Trichobilharzia regentin. sp. (Schistosomatidae, Bilharziellinae), a new nasal schistosome from Europe

Abstract

Tr ic h o b il h a r z ia r e g e n t i n . s p . (S c h is t o s o m a t id a e, B ilh a r z ie llin a e ),A NEW NASAL SCHISTOSOME FROM EUROPE HORÁK P.*, KOLÁŘOVÁ L.** & DVOŘÁK J.* Summary :Members of the genus Trichobilharzia are parasitic in visceral or nasal body parts of their avian hosts. The examination of water snails in South Bohemia revealed a schistosome infection in Radix peregra snails. The experimental infection of ducklings (Anas platyrhynchos, Cairina moschata) confirmed that a new Trichobilharzia species -T. regenti n. sp. -was found. The adults, eggs and larvae (miracidia and cercariae) of the species were morphologically characterized. The adults occupy the nasal blood vessels where they lay the eggs; the miracidia hatch from the eggs directly in the tissue and leave the host during drinking/feeding of the infected birds. KEY W ORDS :Trichobilharzia, Schistosomatidae, nasal schistosome, life cycle, Radix. R é s u m é : Tr ic h o b il h a r z ia r e g e n t i

Avian Schistosomes and Outbreaks of Cercarial Dermatitis

“…Migration and localization have been characterized for a few visceral schistosomes and only one (T. regenti) of the eight nasal schistosomes (205,207). Visceral schistosomes in birds have a migration pattern similar to those of Schistosoma spp.…”

“…(204). Whereas experimental infections with T. szidati and T. regenti last for about 3 to 5 weeks (13,205), the adult worms of a Canadian isolate of T. ocellata were found in the liver at 370 days p.i. (206).…”

“…(205). Immature eggs appeared from day 15 p.i., and at day 19 p.i., eggs were fully developed and observed extravascularly in the nasal mucosa, with the maximum number of eggs seen on day 22 p.i.…”

“…Miracidia that hatched directly in the host tissue were surrounded by lymphocytes, eosinophils, and heterophils, without granuloma formation (221). While an infected bird is drinking/feeding, only the miracidia leave the tissue to enter the water, which represents an exceptional mode of transmission among schistosomes (205). The presence of adults only did not initiate an influx of immune cells to their vicinity, but the presence of large worms and eggs caused the development of focal hemorrhages throughout the nasal mucosa (207,221).…”

Penetration ofTrichobilharziacercariae into mammals: dangerous or negligible event?

“…Contrary to this, many older findings of cercariae and/or adults from various localities and different snail/bird hosts were determined as T. ocellata (C. ocellata), ignoring possible species richness of the genus Trichobilharzia (see Horák et al, 2002for review, Rudolfová et al, 2005. During the last two decades, the situation in Europe has changed substantially due to the discovery of three distinct species: T. franki (Müller & Kimmig, 1994), T. regenti (Horák et al, 1998b) andT. salmanticensis (Simon-Martin &Simon-Vicente, 1999).…”