Implementation and Verification of the Effectiveness of a Regional Control Program for Bovine Viral Diarrhea Virus Infection in Hokkaido, Japan

Abstract

A regional control program for Bovine Viral Diarrhea Virus (BVDV) was initiated in 2006 in the town of Nemuro, Hokkaido, Japan. All dairy heifers were immunized annually with live (L) and killed (K) vaccines (LK method). After 42 months of LK, 90% of cattle were seropositive, with neutralizing antibody titer for BVDV. Samples of bulk tank milk from all 880 dairy herds in the region were screened annually for BVDV through a reverse transcription polymerase chain reaction. Fifty-six persistently infected (PI) heifers were identified in the first 6 years, and the number of PI heifers then decreased every year. Virus isolation from the sera of all heifers raised in public pastures was performed annually. Seven PI animals out of 12,349 heifers were identified as being raised in public pastures, and these animals were immediately slaughtered. This program led to a decrease in the birth of PI animals, and the LK vaccination method had also protected fetuses from BVDV infection since 2008. These results indicated that this regional program based on the vaccination and slaughter of PI heifers was significantly effective as the first step in controlling BVD.