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Definition
and history
Malignant
catarrhal fever (MCF) is a frequently fatal disease syndrome
primarily of certain ruminant species, caused by one of several herpesviruses to
which they are poorly adapted.
The disease is characterized by inflammation, ulceration, and
exudation of the oral and upper respiratory mucous membranes, and
sometimes eye lesions and nervous system disturbances.
The causative viruses exist in nature as subclinical
infections in other species that serve as carriers, to which they
are well-adapted. Two
major epidemiologic forms of MCF are recognized, defined by the
reservoir ruminant species from which the causative virus arises.
One, known as the African form, is referred to as
wildebeest-associated MCF (WA-MCF).
The other is referred to as sheep-associated MCF (SA-MCF).
MCF
has been recognized as a distinct disease for over 200 years.
It was first described in the late 1700’s, and subsequent
mentions of the disease in the literature are scattered throughout
the 1800’s. The
association between wildebeest and MCF in domestic cattle was
recognized early on by Maasai pastoralists and by South African
farmers, who referred to the disease as snotziekte (snotting
sickness) (
45,65
).
Experimental studies on MCF began to appear in the first
third of the 20th century (
16,17,22,43
).
These and other early studies described the basic nature of
the disease and began the process of defining the factors governing
transmission of the MCF viruses between the carrier hosts and the
clinically-susceptible species, a process which continues to this
day. A large
contribution to the understanding of MCF was made by researchers in
Africa such Plowright et al., who isolated the wildebeest (subfamily
Alcelaphinae) strain of MCF virus in vitro and
Plowright and Mushi, who conducted numerous experiments to examine
the basic epizootiology and pathogenesis of the disease and to
define the characteristics of the virus (for reviews, see
52,64,69
).
Knowledge of the sheep-associated agent historically has been
constrained by the fact that it has never been successfully
isolated, and studies on its biology have necessarily used less
direct approaches than were possible with the wildebeest (Alcelaphine)
strains, which can be propagated in vitro.
Development of molecular tools to efficiently detect antibody
and viral DNA have just in the last decade begun to enable
definitive studies on SA-MCF and to facilitate recognition of more
subtle disease expressions than classical MCF, such as mild and
chronic disease (
10,16,24,56,57
),
and recognition of new MCF viruses that originated from neither
sheep nor wildebeest (
33,35
).
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