192 A Nematode Parasite of the Indian Domestic Pigeon
Delicate, slender worms with a pinkish hue when fresh. The cuticle
about the head is inflated to form a vesicular enlargement. The mouth is
simple, unarmed and without visible papillae. The body cuticle has a number
of longitudinal striations. The oesophagus is of medium length. The male
specimens measure 9 to 12 mm. in length and have a bilobed bursa with ill-
defined dorsal lobe. The ventro-ventral rays are close together and parallel
with their tips curving anteriorly; the medio-dorsal ray is comparatively
straight, the postero-lateral and dorso-lateral rays diverging from it, and
the divergence emphasized at the tips, which tend to recurve; the externo-
dorsal ray is shorter than any of the previous rays and is bent posteriorly
near its middle; the dorsal ray is much shorter than other rays and bifur-
cates near its tip into two short branches which are deeply cleft, the internal
branches of the cleft terminating in two short tips. The two spicules are
0.15—0.16 mm. in length and each ends in three, pointed processes and are
united by a membrane to form a protrusible tube. A roughly cross-shaped
telamon is present. It is attached to the dorsal wall of the cloaca and its
two arms form an incomplete ring through which the spicules protrude. The
female specimens measure 18—24 mm. in length. The vulva is situated at
about 5 mm. from the end of the tail. The tail tapers to a narrow, blunt
end bearing a short spine. The eggs measure 0.07—0.075 by 0.038—0.04 mm.
in size, and apparently may be segmenting or contain embryos when laid.
Like those of other Trichostrongylidae, the life-history of this parasite
is of the direct and simple type. The thin-shelled eggs are usually in the
32-64 cell stage when passed in the faeces and develop very rapidly under
favourable conditions, the embryo hatching within nineteen hours. The
subsequent development is similar to those of closely related species of mono¬
xenous nematodes. The third stage larva retains the cuticle of the second
stage which is soon shed after it is ingested by the host. The infective,
unsheathed, filariform larvae usually develop on the third day after the passing
of the eggs in host's faeces. The worms attain maturity in five or six days
after ingestion.
O. quadriradiatus is a parasite with an early acute invasive stage which
is difficult to diagnose and is extremely dangerous to the host. A single
bird may harbour from several hundred to several thousands of worms. In
infected birds the symptoms usually appear on the second or third day, and
death occurs between the second and the fifth day after the ingestion of the
larvae. Thus acute symptoms and even death may occur before the eggs
of the parasite appear in the droppings.
As opposed to the common symptoms of helminthiasis—a prolonged
and progressive afebrile unthriftiness gradually resulting in death—these
parasites produce acute symptoms. Cuvillier [ 1937 ] studied the effects of
these worms during outbreaks, in and near Washington, in each of which
many birds died. The death occurred so rapidly that by the time the owners
sent for aid few birds remained alive, and these were in weakened condition.
Heavily infested birds become droopy, with feathers ruffled and neck retract-
ed. They squat rather than stand and seldom move; when disturbed and