There are three standard CHECS programmes for IBR; Accredited Free (AF) Programme, Vaccinated Monitored Free (VMF) Programme, and Eradication Programme. A gE marker vaccine may be used in all programmes and must be used in the IBR VMF programme.
Where any animal is vaccinated with the marker vaccine, this information must be recorded and noted on the laboratory request form in order to allow the appropriate laboratory test to be carried out during routine screening. Full rules are detailed in the CHECS Technical Document.
IBR is caused by bovine herpes virus (BoHV-1) and, like the herpes virus that causes cold sores in humans, once an animal contracts BoHV-1, it remains infected for life. The virus survives as a latent infection in the nervous system and can be reactivated and shed when the beast goes through periods of stress such as bad weather, poor husbandry, or calving.
IBR is an upper respiratory disease that affects cattle aged over six months old; it can lead to fatal pneumonia. It’s rare to see it in calves but when it does affect them, it usually causes encephalitis where mortality risk is high. IBR can also cause reproductive disease in breeding females.
Surveys suggest that over half of UK herds are infected with IBR. Some European countries have managed to eradicate BoHV-1 from their cattle through national control programmes, so the UK’s IBR infection rates are a potential barrier to the export of live cattle.
Clinical signs vary and most usually are seen following a stressful event like weaning. Acute infection can present as fever, nasal discharges, conjunctivitis, ulceration of mouth and nose, coughing, panting, bad breath, loss of appetite, severe drop in milk yield, abortion and, occasionally, death.
IBR can also form part of a mixed infection with other pneumonia viruses and bacteria, resulting in more generalised respiratory disease. The risk from IBR is especially high in bought in or recently weaned store/finishing cattle of 6-18 months in age.
IBR is endemic in the UK and many other parts of the world. Austria, Finland, Denmark, Norway, Sweden and Switzerland have managed to eradicate it from their cattle populations. Regions of Italy and Germany are also BoHV-1 free.
As has been mentioned, most animals infected with BoHV-1 remain latently infected. The latent virus can be reactivated by stress so it’s important to consider housing conditions, stocking densities, access to food and water and control of other diseases like BVD when managing stress.
Vaccination programmes can prove useful in controlling and preventing IBR but they should be customised in conjunction with your vet according to your herd’s needs.
Biosecurity is, again, very important on farm, not just in preventing nose-to-nose contact but also when purchasing cattle, which is one of the main sources of the virus. You should not buy antibody positive cattle if you are IBR free because of the high risk of them being latently infected.