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IBR - Infectious Bovine Rhinotracheitis

IPV - Infectious Pustular Vulvovaginitis
 
Pathogenic Agent - Bovine Herpes Virus 1 (BHV 1)

(- this article is from the BAYER web site)

Etiology
 
This infection is a serious economic problem for large livestock facilities nearly all over the word. Only a few countries are known to be free of IBR.

Often bought- in- animals are infected, but show no signs because of the virus capability to withdraw into the trigeminal ganglion. It is reactivated by stress caused e.g. through transport and new surroundings. The stressed animals start spreading virus by excretion in nasal, ocular and -in case of IPV- vaginal discharge. After only a couple of days, the entire herd may be infected.
Morbidity can go up to 100%, while mortality ranges from 2 to 12%.

Clinical Signs
 
Infection with BHV 1 may cause different clinical signs:

IBR is characterized by high fever, inflammation of the nose, which reddens and has earned IBR the name red nose disease. 
There may also be serous nasal discharge, which later becomes purulent. The mucous membrane shows pin-sized white plaques and pustules.

Often animals also suffer from conjunctivitis and milk production drops. BHV 1 strains causing IBR may also cause abortion in any stage of pregnancy, usually about 3 to 8 weeks after respiratory diseases occur in herds.
IPV is another form of disease with some BHV 1 strains.Clinical signs are confined to the genital tract and recognized by inflammation of vulva and vagina. You can observe pustules on the mucous membranes and mucopurulent discharge. Frequently these symptoms are joined by temporary fertility disorders.
All signs may subside within a couple of weeks, but the infected animal remains a lifelong virus carrier. These cows start spreading the virus when reactivated by stress, infection by other agents (e.g. BVDV) or subsequent to immunosuppressive treatment.
  

Diagnosis can be confirmed by isolation of the virus from nasal or conjunctival swabs combined with serological tests.
At necropsy, you will discover focal necroses in liver and kidney by dissection of aborted fetuses. 
Herd diagnosis is commonly based on serological tests, such as ELISA, VNT, etc. Bulk milk may also be tested. The presence of antibodies indicates a latent infection among the herd. Stressful events may trigger a reactivation of the virus. Some countries run national eradication programs by using gE-neg. marker vaccines.

Serological tests (gE ELISA) have been designed to distinguish the type of antibodies resulting from gE deleted marker vaccines from the ones that follow natural infection. Thus vaccinated herds maintain their IBR free status in spite of seroconversion.
 
Differential Diagnosis
 
Enzootic bronchopneumonia, FMD, malignant catarrhal fever , BVD/MD, shipping fever pneumonia.
 
Prevention
 
Assure hygienic standards to prevent spreading of virus 
Rodent control
Fly control
Disinfection
Optimize housing and management conditions do not Purchase BHV 1 - positive - stocks 
Isolate new animals for at least a week and screen them for diseases 
Improve endogenous defense mechanisms in herds at risk by immunostimulation
Start a vaccination program 
Vaccinate cattle with gE deleted marker vaccine to guarantee the distinction of vaccinated and infected animals 
Vaccinate very young calves intranasally with live vaccine 
Revaccinate after 5 weeks 
Booster every 6 months ...or according to recommendations by your vaccine manufacturer
 
Treatment
 
The frequent occurrence of secondary bacterial infection requires antimicrobial therapy.
Symptomatic and supportive treatment includes immunostimulating drugs, bronchodilatators, secretolytics and non-steroidal anti-inflammatory drugs (NSAID) in severe cases. 
Also, this is one of the few diseases where an putbreak can improve greatly by Vaccination, even in the face of an outbreak. The nasal route for vaccination protects animal very quickly.
 
Read about this highly infectious viral respiratory disease in an extract from the MERIAL web site. ::CLICK HERE
 
It PAYS to be IBR-free  (data from Intervet web site)
 
IBR is of economic importance to both dairy and beef herds.  The main financial loss following IBR in a dairy herd is due to a drop in milk production.  For beef it results in a longer time to reach slaughter weight.  Several countries have recognised the losses caused by the disease and have instigated eradication programmes through vaccination schemes.  Most have been very successful, with farmers in some countries even receiving premiums for disease free herds, and many countries will not accept livestock from infected herds.  Bovilis IBR and Bovilis IBR marker are two key vaccines for controlling the spread of infection.
 
When a dairy herd becomes infected, losses of 14 litres per day per clinically affected animal can be seen for around five days.  In beef herds, clinically affected animals can take as much as four weeks longer to reach target slaughter weight.  Then there are the potential hidden costs associated with treating sick animals or from abortions caused by the disease that need to be taken into consideration.
 
There are potentially significant financial benefits to be had from eradicating the disease from a herd.  In Holland, for example, an eradication programme has almost halved the incidence, and Dutch farmers with disease-free herds are better-off to the equivalent of £9.30 per cow per year.
 
IBR can be confirmed by a relatively simple test.  Farms with a history of the disease or those that buy in significant numbers of replacements should contact us to arrange for their herd to be tested.  Vaccination with IBR vaccine or IBR marker should be seen a valuable part of any eradication programme, when IBR has been confirmed in a herd.

Control strategies for two of the most widespread diseases in the UK - IBR and BVD

Two of the most prevalent, but frequently neglected, cattle diseases are BVD and IBR.  National surveillance puts infection and exposure rates at 95% of all dairy cows for BVD and 50% IBR.  So why is this the case and should we be striving to control them more effectively?
 
Both BVD and IBR can be controlled with vaccination and then require stringent bio-security to maintain a herd's infection-free status.  Even with vaccination in place, there have been cases of bought-in animals (possibly in-calf and infected) that have calved down with a BVD PI (Persistently Infected) calf, thereby bringing infection onto a farm.  

Around 30% of the national herd is now vaccinated against BVD and keeping a relatively closed herd and vaccinating replacements should protect you.  However, anyone buying in animals, grazing them near other herds or concerned about higher than expected levels of abortion, poor fertility or above average calf pneumonia, should consider testing for BVD status by making use of Bovilis BVD's bulk milk testing scheme.
 
IBR control is a 'hot topic' in the vet world at the moment.  In adult cows, acute infection is associated with a severe and prolonged drop in milk yield, reduced fertility and abortions. The virus is usually shed in secretions from the respiratory tract but can also be spread in the semen of infected bulls.
Once an animal has become infected it remains so, for its life time despite the development of an effective immune response and these animals can shed virus at any time when stressed.   Movement of such animals into a herd is often the source of new infections. 

A recent international meeting of vets and other IBR experts organised by Intervet sought to understand IBR control options by examining how different countries have done this.  The table below shows disease levels 10 years ago and, it is interesting to see that, since then, Scandinavia, Austria and some parts of Italy are now IBR-free and national eradication programmes now exist in Germany, Hungary, the Czech Republic and Slovakia. 

Table 1: IBR prevalence in 1996
 
Country   % of national herd affected
Hungary    80
Netherlands    70
Belgium    63
Italy     60
UK     50
Germany    50
Spain     25
France    10
Sweden    0
Finland    0
Austria    0
Denmark    0
Norway    0
Switzerland    0
 
The UK is not considering an eradication programme at present, but simply advises each farm to control the disease with vaccination.  Anyone planning to re-enter the live export market, should research the IBR status of any market they plan to sell into, and discuss control strategies with us. 

Further information is available direct from the Large-Animal vets at Parkside