Malignant catarrhal fever is an infectious viral disease of cattle.
Two viruses are responsible for the disease, one harboured by wildebeest
and the other by sheep. The wildebeest related infection only occurs in
Africa, while the other has been reported in most countries when cattle
are raised. The course of the disease ranges from the peracute form of
1 or 2 days to an extreme of 4 weeks. The usual rang, however, is between
4 and 14 days. The disease is usually fatal with death occurring within
10 days. Treatment is of little value and no vaccines have been developed
so far. Emphasis should be on the prevention of the disease. Cattle should
be prevented from contacting wildebeest when calving. For the sheep associated
infections, the infected animals should be isolated and the separation
of sheep and cattle may be helpful, particularly at lambing time.
Clinical signs:
The most common first signs of malignant catarrhal fever are clear,
copious nasal discharge and lacrimation which are quickly followed by a
mucopurulent, dark, nasal discharge with encrustation of the nostrils.
This may cause the affected animals difficulties in breathing. Discharges
from the eyes may also be observed on these animals. Soon after, the affected
animals may also develop a high fever and appear to be very depressed and
stop eating. They may quickly get dehydrated and the lymph nodes on the
head and neck become enlarged. These animals appear to dislike the light
and blink excessively. Eventually, the eyes may become opaque. In sheep-related
infections, blood-stained diarrhoea can often be observed. There may be
inflammation of the soft tissues under the hooves which can cause the feet
to be hot and painful.
Treatment:
Treatment is of little value, however, administration of antibiotics
or sulfonamides for control of secondary infection, or the use of supportive
therapy (fluid) may be worthwhile in valuable individuals. In general,
emphasis should be on the prevention of the disease.
Control measures:
MCF is usually fatal, however, the incidence is usually not high enough
to justify herd disposal or the development of a vaccine. The wildebeest
associated infections can be avoided by preventing cattle from contacting
wildebeest herds, especially, when they are calving. To control the sheep-related
infections, contact between cattle and sheep should be avoided, particularly
during the lambing season.
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