National Institute of Animal Health (NIAH)

Topics in Animal Health Research 2000

18. Lymphopenia in Naturally Acquired Cases of Postweaning Multisystemic Wasting Syndrome (PMWS)

Japanese

  Postweaning multisystemic wasting syndrome (PMWS) is an emerging disease of swine. One interesting aspect of PMWS is that the disease is frequently associated with concurrent infection with various pathogens, suggesting that the disease degrades host defense mechanisms. In this study, we investigated blood lymphocyte counts in pigs affected by PMWS, and attempted to clarify the association between the changes in lymphocyte and lesions. Pigs affected with PMWS showed significantly decreased lymphocyte number in the blood in comparison to control animals. The number of T and B cells markedly declined in blood of pigs affected with PMWS. In surviving pigs, lymphopenia gradually improved in accompaniment with improvement in clinical condition. In the lymphatic organs of pigs severely affected with PMWS the percentage of T and B cells decreased in comparison to pigs in convalescence. Severely affected pigs had typical pathologic changes of PMWS with a copious amount of PCV2 in lymphatic tissues. In total, these results suggest that lymphopenia is a typical event of PMWS. (Environmental Hygiene Section, Shichinohe Research Unit, TEL +081-176-62-5115)

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