In the CSF outbreak in the U.K., what was the probable route of virus introduction into this previously CSF-free country?

• A. Exposure to contaminated food discarded by people on a footpath adjacent to a pig farm
• B. Import of an infected animal/animals
• C. Contaminated vaccines
• D. Transmission of the virus from an infected insect vector that was accidentally introduced into the U.K.

Answer: (A)

Classical swine fever can be introduced into a CSF-free country when contaminated pork products or meat-containing waste reach pigs, a route known as swill feeding. The virus can persist in meat and scraps, so discarded food on a footpath near a pig farm provides a realistic way for pigs to ingest infectious material and become infected. This pattern has been seen in outbreaks where illegal swill feeding or improper disposal of contaminated meat near holdings was involved, making it a highly plausible introduction path. Insect vectors and vaccine contamination are not typical routes for CSF, and while importing infected animals is possible, the described scenario most strongly points to contaminated food waste as the source.