Bovine alpha-herpesvirus 1 (BoHV-1 or BoAHV-1) causes various clinical conditions in cattle: infectious bovine rhinotracheitis (IBR), infectious pustular vulvovaginitis (IPV) and infectious balanoposthitis (IBP). There is no risk of infection to humans.

worldwide

The main hosts are cattle and bovids (e.g. water buffalo).

Transmission occurs through direct contact from animal to animal. Indirect transmission through people and contaminated clothing, transport vehicles and equipment (stable utensils) is also possible.

2 to 6 days

Infection with bovine alpha-herpesvirus 1 can manifest in two forms: as IBR (respiratory form), with symptoms including lethargy, loss of appetite, fever (up to 42 °C), nasal discharge and coughing; or as IPV/IBP (genital form). Clinical symptoms may be absent or only mild in adult cattle.

There is no therapy

IBR/IPV/IBP is a notifiable animal disease. In case of suspicion of disease, the legal requirements must be followed. Vaccination is prohibited in Austria.

Since 1999, Austria has had the status of "disease-free" in accordance with Implementing Regulation (EU) 2021/620 (formerly Directive 64/432/EEC official additional guarantees). In order to maintain this status, annual surveillance programmes are carried out in accordance with national legislation.

On 12 June 2022, four imported cattle were found to be IBR/IPV-infected on the basis of recruitment tests on a farm in Lower Austria. The BHV-1-infected animals were slaughtered in accordance with animal welfare regulations. Early detection of the infection prevented it from spreading and no other Austrian farms or cattle were affected.

The pathogen, Bovine Alpha Herpesvirus 1 (BoHV-1 or BoAHV-1), which has various subtypes, is a double-stranded DNA virus and belongs to the Herpesviridae family. As is characteristic of herpesviruses, following infection the virus can retreat into the nerve ganglia at the site of entry. Infected animals remain lifelong carriers of the virus and can become shedding animals again following reactivation of the virus due to various stress situations (e.g. transport, birth, illness, change of feed). These infected animals (‘reagents’) represent a permanent potential source of infection for the herd. The pathogen is usually introduced into BoHV1-free herds through the purchase of latently infected animals or via animals in the incubation phase. The spread of the disease is facilitated by intensive animal movements, e.g. through livestock markets and livestock dealers.

Transmission within the herd occurs predominantly through direct animal contact, e.g. via pathogen-containing tear and nasal secretions (droplet infection), via the mucous membranes of the genital tract, but also via faeces. Indirect transmission is also possible – for example via people, contaminated clothing, inadequately cleaned transport vehicles, equipment or instruments (e.g. injection needles). Consistent adherence to biosecurity and hygiene measures is therefore crucial to prevent the introduction and further spread of the disease.
Viral shedding via the nose can last up to two weeks. Male animals play an important role in the spread of IBR/IPV/IBP (dispersal of infected semen!).

Affected cattle develop serologically detectable antibodies approximately 7–14 days after infection. Maternal antibodies are passed on to calves via colostrum, providing them with biological protection against clinical disease. These antibodies can usually be detected for up to nine months, and in some cases even longer.

Small ruminants can become infected and shed the virus, but do not show any clinical signs of disease. Wild ruminants can act as a reservoir in BoHV-1-endemic areas.

Symptoms

Infection with BoHV-1 can manifest in two clinical forms; the symptoms vary depending on the age of the infected animals:

IBR = respiratory form: lethargy, loss of appetite, fever (up to 42 °C), nasal discharge, hyperaemia of the nasal and oral mucosa (‘red nose symptom’), conjunctivitis, coughing, dyspnoea, abortion. Fattening animals show reduced growth performance. Lactating animals show a sharp decline in milk yield right from the onset of the disease. In calves, IBR primarily presents as a febrile systemic disease with a predominance of respiratory symptoms and often diarrhoea. The mortality rate is significantly higher than in adult animals.

IPV/IBP = genital form (usually limited to the vaginal and prepuce mucosa): lethargy, loss of appetite, fever (up to 42 °C), swollen and oedematous labia, hyperaemic mucosa (vestibule, vagina, penis), vesicles on the mucosa, abortion, orchitis, endometritis.

Under the European Animal Health Law (Regulation (EU) 2016/429) and Delegated Regulation (EU) 2018/1882, BoHV-1 is a listed animal disease and is classified in categories C, D and E. Bovidae from non-free Member States are subject to mandatory BoHV-1 testing. Classification in categories D and E also requires entry and surveillance testing for camelids and cervids.
 

Sample material for indirect detection (ELISA, serum neutralisation test):

• Whole blood (without anticoagulant, volume > 7 ml) or serum
• Batch milk or individual milk

Sample material for direct detection (PCR, virus culture)

• Nasal swab, eye swab, genital swab
• Head including tonsils and larynx
• Oesophagus 20 cm

Affected organs:

• A fist-sized piece of lung
• Lymph nodes
• Uterus, ovaries
• Organs from the foetus and placenta