A qualitative risk assessment of imports of animal feed as a potential pathway for Aujeszky's disease virus incursion

Aujeszky's disease (AD) is a highly contagious disease of pigs that primarily transmits by respiratory and oral routes. Evidence from recent outbreaks suggests that some swine viruses can survive in contaminated animal feed, thus posing a risk of entry via imports from other countries. To this end, a qualitative risk assessment was undertaken to determine the risk of introduction of AD virus (ADV) and infection of pigs via this route to determine if contaminated animal feed is a viable pathway for the spread of ADV. The feed categories investigated were soya bean/meal/oilcake, pet food, choline/lysine and spray dried porcine plasma. These were chosen based on their use in animal feed and the available data on viral contamination. The overall probability of an animal becoming infected from the importation of feed contaminated with ADV was estimated as Negligible or Very Low for all feed categories. The uncertainty associated with the estimates was assessed as Medium, due to the lack of data around the mechanisms that ADV could contaminate feedstuffs and for infection of susceptible animals from ADV infected feed.