Malignant Catarrhal Fever (MCF)

• Malignant Catarrhal Fever (MCF) is a generally fatal disease of cattle, deer, bison and pigs and is the most serious viral disease of farmed deer and bison worldwide
• The commonest clinical signs in cattle include high fever, enlarged lymph nodes, mucopurulent discharge from eyes & nose, lesions in the mouth and muzzle, inflammation, cloudiness of the eyes and sometimes diarrhoea
• In the UK, MCF in cattle is caused by Ovine herpesvirus-2 (OvHV-2) and OvHV-2 infects most sheep throughout their lives without causing clinical disease
• 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
• Most MCF cases are sporadic. The disease usually affects small numbers of animals, but occasional outbreaks can affect up to 40% of a herd. The reasons for this are not clear
• 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 spread 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
• MCF affected animals cannot pass the disease on to other animals as they do not excrete any infectious virus There are currently no treatments or commercial vaccines available for MCF

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.