Bovine malignant catarrhal fever (BMCF) is a fatal lymphoproliferative disease[1] caused by a group of ruminant gamma herpes viruses including Alcelaphine gammaherpesvirus 1 (AlHV-1)[2] and Ovine gammaherpesvirus 2 (OvHV-2)[1][3] These viruses cause unapparent infection in their reservoir hosts (sheep with OvHV-2 and wildebeest with AlHV-1), but are usually fatal in cattle and other ungulates such as deer, antelope, and buffalo.

There is a particular problem with Bali cattle in Indonesia,[6] bison in the US[7] and in pastoralist herds in Eastern and Southern Africa.

[12] The term bovine malignant catarrhal fever has been applied to three different patterns of disease: The incubation period of BMCF is not known, however intranasal challenge with AHV-1 induced MCF in one hundred percent of challenged cattle between 2.5 and 6 weeks.

Typical symptoms of this form include fever, depression, discharge from the eyes and nose, lesions of the buccal cavity and muzzle, swelling of the lymph nodes, opacity of the corneas leading to blindness, inappetence and diarrhea.

The number of animals in the herd, population density and species of the susceptible hosts are huge factors.

[34] The World Organisation for Animal Health[27] recognises histopathology as the definitive diagnostic test, but laboratories have adopted other approaches with recent developments in molecular virology.

[1] Bovine malignant catarrhal fever is usually fatal in susceptible species like cattle and bison, and any animal that survives will remain infectious for the rest of its life even if it shows no subsequent signs of the disease.

Latent infections may go unrecognised until recurrence, explaining signs of disease in animals with no known history of contact with reservoir species.

The viral life cycle is outlined in three stages: entry, maintenance, and shedding.

Entry occurs through the sheep's nasal cavity and enters into the lungs where it replicates.

The virus undergoes a tropic change and infects lymphocytes, also known as white blood cells, which play a role in the sheep's immune system.