Swine Influenza Virus Introduction in Pig Farms: A Semi-Quantitative Risk Assessment in Northern Italy.

Swine influenza is a viral zoonotic respiratory disease of pigs threatening both animal and human health due to its pandemic potential. We conducted a semi-quantitative risk assessment to classify 22 commercial pig farms in northern Italy in terms of the likelihood of introduction of influenza, evaluating their biosecurity systems and geographical locations. We used a modified Failure Mode and Effect Analysis (FMEA) to calculate Risk Priority Codes (RPCs), indicating increasing risk levels (from 1 to 5) for six biosecurity criteria: (A) personnel, (B) animal management, (C) shelter management, (D) animal transport, (E) materials management, and (F) buildings and access control. Then, an overall risk index, including the geographical risk, was calculated to obtain the final risk ranking of the farms. All farms obtained the highest risk level (RPC = 5) for criterion F (buildings and access control), mostly due to poor control of visitor access. Fifteen farms scored a medium risk level (RPCs = 3) for criterion related to personnel due to some weaknesses in the use of personal protective equipment, although 90% of personnel had recent biosecurity training. In an endemic context, risk assessment helps identify high-risk farms, supporting surveillance for early detection of new influenza strains.