| Animal Health: Infectious Bovine Rhinotracheitis |
What is IBR?
IBR is Infectious Bovine Rhinotracheitis, a disease that affects the upper respiratory tract of cattle, i.e. nose and throat of cattle.
Clinical signs include coughing, nasal and ocular discharge, high temperatures, drooling, loss of appetite, milk drop, infertility etc.
What causes IBR?
IBR is caused by Bovine Herpes Virus 1(BHV-1)
What is the significance of a Herpes virus involvement?
Herpes viruses are capable of becoming latent. This means that when an animal is infected with the virus, and clinical signs (of respiratory disease etc) subsequently resolve, the virus remains in the animal’s body, usually in the nerves. Other examples of Herpes virus are the Human ‘cold-sore’ virus and the Shingles virus.
The significance is that any animal that has been exposed to IBR at any stage may be a carrier of the virus. Latent IBR infection, where the IBR virus is dormant in the nerves can be reactivated by stress. Reactivation means the IBR virus becomes active again and the animal can shed the virus to other animals or become sick with the disease themselves.
What other diseases can IBR/BHV-1 virus cause?
Apart from respiratory disease the IBR virus can cause fertility problems, abortions, milk drop and vulvovaginitis in cows. IBR can also cause infertility problems in bulls.
Why is it necessary for Bulls to be free of IBR to enter AI stations or progeny testing centres?
It is a requirement under EU legislation that bulls producing semen for commercial production must be free of IBR antibodies. (EU Council Directive 88/407/EEC)
This means that these bulls cannot be exposed to IBR (BHV-1) or vaccinated with any IBR vaccine.
How is IBR spread?
IBR is most commonly spread by nose to nose contact with infected cattle to susceptible cattle. IBR carrier bulls will have IBR positive semen and can infect any cow or heifer they mate with.
What types of IBR vaccines are available in Ireland?
All IBR vaccines available in Ireland are marker vaccines. There are both live and inactivated IBR marker vaccines available.
What is a marker vaccine?
All vaccines work with the animal’s immune system to provide immunity. Vaccines are closely related to the disease agent, but stimulate immunity without causing disease. With conventional IBR vaccines it was not possible to know if the animal had been exposed to the wild virus (i.e. exposed to the disease and hence a carrier) or if they had been vaccinated.
IBR negative marker vaccines have a section deleted so it is now possible to tell on a blood test if the animals have been exposed to the disease or if it has been vaccinated.
What is the difference between live and inactivated IBR vaccines?
Live IBR vaccines are ideal in an IBR outbreak situation as they stimulate a rapid immune response, particularly when used intranasally.
Live IBR vaccines are good at overcoming maternal antibodies (protection calves get from their mother and colostrum) so if vaccinating young calves for IBR, live vaccines should be used.
Live vaccines are also ideal for store cattle as one dose intramuscularly will protect against IBR respiratory disease for 6 months.
The main disadvantage of live vaccines is that the vaccinated animal may shed vaccines virus, particularly if vaccinated intranasally.
This vaccine virus will not cause in contact animals to become sick but it lead to a bull that is fit for AI to become accidentally ‘vaccinated’
Inactivated IBR vaccines are more suited to control and eradication programmes, they are not a ‘quick fix’ for an IBR outbreak problem.
Animals vaccinated with inactivated IBR vaccines cannot shed vaccine virus so inactivated vaccines are far safer to use in pedigree herds.
Also inactivated IBR vaccines provide higher levels of protection over a longer time. This high level of protection is better at reducing shedding of virus from latently infected animals.
When should you vaccinate for IBR?
If you herd is free from IBR you should not need to vaccinate for IBR. However you should take every precaution to prevent the virus entering your herd.
* Maintain a closed herd
* Do not buy in animals of unknown status
* When buying animals, e.g. Bull, replacement heifers, blood test on arrival and 3-4 weeks later. Check blood for IBR antibodies. Keep the bought in animals away from the herd, e.g. out farm until blood results come back.
* Maintain good boundaries with neighbouring farms if they have IBR in herd, ideally 2-3 meter wide perimeter fence.
* Remember keeping the virus out will be a lot cheaper than implementing a vaccination & eradication programme over 5- 10 years!
If there is an IBR outbreak use live vaccine intranasally to stimulate rapid local immunity. If there are pedigree bulls remove them from the problem situation to isolation, and monitor situation. If they get sick with IBR you will have nothing to lose by vaccinating them as they will be positive for IBR anyway.
If IBR status unknown you can screen your herd to check status.
* blood test approximately 5 animals from each management group, e.g. weanling, replacement heifers, bullocks, bulls and cows.
* Ask you vet to screen the bloods for exposure to IBR. If animals have been exposed to IBR wild virus they will have antibodies to IBR. The number of animals positive for antibodies to IBR can help estimate the level of active infection in your herd.
* Dairy farmers can also get the bulk tank sampled for IBR antibody levels in conjunction with the blood sample screening.
* Discuss with your vet the possibility of using the blood sample for other disease investigations. It is useful to use blood samples to screen for other infectious disease such as BVD, RSV, Pi3, Johnes etc at the same time.
If you decide to implement an IBR vaccination/eradication programme use a rational approach and keep good records of animals’ blood sampled at any stage for IBR.
* Any animals (over 6 months or so) that test positive for IBR antibodies to wild virus are carriers of the virus. There is no need to test them for IBR again at any stage in their life.
* Use inactivated IBR marker vaccine in the breeding animals
* Inactivated IBR vaccines are better at reducing shedding of virus over time so will reduce the level of IBR in your herd over a number of years
* Do not vaccinate animals fit for AI stations/progeny testing centres
* When initiating an inactivated IBR vaccine programme it is necessary to start with 2 doses for initial vaccination course.
How often are booster vaccines required?
Currently all IBR vaccines (both live and inactivated) available in Ireland have a 6 months duration of immunity. Therefore booster vaccines should be administered every 6 months.
Why do you need IBR fertility protection?
Anecdotal evidence suggests that IBR does have an important role to play in fertility disease, particularly in Dairy herds as they are under more production stress than Beef herds. Recent reports for Irish veterinary laboratories indicate that IBR does cause abortion in Ireland. Any virus that causes marked increase in temperature in pregnant animals or breeding bulls can cause fertility problems. Therefore it would be prudent to use vaccines that provide fertility protection as well as herd IBR protection.
The Rispoval IBR marker vaccines, both live and inactivated, provide fertility protection against IBR.
Rispoval IBR marker live reduces fertility losses associated with IBR whereas Rispoval IBR marker inactivated prevents fertility losses associated with IBR. Therefore it is advisable to use Rispoval IBR marker inactivated in your breeding herd when implementing an IBR control and eradication programme.
Do you need to vaccinate all animals in the herd?
When planning a vaccine programme it is advisable to vaccinate all susceptible animals in the herd, but do not vaccinate bulls for AI stations. | |
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