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Equine Encephalomyelitis in India
(d) ' Joest—Degen ' bodies have not been found, and (e) the clinical disease
is usually acute.
In India, there appears a tendency for the disease to appear in sheep
suddenly pastured on lush grass and it has been recorded from Baluchistan
(Quetta and Loralai) that the feeding of green maize to horses caused a sudden
outbreak of equine encephalomyelitis, three horses being affected. If the
symptoms of the disease had been referable to the ingestion of green maize,
then more horses would have been affected in the regiment. Quetta and
Loralai are enzootic areas and it is probable that the horses in question were
already infected and that the green maize precipitated a crisis. The lesions
at post-mortem were typical of equine encephalomyelitis.
Hupbauer records, in Yugoslavia, a similar syndrome in which the
feeding of soya-beans appeared to be a determinant factor in the incidence
of equine encephalomyelitis.
It is this obscure relationship between diet and infection, undoubtedly
existing, which has led many workers to look upon forage poisoning as the
fundamental cause of equine encephalomyelitis.
In addition to possible initiation of equine encephalomyelitis by in-
gestion of certain grasses, climate, as has been shown, is an important exciting
factor. Sudden chills, especially after severe exercise, and stables constructed
without suitable protection from prevailing autumn winds, are well-known
factors predisposing to Kumri. The construction of suitable stables has,
according to some authorities, a beneficial effect in lowering the incidence
of Kumri. During the course of an outbreak of equine encephalomyelitis,
when the development of further cases seems in abeyance, a sharp lowering
of temperature is a factor sufficient to produce an exacerbation of mild cases
previously considered recovered, and in addition a crop of fresh cases. The
probable explanation of these phenomena is that many cases already harbour
the virus and severe depressants may initiate symptoms of the disease.
It will be seen that the essential epizootology of equine encephalomye-
litis in India is strictly comparable with that observed in countries where the
disease is enzootic. The peculiar erratic fashion in which the disease affects
individual or groups of horses during the course of an epizootic has been well
portrayed by Mosley, Heane and Shirlaw [ 1934 ], and is typical of the disease
in India.
It is now possible, in India, to map out enzootic areas in which, it may
truly be said danger of infection lurks. The risk of introducing fresh equine
stock into such infected areas has been well shown by Sahai [ 1938 ] in his
account of an outbreak of equine encephalomyelitis among police horses
brought to Jamshedpur from Calcutta for summering. Jamsehdpur has
proved to be a graveyard for imported horses.
The movements of cavalry from infected areas to clean areas has not,
so far fortunately, resulted in an extension of areas of infection, but it is a
danger that cannot be lightly considered. Sporadic cases of equine ence-
phalomyelitis are not uncommon, in the writer's opinion, throughout India
and possibly clean areas are not so numerous as supposed, if they exist at
all, and are only of relative importance in terms of latent infection.
The occurrence of ' septicaemic ' cases during the course of an outbreak
has been noted, but it was found impossible to correlate these cases with a