Evaluation of control measures for bovine viral diarrhea implemented in Nemuro District, Hokkaido, Japan, using a scenario tree model

ISODA, Norikazu; ASANO, Akihiro; ICHIJO, Michiru; WAKAMORI, Shiho; OHNO, Hiroshi; SATO, Kazuhiko; OKAMOTO, Hirokazu; NAKAO, Shigeru; KATO, Hajime; SAITO, Kazuma; ITO, Naoki; USUI, Akira; TAKAYAMA, Hiroaki; SAKODA, Yoshihiro

doi: 10 .1292/jvms. infection (TI) of BVDV in adult ruminants shows subclinical or non-severe symptoms [8, 25] ; however, BVDV viruses can be transmitted to the fetus in pregnant cattle during the 40-120 days of gestation, thereby inducing fetus immune tolerance to BVDV and resulting in the delivery of persistently infected (PI) calves [3, 9-10, 17, 22, 26] . The PI calves shed BVDVs through oculonasal discharge and other secretions throughout their lives, without showing apparent clinical manifestations except for fatal mucosal disease [7, 12] . It is commonly believed that PI cattle are the primary source of BVDV infection in a herd [17, 27] . Therefore, it is essential for the control of BVD that PI cattle are promptly detected and culled [1] .