Swine outbreak of pandemic influenza A virus on a Canadian research farm supports human-to-swine transmission.

Background: Swine outbreaks of pandemic influenza A (pH1N1) suggest human introduction of the virus into herds. This study investigates a pH1N1 outbreak occurring on a swine research farm with 37 humans and 1300 swine in Alberta, Canada, from 12 June through 4 July 2009.

Methods: The staff was surveyed about symptoms, vaccinations, and livestock exposures.