Infectious bovine rhinotracheitis/infectious pustular vulvovaginitis

Signs begin 2-4 days after exposure according to WOAH, or 2-6 days according to MSD. Fever, dullness, poor appetite, drooling and a clear nasal discharge appear first, turning mucopurulent within days, with a reddened muzzle (red nose), cough and conjunctivitis; conjunctivitis may be the only sign. Laryngeal obstruction can cause laboured breathing. Genital infection causes pustular vulvovaginitis in cows and balanoposthitis in bulls. Abortion may follow respiratory disease, typically at four to seven months of gestation, and milk yield falls. Newborn calves can develop severe generalised disease. At necropsy there are clusters of grey necrotic foci and fibrinous plaques in nasal passages, larynx and trachea.

IBR/IPV is caused by bovine herpesvirus 1 (BoHV-1), an enveloped DNA alphaherpesvirus of the genus Varicellovirus. After airborne exposure it multiplies to high titres in the mucosa of the upper airways and tonsils, spreads to the conjunctiva, and travels along nerve axons to the trigeminal ganglia. After genital exposure it replicates in vaginal or preputial mucosa and becomes latent in the sacral ganglia. Viral DNA probably stays in these neurons for life; stress such as transport or calving, or corticosteroid treatment, reactivates it so the animal sheds virus again without showing illness. Damaged airway mucosa lets secondary bacteria cause pneumonia, and the virus can cross to the fetus, causing abortion.

Domestic and wild cattle are the main hosts, and goats, sheep, water buffalo and camelids can also be infected. The virus occurs wherever cattle are kept, except in countries that have eradicated it, as several European states have. Nasal secretions carry large amounts of virus for up to about two weeks after infection, and infected bulls shed it in semen, so natural mating and artificial insemination both transmit it. Because infection is lifelong and reactivates, every antibody-positive animal is treated as a carrier (except after inactivated vaccine or from colostral antibodies). With secondary agents it forms part of the severe respiratory complex of young cattle known as shipping or crowding fever.

Nasal cavity, larynx, trachea, lungs, conjunctiva, tonsils, trigeminal and sacral ganglia, vulva and vagina, prepuce and penis, placenta and fetus (liver), mammary gland (milk yield)

Inactivated or modified live vaccines, including gE-deleted marker vaccines that allow infected and vaccinated cattle to be told apart; avoid parenteral modified live vaccine in naive pregnant cows; test-and-removal eradication programmes.

Most infections are mild or subclinical; uncomplicated cases last about 5-10 days and deaths are low. Secondary bacterial pneumonia can kill, newborn calves suffer high mortality, and recovered animals stay latent carriers for life.