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Stephanofilariasis among Buffaloes in Assam
[Vol. XVIII, Part IV
NATURE OF OCCURRENCE
The disease occurs generally in a sporadic form. A few buffaloes in a herd are affected and there
is hardly any indication either for a slow or for a rapid spread to other animals. Stray cases in a
village are also observed. However, it occasionally assumes the form of an outbreak affecting a
large number of buffaloes in a village and even spreading to a few villages in an area having large
buffalo population. In such cases, the prevalence of the disease is seasonal ; the outbreaks being
noticed in the rainy season, especially soon after the first showers in February and March. But
stray cases, not of acute or severe type, have been observed in almost all the months of the year. It
seems that the lesions are quiescent in winter season and become active during rains and in this
respect the behaviour is similar to that of hump-sore of cattle.
The occurrence of the disease is observed in all the districts in the plains of Assam, particularly
in lowlying localities on either bank of the Brahmaputra and the Surma rivers and their major
tributaries. In fact, the first investigation of affected cases was carried out in silchar on the bank
of the Barak river, a tributary to the Surma, in Cachar district in November, 1939. Subsequently
the disease was investigated in several localities of other districts, all of them situated on the bank of
rivers. Cases are often seen in herds that are usually maintained in marshy low-lying areas or in
riverain tracts that abound in grazing pastures. The occurrence of the disease is more common in
the Surma Valley and the Lower Assam Valley than in the Upper Assam Valley. It is noteworthy
that the disease has not been observed in buffaloes in the hill districts of the province.
Buffaloes of both sexes and of all ages seen equally susceptible. But more cases are often seen
among the adult and old animals. The disease is very rarely fatal even though the incidence of
affected animals in an outbreak may vary from 20 to 50 per cent depending upon the severity of the
outbreak.
Outbreak in Nowgong district
Investigation into this condition was carried out in March 1942 and in subsequent years in
Kampur, Nowgong district. In the first instance, it prevailed in the form of an epidemic affecting
about 30 buffaloes in Kampur and two adjoining villages. The outbreak was noticed about ten
days after the rains. The first case was observed at Kampur in the middle of March and subse
quently more cases were reported in the three villages.
The villages are situated on either bank of a river that winds its way near Kampur. The whole
area is low-lying and is usually flooded during rains. Fairly extensive grazing area is available in
the marshy banks of the river and around low lying pools where buffaloes graze and lie down
for rest in the stagnant water for some part of the day.
Symptoms
Frequent shaking of the ear and sometimes slightly offensive odour near the animal, are first
observed. Examination reveals the inflamatory condition at the base of the ear near about the
meatus while the external ear becomes more or less thickened presenting cracked surface of the skin.
Appetite is diminished and there is definite decrease in milk yield. The inflammed area shows
numerous minute pin-point congested spots. Frequent rubbing or scratching of the ear to poles or
trees is often seen. One or both the ears are affected. If one ear is affected the animal holds its
head side ways with the diseased ear down.
Slight watery discharge is observed at the early stage which later becomes purulent, light or
dirty yellow in colour with offensive odour. Sometimes ulceration of lining of the ear is seen. The
exudate is occasionally streaked with blood. There is usually extraneous infection. The animal
shows much pain when handled. Occasionally pharyngitis and congestion of the nasal mucous
membrane with profuse discharge, are noticed. Submaxillary lymph glands become sowllen.
Neglected cases become fly-blown and even maggots are formed. In severe cases, when both ears
are affected there is constitutional disturbance which interferes with the working capacity of the