EASY TO CATCH, HARD TO DETECT
- BVDV is a highly contagious virus that can infect both beef cattle and dairy cattle
- Most infections are subclinical, meaning cattle show few or no signs
- The virus mutates and changes over time
- The most common BVDV subtypes include Type 1b, which is the most prevalent strain, Type 1a and Type 21
- BVDV can contribute to reproductive disease (abortions and birth defects), respiratory disease and, less commonly, diarrhea
ECONOMIC IMPACT
- Poor reproduction
- Decreased or delayed conception
- Early embryonic death
- Abortions and stillborns
- Birth defects, weak calves
- Longer calving interval
- Persistently infected calves
- Increased incidence of other bovine health problems
- Mastitis, decreased milk production
- Bovine respiratory disease/Pneumonia
- Calf scours
- Increased mortality
HOW BVDV IS SPREAD
1. From an infected dam to the fetus
- The virus is spread through the bloodstream to the fetus (vertical transmission)
- Infection may cause resorption, abortions and stillbirths
- Calves that survive may have birth defects or become persistently infected (PI), shedding the virus for a lifetime
2. From infected cattle to healthy cattle
- Infected animals can shed the virus in saliva, nasal and eye discharge, urine, feces, milk and semen, exposing other animals (horizontal transmission)
- In addition to nose-to-nose contact, transmission occurs when the virus is ingested or inhaled, and when animals are exposed to contaminated objects (fomites) such as boots and tools
TWO TYPES OF INFECTION
PERSISTENT INFECTION
- Acquired from dam while in uterus
- Lasts a lifetime
- Major source of viral shedding
TRANSIENT INFECTION
- Acquired from other animals after birth
- Lasts a few weeks
- Minor source of viral shedding
MOST INFECTED CATTLE ESCAPE DETECTION
- 70–90 percent of BVDV infections are subclinical (no obvious signs) and go unnoticed
- Most common indication is poor reproductive performance: decreased conception rates, abortions, stillbirths, weak calves
- Infection suppresses the immune system, making cattle more susceptible to other infectious diseases:
- In calves, may result in decreased weaning weight, scours, pneumonia and death
- In older animals, may lead to respiratory disease and bleeding disorders
SIGNS OF TRANSIENT INFECTION
Signs can vary from mild to severe and may include:
- Depression
- Loss of appetite
- Decreased milk production
- Increased respiratory rate
- Nasal and/or eye discharge
- Diarrhea
- Oral ulcers
- Fever
- Death
