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Malignant Catarrhal Fever (MCF)

Malignant Catarrhal Fever (MCF) is a fatal systemic disease of cattle, deer, bison and other hoofed animals.  It is caused by members of a group of herpesviruses and is almost always fatal. There is no licensed treatment or a commercial vaccine currently available. 

MCF causes problems for UK cattle producers but is a more serious issue for the deer and bison industry worldwide.  In sub-Saharan Africa, wildebeest carry a similar virus which causes MCF throughout the wildebeest range. MCF is therefore be serious problem for pastoralist herdsmen and their cattle during wildebeest migration and is a particular issue in South Africa where it is a source of conflict between wildlife and cattle ranchers.

In the UK, MCF is mostly caused by Ovine Herpesvirus-2 (OvHV-2). This virus naturally infects most sheep without causing clinical disease and persists for the lifetime of the animal. Sheep are therefore considered to be the reservoir species for this virus in the UK.

MCF is a sporadic disease, usually affecting small numbers of animals but occasional outbreaks can affect up to 50% of a herd. The reasons for this are not clear.

The clinical signs of MCF 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.  Cattle may survive two weeks after onset of signs while bison and deer die within a few days.

Key Points

  • Malignant Catarrhal Fever (MCF) is a fatal disease of cattle and some 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) carried by sheep.
  • Clinical signs in cattle include fever, enlarged lymph nodes, discharge from eyes & nose, lesions in the mouth and muzzle, inflammation and cloudiness of the eyes and sometimes diarrhoea. 
  • The clinical signs of disease in cattle are similar to mucosal disease, foot-and-mouth disease, bluetongue disease, papular stomatitis and vesicular stomatitis. Therefore correct diagnosis is essential.
  • MCF cases are sporadic. The disease usually affects individual animals, but occasional outbreaks can affect up to 50% of a herd. The reasons for this are not clear.
  • Sheep are the reservoir species for OvHV-2. They are infected for life but do not show clinical disease. 
  • Infected sheep shed virus occasionally in their nasal secretions. These periods of shedding are short (less than 24 hours) but intense.  Lambs normally become infected in the first few months of life and during this initial infection may shed virus for longer periods, until the immune response controls the infection.
  • The likely routes of infection are by aerosol, by contact and by ingestion from 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 only a few animals recover.
  • 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.

Research at Moredun

Current interests and future aims:

  • Research at Moredun focuses on understanding the pathogenesis and epidemiology of MCF viruses and on the development of an effective vaccine.
  • We have also developed diagnostic assays to detect MCF viruses (PCR) and the antibody response in infected animals (ELISA).
  • The wildebeest virus, alcelaphine herpesvirus-1 (AlHV-1), has been a focus of research on MCF as this is the only MCF virus that can currently be grown in the laboratory.
  • A vaccine for wildebeest-associated MCF has been developed based on attenuated AlHV-1.
  • Currently research is aimed at further development of the MCF vaccine for use in Africa.
  • This virus is also being used as the basis to produce a vaccine for sheep-associated MCF.

Farming and Veterinary Outreach

For further Information about MCF please see Moredun Newssheet 5.3 - Malignant Catarrhal Fever (MCF):