It is an acute highly contagious viral disease of cattle characterized by high temperature rhinitis, dyspnoea, abortion, mengio encephalitis, keratoconjunctivitis and pustular vulvovaginitis.
Distribution
The disease is widely prevalent in all parts of the cattle in the world. The disease was first noted in USA as an emerging disease in 1950. The name infectious pustular vulvo-vaginitis has been assigned by Kendrik (1958). The disease has been noted in cattle of Europe, Asia, North America, Africa, Australia and New Zealand.
In India, the disease has been recorded from Uttar Pradesh, Kerala, Gujarat, Tamil Nadu, Orissa, Andhra Pradesh and Karnataka.
Various incidence rates has been reported from India. Mehrotra and Rajya (1981) recorded 73% incidence, Samal (1981) recorded 56.6% incidence, Suri babu and Matick (1983) 55.5% incidence, Suri babu (1984) 6.6% incidence, Pandita and Srivastava (1993) recorded 11.43% incidence in heifers using ELISA kit and 76.47% in herds with history of abortion. A Sandwich indirect ELISA test has revealed 19.23% sero positive cases in sero epidemiological study in cattle from Karnataka. A seroprevalence study comprising 18 States indicated 38.01% rate positive for BHV-1 antibody.
Aetiology
The disease is caused by bovid herpes virus-1 or bovine herpes virus. The virus is morphologically indistinguishable from other herpes virus group. The virus is stable at pH 6.9 and can remain alive for a long-period but is susceptible to lower pH, ether, acetone and alcohol. The virus is antigenically different from other herpes virus but has got antigenic relation with equine rhinopneumonitis virus. The virus can be cultivated in cell culture of calf kidney, skin and testis with distinct cytopathological changes.
Susceptible Hosts
Cattle of all ages are affected. Dairy and beef cattle are equally susceptible. Besides cattle, the disease has been traced in goat, swine and water buffalo. The disease has also been identified in wild ruminants. Wild animals remain as reservoir of infection. The disease has been noted more in beef cattle probably due to aggregation, stress, shipment and social acclimatization. 29% deer population suffered in Britain.
Clinical Findings
The clinical signs may vary widely. The clinical signs have been grouped as:
- Respiratory form affecting the respiratory tract.
- Vulvo-vaginal form affecting the genital tract.
- Occular form affecting the eyes.
- Encephalomyelitic form affecting the central nervous system.
- Abortive form causing abortion
Diagnosis
Diagnosis is based on clinical findings and characteristic lesions. A definite diagnosis can be made through laboratory studies. The disease may be confused with bovine viral diarrhoea, rinderpest, malignant cattarh, pulmonary pasteurellosis. The nervous form may be confused with rabies and pseudo rabies. The laboratory tests e.g. virus isolation, FAT using liver and spleen of the foetus, Serum neutralization test is the routine serological test to evaluate antibody titre of current or recent infection. ELISA sandwitch indirect ELISA has been suggested.
FAT and electron microscopy can be made to diagnose the disease. Virus can be isolated from conjunctival swab, aborted materials, nasal swab, vaginal swab, semen, placenta, uterine mucous and blood serum. Besides, immuno peroxidase test, dot-blot hybridization assay has been suggested for the detection of virus in pyrexic phase and in semen. Recently, employing endonuclease finger printing technique, it has been possible to differentiate IBR from IPV virus.
Treatment
There is no fruitful treatment. Superimposed bacterial infection can be checked by broad spectrum antibiotic or sulphonamide. Ancillary treatment include restoration of fluid and electrolyte balance and provision of adequate ration and shelter. Hyper immune serum may be tried. Corticosteroid should never be given.
Control
- Strict isolation of the affected animals should be made.
- Number of modified live virus vaccines have been used. An inactivated vaccine along with Pasteurella bactrin and killed para influenza 3 vaccine is used in some parts of the world. Calves after 5 months of age are vaccinated. Immunity develops within 10-14 days. Live attenuated vaccines either through intramuscular or intranasal route may be given. In case of an outbreak intranasal vaccine will be more helpful.
The intranasal vaccine virus must have the ability to multiply on the nasal mucous membrane. Vaccine may be instilled into one or two nostrils.
In India, now such vaccine is available. But, in some countries vaccine containing multivalent antigens containing BHV-1, para influenza-3, bovine virus diarrhoea, bovine respiratory syncytial virus even Leptospira and campylobacter are used.
Commercial Vaccine
Ibrivax Dose: Cattle and buffalo 2 ml SC or IM. Booster dose after 3 months. Revaccination annually.
Calf – 2 ml SC or IM at 4-6 weeks of age, booster dose at 3 months after.
It has been noted that use of human leukocyte A interferon daily for 7 days simultaneously with BHV-1 may lessen the severity of clinical signs.
Administration of bovine recombinant inter leukin-2 may afford immunity against BHV-1 and thus recommended as an ancillary way of protection.
