DIRO-FILARIA REPENS INFESTATION OF DOGS
By R. G. DHAYAGUDE, M.D., Department of Pathology and Bacteriology, Seth G. S. Medical College,
Bombay
(Received for publication on 15 August 1942)
(With Plates XIII and XIV)
IN the course of post-mortem examinations,
multiple nodules varying in size from 25 mm.
to 2 cm. were encountered in the spleen of human
beings. These nodules had a dark red colour,
were well circumscribed, had a firm consistency
and projected above the surface of the spleen
when lying in a superficial position. Histo-
pathological examination showed that they were
of the nature of granulomata, probably parasitic
in nature. Further investigations brought forth
evidence to show that they were microfilarial
in origin. Microscopic study of the microfilarial
obtained from the nodules revealed that the micro-
filarice in question were those of Wuchereria
bancrofti (Dhayagude & Amin 1942).
Filarial worms are parasitic to humans as
well as a number of domesticated and wild animals.
It is not known whether nodules of type men-
tioned above have ever been described in the
spleen of animals infested with filaria. From
a comparative point of view, it is interest-
ing to make a study of one of the domesticated
animals infested with filaria. Dogs are known to
be infested with this worm, and in this paper an
account is presented of the study of filarial infec-
tion of the dogs in Bombay.
Neumann [ 1905 ] gives the following six species
of microfilaria as parasitic to dog: (1) Dirofilaria
immitis. (2) Dirofilaria repens, (3) Dirofilaria
ochmani, (4) Acanthocheilonema recondita, (5)
Achanthocheilonema dracunculoides and (6) Micro-
filaria acquieri. Bhalerao [ 1935 ] in his mono-
graph of helminth parasites of domesticated ani-
mals in India makes no mention of Dirofilaria
ochmani. According to him, there are four
members of the super-family of filariodea which
are parasitic to the dog. Of these, two belonging
to the genus of Dirofilaria are more common
than the other three, viz. Dracunculus medinensis,
Dipetalonema reconditum and the undescribed
adult of Microfilaria lewisii [ Korke, 1924 ].
The genus Dirofilaria consists of two species:
(1) immitis and (2) repens. Dirofilaria immitis
has been found in Bengal, Punjab, Madras, United
Provinces, Ceylon and Burma. Repens, on the
other hand, has been encountered in Bihar and
Orissa. Immitis being the more widely spread
species, it was expected that it would be met with
in Bombay. It has, however, been observed
that, in a study of over two hundred dogs, no
specimen of immitis could be obtained, while in
a small number of them repens variety was found
to be parasitic.
Material. The dogs that were examined were
from amongst those collected from different parts
of Bombay island by the Bombay Municipality
for destruction. The blood of these dogs was
investigated for microfilaria on three successive
days, and the dogs whose blood did not contain
them were returned, only the positive ones being
retained for further study.
The work of blood examination was carried on.
for a period of six months and Table I gives
the month, the number of dogs examined and
the number which showed the presence of micro-
filaria in the blood.
TABLE I
Month
September 1941 . .
October 1941 . . .
November 1941 . .
December 1941 . . .
January 1942 . . .
February 1942 . . .
6 months—Total . .
No. of
dogs
examined
73
29
12
44
36
7
201
No. of
dogs
positive
5
2
Nil
Nil
2
Nil
9
It will be seen from this table that out of 201
dogs examined only nine showed the presence
of microfilaria in their blood. Panda [ 1932 ]
observed a much greater infestation of dogs
in Bihar and Orissa. He mentions that 10 per
cent of the dogs he studied showed microfilaria
in their blood.
Microfilaria. The microfilaria (Plate XIII, Fig. 1)
seen in the peripheral blood are large in size; aver-
age dimensions taken from a number of specimens
shows that their length is 353µ with a variation
from 337.2µ to 379.7µ, while their breadth is
171