[Endemic viral diseases: a serious economic problem in the Japanese pig industry]

As of February 2009, the Japanese pig industry included 6,890 farms housing a total of 9,899,000 pigs, and produces approximately half of the pig meat consumed in the Japanese domestic market. Although the number of pigs has not substantially changed over the past 20 years, the number of farms has decreased by 86%, indicating the rapid progression of scale expansion in Japan. Against this background, two emerging viral diseases first noted in the 1990s, porcine reproductive and respiratory syndrome (PRRS) and porcine circovirus associated diseases (PCVAD), are now endemic in many farms and causing serious economic losses. This review provides a brief overview of clinical aspects of these two endemic viral diseases and describes the current status of control efforts.