presenting with weight loss, anorexia, dry shanks, dehydration and lethargy. The bird belonged to a confined flock with 12 other pigeons raised by a hobbyist. Two pigeons in the flock reportedly had died with a history of similar clinical signs. On gross examination, the liver and the spleen were diffusely dark brown to black. Histopathology revealed moderate to large amounts of anisotropic, intracytoplasmic black pigment, compatible with hemozoin, in the spleen, liver, lung and kidneys, with small amounts in the heart and meninges of the brain. Marked plasmacytic infiltrates were observed in liver, lungs, heart and kidneys. Blood smears from a clinically affected concomitant pigeon from the flock revealed numerous light-blue, round to oval, intraerythrocytic trophozoites and meronts suggestive of Plasmodium spp. PCR and sequencing tests were performed from spleen and ceca using fragments of the 18S ribosomal RNA and the mitochondrial cytochrome B (cytB) genes. Sequencing results confirmed the presence of Plasmodium in the affected pigeon. Although an exact genetic match could not be determined, the most similar species to the isolate from this study are P. relictum , P. matutinum, P. lutzi and P. homocircumflexum .

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.

Chlamydiosis in a Gouldian Finch (Erythrura gouldiae).

Avian chlamydiosis is an infection caused by obligate intracellular and Gram-negative bacteria belonging to the family Chlamydiaceae and has been reported in more than 450 avian species distributed in 30 orders. In particular, a high prevalence of infection has been demonstrated in wild passerine populations, including both asymptomatic and clinically ill individuals, suggesting a role of these avian species as important carriers. In May 2018, avian chlamydiosis was diagnosed in a 1-year-old male Gouldian finch (Erythrura gouldiae) at the Turlock Branch of the California Animal Health and Food Safety Laboratory System. The bird belonged to an outdoor aviary with mixed avian species, including Gouldian finches, doves (Geopelia cuneata and Spilopelia chinensis), and psittacines (Aratinga, Psittacula, Pyrrhura, and Trichoglossus sp.). Severe respiratory distress and mortality were noted among the finches. Gross and histopathologic lesions were concentrated in the liver and spleen, with a mild involvement of the upper respiratory tract. Chlamydia spp. were detected in the spleen and kidney by real-time PCR and were further confirmed by immunohistochemistry. Subsequently, Chlamydia psittaci was isolated from the liver and spleen and characterized as a CP3-like strain (genotype B). In addition, viral particles compatible with circovirus were identified in the liver by direct electron microscopy. To the authors' knowledge, this is the first report of avian chlamydiosis with hepatic viral particles consistent with circovirus infection in a Gouldian finch.

Reporte de caso- Clamidiosis en un pinzón diamante de Gould (Chloebia gouldiae). La clamidiosis aviar es una infección causada por bacterias intracelulares y Gramnegativas obligadas que pertenecen a la familia Chlamydiaceae y se ha reportado en más de 450 especies de aves distribuidas en 30 órdenes. En particular, se ha demostrado una alta prevalencia de infección en poblaciones de paseriformes silvestres, incluyendo individuos asintomáticos y clínicamente enfermos, lo que sugiere un papel de estas especies aviares como portadores importantes. En mayo del año 2018, se diagnosticó clamidiosis aviar en un pinzón diamante de Gould (Chloebia gouldiae) de un año de edad remitido a la sede en Turlock del Sistema de Laboratorios de Salud Animal y Seguridad Alimentaria del Estado de California. El ave pertenecía a un aviario al aire libre con especies mixtas de aves, incluyendo los diamantes de Gould, palomas (Geopelia cuneata y Spilopelia chinensis) y psitacinas (Aratinga, Psittacula, Pyrrhura y Trichoglossus sp.). Se observaron problemas respiratorios severos y mortalidad entre los pinzones. Las lesiones macroscópicas e histopatológicas se concentraron en el hígado y el bazo, con problemas leves en el tracto respiratorio superior. Se detectó Chlamydia spp. en el bazo por PCR en tiempo real y fueron confirmados por inmunohistoquímica. Posteriormente, se aisló Chlamydia psittaci del hígado y el bazo y se caracterizó como una cepa de tipo CP3 (genotipo B). Además, se identificaron partículas virales compatibles con circovirus en el hígado mediante microscopía electrónica directa. Según el conocimiento de los autores, este es el primer informe de clamidiosis aviar con partículas virales hepáticas compatibles con infección por circovirus en un pinzón diamante de Gould.

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.

Partial Molecular Characterization and Pathogenicity Study of an Avian Reovirus Causing Tenosynovitis in Commercial Broilers.

This study describes the molecular characterization of avian reoviruses (ARVs) isolated during an outbreak in commercial chickens between 2015 and 2016. In addition, a pathogenicity study of a selected ARV strain isolated from a field case of viral tenosynovitis in commercial broiler chickens was performed. On the basis of phylogenetic analysis of a 1088-bp fragment of the ARV S1 gene, the investigated sequences were differentiated into five distinct genotypic clusters (GCs), namely GC1, GC2, GC3, GC4, and GC6. Specific-pathogen-free (SPF) and commercial broiler chickens were challenged with the GC1 genetic type MK247011, at 14 days of age via the interdigital toe web. No significant effects in body weight gain and feed conversion were detected in both chicken types. The Δ interdigital web thickness was most severe at 4 days postchallenge (DPC) in both the SPF and broiler subgroups. The inflammation in SPF birds was slightly more severe compared with broilers. Neither mortality nor clinical signs occurred in the infected groups for the duration of the experiment, despite the presence of significant microscopic lesions in challenged birds. Microscopic changes of tenosynovitis became evident at 3 DPC, with the highest incidence and severity detected at 14 and 21 DPC, respectively. Seroconversion against ARV occurred 3 wk postchallenge, and the microscopic lesions detected in tendon and heart sections were highly compatible with those described in the field. Increased severity of tenosynovitis and epicarditis lesions were noted in the ARV-challenged groups compared with the control groups. Although SPF and broiler chickens showed comparable responses to the challenge with an ARV genetic variant, detected lesions were subclinical, denoting the limitations of our challenge approach. The age selected in this experiment possibly influenced the course of the infection. Data from this study highlight the genotypic diversity of isolates in California, and the outcome of the pathogenicity study can be used as a basis to improve protocols for pathogenicity studies to characterize ARV variants causing clinical disease in the field.

Caracterización molecular parcial y estudio de patogenicidad de un reovirus aviar que causa tenosinovitis en pollos de engorde comerciales. Este estudio describe la caracterización molecular de reovirus aviares (ARV) aislados durante un brote en pollos comerciales entre los años 2015 y 2016. Además, se realizó un estudio de patogenicidad de una cepa de reovirus seleccionada que fue aislada de un caso de campo de tenosinovitis viral en pollos de engorde comerciales. Con base en el análisis filogenético de un fragmento de 1088 pb del gene S1 de reovirus, las secuencias investigadas se diferenciaron en cinco grupos genotípicos distintos (GCs), denominados, GC1, GC2, GC3, GC4 y GC6. Aves libres de patógenos específicos (SPF) y pollos de engorde comerciales se desafiaron con el tipo genético GC1 MK247011 a los 14 días de edad a través de la membrana interdigital. No se detectaron efectos significativos en el aumento de peso corporal ni en la conversión de alimento en ambos tipos de aves. El grosor de la banda interdigital diferencial fue más severa a los cuatro días posteriores al desafío en las aves libres de patógenos específicos y en los pollos de engorde. La inflamación en las aves libres de patógenos específicos fue ligeramente más severa en comparación con los pollos de engorde. No se presentó mortalidad ni signos clínicos en los grupos infectados durante la duración del experimento, a pesar de la presencia de lesiones microscópicas significativas en las aves desafiadas. Los cambios microscópicos de la tenosinovitis se hicieron evidentes a los tres días postinoculación, con la mayor incidencia y severidad detectadas a los 14 y 21días postinoculación, respectivamente. La seroconversión para reovirus ocurrió tres semanas después del desafío, y las lesiones microscópicas detectadas en secciones de tendón y corazón fueron altamente compatibles con las descritas en el campo. El aumento en la severidad de las lesiones de tenosinovitis y epicarditis se observó en los grupos expuestos a reovirus aviar en comparación con los grupos de control. Aunque las aves libres de patógenos específicos y los pollos de engorde mostraron respuestas comparables ante el desafío con una variante genética de reovirus, las lesiones detectadas fueron subclínicas, lo que denota las limitaciones de nuestro enfoque de desafío. La edad seleccionada en este experimento posiblemente influyó en el curso de la infección. Los datos de este estudio resaltan la diversidad genotípica de los aislamientos en California y el resultado del estudio de patogenicidad se puede usar como base para mejorar los protocolos de los estudios de patogenicidad para caracterizar las variantes de reovirus que causan enfermedades clínicas en el campo.

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.

Streptococcosis in Commercial and Noncommercial Avian Species in California: 95 Cases (2000-2017).

Streptococcal bacterial species represent common inhabitants of the intestinal tract of animals and humans with a potential for opportunistic infections. Streptococcosis has been identified in turkey poults ( Meleagris gallopavo), ducklings and goslings (Anatidae), broiler chickens, semimature-adult chickens ( Gallus gallus domesticus), and young and adult pigeons (Columbidae). However, the exact underlying factors that lead to bacterial invasion of the blood stream and tissue colonization have not been completely elucidated. The electronic database of the California Animal Health and Food Safety laboratory (Fresno, Tulare, and Turlock branches) was searched for necropsy cases in which streptococcosis was diagnosed in different avian species between January 2000 and August 2017. A total of 95 cases, involving both commercial operations and noncommercial premises, were analyzed. Streptococcus spp., Streptococcus bovis, and Streptococcus gallolyticus were identified from multiple organs, with macroscopic or histopathologic lesions (or both) indicative of septicemia in 23 (24%), 40 (42%), and 30 (32%) cases, respectively. Streptococcus pluranimalium and Streptococcus lutetiensis were also isolated from one (1%) and two (2%) cases, respectively. Turkey poults, broiler chickens, and ducklings were the most-commonly affected species with streptococcosis. Splenitis and hepatitis were the most-common lesions observed and these were the organs with the highest isolation rate. An overview of the clinical and pathologic presentation, and possible predisposing conditions associated with this bacterial infection, is provided.

Serologic Surveillance of Wild and Pen-reared Ring-necked Pheasants ( Phasianus colchicus) as a Method of Understanding Disease Reservoirs.

We investigated exposure to infectious diseases in wild ( n=33) and pen-reared ( n=12) Ring-necked Pheasants ( Phasianus colchicus) in the Central Valley of California, US during 2014 and 2015. Serologic tests were positive for antibodies against hemorrhagic enteritis, infectious bursal disease, and Newcastle disease viruses in both wild and pen-reared pheasants.

Pathogenicity of Genome Reassortant Infectious Bursal Disease Viruses in Chickens and Turkeys.

Infectious bursal disease virus (IBDV) contains two genome segments (segment A/segment B) that can reassort among the viruses. Reassortant IBDVs have been identified in several countries including the United States. These reassortant viruses usually include at least one genome segment from a very virulent (vv)IBDV strain. In vivo virulence of six reassortant IBDV from the United States was assessed relative to the virulence of three frequently described IBDV pathotypes: vvIBDV (rB strain), classic virulent (cv)IBDV (STC strain), and subclinical (sc)IBDV (Del-E strain). Morbidity and mortality in 4-wk-old specific-pathogen-free (SPF) leghorns indicated that reassortant IBDV with a vv genome segment A and non-vv segment B were less pathogenic than the vv/vv rB strain but more pathogenic than the cv/cv STC strain. The sc/vv IBDV strain D6337 (sc/vv) was comparable to the STC strain in pathogenicity. Viruses with a serotype 2 (ser2) genome segment A, regardless of the type of genome segment B, did not cause clinical disease in SPF chickens or turkeys. None of the reassorted viruses caused morbidity, mortality, or gross lesions in SPF turkeys. Histopathologic lesions in the bursa of turkeys were not observed in any group except those challenged with the serotype 2 OH strain, which had a mild lymphocytic depletion. No mortality was observed in maternally immune broilers inoculated with any of the IBDV pathotypes at 1, 2, 3, and 4 wk of age. No bursal lesions were observed in any of the broiler chicken groups at 1 wk of age except for the D2712 (ser2/cv)-inoculated birds that had mild lymphocyte depletion. Based on evaluation of bursal lesion scores and IBDV reverse transcriptase-PCR on broilers challenged at 2 wk of age, the K669 (vv/ser2) virus broke through the maternal immunity while the STC, Del-E, rB, D2712 (ser2/cv), and 7741 (vv/cv) viruses did not. All viruses broke through maternal immunity in the broilers at 3 wk of age except the Del-E scIBDV and D2712 (ser2/cv) reassortant IBDVs. At 4 wk of age, maternal antibodies were very low and bursal lesions were observed in all broilers challenged with the viruses. The data indicate that genome reassortant IBDVs are less pathogenic than is the rB (vv/vv) IBDV. However, the reassortant viruses with a vv genome segment A can still cause morbidity and mortality in SPF chickens, and they were able to break through maternal immunity produced via use of commercial classic and variant vaccines at an early age. This suggests that current breeder vaccination programs may not adequately protect against the reassortant vv/ser2 and vv/cv IBDV strains.

Yersinia pseudotuberculosis in Eurasian Collared Doves (Streptopelia decaocto) and Retrospective Study of Avian Yersiniosis at the California Animal Health and Food Safety Laboratory System (1990-2015).

In February 2015, two Eurasian collared doves (Streptopelia decaocto) were submitted dead to the California Animal Health and Food Safety (CAHFS) Laboratory, Turlock branch, from a private aviary experiencing sudden, high mortality (4/9) in adult doves. In both doves, the gross and histologic lesions were indicative of acute, fatal septicemia. Grossly, there were numerous pale yellow foci, 1 to 2 mm in diameter, in the liver and spleen. Microscopically, these foci were composed of acute severe multifocal coagulative necrosis of hepatocytes and splenic pulp with infiltration of heterophils mixed with fibrin and dense colonies of gram-negative bacteria. Yersinia pseudotuberculosis was isolated from the lung, liver, spleen, heart, ovary, kidney, and trachea. The organism was susceptible to most antibiotics it was tested against, except erythromycin. Based on a retrospective study of necropsy submissions to CAHFS between 1990 and 2015, there were 77 avian case submissions of Y. pseudotuberculosis. There were 75/77 cases identified from a wide range of captive avian species from both zoo and private facilities and 2/77 cases from two backyard turkeys submitted from one premise. The largest number of cases originated from psittacine species (31/77). The lesions most commonly described were hepatitis (63/77), splenitis (49/77), pneumonia (30/77), nephritis (16/77), and enteritis (12/77). From 1990 to 2015, there was an average of three cases of avian pseudotuberculosis per year at CAHFS. Although there were no cases diagnosed in 1993 and 1994, in all other years, there were between one and eight cases of Y. pseudotuberculosis detected from avian diagnostic submissions.

Molecular evidence for a geographically restricted population of infectious bursal disease viruses.

A population of infectious bursal disease virus (IBDV) in northeast Ohio that appears to be geographically restricted was identified. Thirteen broiler farms containing a total of 36 houses were examined for the presence of IBDV. Twenty-four of the 36 houses were positive for IBDV, and of those viruses, 15 viruses from six different broiler farms formed a unique phylogenetic group. Nucleotide sequence analysis identified glutamic acid (E) at position 253 in all 15 viruses. Only one other virus in the GenBank database contained this mutation, and it was also from northeast Ohio. All 15 viruses from this study and the one identified in GenBank also had a unique VP1 sequence. The amino acids located at position 253 in VP2 are typically histidine (attenuated viruses) and glutamine (pathogenic viruses). Because amino acid 253 has been linked to pathogenicity in IBDV, two viruses from the E253 population were selected for pathogenicity studies. They were observed to be pathogenic in 4-wk-old specific-pathogen-free layer chicks. When these two viruses were used to challenge broilers from the parent flock that supplies the birds to all 13 broiler farms examined in this study, the viruses were able to break through the maternal immunity at 14 and 21 days of age but not at 7 days of age. A similar scenario was observed on the six broiler farms that had these viruses. The phylogeographic data suggest this population of IBDV has been restricted for more than 14 yr to northeast Ohio. Because commercially available classic and variant vaccines do not effectively control this population of IBDV, other alternatives are needed.

Pathogenicity associated with coinfection with very virulent infectious bursal disease and Infectious bursal disease virus strains endemic in the United States.

The pathogenicity induced by co-challenge with the rB strain of very virulent Infectious bursal disease virus (vvIBDV) and IBDV pathotypes endemic in the United States was evaluated in specific pathogen-free chickens. Four- and 6-week-old birds were simultaneously challenged with a 10(5) 50% egg infectious dose (EID50) of rB mixed with a 10(5) EID50 of one of the following viruses: standard classic (STC), subclinical variant (Del-E), subclinical variant (T1), or avirulent serotype 2 (OH). Each challenge group consisted of 5 chickens. The severity of disease was assessed by comparing the 5-day mortality rates, bursal lesions (mean bursal lesion scores), and mean bursal-to-body weight ratios in each of the challenged groups. A mortality of 100% (10/10 and 5/5) was observed in birds inoculated with only the vvIBDV (rB) strain at 4 weeks and 6 weeks of age, respectively. Although the sample sizes were low, a significant reduction in mortality and severity of disease, based on mean bursal lesion scores, was observed in groups co-challenged with rB and the less virulent pathotypes Del-E, T1, or OH at 4 weeks of age. Co-challenge with rB and the antigenically similar STC strain did not result in a significant decrease in mortality compared to challenge with the pathogenic rB strain at 4 weeks of age, but a significant reduction in the mean bursa lesion score was observed. At 6 weeks of age, a significant decrease in mortality and mean bursa lesion score was observed in the rB groups co-challenged with STC, Del-E, or T1 but not OH.

Diversity of genome segment B from infectious bursal disease viruses in the United States.

Several phylogenetic lineages of the infectious bursal disease virus (IBDV) genome segment B have been identified. Although this genome segment has been shown to contribute to virulence, little is known about the genetic lineages that exist in the United States. The nucleotide genome segment B sequences of 67 IBDV strains collected from 2002 to 2011 in the United States were examined. Although they were from nine different states, a majority (47) of these viruses were from California. A 722-base pair region near the 5' end of genome segment B, starting at nucleotide 168 and ending at 889, was examined and compared to sequences available in GenBank. The nucleotide sequence alignment revealed that mutations were frequently observed and that they were uniformly spaced throughout the region. When the predicted amino acids were aligned, amino acids at positions 145, 146, and 147 were found to change frequently. Six different amino acid triplets were observed and the very virulent (vv) IBDV strains (based on presence of vvIBDV genome segment A sequence) all had the triplet T145, D146, and N147. None of the non-vvIBDV strains had this TDN triplet. Phylogenetic analysis of the 67 nucleotide sequences revealed four significant genome segment B lineages among the U.S. viruses. One of these included the genome segment B typically found in vvIBDV and three contained non-vvIBDV genome segment B sequences. When the available sequences in GenBank were added to the analysis, two additional lineages were observed that did not contain U.S. viruses; one included viruses from China and the other contained viruses from the Ivory Coast. Although the samples tested do not represent all poultry producing regions in the United States, serotype 1 viruses from states outside California all belonged to one genome segment B lineage. The other three lineages observed in the United States were populated with viruses exclusively found in California, except the serotype 2 lineage, where the type strain was a serotype 2 virus from Ohio. The data provide further evidence for the importance of genome segment B identification during routine molecular diagnosis of all IBDV strains.

Identification and pathogenicity of a natural reassortant between a very virulent serotype 1 infectious bursal disease virus (IBDV) and a serotype 2 IBDV.

Infectious bursal disease virus (IBDV) causes an economically important, immunosuppressive disease in chickens. There are two serotypes of the virus that contain a bi-segmented double-stranded RNA genome. In December 2008, the first very virulent (vv)IBDV was identified in California, USA and in 2009 we isolated reassortant viruses in two different locations. Genome segment A of these reassortants was typical of vvIBDV serotype 1 but genome segment B was most similar to IBDV serotype 2. The CA-K785 reassortant caused 20% mortality in chickens but no morbidity or mortality in commercial turkey poults despite being infectious. There have been previous reports of natural reassortants between vvIBDV and other serotype 1 strains, but a natural reassortant between IBDV serotypes 1 and 2 has not been described. The apparent reassorting of California vvIBDV with an endemic serotype 2 virus indicates a common host and suggests vvIBDV may have entered California earlier than originally thought.

The diagnosis of very virulent infectious bursal disease in California pullets.

This report documents the occurrence of a very virulent infectious bursal disease virus (vvIBDV) in Northern California commercial brown pullets. Diagnosis was made from multiple accessions from two neighboring and epidemiologically related ranches submitted to the California Animal Health and Food Safety (CAHFS) laboratory. Pullets, 11 and 14 wk of age from ranch A (rA) and ranch B (rB) respectively, were submitted from infectious bursal disease virus vaccinated flocks experiencing a drastic increase in mortality. The December 2008 outbreak resulted in 26% and 34% mortality on rA and rB respectively. Gross and histologic lesions characteristic of acute vvIBDV were observed. Gross lesions included edematous bursas, hemorrhages at the junction of the proventriculus and gizzard as well as hemorrhages on skeletal muscles. Microscopic lesions included severe lymphoid necrosis and inflammation in edematous bursas, lymphoid necrosis in thymus, spleen, Peyer's patches and cecal tonsils. Diagnosis of vvIBDV was confirmed by molecular characterization of the IBDV from bursas as well as viral pathogenicity in specific-pathogen-free birds. RT-PCR and nucleotide sequencing of the hypervariable region of the VP2 (vVP2) gene segment of the IBDV genome was performed on rA, rB and embryo passaged rA virions.The amino acids compatible with vvIBDV isolates: 222(Ala), 242(Ile), 256(Ile), 294(Ile) and 299(Ser) were reported from both ranches. In addition, nucleotide sequencing of a fragment of the VP1 gene demonstrated the viruses have the segment B genotype associated with highly pathogenic vvIBDV. Inocula of 10(5.5) 50% egg infective dose of vvIBDV virus from rA and rB were introduced orally into two groups (g1 and g2 respectively) of 4 wk 2-day-old SPF leghorns. At 4 days postinoculation, there was 100% (22/22) morbidity in g1 and g2; 91% (20/22) mortality in g1; 100% (22/22) mortality for g2; 0% (0/20) morbidity and 0% (0/ 20) mortality was reported in the control group. This is the first occurrence of vvIBDV reported from birds in the United States.

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.