Infectivity, growth and development of Echinostoma revolutum (Trematoda) in the domestic chick.

Infectivity, growth and development were studied in 23 one-day-old domestic chicks each fed 25 pre-selected metacercarial cysts of Echinostoma revolutum. All chicks were infected at necropsy one to 44 days post-exposure with one to 18 flukes/chick. From the 575 cysts fed to chicks, 145 (25%) flukes were recovered from the ileum, caeca, rectum-cloaca and bursa of Fabricius. Length measurements on 113 uncurled flukes fixed in hot alcohol-formalin-acetic acid showed that worms grew slowly to 1.0 mm by day 3, rapidly to 6 mm by day 14, and less rapidly to 9 mm by day 36. Worms became ovigerous by day 9. As worms aged in the chick, the body length increased relative to the width, the acetabulum shifted more anteriad and the size of the excretory bladder increased.