New Programme to Control IBR

An outbreak of Infectious Bovine Rhinotracheitis in dairy cattle in the UK could cost producers around two litres of milk per cow per day or the equivalent of about £180 in a year, writes Chris Harris, Editor in Chief.

23 July 2012

4 minute read

The highly infectious virus that is typified with symptoms of fever, nasal discharge and coughing can also result not only in drop of milk yield, but also potentially abortion in cows and death of young calves.

And an infected animal can infect another seven animals within a week to 10 days.

The virus is also persistent, because while the cow might recover, it is never removed from the animal and remains a lifelong infection that is capable of flaring up particularly if the animal comes under stress.

Peter Nettleton, an independent veterinary virologist, formerly of the Moredun Research Institute in Edinburgh said: "IBR stays as a lifelong infection. The animal can never be considered safe. It is latently infected and it can excrete the virus at any time."

IBR is also a barrier to international trade preventing any product or animal that is carrying the antibodies to be exported, including products such as semen. As well as live animal exports.

Even animals that have recovered or that have been vaccinated against the disease are subject to export barriers because they will still carry antibodies that could be considered a threat.

While there are several countries, particularly in Europe such as Italy, the Netherlands and Belgium and Germany that have introduced policies to eradicate the disease from the national herd, the UK is lagging behind.

In the UK, one survey in South Wales, vet Rob Davies at Allen & Partners in Whitland has found 75-80 per cent of herds positive for IBR, based on bulk milk antibody surveillance in client herds.

Over England and Wales as a whole, a 1998 paper in The Veterinary Record reported that 69 per cent of dairy herds were seropositive since when Mr Davies suggests the figure is much more likely to have risen than subsided.

A study reported in 2009 identified that 96 per cent of dairy herds in south west England contained at least one seropositive animal.

Dr Nettleton said that every farm should be talking to its vet about the farm's IBR status.

He also advised that a way to tackle the virus is to use a live vaccine against a new outbreak of the disease and a dead vaccine to control the virus in commercial herds.

Now, the animal health company Pfizer has developed a programme using both live and inactive virus to give herd protection all the year round. The programme advises the vaccination of animals that have not had the disease with a live vaccine initially and then this to be followed up with a dead vaccine for control purposed after six months.

Those animals that have already been infected with IBR or that have received the live vaccine require just one vaccination with an inactive vaccine annually to control and suppress the disease.

"The new programme is a strategic use of vaccines," said the national veterinary manager for Pfizer Carolyn Hogan.

"The aim is for those that have already been infected to reduce shedding."

Currently there are three live vaccines that are on the market in the UK and one inactive vaccine.

She said that animals that have never been infected, generally young heifers in dairy herds need to be vaccinated with a live virus to stop the infection taking hold.

Dr Hogan said that following surveys it is generally thought that the young animals have not been infected and do not become infected until they join the main dairy herd where they mingle with animals that have the virus.

"By vaccinating the naïve animals with a live virus you get a faster immune response and the live vaccines are better at stimulating the response."

However, she said that using the live and inactive vaccines said by side has not been an easy process, but now they have been licensed and by combining the live with the inactive vaccine the herds can have 12 months protection.

Dr Hogan said that the best time to give the live vaccine is when eh heifers are calving down and then they should have the inactive vaccine when they are introduced to the herd.

The vaccines that are being used in the Pfizer programme are 'Rispoval® IBR-Marker Live' and 'Rispoval® IBR-Marker Inactivated'. The cost of both in the UK is around £2 to £2.10 a dose.