Bovine Viral Diarrhea Mucosal Disease
The majority of infections with BVD viruses are asymptomatic. Possible symptoms are diarrhea, fever, respiratory diseases, mucosal erosions, feeding instability, reduced milk yield, and fertility problems. Pregnant animals may reject, give birth to malformed or weak calves. Mucosal disease, which is fatal, occurs as a special disease variant.
Bovine Viral Diarrhea/Mucosal Disease is one of the most economically important infectious diseases of cattle worldwide. Many countries have adopted active control and surveillance programs for BVD/MD. The disease is caused by a pestivirus, family Flaviviridae, and has a worldwide distribution. Host animals are cattle, sheep, goats and wild ruminants.
The route of transmission of BVD is mainly through persistently (permanently) infected animals (PI animals). They are the main source of virus spread. The emergence of a PI animal occurs through infection of the unborn calf via the dam between the 40th and 120th day of gestation. At this time, the immune system of the fetus is not fully developed, immune tolerance to the virus develops, and the animals remain infected throughout their lives and excrete the virus. Excretion occurs through all body secretions and excretions.
The majority of BVD virus (BVDV) infections are asymptomatic. Possible symptoms include diarrhea, fever, respiratory disease, mucosal erosions, feeding instability, reduced milk yield, and fertility problems. Pregnant animals may reject, give birth to malformed or weak calves.
Mucosal disease (MD) occurs as a special disease variant. It occurs when a PI animal is additionally infected with another strain of the virus. MD is characterized by a severe course of disease and is fatal. Symptoms of MD include bloody diarrhea, high fever, mucosal erosions, and ulceration (at the potty mouth, nose, interclaw cleft).
To control BVD, virus excretors (PI animals) present in the herd are eliminated to protect the herd from reinfection.
Antibody detection: Infection with BVDV leads to the formation of antibodies (detectable in blood, individual and tank milk).
Antigen detection: direct pathogen detection (serological and molecular biological methods from blood, tissue and organ samples)
Detection in ear tissue samples: for antigen detection in newborn calves (especially in herds suspected of having BVD)
One of the most important goals in BVD diagnostics is the timely detection of a PI animal. Serological testing using maternal antibodies (antibodies passed from the mother to young animals via colostrum) can mask BVD viruses in the blood, making early detection impossible. This so-called "diagnostic gap" does not play a role in the examination of tissue samples and the detection and eradication of PI animals is already possible in the first week of life. Equally problematic is the delayed rise of antibodies after BVD infection. BVD antibodies are not detectable until approximately day 7 after infection. This time delay is even greater when testing tank milk.
There is no diagnostic gap for PCR diagnostics from a blood sample or when examining an ear punch using PCR.
Last updated: 21.07.2023