Malignant Catarrhal Fever (MCF)
Summary written by George Russell BSc PhD
Taken from Moredun Foundation Newsheet Volume 5 No. 3 (2009)
- Malignant Catarrhal Fever (MCF) is a generally fatal disease of cattle, deer, bison and certain other hoofed animals.
- MCF is the most serious viral disease of farmed deer and bison worldwide.
- In the UK, MCF in cattle is caused by Ovine herpesvirus-2 (OvHV-2). The clinical signs of disease in cattle are similar to mucosal disease, foot-and-mouth disease (FMD), bluetongue disease (BTD), papular stomatitis and vesicular stomatitis.
- The commonest clinical signs include high fever, enlarged lymph nodes, discharge from eyes & nose, lesions in the mouth and muzzle, inflammation and cloudiness of the eyes and sometimes diarrhoea.
- MCF cases are sporadic. The disease usually affects small numbers of animals, but occasional outbreaks can affect up to 50% of a herd. The reasons for this are not clear.
- OvHV-2 also infects most sheep throughout their lives without causing clinical disease. Sheep are therefore considered to be the reservoir species for OvHV-2.
- The virus is occasionally shed in the nasal secretions of infected sheep. These periods of shedding normally last less than 24 hours in the adult animal. Lambs become infected in the first few months of life and during this initial infection can shed the virus for days or even weeks until the immune response controls the infection.
- The likely routes of infection are by aerosol, by contact and by ingestion of contaminated feed, water and bedding.
- Cattle or deer can become infected when kept in close contact with sheep or lambs: shared grazing, housing, feeding troughs or water supplies may all contribute to the likelihood of infection.
- Stressful situations, such as transportation, shearing or lambing, may increase the shedding of virus by sheep and therefore increase the risk of transmission to cattle.
- Cattle can only get MCF through contact with sheep; infected cattle cannot pass the disease on to other animals.
- There is no treatment or vaccine for MCF and the disease is almost always fatal.
- The best method of control is to keep sheep separate from susceptible species such as cattle and deer. To help reduce the risk of transmission avoid shared grazing, housing and the sharing of food and water troughs.
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