PARASITES
AND
PARASITIC DISEASES OF DOMESTIC ANIMALS
Syngamus trachea
Syngamus trachea is a parasite of the upper respiratory tract of non-aquatic birds. It is commonly known as the "gapeworm" and may be responsible for respiratory distress and death in domestic fowl and game birds such as pheasants and partridges.
Life Cycle
Eggs are passed in the feces of infected birds. Unlike other strongyloids, S. trachea larva develops within the egg until it reaches the L3 stage.
Infection may occur in one of three ways.
1. By ingestion of an egg containing an L3 (A).
2. By ingestion of the hatched L3 (B).
3. By ingestion of a transport host containing encapsulated L3s (C).
(
) Following
ingestion, the L3s exsheath in the duodenum (D)
of the final host, moult, and pair off. They penetrate the intestine and travel
first to the liver and then to the lungs (E)
via the bloodstreamd. Two parasitic moults take place in the lungs within 4-7 days
after infection. Adult males and females pair off move up to the trachea and begin
copulation in the bronchi and trachea (F).
(
) Eggs escape
from the vulva under the bursa of the permanently attached male and are carried up the
trachea in the excess mucus produced in response to infection. They are then
swallowed and passed in the feces, completing the cycle.
The prepatent period is approximately two weeks with a range of 12-17 days.
Various reports have shown that adults may survive for 23-147 days in chickens, 48-224 days in turkeys and approximately 98 days in guinea fowl.
