No clinical abnormalities were observed in all the pigs in the infected farm through surveillance conducted by the prefectural veterinary authority on 22 October 2009.
A total of 102 nasal swabs were collected from all 42 pigs kept in the same pen as the cases, 20 pigs in the same house and other 40 pigs in the same premises. Samples were submitted for PCR test for influenza A subtype H1 and all results were negative.
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