BackgroundMycoplasma synoviae (MS) is an important poultry pathogen worldwide. This bacterium may cause eggshell changes including an altered shell surface, thinning, and increased translucency in different areas, which leads to a greater incidence of eggshell cracks and breaks. In the present study the association between experimental infection of birds with two field strains of MS from different genotypes and the production of abnormal eggs is described. The analysis of those eggshells using a full-field optical coherence tomography (FF OCT) scanner is also reported.ResultsEggshell samples were obtained from three experimental groups of chickens: one control and two infected tracheally with field strains of MS which produced abnormal eggs. In both experimental groups infected with MS a reduction of mean daily egg production by 11% was observed compared to the control group, which started at 21 to 42 dpi. Eggshell apex abnormalities increased to 24.5% of eggs and in some cases, soft-shelled eggs were produced. This study provides the first analysis of shells from anomalous eggs carried out using FF OCT, which allows three-dimensional structural imaging of an investigated sample at micrometre scale. FF OCT showed ultrastructural changes in eggshells and a smaller number of pores on the entire surface of the affected shells.ConclusionsThe eggshell pathology and the concomitant egg production losses that result from infections highlight the economic significance of MS in commercial poultry. There are differences in the strains of MS which may induce eggshell apex abnormalities (EAA) and egg production losses. The use of FF OCT, which is a noninvasive measurement method based on analysis of the light backscattered from the measured object, will confer the ability to control the quality of eggshells in flocks infected with MS.

Broiler chickens with clinical signs of uneven growth, depression, and dull feathers were submitted to our laboratory and, at necropsy, lesions in proventriculus, gizzard, and intestines were detected. Fowl adenovirus serotype 1 (FAdV-1) was isolated from digestive tissues. The virus, assigned as FAdV-PL/G068/08, showed 99.5% nucleotide homology and 99.2% amino acid homology in hexon gene with chicken embryo lethal orphan (CELO) strain classified as the European reference of FAdV-1. One-day-old and 21-d-old SPF chickens were inoculated with FAdV-PL/068/08 by both nasal and ocular routes and then observed daily and examined by necropsy at 6, 10, and 14 d postinoculation. Experimental infection with isolated virus was fatal for younger chickens and major lesions occurred in the gizzards. No clinical or pathological changes were observed in chickens infected at 21 d of age, but the presence of intranuclear inclusion bodies in gizzard epithelial cells was detected. Molecular characterization was based on the long and short fibers genes sequencing and comparison of obtained sequences with other FAdV-1 strains. The homology between FAdV-PL/G068/08 and other sequences available in GenBank was between 98.9 and 99.8% (short fiber region) and 99.0 and 99.7% (long fiber region) at nucleotide level and between 98.4 and 100% (short fiber region) and 99.3 and 99.9% (long fiber region) at amino acid level. No correlation between identified amino acid changes in short and long fiber proteins and pathogenicity of studied FAdV-1 strains was observed. Although short and long proteins were indicated as factors influencing virus pathogenicity, the role of identified sequence differences in infectivity determination remain unclear.

In April/May 2013, four outbreaks of avian influenza virus (AIV) infections caused by H9N2 subtype were diagnosed in Poland in fattening turkey flocks exhibiting a drop in feed and water intake, depression, respiratory signs and mortality. The subsequent serological survey carried out on samples collected between June 2012 and September 2013 from 92 poultry flocks detected positive sera in two additional meat turkey flocks located in the same province. The analysis of amino acids in the haemagglutinin and neuraminidase glycoproteins revealed that the detected H9N2 viruses possessed molecular profiles suggestive of low pathogenicity, avian-like SAα2,3 receptor specificity and adaptation to domestic poultry. Phylogenetic studies showed that these H9N2 AIVs grouped within the Eurasian clade of wild bird-origin AIVs and had no relationship with H9N2 AIV circulating in poultry in the Middle East and Far East Asia over the past decade. Experimentally infected SPF chickens with the index-case H9N2 virus remained healthy throughout the experiment. On the other hand, ten 3-week-old commercial turkeys infected via the oculonasal route showed respiratory signs and mortality (2/10 birds). Additional diagnostic tests demonstrated the consistent presence of DNA/RNA of Ornithobacterium rhinotracheale, Bordetella avium and, less frequently, of astro-, rota-, reo-, parvo- and adenoviruses in turkeys both from field outbreaks and laboratory experiment. Although no microbiological culture was performed, we speculate that these secondary pathogens could play a role in the pathogenicity of the current H9N2 infections.

IntroductionRepeated incursions of highly pathogenic avian influenza virus (HPAIV) H5 subtype of Gs/GD lineage pose a serious threat to poultry worldwide. We provide a detailed analysis of the spatio-temporal spread and genetic characteristics of HPAIV Gs/GD H5N8 from the 2019/20 epidemic in Poland.Material and methodsSamples from poultry and free-living birds were tested by real-time RT-PCR. Whole genome sequences from 24 (out of 35) outbreaks were generated and genetic relatedness was established. The clinical status of birds and possible pathways of spread were analysed based on the information provided by veterinary inspections combined with the results of phylogenetic studies.ResultsBetween 31 December 2019 and 31 March 2020, 35 outbreaks in commercial and backyard poultry holdings and 1 case in a wild bird were confirmed in nine provinces of Poland. Most of the outbreaks were detected in meat turkeys and ducks. All characterised viruses were closely related and belonged to a previously unrecognised genotype of HPAIV H5N8 clade 2.3.4.4b. Wild birds and human activity were identified as the major modes of HPAIV spread.ConclusionThe unprecedentedly late introduction of the HPAI virus urges for re-evaluation of current risk assessments. Continuous vigilance, strengthening biosecurity and intensifying surveillance in wild birds are needed to better manage the risk of HPAI occurrence in the future.

Mycoplasma gallisepticum is one of the most important poultry pathogens that can also infect wild birds, but knowledge of potential non-poultry hosts that could be reservoirs of M. gallisepticum is limited. For the paper presented here, we screened three databases (PubMed, Scopus, and the Web of Knowledge) to find articles on the occurrence of M. gallisepticum in different wild bird species that were published between 1951 and 2018. Among 314 studies found, we selected and included 50 original articles that met the pre-established criteria. From those publications we extracted the following information: name of the first author, year of publication, year of sample isolation, country, region, number of birds sampled, number of birds tested by each method, number of positive samples, diagnostic criteria, and if birds were wild or captive. Because different detection techniques were used to confirm the presence of M. gallisepticum in one animal, we decided to perform the meta analyses separately for each method. The estimated prevalence of M. gallisepticum in wild birds was different by each method of detection. Our summary revealed that M. gallisepticum was present in 56 species of bird belonging to 11 different orders, of which 21 species were reported suffering both past and current infection. Our work provides information on wild bird species that could be considered potential reservoirs or carriers of M. gallisepticum and could be helpful to set the direction for future research on the spread and phylogeny of M. gallisepticum in different hosts.