National Institute of Animal Health (NIAH)

Topics in Animal Health Research 2006

07. Epidemiological investigation of the prevalence and features of postweaning multisystemic wasting syndrome in Japan

Japanese

  To investigate the prevalence and features of postweaning multisystemic wasting syndrome (PMWS) in Japan, an epidemiological study was conducted in 692 weaned pigs with wasting or weight loss which were collected from 129 swine farms between 2000 and 2003. The presence of PMWS was diagnosed by detecting characteristic histological lesions and moderate-to-large amounts of porcine circovirus type 2 (PCV2) antigen within the lesions in multiple lymphoid tissues. PMWS was positive in 23.4% of pigs (162/692) over the course of the study and occurred on 50.4% of the farms (65/129). Mortality in 30 to 120-day-old pigs on the farms that were positive for PMWS varied from 0.1% to 32.0%. No significant difference in mortality was seen between PMWS-positive and PMWS-negative farms (p = 0.1). However, mortality was significantly higher in the PMWS-positive farms where PMWS was diagnosed in more than 50% of the pigs examined compared to farms negative for PMWS (p = 0.02). These findings indicate that PMWS has spread widely in Japan. Moreover, subclassification of PMWS into epidemic and endemic forms may be needed in the case definition of PMWS. A case-control study suggested that risk factors for the occurrence of PMWS include porcine reproductive and respiratory syndrome (PRRS) pneumonias and Mycoplasma hyorhinis infection.
(Research Team for Viral Diseases, TEL +81-29-838-7763)

Reference:

Kawashima et al. (2007) J Vet Diagn Invest 19 : 60-68.

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