Migration and development of Trichobilharzia ocellata (Trematoda: Schistosomatidae) in its duck hosts

Abstract

Migration and development of Trichobilharzia ocellata in ducks was studied by examining tissues and perfusate from birds which had been exposed to cercariae 5 min to 370 days earlier. Cercariae penetrated rapidly and were carried to viscera within 24 h. In the lungs, schistosomula left the vascular system to occupy air spaces, later to reenter veins in bronchial tissue. In the liver, worms were predominantly in sinusoids on days 1–6, in veins on days 7–9, and absent on days 10 and 11. Small numbers returned to the liver, which was the only organ harboring worms between days 89 and 370. Most worms found between days 10 and 21 were in the veins and tissues of the gut but none were there after day 21. Oviposition began on day 9, and peak numbers of eggs were found in the gut wall on days 14–16. Growth and development of T. ocellata were rapid. Caecal union was complete by day 2, organogeny by day 4, gametogeny by day 6, and sexual maturity and adult size by day 7. Morphological description of developing forms and of adults are given, the latter based upon examination of forty 9-day-old specimens of each sex.