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Bovine viral scours, Bovine winter dysentry, Coronaviral enteritis of calves, scours, winter dysentery.

Also know as: '''Bovine Viral Scours — Bovine Winter Dysentry — Coronaviral Enteritis of Calves — Scours — [[Winter Dysentery]]

 

== Introduction ==

== Introduction ==

Bovine coronavirus (BCV) was characterized as a viral cause of calf enteritis by Mebus et al. (1973) and is now recognized as a leading cause of calf enteritis around the world. The virus infects the enteric and/or upper respiratory tract of calves that are 1-week to 3-months-old and contributes to [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]. In adult animals, the disease is usually sub-clinical, and the virus may be excreted intermittently at low titre (Schoenthaler and Kapil, 1999). Bovine coronavirus has also been identified as the etiological agent of [[Winter Dysentery|Winter dysentery]]  in adult cows (Saif, 1990). The incidence of BCV varies in different parts of the world but published and annual reports indicate that BCV causes 15-30% of calf enteritis cases (Langpap et al., 1979). The incidence of diarrhoea from bovine coronavirus may be underestimated because many laboratories around the world are not equipped with BCV antigen detection methods such as electron microscopy and BCV ELISA; also the isolation of BCV in tissue culture is difficult (Kapil et al., 1996). Bovine coronavirus infection occurs in combination with other enteric viral, bacterial, parasitic, and protozoal pathogens.  

Bovine coronavirus (BCV) was characterized as a viral cause of calf enteritis by Mebus et al. (1973) and is now recognized as a leading cause of calf enteritis around the world. The virus infects the enteric and/or upper respiratory tract of calves that are 1-week to 3-months-old and contributes to [[Enzootic Pneumonia - Calves|Enzootic pneumonia of calves]]. In adult animals, the disease is usually sub-clinical, and the virus may be excreted intermittently at low titre (Schoenthaler and Kapil, 1999). Bovine coronavirus has also been identified as the etiological agent of [[Winter Dysentery|Winter dysentery]]  in adult cows (Saif, 1990). The incidence of BCV varies in different parts of the world but published and annual reports indicate that BCV causes 15-30% of calf enteritis cases (Langpap et al., 1979). The incidence of diarrhoea from bovine coronavirus may be underestimated because many laboratories around the world are not equipped with BCV antigen detection methods such as electron microscopy and BCV ELISA; also the isolation of BCV in tissue culture is difficult (Kapil et al., 1996). Bovine coronavirus infection occurs in combination with other enteric viral, bacterial, parasitic, and protozoal pathogens.  

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Bovine coronavirus has been found in cattle worldwide. Wild ruminants are also infected with the virus. Even though wild ruminant coronavirus may be antigenically, genetically, and biologically very close to [[:Category:Coronaviridae|coronaviruses]], it is an accepted rule that a coronavirus isolated from any species is named after that host. Elk coronavirus has been found to be related closely to BCV both genetically (Majhdi et al., 1997) and antigenically (Daginakatte et al., 1999). Distinguishing between different BCV isolates with monoclonal antibodies is difficult. Most BCV isolates and wild ruminant strains can be distinguished on the basis of a haemagglutination inhibition test using mouse erythrocytes.  

Bovine coronavirus has been found in cattle worldwide. Wild ruminants are also infected with the virus. Even though wild ruminant coronavirus may be antigenically, genetically, and biologically very close to coronaviruses, it is an accepted rule that a coronavirus isolated from any species is named after that host. Elk coronavirus has been found to be related closely to BCV both genetically (Majhdi et al., 1997) and antigenically (Daginakatte et al., 1999). Distinguishing between different BCV isolates with monoclonal antibodies is difficult. Most BCV isolates and wild ruminant strains can be distinguished on the basis of a haemagglutination inhibition test using mouse erythrocytes.  

 

The primary routes of entry for bovine coronavirus are through the mouth (faecal- oral route) or the nasal cavity (Clark, 1993). Adult cattle are carriers and excrete the virus at low titre; however, during parturition, cows shed higher titres of the virus.  

The primary routes of entry for bovine coronavirus are through the mouth (faecal-oral route) or the nasal cavity (Clark, 1993). Adult cattle are carriers and excrete the virus at low titre; however, during parturition, cows shed higher titres of the virus.  

 

== Signalment ==

== Signalment ==

This condition affects cattle and zebu worldwide and can also affect wild ruminants such as deer. Calves are usually affected around 2 weeks of age. In cattle where the disease causes winter dysentry, this occurs in autumn and winter when the cattle are housed.

This condition affects cattle and zebu worldwide and can also affect wild ruminants such as deer. Calves are usually affected around 2 weeks of age. In cattle where the disease causes winter dysentry, this occurs in autumn and winter when the cattle are housed.

== Clinical Signs ==

== Clinical Signs ==

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Respiratory signs may include serious nasal discharge, progressing to purulent if secondary bacterial infection is present, coughing, dyspnoea and tachypnoea.  

Respiratory signs may include serious nasal discharge, progressing to purulent if secondary bacterial infection is present, coughing, dyspnoea and tachypnoea.  

== Diagnosis ==

== Diagnosis ==

No diagnostic tools are available for cow-side testing or in-office testing for veterinarians. When sending samples to diagnostic services it is important to include at least five sections from different parts of the gut, including the spiral colon because this is the common site of virus persistence (Kapil et al., 1994a; Kapil et al., 1994b).

No diagnostic tools are available for cow-side testing or in-office testing for veterinarians. When sending samples to diagnostic services it is important to include at least five sections from different parts of the gut, including the spiral colon because this is the common site of virus persistence (Kapil et al., 1994a; Kapil et al., 1994b).

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In respiratory coronavirus disease the viral antigen can easily be demonstrated in washed nasal epithelial cells by direct fluorescent antibody test using conjugate obtained from National Veterinary Services Laboratory (Kapil et al., 1991). Demonstrating the antigen in the lower respiratory tract is difficult. In the future, diagnosis could be made more specific, if antibodies against spike protein (protective antigen) are monitored through a sub-unit ELISA.

In respiratory coronavirus disease the viral antigen can easily be demonstrated in washed nasal epithelial cells by direct [[Immunofluorescence|fluorescent antibody test]] using conjugate obtained from National Veterinary Services Laboratory (Kapil et al., 1991). Demonstrating the antigen in the lower respiratory tract is difficult. In the future, diagnosis could be made more specific, if antibodies against spike protein (protective antigen) are monitored through a sub-unit [[ELISA testing|ELISA]].

Serological tests, such as indirect fluorescent antibody, are used to monitor the presence of antibody in colostrum, serum, and intestinal contents. However, these are not yet commercially available.

Serological tests, such as indirect fluorescent antibody, are used to monitor the presence of antibody in colostrum, serum, and intestinal contents. However, these are not yet commercially available.

== Treatment and Control ==

== Treatment and Control ==

Treatment of BCV is generally symptomatic. Fluid therapy is given orally or intravenously. Astringents also are used to control diarrhoea. Additional feeding of fortified colostrum may be useful in preventing the clinical disease in newborn calves (Murakami et al., 1986). It is suggested that milk containing high amounts of coronavirus-specific antibodies be fed to calves for the first 14 days of life to reduce the incidence and duration of viral shedding (Heckert et al., 1991). Addition of the neutralizing monoclonal antibody (Z3A5) against the spike protein to immune colostrum might also provide protection, but it is not yet commercially available. It has also been reported that in vitro Hygromycin B inhibits the replication of virus in cell culture (Zhang et al., 1997); however, the drug has not been tested in calves.

Treatment of BCV is generally symptomatic. Fluid therapy is given orally or intravenously. Astringents also are used to control diarrhoea. Additional feeding of fortified colostrum may be useful in preventing the clinical disease in newborn calves (Murakami et al., 1986). It is suggested that milk containing high amounts of coronavirus specific antibodies be fed to calves for the first 14 days of life to reduce the incidence and duration of viral shedding (Heckert et al., 1991). Addition of the neutralizing monoclonal antibody (Z3A5) against the spike protein to immune colostrum might also provide protection, but it is not yet commercially available. It has also been reported that in vitro Hygromycin B inhibits the replication of virus in cell culture (Zhang et al., 1997); however, the drug has not been tested in calves.

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A dam vaccine is avaliable as a control measure for this disease. This should be given mid- late gestation to increased the number of BCV antibodies in the dams' colostrum. At birth, the calf must drink this colostrum for the vaccine to have been of any effect.

A dam vaccine is available as a control measure for this disease. This should be given mid-late gestation to increased the number of BCV antibodies in the dams' colostrum. At birth, the calf must drink this colostrum for the vaccine to have been of any effect.

General husbandary measures such as ensuring good hygiene and ventillation in calving pens is important.

General husbandry measures such as ensuring good hygiene and ventillation in calving pens is important.

 

== References ==

== References ==

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Daginakatte GC, Chard-Bergstrom C, Andrews GA, Sanjay Kapil, 1999. Production, characterization, and uses of monoclonal antibodies against recombinant nucleoprotein of elk coronavirus. Clinical and Diagnostic Laboratory Immunology, 6(3):341-344; 15 ref.

Daginakatte GC, Chard-Bergstrom C, Andrews GA, Sanjay Kapil, 1999. Production, characterization, and uses of monoclonal antibodies against recombinant nucleoprotein of elk coronavirus. Clinical and Diagnostic Laboratory Immunology, 6(3):341-344; 15 ref.

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Kapil S, Goyal SM, Trent AM, 1994. Cellular immune status of coronavirus-infected neonatal calves. Comparative Immunology, Microbiology and Infectious Diseases, 17(2):133-138; 16 ref.

Kapil S, Goyal SM, Trent AM, 1994. Cellular immune status of coronavirus-infected neonatal calves. Comparative Immunology, Microbiology and Infectious Diseases, 17(2):133-138; 16 ref.

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[[Category:Coronaviridae]][[Category:Cattle Viruses]]

[[Category:Coronaviridae]][[Category:Cattle Viruses]][[Category:Respiratory Diseases - Cattle]][[Category:Intestinal Diseases - Cattle]]

[[Category:To_Do_-_CABI review]]

[[Category:CABI Expert Review]]