Detection of a novel enterotropic Mycoplasma gallisepticum-like in European starling (Sturnus vulgaris) around poultry farms in France.

Recent outbreaks of highly pathogenic avian influenza in southwest France have raised questions regarding the role of commensal wild birds in the introduction and dissemination of pathogens between poultry farms. To assess possible infectious contacts at the wild-domestic bird interface, the presence of Mycoplasma gallisepticum (MG) was studied in the two sympatric compartments in southwest France. Among various peridomestic wild birds (n = 385), standard PCR primers targeting the 16S rRNA of MG showed a high apparent prevalence (up to 45%) in cloacal swabs of European starlings (Sturnus vulgaris, n = 108), while the MG-specific mgc2 gene was not detected. No tracheal swab of these birds tested positive, and no clinical sign was observed in positive birds, suggesting commensalism in the digestive tract of starlings. A mycoplasma strain was then isolated from a starling swab and its whole genome was sequenced using both Illumina and Nanopore technologies. Phylogenetic analysis showed that it was closely related to MG and M. tullyi, although it was a distinct species. A pair of specific PCR primers targeting the mgc2-like gene of this MG-like strain was designed and used to screen again the same avian populations and a wintering urban population of starlings (n = 50). Previous PCR results obtained in starlings were confirmed to be mostly due to this strain (20/22 positive pools). In contrast, the strain was not detected in fresh faeces of urban starlings. Furthermore, it was detected in one cloacal pool of white wagtails, suggesting infectious transmissions between synanthropic birds with similar feeding behaviour. As the new Starling mycoplasma was not detected in free-range ducks (n = 80) in close contact with positive starlings, nor in backyard (n = 320) and free-range commercial (n = 720) chickens of the area, it might not infect poultry. However, it could be involved in mycoplasma gene transfer in such multi-species contexts.

Backyard poultry flocks in France: A diversity of owners and biosecurity practices.

Over the past few years, the number of backyard poultry flocks has been increasing in France. A mandatory step to improve backyard poultry management is to assess health risks by characterizing the flocks and understanding the owners' motivations for keeping poultry and their husbandry practices. A survey of backyard poultry owners was conducted in France to gather information about their motivations for owning poultry, flock characteristics, and breeding and biosecurity practices. The survey was completed by 1,160 owners. The major motivations for owning poultry flocks were egg consumption (93.3 %), recycling (72.4 %) and having pet animals (53.2 %). Most owners had already heard about avian influenza (96.7 %), but were less aware about other diseases such as Newcastle Disease (41.6 %), salmonellosis (79.1 %), or campylobacteriosis (18.6 %). Owners mainly kept only egg-layers (78.4 %), and the median size flock was five egg-layers. Owners gave eggs to their relatives, occasionally or regularly, in 86.6 % of the cases. Contacts with other family poultry owners were frequent (68.9 %) and biosecurity practices were poorly implemented: 50 % of owners did not wash their hands systematically after visiting the flock and more than 60 % of owners did not wear specific shoes. Drawing from the survey data, five profiles of family poultry flocks were identified with multiple correspondence analysis and hierarchical cluster analysis. The profiles, based on flock characteristics and owners' practices and motivations, illustrate the heterogeneity of the backyard poultry sector: 1) urban poultry, 2) traditional poultry, 3) student poultry, 4) pet poultry and 5) hobby poultry. Urban poultry consisted of recently constituted (< 2 years old), small (< 3 birds) flocks of layers, and traditional poultry of older, medium-sized flocks belonging to retired and older people. These two profiles were characterized by limited contacts (direct or indirect) with other flocks and owners. Student poultry consisted of younger owners (<30 years old) with flocks over 5 years old. Pet poultry consisted of recently established, medium-size flocks of layers located in both rural or urban environments. Hobby poultry consisted of dedicated owners who breed and sell poultry and participate in exhibitions and poultry shows. Pet and hobby poultry profiles were characterized by greater knowledge of diseases and biosecurity practices, more bird movements, and reported more frequent clinical signs. The observation of different profiles can help target veterinary and public health education messages to prevent disease transmission in backyard poultry flocks in France.

Viral tropism and detection of clade 2.3.4.4b H5N8 highly pathogenic avian influenza viruses in feathers of ducks and geese.

Highly Pathogenic Avian Influenza viruses (HPAIVs) display a tissue pantropism, which implies a possible spread in feathers. HPAIV detection from feathers had been evaluated for H5N1 or H7N1 HPAIVs. It was suggested that viral RNA loads could be equivalent or higher in samples of immature feather compared to tracheal (TS) or cloacal swabs (CS). We investigated the suitability of feathers for the detection of clade 2.3.4.4b H5N8 HPAIV in ducks and geese field samples. In the six H5N8 positive flocks that were included in this study, TS, CS and immature wing feathers were taken from at least 10 birds. Molecular loads were then estimated using real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) targetting H5 and M genes. In all flocks, viral loads were at least equivalent between feather and swab samples and in most cases up to 103 higher in feathers. Bayesian modelling confirmed that, in infected poultry, RT-qPCR was much more likely to be positive when applied on a feather sample only (estimated sensitivity between 0.89 and 0.96 depending on the positivity threshold) than on a combination of a tracheal and a cloacal swab (estimated sensitivity between 0.45 and 0.68 depending on the positivity threshold). Viral tropism and lesions in feathers were evaluated by histopathology and immunohistochemistry. Epithelial necrosis of immature feathers and follicles was observed concurrently with positive viral antigen detection and leukocytic infiltration of pulp. Accurate detection of clade 2.3.4.4b HPAIVs in feather samples were finally confirmed with experimental H5N8 infection on 10-week-old mule ducks, as viral loads at 3, 5 and 7 days post-infection were higher in feathers than in tracheal or cloacal swabs. However, feather samples were associated with lower viral loads than tracheal swabs at day 1, suggesting better detectability of the virus in feathers in the later course of infection. These results, based on both field cases and experimental infections, suggest that feather samples should be included in the toolbox of samples for detection of clade 2.3.4.4b HPAI viruses, at least in ducks and geese.

Role of Backyard Flocks in Transmission Dynamics of Highly Pathogenic Avian Influenza A(H5N8) Clade 2.3.4.4, France, 2016-2017.

Highly pathogenic avian influenza A(H5N8) clade 2.3.4.4 spread in France during 2016-2017. We assessed the biosecurity and avian influenza virus infection status of 70 backyard flocks near H5N8-infected commercial farms. One flock was seropositive for clade 2.3.4.4. Backyard flocks linked to commercial farms had elevated risk for H5 infection.