Malignant Catarrhal Fever Quick Fact Sheet
Definition and clinical signs: A viral disease of exotic and domestic ruminants, causing ulcerations of oral and upper respiratory mucus membranes, profuse oral and nasal discharge, high fever, corneal opacity, ophthalmia, leukopenia, wasting, and generalized lymphadenopathy. Necrotic skin lesions and neurologic signs may occasionally be seen. Some species of cervids may present with hemorrhagic enterocolitis. In carrier species, there may be no clinical signs.
Epidemiology: Malignant catarrhal fever (MCF) is caused by a group of herpes viruses in the family Gammaherpesvirinae. Current research describes two major strains of MCF virus, wildebeest associated and sheep associated.
In both strains, virus is shed in nasal and ocular secretions. Transmission is usually from carrier species to susceptible species. Intimate contact is usually required, but transmission can occur remotely by mechanical vectors.
· The wildebeest strain is known as Alcelaphine herpesvirus-1 (AlHV-1).
· Occurs in wildebeest in Africa and in zoos and game farms that host these species in other countries.
· Carried as a latent infection in wildebeest, but can cause disease in any susceptible ruminant species.
· Highly cell-associated in adults, rarely transmissible, and has low shedding except during stress
· Cell-free virus is shed in large amounts from calves, which serve as the major source of infection to other animals
· Virus is rapidly inactivated in the environment
· The sheep associated strain is known as Ovine herpesvirus-2 (OvHV-2)
· Ubiquitous in sheep worldwide
· Reduced infectivity compared to AlHV-1
· Transmission between susceptible species is rare and only occurs uncommonly in highly sensitive species (e.g. Pere David’s deer, American Bison).
· Shedding of virus in lambs is controversial – studies do not agree; University of Washington study claims that shedding does not occur in lambs until greater than 5 months of age (in contrast to the wildebeest strain).
Diagnosis: Washington State University, Washington Animal Disease Diagnostic Laboratory offers the following:
· Competitive inhibition ELISA for general serum antibody against any of MCF group of viruses.
· PCR specific for OvHV-2
· PCR specific for other MCF group viruses (AlHV-1 included) by special request
Prevention and control in zoos: General preventative measures in zoos include separation of known carrier and susceptible species, and separation of keeper staff and equipment between these species. As an enveloped virus, it is not stable in the environment and most commonly used disinfectants will be effective.
Serologic screening with ELISA and PCR assay potentially may be used prior to animal acquisitions to maintain MCF negative herds of animals.
Culling of non-clinical positive animals need not occur in zoo settings if good preventative practices are in place, especially regarding separation of susceptible species from carrier species.
There are no specific treatments and there is no vaccine available.
Note: MCF, wildebeest strain is a National Animal Health Reporting System, Office International des Epizooties, List B disease.
Malignant Catarrhal Fever Overview: http://www.vetmed.wsu.edu/mcf/MCFOverView.htm.
Washington State University, Washington Animal Disease Diagnostic Laboratory.
Heuschele, W P 1992. Malignant Catarrhal Fever. In: Foreign Animal Diseases, 5th ed. United States Animal Health Association, Richmond, Virginia. Pp. 273-284.
Heuschele, W P 1993. Malignant Catarrhal Fever. In: Fowler, M. E. (ed.). Zoo & Wild Animal Medicine, 3rd ed. W. B. Saunders Co., Philadelphia, Pennsylvania. Pp. 504-506.