Bovine viral diarrhoea, Biology

Bovine viral diarrhoea

Bovine viral diarrhoea (BVD) and mucosal disease (MD) are clinically dissimilar disease syndrome yet have a common viral etiology. The acute disease is called as BVD. The term mucosal disease is reserved for chronic disease associated with persistent infection. The pathologic manifestations of infection in individual cattle vary with age and pregnancy status. BVD virus belongs to the genus Pestivirus in the family Flaviviridae. The disease affects dairy and beef-cattle cattle causing fever, explosive diarrhoea, buccal erosions and in adult cattle causing abortion, ocular and cerebral defects.

Clinical signs: Three situations are considered, which include postnatal infection in non-pregnant cattle, infection in pregnant cows and postnatal infection in calves, and mucosal disease in adult cattle.

Postnatal infection in nonpregnant animals, the disease occurs when maternal antibody levels decline by 3-8 months of age. There is fever, leucopenia, diarrhea, nasal and ocular discharge and immunosuppression.

Infection in pregnant animals results in transplacental spread of virus to the fetus. Infection in early pregnancy causes embryonic death and resorption. Infection before development of fetal immunocompetence (80-125 days) results in fetal death or growth retardation, congenital defects. Surviviing calves remain infected for life and never develop effective immune response to the virus. They shed virus in all body secretions and excretions. These animals may develop mucosal disease. Fetuses infected after

125 days of gestation usually survive and develop neutralizing antibody and eliminate the virus.

Persistent infection and mucosal disease develop in some calves. Mucosal disease occurs when two biotypes of BVDV (cytopathic and noncytopathic) are present. There is sudden onset, fever, profuse watery diarrhea, nasal discharge, erosive and ulcerative stomatitis and death.

Diagnosis: Virus isolation in cell culture from feces, nasal exudates, blood and tissues and aborted fetuses. Viral antigen detection can be done in tissues or cell cultures by immunofluorescence and viral RNA can be detected in tissues by   reverse transcription (RT-PCR). Serology with paired serum samples using virus neutralization, agar-gel immunodiffusion, complement fixation and fluorescent antibody and enzyme- linked immunosorbent assay. However, immunological tolerant animals are not detected serologically.

Prevention and control: In most herds, immunization is the only control strategy used. Although vaccines were designed for its control, they have several drawbacks and are not very safe and effective. Vaccines are administrated at 6 months of age. Attenuated virus vaccines produced in cell culture are widely used but there is evidence that vaccination of presently infected immunologically tolerant animals can result in severe mucosal disease in bovine calves.

Posted Date: 9/18/2012 8:16:29 AM | Location : United States







Related Discussions:- Bovine viral diarrhoea, Assignment Help, Ask Question on Bovine viral diarrhoea, Get Answer, Expert's Help, Bovine viral diarrhoea Discussions

Write discussion on Bovine viral diarrhoea
Your posts are moderated
Related Questions
Plants - Rapidly Flowing Waters Among the plants only small, well attached forms, such as sessile algae can survive here. Thus, due to the presence of only a few plants, the n

Active instruments - Do groove occlusally or buccally until reach tooth structure - Apply this instrument then screw to break the bond between tooth structure and crown GC

Origin and Delivery - Transport in Phloem We have stated above that transport of photosynthates starts from leaves and ends up in one or the other sink tissue. Though this is

Salmonellosis Salmonellosis is an infection caused by bacterial species belonging to the genus Salmonella and usually associated with the ingestion of food containing salmonel

Define Energy Requirement for Cancer Patients? It must be clear to you that cancer imposes increased energy demands because of the hyper-metabolic state of the disease process

Write short notes on Urine? The concentrated filtrate produced by the kidney is called urine, and is composed mainly of water, urea, toxins, and mineral salts. Urine from the c

Why Vegetable and Fruit are important for human body? The vegetables and fruits add colour and variety to our diets in addition to providing a host of essential nutrients and p

Differential reinforcement (Training of incompatible behaviour)- Differential reinforcement of incompatible behaviour (DRI) is used to decrease a frequent behaviour without pun

Emulsions  You may have eaten Mayonnaise. Some  of you may also know how it is made. Mayonnaise is a liquid in liquid  dispersion, in fact a true  emulsion.  A true emulsion re

Which law of thermodynamics explains the fact that we must eat to gain the energy to perform the functions of life, such as breathing? a. fourth law b. first law c. second law d