Bovine Viral Diarrhoea (BVD)

Master Preventive Medicine – Notes, Case Studies and Practical Insights – with Lomash

Bovine Viral Diarrhoea (BVD)

Syn: Mucosal disease

It is subacute, acute or inapparent contagious disease of cattle characterized by high fever, diarrhoea, erosion of mouth, esophagus, rumen, abomasum and intestine.
It also produces sub-clinical infection.
It is associated with fertility problems in cow, heifers and have detrimental effects on immune system of animals.
It is most common in beef cattle and rare in dairy cattle.
Pig, sheep and buffaloes may also be affected.

Etiology:

Bovine viral diarrhoea virus of genus Pestivirus, Family; Flaviviridae
RNA virus
It is distinct with rinderpest virus but has antigenic relationship with swine fever virus.
It is sensitive to chloroform, ether, trypsin and common disinfectants.

Epidemiology:

Disease was first identified in USA. Disease has been reported from Africa, India, Bangladesh, Pakistan, Burma, Sri Lanka
Virus can be grown on tissue culture
Disease is principally noted in cattle. Serologically, positive cases have been recorded in deer, buffalo, and wild ruminants.
Prevalence was recorded to be 39.5%, 45.2%, 49.9%, and 21.6% for sub-Saharan Africa, South America, Middle East and Asia respectively.
Disease occur during all season; but higher incidence is noted during rain and winter.
Incidence is more in 6-24 months of age.

Transmission:

Virus is present in excretions and secretions of affected cattle.
In field, disease often rapidly spreads by direct or indirect contact with infected animal.
In crowded and feedlot cattle, virus spreads from affected cattle to face, nose, eyes of susceptible animals.
Contaminated food and water are important source of infection.
Urine and nasal discharge may also act as a source of transmission.
Ingestion of contaminated materials of diseased animal.
Calves harbouring the cytopathic strain of the virus are the principal source of infection in a herd.

Pathogenesis:

Entry of virus
Virus resides in gastrointestinal tract and multiplies
Virus reaches to blood circulation and produces viremia, but stays fixed in mucus membrane of GI tract and buccal cavity.
Inflammatory changes in GI tract and edema.
Hyperemia, necrosis, ulceration and erosion in GI tract
Ultimately enteritis, stomatitis; also, erosion in Peyer’s patches of SI and LN
Virus crosses placenta and causes abortion, fetal abnormalities and mummification.

Clinical Signs:

Incubation period: 2-3 weeks
Clinical signs can be grouped as three forms:
- Severe acute form
- Mild form
- Sub-acute or chronic form

Severe acute form:

It is also known as epidemic form.
High rise of temperature (106°F). Temperature may be biphasic in nature; usually persist for 4-7 days and there may be second rise.
Anorexia, depression, polypnea, tachycardia, polydipsia
Nasal discharge; mucoid to muco-purulent in nature. Moist coughing develops at later stage.
Muzzle; rough, dry and crustated; Erosion may be noted under the crust.
Signs of conjunctivitis accompanied by ocular discharge. Some may develop corneal opacity.
Profuse foul-smelling watery feces are excreted at end of temperature reaction and continues for 3-5 days.
Oral lesion appears following 1-3 days of diarrhoea. Hyperemia and ulceration of oral mucosa, tongue, palate and gum.
Profuse salivation
Abortion in pregnant cattle. Fetus is abnormal and malformed.
Infected animals may show lameness due to lesion in interdigital epithelium.
Animal dies due to septicaemia and severe dehydration.

Mild form:

Sub-acute or Chronic Form:

PM Findings:

Hyperemic, erosive, ulcerative and necrotic lesion in oral mucosa, esophagus, rumen, reticulum, omasum and intestine.
Destruction of Payer’s patches.
Destruction of lymph nodes
Colitis and proctitis characterized by hemorrhagic, ulcerative and necrotic changes.
Histopathological changes in glandular epithelium of intestine: lesion consist of focal areas of ballooning of cells of stratum spinosum accompanied with nuclear keratolysis or pyknosis.

Diagnosis:

On the basis of clinical findings
On the basis of PM findings
Isolation and identification of virus through conjunctival swab, sample of blood and feces.
Serological test: CFT, ELISA, VNT, Immunofluorescence test
Hematology: leukopenia, thrombocytopenia and neutropenia
Biochemical test: Elevated BUN, hyponatremia, hypokalemia, hypochloremia

Differential Diagnosis:

Treatment and Control Measures:

Since it is viral disease, it has no specific treatment. Symptomatic treatment is done.
Antidiarrheal drugs are administered to prevent diarrhoea. Activated charcoal @ 1-2g/kg, PO repeated at 4-6 hour. Kaolin-pectin @3-4mL/kg, PO, 6-8h in horse.
In cattle, most commonly used drugs are sulphonamides. Cotrimoxazole @15-20 mg/kg, b.wt. PO, OD
Antibiotics are administered to prevent secondary bacterial infection.
Fluid therapy to counter dehydration and ion loss in animals. D5, D10, RL can be administered to replenish electrolytes as well as water in body.
Supplementation of animals with vitamins, minerals for body support.
Infected calves should be culled to prevent spread of BVD.
Vaccination in endemic areas:
- Modified live virus vaccine for 6 months calves.
- Inactivated vaccine; safe for pregnant cattle
- 2 doses- female before breeding, immunity is temporary.