Avian diseases最新文献

Spotty liver disease (SLD) caused by Campylobacter hepaticus has emerged as an important cause of disease in table egg layers in the United States. The disease associated with C. hepaticus results in focal lesions on the livers of infected birds, reduced egg production, and increased mortality of layer hens. Currently, there are no approved treatments and no commercial vaccine available for C. hepaticus, and very limited research is available supporting best approaches for the control of C. hepaticus in organic or antibiotic free-laying hens. We assessed the potential effects of water acidification treatments for the control of C. hepaticus in challenged specific-pathogen-free (SPF) chickens and transmission of the organism to naïve birds. The objective of this study was to develop a challenge and treatment model to assess the effects of oregano, apple cider vinegar, and citric acid as potential control measures for C. hepaticus in challenged birds. We divided 148 SPF chickens, 17 wk of age, into five groups; four groups (with 51% of the birds in each group orally challenged with C. hepaticus) and one negative control group (n = 8). A dose of 10⁷ cfu/ml of C. hepaticus was given on day 1, day 4, and day 7 by oral gavage. At day 10 after the day 1 challenge, three challenged groups were treated for 5 days with either oregano, apple cider vinegar, or citric acid in the water. One challenged but not treated group and the negative control received only water as treatment. Bile and liver samples from challenged and nonchallenged naïve exposed birds were collected from euthanatized birds at days 9, 15, 20, and 27 after the first day challenge to evaluate the presence of C. hepaticus gross lesions and detection via culture and polymerase chain reaction (PCR) confirmation. Results showed that challenged birds were able to develop mild to moderate multifocal liver lesions resembling SLD. Severe lesions were evident in the naïve, exposed nonchallenged birds. Positive bacterial culture and colony PCR positives were found in challenged birds in each challenge group. Results from PCR of DNA extracted from liver samples were able to detect a greater number of C. hepaticus-positive samples than culture PCR of bile alone. Treatment with oregano, apple cider vinegar, or citric acid was not able to clear C. hepaticus from challenged birds because more than 44% of the challenged birds remained positive on liver PCR analysis posttreatment. Results also found that C. hepaticus could be passed horizontally because more than 29% of the naïve nonchallenged birds became C. hepaticus positive postintroduction to challenged birds. Overall, this study found that this challenge model for C. hepaticus was successful and that treatments did not clear C. hepaticus in challenged birds. Nevertheless, it appears that acidifying the water could help to re

Streptococcus gallolyticus, formerly known as Streptococcus bovis, is a Gram-positive coccus bacterium that is a facultative anaerobe. Although it was previously considered a commensal bacterium that caused secondary disease because of a stressor, S. gallolyticus can now be considered a causative agent of disease associated with a variety of infections in both humans and animals. Streptococcus gallolyticus has become an emerging pathogen in the poultry industry, particularly in turkey poults, causing acute mortality, usually without any premonitory signs. In the southern portion of the United States, there has been an influx of S. gallolyticus infections occurring predominately in July and August. A majority of turkey poults most susceptible to this disease range in age between 1.5 and 2.5 wk of age. It is suggested that virulence capability relies on accessory genome components that may not be core to all S. gallolyticus strains. In this review, we aim to provide an overview of the nomenclature changes, identification, and emergence of S. gallolyticus in turkeys.

Enterococci infections may result in acute and chronic disease. Lesions, such as osteomyelitis, arthritis, or endocarditis, depend on the Enterococcus species involved. In this case report, an outbreak of Enterococcus hirae-associated endocarditis affecting young broiler breeders is presented. On a rearing farm with 46,500 broiler breeders, a slight increased mortality (1.02%-1.42%) within the female line was observed between 2 and 6 wk posthatch (ph). Between days 12 and 47 ph, 256 birds were pathologically examined, and bacteriologic samples were taken. In 191 (51.8%) of the examined female line chickens, endocarditis was observed on at least one of the atrioventricular valves, while no endocarditis was diagnosed in chickens of the male line (n = 65). Enterococcus hirae was isolated from 64.4% of the bone marrow samples and from two heart samples taken from chickens of the female line. Enterococcus hirae was not isolated from samples taken from the male line. In addition, natural antibody titers (immunoglobulin G) were significantly higher in serum of the female line compared with the male line. This case gives an overview of gross lesions and bacteriology of E. hirae affecting only the female line of broiler breeders.

Since the early 2000s, skeletal effects, specifically enterococcal spondylitis, related to pathogenic Enterococcus cecorum (EC), have been observed in older broiler chicken flocks. This skeletal involvement has typically been associated with persistent EC infections in the free thoracic vertebrae leading to paralysis. However, the emergence of virulent EC in young broiler chicken flocks causing clinical septicemia requires further investigation. The purpose of this review is to provide an update on EC-related research and pending industry needs.

Enterococcus cecorum (EC) is a dominant enteric commensal in broiler chickens. However, pathogenic strains of EC cause increased morbidity and mortality from septicemic disease in broiler production worldwide. EC infections can present as pericarditis and paralytic spinal lesions from which pathogenic EC can be isolated. However, the inability to distinguish between commensal and pathogenic EC strains has confounded the search for the source of pathogenic EC in environmental or hatchery samples. This issue is exacerbated by poor sensitivity of standard sampling and culture methods. Comparative genomic analysis of EC isolates previously identified a conserved capsule region in pathogenic EC strains that is absent or variable in commensal strains. Based on a capsular synthesis gene, cpsO, and EC species-specific sodA primers, we designed a standard multiplex PCR to distinguish pathogenic EC from commensal EC strains. To allow for increased sample throughput, a real-time PCR protocol was developed in tandem based on detection of these genes. To increase the culture sensitivity, a selective enrichment protocol using Todd-Hewitt Broth with 1% yeast extract and four antibiotics enabled the isolation of pathogenic EC from egg transfer residue and culled eggs at hatcheries. Pulsed-field gel electrophoresis was used to genotype recovered hatchery isolates, which identified clonal pathogenic EC strains isolated from hatchery residue and a spinal lesion of a broiler. The ability to distinguish pathogenic EC from commensal EC coupled with modified culture methods will facilitate improved surveillance of pathogenic EC throughout broiler production, ideally leading to decreased incidence or eradication of this disease.

Ornithobacterium rhinotracheale (ORT) is a Gram-negative, pleomorphic rod-shaped bacterium that causes respiratory disease in the commercial poultry industry. This bacterium has been causing severe disease in chickens and turkeys since it emerged in the 1980s. In birds, increased mortality, reduced egg production, and loss in weight gain gives ORT the potential to have severe economic implications. In older birds, ORT causes more severe lesions and increases in mortality; therefore it is of particular concern in the breeder industry because infection and loss of production in breeders impact all stages of production. Despite the importance of ORT, few published studies have contributed to understanding of the diagnostics, treatment, and prevention of this disease. This review discusses the evolving landscape of ORT and summarizes an update on important issues related to ORT.

Erysipelas is a zoonotic disease, causing acute infections in swine, poultry, and a wide variety of animals, including humans. In layers, erysipelas is considered an emerging disease characterized by hepatomegaly, splenomegaly, septicemia, and acute death. It affects flocks between 43 and 73 wk old and can result in 50% overall mortality. Layer hens possibly affected by an erysipelas outbreak were sampled in this study. Organs at necropsy showed the typical erysipelas lesions; the presence of Erysipelothrix rhusiopathiae was confirmed by selective plating and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The antimicrobial effect of a set of 20 proprietary Bacillus direct-fed microbials (DFM), individual strains and in combinations, was analyzed against confirmed E. rhusiopathiae isolates, by agar-well diffusion assay. Nine of the Bacillus strains screened in this study were found effective at inhibiting the growth of all four E. rhusiopathiae isolates from erysipelas cases. The findings of this study highlight the potential of using the Bacillus DFMs in vivo to evaluate their efficacy as biocontrol alternatives to reduce the growth E. rhusiopathiae in poultry production.

Despite being a disease known to affect poultry for well over 100 years, several aspects of erysipelas, caused by Erysipelothrix rhusiopathiae, are still poorly understood. For many years, erysipelas in poultry was considered a disease of interest primarily in turkeys, with only a few cases reported in chickens and other poultry species. However, since the change of housing systems for layers from conventional battery cages to litter-based systems, sometimes with access to the outdoors, there has been an increase in the number of outbreaks, especially in Europe, and erysipelas is now considered to be an emerging disease in layers. The aim of this review is therefore to provide a summary background on erysipelas in general, as well as in other poultry species, after which the focus is directed to the disease in chickens, with special emphasis on recent advances in knowledge on immune responses.

Enterococcus faecalis is a commensal bacterium that colonizes the intestines of mammals and birds. It is characterized as an opportunistic pathogen and has been commonly associated with late-stage embryonic mortality, omphalitis, growth depression, sepsis, and amyloid arthropathy in poultry. In this study, E. faecalis isolates recovered from a flock of 6200 layer pullets located in Canada exhibited impaired growth, poor uniformity, and sporadic lameness that started at 1 wk of age and extended throughout the rearing phase. Enterococcus faecalis was isolated from swollen tarsometatarsal joints of lame pullets that contained yellow-orange material and from the house environment. Two sequence types (STs) known to be pathogenic to chickens, ST82 and ST49, were identified among the joint isolates. Seventeen known E. faecalis virulence genes were detected in these strains, including gelE for gelatinase production and the fsrB quorum-sensing signaling peptide gene required for virulence regulation. Phylogenetic analysis revealed that an ST82 strain isolated from an environmental sample was clonally related to the joint isolate. Furthermore, both sequence types, ST82 and ST49, had antimicrobial-resistance genes against tetracyclines, lincosamide, and streptogramin antimicrobials. ST49 had additional resistance genes to common ionophores used in poultry production. An embryo lethality assay was conducted to determine the pathogenicity of isolates. Inoculation with ST82 resulted in significantly lower survivability of embryos compared to ST49. To date, cases of amyloid arthropathy caused by E. faecalis are reported in European countries, but rarely from North American poultry operations. Further characterization of these E. faecalis strains is needed to elucidate transmission routes, uncover environmental reservoirs, and identify specific virulence genes in the development of amyloid arthropathy in poultry.

Spotty liver disease (SLD) is a reemerging infection caused by Campylobacter species that results in increased mortality and reduced egg production, with increased incidence in cage-free commercial layer hens. Recently, Campylobacter hepaticus has been identified as a key pathogen responsible for SLD. The laboratory diagnosis of SLD primarily relies on isolating C. hepaticus colonies, a process hindered by the bacterium's fastidious nature and the requirement for time-consuming and specialized culture conditions. Molecular diagnosis using quantitative real-time PCR (qPCR) overcomes these limitations and offers a more sensitive and specific alternative. However, the existing qPCR assay using a DNA-binding dye chemistry suffers from nonspecific binding to any double-stranded DNA in the sample, which could potentially lead to an increased incidence of false-positive cases. In this study, we present the development of a more specific TaqMan probe-based qPCR assay targeting the glycerol kinase gene of C. hepaticus. This assay demonstrated excellent analytical specificity and sensitivity, with a detection limit of 5 copies/µl and a PCR efficiency of 95.15%. Additionally, it exhibited 100% diagnostic specificity and sensitivity. Furthermore, probe-based PCRs are the most commonly used type of diagnostic PCR assay and are much better suited for routine diagnostics compared to other types of PCRs. In conclusion, the newly developed assay represents a significant advancement in the accurate and efficient diagnosis of SLD caused by C. hepaticus directly from clinical samples.