Bovine viral diarrhea

Viral disease affecting cattle

Tongue ulcers caused by Bovine Viral Diarrhea

Bovine viral diarrhea (BVD) is a significant infectious disease affecting cattle worldwide. It is caused by the Bovine viral diarrhea virus (BVDV), which belongs to the genus Pestivirus in the family Flaviviridae. BVD can lead to a range of clinical manifestations, from subclinical infections to severe disease, impacting the health and productivity of cattle.

Virology

Bovine viral diarrhea virus CP7 strain

BVDV is an RNA virus with a single-stranded, positive-sense RNA genome. The virus is classified into two main genotypes, BVDV-1 and BVDV-2, each with multiple subtypes. These genotypes can further be divided into cytopathic (cp) and non-cytopathic (ncp) biotypes based on their effects on cultured cells. The ncp biotype is more commonly associated with persistent infections in cattle.

Transmission

BVDV is primarily transmitted through direct contact with infected animals. The virus can be spread via bodily secretions such as saliva, nasal discharge, urine, and feces. Vertical transmission from dam to fetus can occur, leading to persistently infected (PI) calves if the infection occurs during early pregnancy.

Clinical Signs

The clinical presentation of BVD can vary widely. In acute infections, cattle may exhibit fever, diarrhea, respiratory distress, and immunosuppression. In pregnant cows, BVDV can cause reproductive issues such as abortion, stillbirth, or the birth of weak calves. PI animals often appear normal but can develop mucosal disease, characterized by severe ulceration of the gastrointestinal tract and high mortality.

Diagnosis

Diagnosis of BVD involves a combination of clinical observation, serological testing, and molecular techniques. Polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) are commonly used to detect viral RNA and antibodies, respectively. Identifying PI animals is crucial for controlling the spread of the virus.

Prevention and Control

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Fetal calf serum from a different animal

Effective control of BVD involves a combination of biosecurity measures, vaccination, and management practices. Vaccination programs can help reduce the incidence of acute infections and prevent fetal infections. Biosecurity measures include testing and culling PI animals, controlling animal movement, and maintaining closed herds.

Economic Impact

BVD has a significant economic impact on the cattle industry due to decreased productivity, increased veterinary costs, and losses from reproductive failures. The presence of PI animals in a herd can lead to ongoing transmission and outbreaks, further exacerbating economic losses.

Related Pages

• Pestivirus
• Flaviviridae
• Viral disease in cattle
• Animal virology