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Occurrence of Gapeworm in Fowls
hatch and infection may result by the ingestion of eggs containing fully deve-
loped larvae. Although the intercalation of an invertebrate intermediate host,
such as earthworms, snails and slugs, in the life-cycle of this parasite is not
necessary, they often act as reservoirs for the larvae. When larvae and mature
eggs are ingested along with soil by earthworms they migrate from the gut
to their muscular parts and remain alive there for over three years. The
earthworm thus plays an important role in the collection of larvae from the
soil, in carrying over the infection from season to season and in transferring
them to the final host. On being swallowed by the final host, the larvae
quickly migrate to the lungs where they undergo a further moult and sex
differentiation and pairing take place. After pairing the worms leave the
smaller air-passages and work their way to the large windpipes. Sexual
maturity is attained in ten to fourteen days after the worms reach the trachea.
The entire life-cycle is completed in a month or so.
The worms inhabit the trachea and bronchi of the turkey, fowl, pheasant
goose, duck, pigeon, guinea-fowl, pea-fowl, partridge and various species of
other birds. Chicks, turkey poults and young pheasants are particularly sus-
ceptible and may die in large numbers. However, chickens invariably
develop a very definite immunity when eight or nine weeks old, and once this
age immunity develops any worms which may be present die and a reinfec-
tion is impossible. The turkey on the other hand does not develop any age
immunity and may remain infested throughout. Turkeys do not show any
symptoms, unless very heavily infested, and hence may serve as carriers for
the parasite.
The ' gape ' disease in young birds is probably mainly due to the mechani-
cal blockage of the trachea, which is brought about by the presence of the para-
site, local oedema of the mucosa at the seat of attachment and the accumula-
tion of mucus. The migration of the larvae through the lungs does not appear
to have any serious effect. Though the worms are blood suckers, the actual
loss of blood is probably negligible. The symptoms are mainly those of
suffocation. There is a peculiar cough or sneeze, the bird tosses its head,
the neck is stretched forward with open beak in an attempt to take in more
air. The death is usually due to suffocation though progressive emaciation
is undoubtedly a contributory factor.
In the absence of any satisfactory treatment the practice of mechanically
dislodging the worm, with or without the aid of certain chemicals, is wide-
spread. A loop of horse hair is introduced into the trachea, twisted to entangle
the worms and then withdrawn. The tip of a feather moistened with clove
oil or turpentine is also often used in dislodging the parasite. In the case of
valuable birds intratracheal injection of 1 c.c. Lugol's iodine or five per cent
aqueous salicylic acid may be tried. Fumigation with such substances
as heated carbolic acid, tobacco smoke or burning sulphur is of little value and
may even be dangerous. Sodium salicylate at the rate of three drams to every
quart of drinking water or pounded garlic in the proportion of one bulb per
day added to the food of ten birds may result in the expulsion of the worms.