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

Models to assess the risk of introduction of selected animal viral diseases through the importation of live animals as a key part of risk analysis

“…The risk of introduction of several infectious viral diseases of animals into an importing country has already been assessed quantitatively using probabilistic models (2, 3, 6, 9, 11, 13, 14, 15, 17, 18, 19, 20, 21, 23, 29, 30, 32, 34). The step prior to the models’ development was the formulation of the chain of events needed for the entry into and possible further spread within the specific population of the virus of interest in an importing country ( 13 , 14 , 29 ). The events were expressed as probability distributions.…”

“…This model was subsequently adapted to the assessment of the risk for Poland ( 13 ). The multilevel binomial model was also used to estimate the probability of low pathogenic avian influenza virus’s (LPAIV) introduction into Poland and CSF’s into Denmark ( 3 , 14 ). The one-level binomial model, in turn, was applied to the risk assessment of the introduction of CSF and of several other viral infectious diseases such as Aujeszky’s disease, FMD, and ASF (6, 9, 15, 17, 18, 19, 20, 21, 23).…”

“…The probability of classical swine fever virus (CSFV) introduction into EU member states via import of pigs and pork products, returning livestock trucks and contact with wild boars was high for several countries: as an example, it was shown that the Netherlands can expect on average one CSF outbreak every 18 years in line with this multiple-risk pathway model ( 9 ). Introductions of CSFV into Spain through pig and wild boar movement, foot and mouth disease virus (FMDV) into the Malaysia–Thailand–Myanmar peninsula through livestock movement and LPAIV into Poland through importation of poultry were also likely scenarios and might cause one outbreak approximately every 9, 9 and 11 years, respectively ( 14 , 20 , 34 ). In contrast, the probability of highly pathogenic avian influenza virus (HPAIV) introduction into Spain and Poland via poultry trade was almost negligible and one outbreak respectively every 735 and 326 years would be expected to occur in these two countries ( 13 , 29 ).…”

“…Among the input parameters of the models, some of the most influential were the ones associated with the epidemiological situation in the country of origin, such as inter- and intra-herd prevalence ( 2 , 3 , 14 , 17 , 18 , 23 ) and the expected number of outbreaks before the detection of a disease ( 3 , 23 ). The other weighty parameters were the ones associated with the mitigation of risk through the implementation of biosecurity measures in the destination country, such as quarantining animals ( 2 , 15 , 19 ), serological testing ( 17 ) or disinfecting animal transport vehicles ( 2 , 3 , 9 ).…”

“…The other weighty parameters were the ones associated with the mitigation of risk through the implementation of biosecurity measures in the destination country, such as quarantining animals ( 2 , 15 , 19 ), serological testing ( 17 ) or disinfecting animal transport vehicles ( 2 , 3 , 9 ). The disease-related parameters of length of the infectious period of a subclinically infected flock ( 14 ), probability of survival of an infected animal ( 23 ) and probability of the presence of detectable signs of infection during quarantine ( 34 ) also altered the introduction probability output value. This probability also differed greatly between different species of animals: for instance, animals carrying a virus asymptomatically posed a higher risk of introducing a disease because of the possibility of viral infection going undetected in their herd in the country of origin and subsequently during shipment or even the quarantine period.…”