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This article was published in 1981
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Malignant Catarrhal Fever in Deer
S. Love, B.V.Sc., Veterinary Inspector, Coonamble
MCF - General
Among domestic animals, MCF occurs clinically in cattle and - Buffalo (and also deer); sheep, goats, and wild ruminants (e.g. Wildebeest) develop inapparent infections.
MCF is a multi-system disease associated with a herpes virus. (Clinical signs are referable to the upper respiratory tract, alimentary tract, lymph nodes, skin, eyes and central nervous system). In 1972, Snowden considered MCF (or BMC) a clinico-pathological entity rather than an aetiological entity. He stated that a strongly cell associated herpes virus is the causative agent of the wildebeest-associated BMC, but also stated that the causative agent (suspected to be a virus) of the sheep-associated disease has not been isolated. (Snowden 1972).
The mode of infection is uncertain. Sheep, goats and wild ruminants may carry the disease. Wildebeest (2 species) provide a source for infection of cattle in Africa. (A cell-free virus strain can be recovered from wildebeest.) Sheep and possibly goats apparently also often provide the source of MCF infection for cattle.
There is evidence that persistent infection, a carrier state and congenital infection may occur. (Huxtable 1979).
While gross pathology may vary in different outbreaks, typical and diagnostic mononuclear cell infiltration and accumulations occur in a variety of tissues, so that diagnosis is made of a histopathological entity. (Littlejohns 1979).
MCF has a lympho-proliferative pathology similar to herpes virus saimiri infection of marmosets and Epstein-Barr herpes virus infections of man. (Rossite 1980).
MCF - Cattle
MCF is seen in cattle of all ages, but is more common in adults. It was first seen in Australia in the Gundagai district in 1953. (Seddon/Albiston 1966).
Generally the morbidity rate is very low, while the mortality rate is usually very high. Most records indicate a close association between outbreaks of MCF (or BMC) and communal grazing of sheep and cattle.
Respiratory signs are commonly prominent. This so-called 'head and eye' form often involves an oculo-nasal muco-purulent discharge, corneal opacity (beginning at the periphery), as well as other signs.
MCF in Deer
MCE is known to occur in farmed deer. Often aspects of the disease in deer are quite different from those in cattle.
MCF in Deer in New Zealand
MCF has resulted in both sporadic and multiple deaths on a number of New Zealand deer properties.
Morbidity rates can be quite high. On one New Zealand property 50% of a herd of 98 succumbed to MCF over a period of 6 weeks (Wilson (1979)). In a case in Texas, 26 deaths occurred from a herd of 40 over 12 months. (Clarke et al.. 1970). Thus it appears that MCF in deer can be highly contagious and where stock densities are high the mortality rate is often correspondingly high (Wilson 1979).
In many instances outbreaks have occurred where deer have had contact with sheep and cattle, but in other cases, no contact with other domesticated stock has occurred. It is possible therefore that farmed deer may carry the virus without displaying clinical signs. (Wilson 1979).
MCF in Deer in New South Wales
The confirmed cases of MCF in a herd of Chital deer in the Coonamble district are among the first in N.S.W. It appears that the first confirmed cases were at Orange (Chital deer), and Mudgee (rusa deer). (English 1980 Pers. comm.).
The Coonamble Chital herd originated from herds in the Charters Towers, Queensland area. There are no sheep or goats in that area, and MCF has not been recorded in cattle or deer in the Charters Towers area. (Norman 1981 Pers. comm.).
Two consignments of mixed sexes were purchased; a consignment of 12 in December, 1978 and another consignment of 12 in April, 1979. Sheep (weaners) had free access to part of the fence of the deer paddock until March, 1979, and thereafter had very infrequent access to the fence. Communal grazing of the deer with other stock was never practised.
Deaths began soon after the arrival of the second consignment, and continued over 9 months until February, 1980. 8 does, 3 bucks, and a 3/4 grown fawn (total 12) died out of an initial herd of 24.
Of the 12 cases, the latter 7 were confirmed histopathologically as cases of MCF. Veterinary assistance was not sought until the occurrence of cases 4 and 5. A private practitioner submitted specimens for histopathology from these cases, but MCF was not diagnosed. (Later re-examination of these specimens showed suggestive vascular changes). (Walker 1979 Pers. Comm.). A.R. Jackson and B.F. Chick of the Regional Veterinary Laboratory, Armidale; and the writer, were involved in subsequent cases.
Clinical signs were usually nonspecific and consisted of weight loss, depression and isolation and victimisation by other deer. Affected deer continued to feed virtually until they died. Unlike the common 'head and eye' form in cattle, ocular lesions and apparent visual defects were not constant findings (noted only in 2 cases).
Typically, the course of the clinical disease covered from 2 to 4 weeks.
Post-mortem findings varied in intensity and distribution through the carcase. Haemorrhages in at least some lymph nodes, the lungs, trachea, and haemorrhagic and/or ulcerative changes in parts of the gastrointestinal tract were fairly constant findings. In one doe, the GIT appeared normal, but the urogenital tract exhibited intense haemorrhagic lesions. Other signs included renal infarcts and haemorrhages, pulmonary congestion and oedema, and in one buck, ulceration of the tongue and petechiation of the soft palette.
At least 7 of the 12 mortalities involved the second consignment; the origin of the 5 other dead deer could not be definitely established. However, it is quite possible that it was the entire second consignment that succumbed to MCF.
It is quite evident that MCF can be a very important disease in farmed deer.
References
Clarke et al. (1970) cited by Wilson, P.R. (1979)
English, A.W. (1980) (Pers. comm.), Rural Vet. Centre, Uni. Sydney
Huxtable, C.R. (1979) Proc. 42 (Cattle Diseases) Post. Grad. Comm. in Vet. Sc. p. 102
Littlejohns, I.R. (1979) Proc. 42 (Cattle Diseases) Post. Grad. Comm. in Vet. Sc.
Norman, J. (1981) (Pers. comm.) Vet. Officer, Qld. D.P.I. - Townsville
Rossite, P.B. (1980) Brit. Vet. J. Vol. 136 No. 5 p.482
Seddon, H.R. (1966) Dis. Domest. An. in Aust. C'wealth Dept. Health (Part 4) Revised Albiston, H.E. (1966)
Snowden, W.A. (1972) Proc. 16 (Virology and Virus Diseases). Post Grad. (Comm.) in Vet. Sc., Uni. Sydney p.321
Walker, K. (1979) (Pers. comm.) Vet. Res. Officer, N.S.W. Dept. Ag.
Wilson, P.R. (1979) Proc.49 (Deer Refresher Course) Post Grad. Comm. in Vet. Sc., Uni. Sydney