What is bvd

What is Bovine Viral Diarrhea?

Bovine viral diarrhea (BVD) is a contagious viral disease caused by a pestivirus that affects cattle populations worldwide. The disease was first identified in the 1940s and remains a significant problem in beef and dairy cattle operations globally. BVD causes economic losses through reduced production, increased mortality, and costs associated with treatment and prevention.

Viral Characteristics

The BVD virus is a member of the pestivirus genus and has two biotypes: non-cytopathic (NCP) and cytopathic (CP). The non-cytopathic form is more common and transmissible, while the cytopathic form typically emerges in persistently infected animals. The virus is relatively fragile and is inactivated by heat, drying, and common disinfectants, but survives well in cool, moist conditions.

Two Forms of Infection

BVD presents in two distinct patterns:

• Acute infection: Temporary infection lasting 1-2 weeks with clinical signs including fever, diarrhea, and nasal discharge, followed by recovery and immunity
• Persistent infection (PI): Lifelong infection in cattle infected in utero or as newborns, resulting in stunted growth and continuous virus shedding; PI animals are the primary reservoir

Clinical Signs and Symptoms

Infected cattle commonly exhibit fever (104-107°F), depression, reduced appetite, diarrhea ranging from mild to severe, nasal discharge, and oral ulcerations. The virus causes severe immunosuppression, leaving cattle susceptible to secondary bacterial infections including pneumonia and respiratory disease. Some cattle develop hemorrhagic disease or sudden death.

Transmission and Spread

BVD spreads through direct contact with infected cattle, contaminated feed and water, shared equipment, and fomites. Aerosol transmission occurs through nasal secretions. Persistently infected cattle are the most significant source of transmission, shedding virus continuously in all body secretions.

Prevention and Control

Effective BVD control involves a comprehensive approach: identification and removal of persistently infected animals through testing, implementation of vaccination programs, strict biosecurity measures to prevent introduction of the virus, and quarantine of new animals. Many countries have implemented BVD eradication programs with significant success in reducing disease prevalence.