Malignant Catarrhal Fever (MCF) is an often fatal, infectious viral disease affecting ruminants, particularly bison and certain deer species. It's caused by a group of herpesviruses. In North America, the most common cause is ovine herpesvirus-2 (OHV-2), carried by sheep without causing them any harm.
Key Aspects of MCF:
- Causative Agent: Herpesviruses, primarily ovine herpesvirus-2 (OHV-2) in North America.
- Host Species: Primarily affects ruminants such as:
- Bison
- Certain Deer Species (e.g., Père David's deer)
- Cattle (less frequently affected)
- Transmission: Sheep are the primary reservoir and shed the virus, often without showing any clinical signs. Susceptible species contract the disease through contact with sheep, though the exact mode of transmission isn't completely understood.
- Clinical Signs: MCF presents in a variety of forms, but common signs include:
- High fever
- Depression
- Ocular and nasal discharge
- Corneal opacity (clouding of the eye)
- Enlarged lymph nodes
- Erosion of the mucous membranes in the mouth and nose
- Diarrhea
- Diagnosis: Diagnosis is often based on clinical signs and confirmed through laboratory testing, such as PCR (polymerase chain reaction) to detect the virus.
- Treatment: There is no specific treatment for MCF, and the prognosis is generally poor. Treatment focuses on supportive care to alleviate symptoms.
- Prevention: Preventing contact between susceptible species and sheep is the most effective control measure. However, this can be challenging in areas where sheep and susceptible wildlife overlap.
Why is MCF a Concern?
MCF poses a significant threat to bison and other susceptible ruminant populations, especially those in close proximity to sheep. Outbreaks can result in high mortality rates and economic losses. Understanding the disease and implementing preventative measures are crucial for protecting these vulnerable animal populations.
