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United States Department of Agriculture

Agricultural Research Service

Title: Malignant Catarrhal Fever

Authors
item Crawford, T - WASHINGTON STATE UNIV.
item O'Toole, D - UNIV. OF WYOMING
item Li, Hong

Submitted to: Current Veterinary Therapy Food Animal Practice
Publication Type: Book / Chapter
Publication Acceptance Date: December 20, 1997
Publication Date: N/A

Interpretive Summary: Malignant catarrhal fever (MCF) is a serious, globally-distributed herpesvirus disease of cattle, deer and certain other ruminant animals. At least 2, and probably more, closely-related viruses are associated with MCF. Sheep and wildebeest provide the source of virus for most outbreaks of MCF in cattle. Most ruminant species can be infected with MCF virus. The nature of that infection, however, is variable, ranging from totally no disease in carrier sheep or wildebeest, to rapid death in cattle or deer. The disease is usually sporadic, with only one to a few cases occurring at a given time. Severe outbreaks with heavy losses are, however, not uncommon. A lower percentage of cattle, deer and bison can also be infected without disease expression. Recent studies indicate MCF is a significantly under-reported disease. Fatal cases of MCF often are readily diagnosed, but chronic cases, which occur with some frequency, often are never diagnosed, particularly if animals recover. Improved diagnostic tools have recently enabled recognition of "atypical" cases that have historically gone undetected, allowing a more realistic estimate of MCF losses. At present time physical separation of carriers from clinically-susceptible animals is the only proven control measure available.

Technical Abstract: Malignant catarrhal fever (MCF) is a serious, globally-distributed viral disease syndrome of certain susceptible ruminants. There are at least 2, and probably more, closely-related viruses that are etiologically associated with MCF. They are classified in the subfamily Gammaherpesvirinae. Sheep and wildebeest provide the source of virus for most outbreaks of MCF in cattle. These sources represent the reservoir for the two major MCF viruses, which are closely related antigenically and genetically. However, Their genomes can be distinguished and the `lifestyles' of the two viruses within their respective reservoir hosts appears to differ significantly, although the sign and lesions induced by these two strains of virus are indistinguishable. Most ruminant species are susceptible to infection with MCF virus. The nature and impact of that infection, however, are variable, ranging from totally subclinical in reservoir species, to rapidly lethal in species of high clinical susceptibility. The disease is usually sporadic. However, severe outbreaks with heavy losses are not uncommon. Inapparent infection also exists among clinically- susceptible ruminants. Recent studies indicate MCF is a significantly under-reported disease. Lethal cases of MCF often are readily diagnosed, but the subacute and chronic cases, which occur with some frequency, often are never diagnosed, particularly if animals recover. Improved diagnostic tools have recently enabled recognition of "atypical" cases that have historically gone undetected, allowing a more realistic estimate of MCF lethality.

Last Modified: 10/1/2014
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