Assessment of the cost effectiveness of compulsory testing of introduced animals and bulk tank milk testing for bovine viral diarrhea in Japan

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

In Japan, after the identification of BVD being a notifiable disease in 1998, the number of diagnosed cases has stabilized to between 100 and 200 animals per year [21] . According to the latest survey of PI animals in Japanese dairy farms, the proportions of farms with PI animals and of cattle diagnosed as PI animals were 7.6% [95% confidence interval (CI): 3.1-16.4%] and 0.12% [95% CI: 0.05-0.25%], respectively [21] . Specific control measures, including mass vaccination, screening tests using BTM, and active surveillance for PI cattle, have been voluntarily implemented at areas at a high risk of BVD in collaboration with governments and agricultural parties at the local level [20, 32] . Each of local governments in Japan is required to select the optional control measures under limited human and financial resources. Implementation of these intensive control measures could markedly reduce risks of BVDV infection in BVD endemic areas; however, the sustainability of these control measures should be focused to maintain a very low or negligible level of BVD risk. Mathematical models dealing with BVD have been developed to enable us to simulate its spread in the area specified in the computer program and to identify factors affecting intra-or inter-herd disease spread [8, 10, 12, 17, 18, 39] . Indeed, simulation analyses of various control measures for BVD in Japan using a stochastic model or a scenario tree were recently reported [19, 35] ; however, the cost effectiveness of the BVD control measures was not fully analyzed.