Bovine Viral Diarrhea (BVD) and Mucosal Disease – NAVLE Study Guide

Overview and Clinical Importance

Bovine Viral Diarrhea (BVD) is one of the most economically significant infectious diseases affecting cattle worldwide. Caused by Bovine Viral Diarrhea Virus (BVDV), a member of the genus Pestivirus within the family Flaviviridae, this disease causes immunosuppression, reproductive losses, respiratory disease, and gastrointestinal disorders. Despite its name, BVD does not specifically affect the digestive tract but rather has immunosuppression as its hallmark feature.

Mucosal Disease (MD) is a distinct, invariably fatal syndrome that occurs only in persistently infected (PI) cattle when they become superinfected with a cytopathic biotype of BVDV. Understanding the relationship between BVD and MD is critical for NAVLE success.

Etiology and Classification

Virus Classification

BVDV is classified within the Pestivirus genus, which also includes Border Disease Virus (sheep) and Classical Swine Fever Virus (pigs). The virus is a small (40-60 nm), enveloped, single-stranded positive-sense RNA virus.