Infectious Bovine Rhinotracheitis

Also known as IBR Caused by:Bovine Herpesvirus 1

aerosol transfer

Pathogenesis

BHV-1 infects the respiratory mucosal epithelial cells (intranuclear inclusion eosinophilic inclusion bodies)from nasal mucosa down to bronchioles
- Leading to neutrophilic inflammation of varying severity: serous -> catarrhal -> purulent nasal discharge, sneezing, coughing
Dypsnoea, anorexia
Rhinotracheitis that can develop into bronchopneumonia
Clinical signs include coughing, discharge, lacrimation, and increased respiratory rate
Clinical disease most severe in young calves - can develop mucosal ulcerative lesions in the oesophagus and forestomachs and viraemia with multiorgan infection
Generally high morbidity, low mortality, but up to 75% mortality if concurrent with BVDV, caused by meningo-encephalitis

Diagnosis

Virus isolation and immunofluorescence

Control

Vaccination:
- Two live attenuated vaccines are available in the UK, one is temperature-sensitive
  - Both given intranasally
  - Neither protect against re-infection when given during clinical outbreak, but can lessen the severity of the disease
- Inactivated vaccines: intranasal/intramuscular administration
  - gE deletion makes this a marker vaccine
  - ELISA for gE deletion can enable culling of carrier animals
IPV has mostly been made obsolete by AI

IBR in nasal cavity (Image sourced from Bristol Biomed Image Archive with permission)

IBR in trachea (Image sourced from Bristol Biomed Image Archive with permission)

URT infection with serous nasal discharge, increases respiratory rate, coughing and moderate fever,from nasal mucosa down to bronchioles
Rhinitis, pharyngitis, laryngitis, tracheitis, bronchiolitis
Morbidity is high, mortality is low
Highly infectious URT disease of cattle
Spread by movement of animals, aerosol transmission - requires close contact between animals
Early stages (only first few days) may show intracellular inclusions in the respiratory mucosal epithelial cells
Leading to neutrophilic inflammation of varying severity.... serous -> catarrhal -> purulent
With secondary bacterial infection (eg: Pasturella spp., Mycoplasma spp., Fusobacterium necrophorum) can lead to fibrinous to necrotizing inflammation; mucosal sloughing, ulceration... pyrexia, dyspnoea ... inhalation pneumonia... death
Underlying hyperaemic inflammatory response
Can become latent following primary infection
Clinical signs:nasal discharge, sneezing, coughing, lacrimation, and increased respiratory rate
Clinical disease most severe in young calves - can develop mucosal ulcerative lesions in the oesophagus and forestomachs and viraemia with multiorgan infection
Cause of abortion >5 months of gestation
May contribute to Enzootic pneumonia of calves

May cause cutaneous skin infections.

Caused by herpes virus 1 in cows. Results in abortion late in gestation 3-6 weeks after exposure. Abortion occurs soon after foetal death. Foetus may be autolysed. Intranuclear inclusions present in liver.