Quantitative risk assessment of the introduction of low pathogenic avian influenza H5 and H7 strains into Poland via legal import of live poultry

Low pathogenic avian influenza (LPAI) caused by H5 and H7 viruses is considered a threatening disease for poultry production due to the possibility of prolonged undetected virus circulation in a poultry flock and its potential to mutate to highly pathogenic avian influenza (HPAI). The occurrence of HPAI may have devastating impact on the poultry industry and has serious economic consequences. The possibility of LPAI virus (LPAIV) being introduced into Poland via import of live poultry from EU countries was considered. The main aim of the study was to quantitatively assess the probability of LPAIV H5 and H7 introduction into Poland (PLPAI) via this pathway, to evaluate the relative contribution of exporting countries and species of poultry to this probability and to present the spatial distribution of the introduction probability in Poland. To this end, a stochastic multilevel binomial risk model, taking into account uncertainty and variability of input parameter values, was developed. The results of this model indicate that the mean annual probability of LPAIV H5 or H7 introduction into Poland is 0.088 [95 % uncertainty interval: 0.0575, 0.128], which corresponds to, on average, one outbreak every 11 years. The countries contributing most to this probability are Germany, Czech Republic and Denmark. Importations of ducks, chickens and turkeys contribute most to PLPAI, whereas importations of geese and guinea fowl represent a minor risk. The probability of LPAIV introduction is not equally distributed across Poland with the majority of counties having a high probability of LPAIV introduction being located in the Western part of the country. The results of this study can be used to support decision makers on targeted prevention or risk-based surveillance strategies for LPAI