INFECTIOUS BOVINE RHINOTRACHEITIS (IBR)/ RED-NOSE
Dr.AMIT KUMAR
M.V.Sc Scholar, Department of Veterinary Gynaecology and Obstetrics
Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar-125004 (Haryana) India
*Corresponding author: amitkajal7@gmail.com
Introduction:
IBR is an acute, contagious respiratory disease of cattle caused by bovine herpesvirus type 1 (BHV-1), commonly affecting the respiratory tract and the reproductive system. The disease is characterized by inflammation of the upper respiratory tract. The virus that causes IBR, Bovine herpes virus 1 (BHV 1) also causes infectious pustular vulvovaginitis in the female, and infectious balanoposthitis in the male and can cause abortions and fetal deformities. This virus is highly prevalent in New Zealand cattle. Once infected an animal remains infected for life, and can shed virus on multiple occasions, especially when the animal is under stress. This exposes more cattle to infection. IBR was originally recognized during the early 1950s in feeder cattle in the western US as a respiratory disease of feeder cattle in the western United States. Later, IBR became recognized as a complex of disease syndromes oc¬curring throughout the United States and over the other major cattle-pro¬ducing areas of the world. Cattle and some wild rumi¬nants (cud-chewing animals) are the only known hosts. IBR is also known as red nose and IPV (infectious pustular vulvo¬vaginitis).
Cause
IBR is caused by Bovine Herpesvirus-1 that is capable of attacking many different tissues in the body leading to a variety of clinical diseases as listed above. Abortions caused by IBR can be caused by exposure to a natural disease strain or exposure of non-protected pregnant cows or their calves with modified live IBR vaccine. In the first case, the virus replicates in the respiratory tract and circulates in the blood, crossing the placenta into the fetus. The virus begins to multiply in the fetus causing death 1-3 days after replication begins. Abortion occurs 2-7 days after death of the fetus. The time from infection of the cow to abortion can range from 18 days to 3 months (abortions occur during the 6th to 9th month). In the second case, modified viruses replicate in non-protected pregnant cows and pass through the placenta into the fetus causing infection and death. The genital form of IBR is seen in mature cows and bulls and is called Infectious Pustular Vulvovaginitis (IPV). The time course of the infection is 2-3 weeks and respiratory symptoms and abortions do not occur.
Transmission:
Infection occurs by inhalation and requires contact between animals spreading quickly through the group. The virus is shed in secretions from the eye nose and reproductive organs. IBR is endemic in the UK with around 40% of cattle having been exposed to the virus in the past. Infected cattle develop a latent infection once recovered from the initial infection and despite appearing clinically normal may suffer recrudescence of disease when under stress.
Clinical signs:
In addition to causing respiratory disease, this virus can cause conjunctivitis, abortions, encephalitis, and generalized systemic infections. The virus can also cause a mild venereal infection in adult cattle or a brain infection in calves. The clinical diseases caused by the virus can be grouped into:
1) respiratory tract infections 2 & 3) genital infections 4) abortions 5) eye infections 6) brain infections
- Respiratory syndrome
Respiratory symptoms were the first signs reported for this disease. The animal has diffi-culty inhaling, breathes rapidly, has a profuse watery nasal dis¬charge becoming thicker and darker as the infection pro¬gresses, and stands with its head and neck extended. Depression, higher body tem¬perature (104 to 108 degrees F) and decreased appetite accom¬pany the respiratory signs. As the infection progresses, the animal’s nostrils become encrusted, it loses weight rapid¬ly and may have diarrhea. If the crusts on the nostrils are rubbed off, the underlying tis¬sue appears very red and inflamed, hence the term “red nose.” The respiratory form of the disease usually affects concen¬trated groups of cattle, such as in feedlots. The IBR virus is one of the most common agents involved in shipping fever pneu¬monia of feedlot calves. Keeping many cattle in close contact pro¬vides an ideal situation for the virus to spread rapidly. As the virus passes from animal to ani¬mal, its ability to produce dis¬ease increases. The first signs of the disease appear about a week after infec¬tion. Usually, several animals become sick about a week before a large number of animals show signs of illness. Fifteen to 100 percent of the herd may become ill, with a death rate of 0 to 5 percent of those affected. The respiratory form of this disease is the most frequently observed form under feedlot conditions. - Infectious pustular vulvovaginitis (IPV)
Cattle exhibiting the vulvo¬ vaginitis form of the IBR com¬plex are sexually mature females that do not appear ill. Signs of IPV include a thick yel¬low to brown vulvar discharge that attaches to the vulvar tuft of hair. The vulva is swollen and the vulvar and vaginal lining is reddened, dying and/or contains small whitish-colored pustules. The vaginal-vulvar infection causes irritation, exhibited by frequent tail-switching and uri¬nation. Temporary infertility accompanies this infection. - Infectious pustular balano¬posthitis
Lesions similar to those from IPV may appear on the bull’s penis and prepuce (foreskin). This infection is believed to result from coitus with an IPV¬ infected female. The libido of infected males is usually decreased temporarily. The con¬dition is known as balano¬posthitis. - Abortion
The IBR virus is one of the most common causes of bovine abortion. Possible sources of the virus include new additions (shedders) to the herd, vaccines, birds or wild ruminants. Often this abortion is preceded by a mild respiratory and/or eye infection (pinkeye), although abortion occurs without ob¬served signs of illness. The aborted fetus has no consistent gross characteristic lesions. Abortion may occur at any stage of the gestation period, but is usually noticed in the sec-ond half of gestation. Death and absorption of the fetus may occur in early pregnancy and may be assumed to be an infer¬tility problem. Beef and dairy cattle may be affected, with up to 75 percent of the herd aborting. Abortion has been reported in herds two successive years, possibly indi¬cating that recovery does not produce complete immunity. Abortions have also been reported occasionally in herds where a program of IBR vacci¬nation has been practiced for up to several years before the onset of abortions. After aborting, the animal apparently has no injury to its reproductive tract; normal pregnancy may follow. Abortions may also be pro¬duced by vaccinating pregnant cattle with certain types of mod¬ified live IBR virus vaccine. Other types are labeled for use in pregnant cows or in calves nursing pregnant cows. Be sure to read label directions. Calves may be born infected with the IBR virus. Infection is exhibited as enteritis, weak calves that have difficulty nurs¬ing, or as a respiratory problem. - Pinkeye (keratoconjunctivitis)
The pinkeye form of IBR may accompany or precede the respi¬ratory or abortion form of this disease. The signs are red¬dened, swollen mucous around the eyes and a clear, watery secretion draining over the hair below the eye. The secretions cause the hair to mat and collect dirt and other debris. As the condition progresses, the secretions become thicker and dark¬er. This condition is sometimes called “winter pinkeye” and is differentiated from classic pink¬ eye caused by the bacterium Moraxella bovis by lack of a cen¬tral corneal ulcer. - Encephalitis
Another condition observed in young cattle with the IBR virus is encephalitis. This nerv-ous system infection may look like the nervous form of listerio¬sis.
Differential Diagnosis in a group of cattle
1) Bluetongue.
2) Foot and mouth disease
3) Other causes of respiratory disease in cattle (bovime parainfluenza virus, bovine respiratory syncytial virus, bovine coronavirus, bacterial pneumonia, lungworm) - Postmortem lesions:
- Diseased cattle that have died usually have hemorrhages or a mucofibrinous exudate over the sinuses. A tracheitis is usually present with hemorrhages and a hyperemia. These lesions may extend into the bronchi. Because cattle often have dual infections, typical lesions are seldom observed, and differentiating between shipping fever, mucosal disease or malig¬nant catarrhal fever requires laboratory examination for confirmation.
- Diagnosis:
- Clinical signs of IBR are indicative of BoHV-1 infection but laboratory tests are required for a definitive diagnosis. Often respiratory disease in cattle is caused by multiple concurrent viral and bacterial infections (e.g. Pasteurella multocida, Mannheimia haemolytica etc). Laboratory tests are required for a specific viral diagnosis.
Virus neutralization
Retrospective diagnosis of BoHV-1 infection can be made by measuring antibody levels in paired sera samples. First sample is collected during the clinical phase and a second sample is collected 4 weeks later.
ELISA
There are two types of BoHV-1 ELISA tests currently available for evaluating antibody levels. The use of marker vaccines is important in the differentiation of infected and vaccinated animals. Whole virus antibody ELISAs cannot differentiate between animals that were exposed to vaccine or field virus. IgB ELISAs become positive approximately 3 weeks after exposure to either vaccine or field virus. IgE ELISAs become positive approximately 4 weeks after exposure to field virus or non-marker vaccines. They do not become positive after exposure to marker vaccine. Thus, using antibody testing can allow the differentiation of animals that were only exposed to marker vaccine from those that were exposed to either field virus or non-marker vaccine. - Treatment:
- No medicines are available to treat the IBR viral infection. Secondary infections may be controlled by using antibiotics and sulfonamides through vet¬erinary prescription.
- Control:
- Control of IBR is based on four equally important aspects:
- Selective culling – Reduction of circulating virus can be achieved with the introduction of a vaccination program and progressive culling of those animals that are identified as a potential source of the virus. In farms with a very low sero-prevalence (proportion that are positive on an antibody test) culling without vaccination can be an option. However, in most farms due to the high sero-prevalence it is not economically feasible to test and cull all the sero-positive animals.
- Biosecurity – Maintaining biosecurity involves avoiding introduction of infected animals into the herd and/or implementing strict isolation / quarantine of introductions until proven negative, and restricting access of livestock to external sources of infection e.g. double fencing is in place at all perimeters, considering carefully sources of biological materials such as embryos, semen etc.
- Vaccination – The use of live vaccines is preferred above the inactivated ones because of the superior efficacy in clinical protection and more importantly in reduction of the virus circulation in newly infected animals. MSD Animal health market live (Bovilis IBR Marker Live) and inactivated (Bovilis IBR Marker Inac) vaccines. Further product specific information on Bovilis IBR Marker Live or on Bovilis IBR Marker Inac may be obtained by clicking on the relevant product of interest for your region under the product list tab on the MSD Animal Health homepage. Bovilis IBR Marker Live can now conveniently be mixed with Bovilis BVD and given on the same day for booster vaccination. To view a video demonstrating how to mix the vaccines please click here.
- Monitoring – This varies depending on the nature and risk status of your herd. Appropriate screening programmes can be discussed with your local veterinary practitioner.
Preventing IBR and IPV
Producers should take meas¬ures to prevent IBR and IPV: - Have a veterinarian exam¬ine all new additions to an established herd and ob¬tain a health certificate indicating that they were disease-free at purchase.
- Isolate all new additions for at least 30 days and have a veterinarian reex¬amine them before having contact with the estab¬lished herd.
- Isolate all diseased ani¬mals immediately upon detection. This helps prevent contact and spread of the infection.
- Vaccinate cattle. Numer¬ous IBR vaccines are readily available. Use them only as the instructions on the label indicate.
Economic importance
Its main significance is as a barrier to the export of live cattle to other regions or countries within Europe which have already eradicated the disease. It is also a significant disease for pedigree herds placing animals into AI stations. Bulls destined for use in AI are not permitted to have any antibodies to BoHV-1. Its main significance is as a barrier to the export of live cattle to other regions or countries within Europe which have already eradicated the disease. It is also a significant disease for pedigree herds placing animals into AI stations. Bulls destined for use in AI are not permitted to have any antibodies to BoHV-1.
