Malignant Catarrhal Fever

 

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Large animal section: No. 14

MALIGNANT CATARRHAL FEVER (MCF): SNOTSIEKTE

Aetiology:

Two different infectious agents cause MCF:

  1. Alcelaphine herpesvirus-1 (AHV-1) which is the wildebeest-associated MCF transmitted by blue wildebeest. (Black wildebeest role is uncertain)

  2. Ovine herpesvirus-2, which is the sheep-associated MCF, transmitted from sheep.

Neither spread from infected cattle to other cattle and neither cause disease in their principal host.

Source of infection:

Wildebeest is the main source for AHV-1.

Domestic sheep is the main source of ovine herpesvirus-2. Goats can also act as a source of infection for cattle.

Methods of transmission:

Wildebeest-associated MCF probably spreads by inhalation of aerosol or ingestion of pasture contaminated by virus.

Sheep-associated MCF spreads by unknown means.

At risk animals:

Clinical disease has been described in over 30 species of ruminants.

All breeds of cattle, water buffalo (Bubalis bubalis), bison (Bison bison) and deer are susceptible. Some wild ruminants in zoos may also contract a severe illness.

African buffalo are susceptible to the sheep-associated MCF.

Pathogenesis:

It is a fatal multisystemic disease characterized by lymphoid hyperplasia, and widespread vascular epithelial and mesothelial lesions. (Vasculitis)

Specimens for diagnosis:

  1. Good history of the clinical symptoms.

  2. For histopathology in 10% buffered formalin: brain, kidney, lung, liver, spleen and lymph node samples are the most important, but eye and intestinal wall (especially if ulcers present) can also be submitted.

  3. For PCR (detection of viral DNA): whole blood (EDTA) and serum from the live animal.
    At necropsy: Fresh samples on ice of brain and lymph node.

NB: Wildebeest-associated MCF and sheep-associated MCF cause the exact same clinical and pathological signs and only PCR can distinguish between the two viral strains.

For further information contact:
VetPath Veterinary Pathologists
P.O. Box 8464
Pretoria 0001
Tel: (012) 529 8345/6
e-mail: info@vetpath.co.za

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Copyright © 2004 Bill Robb & Associates
Last modified: Friday June 25, 2004