Repeated 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. Samples 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. Between 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. The 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.

Newcastle and Influenza diseases are important viral diseases and its occurrence and virulence in Iran has increased in recent years. The purpose of this study was to evaluate the humoral immune responses of chickens vaccinated with inactivated dual oil emulsion Newcastle disease and avian influenza vaccine in two methods of intramuscular and subcutaneous injection as well as to assess the possible changes in serum biochemical factors. In this study, after subcutaneous and intramuscular inoculation of inactivated dual oil emulsion Newcastle-Influenza vaccine, the serum antibody level and hematobiochemical factors of these avian were analyzed on 7, 14, 21, and 28 days after vaccine injection.The results showed that the values of biochemical parameters such as albumin, glucose, total protein, triglyceride, cholesterol, ALT, AST, and ALP enzymes, sodium and potassium minerals, and hematocrit and hemoglobin levels in vaccinated and non-vaccinated chickens were not significantly different. Also, in chickens injected with antigen, Newcastle disease and influenza antibody titers were significantly different with those groups containing adjuvant.The results of this study indicate that the intramuscular and subcutaneous injection of dual combination vaccine is similar in terms of changes in biochemical and hematological factors and Newcastle disease and influenza antibody titers. To ensure safety in inactivated vaccines, the presence of proper adjuvant is essential for immune response.