ORIGINAL ARTICLES
CONJUNCTIVITIS OF SHEEP AND GOATS IN INDIA
By J. F.SHIRLAWand N. S. SANKARNARAYAN, Imperial Veterinary Research Institute, Izatnagar
(Received for publication on 8 August 1946)
(With Plate I)
S PECIFIC conjunctivitis of sheep and goats is known to exist in North and South Africa, the
French Congo, the Levant, France, parts of the United States of America, in Uruguay and in
Australia and New Zealand. Coles [1931] defined the cause of the condition in S. Africa as a new
species of Rickettsia for which he proposed the name R. conjunctivæ, and this ætiological finding
is accepted in those countries where the disease exists. According to Donatien and Lestoquard
[1939] the disease is highly infectious and presumably air-borne, spreading rapidly through flocks
and herds through the medium of ocular and nasal discharges. One eye is usually affected, excep-
tionally both, the chief signs of the disease being intense conjunctivitis with lachrymation and pho-
tophobia. The conjunctivæ of the swollen lids show either sparse or numerous fine granulations,
and within a few days of the onset of the disease, muco-pus collects at the inner canthus of the affected
eye. In spite of the sudden and somewhat alarming early signs of the disease, it is essentially benign
in nature and the great majority of cases tend to recover spontaneously within ten days or so from
the onset of the affection. In some cases, however, keratitis develops and pannus-like lesions are
seen, i.e. invasion of the cornea by vascular stems infiltrating from the corneo-sclerotic margin. Cor-
neal opacity is a fairly common sequel in these cases, and, if it be accompanied by ulceration, there
is always the danger of a secondary bacterial infection of the inner eye.
Diagnosis is said to be relatively straightforward. The disease is usually easily transmitted to
healthy sheep or goats by rubbing a little of the infective eye discharge over the healthy eyeball.
preferably after mild scarification of the conjunctiva. The incubation period is 2—3 days. The
causal organism, R. conjunctivæ, is pleomorphic, and spherical, semi-elliptical, and cocco-bacil-
lary forms, the latter possessed of a central clear zone, are seen within the conjunctival cells. These
forms stain a light blue or lilac in Giemsa preparations and are Gram-negative. The parasite mea-
sures 0.4—1.5µ and the average size of cocco-bacillary forms is about 0.6µ. In some cases, horse-
shoe forms of the parasite predominate within the cells, and these are considerably larger, measuring
up to 2.0µ. The infection of the epithelial cells may be massive, the majority being densely packed
with organisms, or clusters of the organism may be situated at the angles or margins of cells; or,
the cell infection may be sparse, with only a few organisms scattered throughout it. A few small
clumps or stray organisms may occasionally be found outside the cells, possibly liberated through
rupture of the cells, and a few may be found within polymorphonuclear leococytes which are generally
present, but phagocytosis is, on the whole, feeble. There are two main fallacies to be guarded against
in diagnosis. Rickettsia-like organisms, so-called Rickettsioides, are not infrequently seen in the
conjunctival cells of healthy sheep and goats. These organisms are considerably larger than R.
conjunctivæ, and are not so pleomorphic but spherical, if of somewhat irregular contour, and are
usually scanty within the conjunctival cells. The organism is apparently feebly pathogenic. The
second fallacy is that pigment granules are commonly seen within the conjunctival cells of sheep
and goats, whether healthy or affected with the disease. However, these granules are easily differen-
tiated from rickettsiæ by their golden-brown colour.
OBSERVATIONS AND RESULTS
In January, 1941, the Veterinary Investigation Officer, Bihar, drew attention to a similar disease
of sheep and goats in that province. This Officer obtained some preliminary evidence as to its trans-
missibility but on repeated tests, found 'that quite frequently the instillation of mixed ocular and
nasal discharge did not reproduce the disease, even after a lapse of twelve days'. Early work at
this Institute indicated that the disease was a specific rickettsial conjunctivitis and this finding was
recorded in the Annual Report of the Institute [1941, as yet unpublished]. Since then, two papers
have appeared—by Nanda and Abdussalam [1943] and Abdussalam [1944] -which indicate the
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