Bovine viral diarrhea virus eradication in Germany: A never-ending success story or just the last 46 PI animals?

Bovine viral diarrhea virus (BVDV) is a globally significant pathogen of cattle, causing significant reproductive failure, immunosuppression, and economic losses. In Germany, a national bovine viral diarrhea (BVD) control program was initiated in 2011, aiming to eliminate the virus through systematic testing and early removal of persistently infected (PI) animals, supported by optional vaccination in the early stage of the program, biosecurity measures, and trade with certified unsuspicious cattle only. By 2024, the PI prevalence among newborn calves had declined from 0.473 % in 2011 to just 0.001 %, with only 46 PI calves detected among over 4 million tested each year. Virus subtyping based on sequencing of the 5' untranslated region of positive samples identified BVDV-1d as the predominant subtype in most affected federal states though with sequence variation between states, while BVDV-1b was limited to Schleswig-Holstein. Comparisons with publicly available sequences reveal that for some federal states the highest nucleotide identity exists to local strains, while for others there are indications of virus introductions from other European countries. Limited transmission and localized virus persistence are suggested by within-state sequence homogeneity and between-state variation. These findings highlight the significant success of Germany's BVDV eradication strategy, which led to 99.994 % BVDV-free herds and thereby demonstrated that systematic identification and removal of PI animals, combined with surveillance and biosecurity, can drive virus prevalence to near-elimination levels. Continued molecular monitoring and rapid response to residual cases remain essential to prevent re-emergence and to safeguard the progress achieved toward national BVDV eradication.