First Record of Trichobilharzia physellae (Talbot, 1936) in Europe, a Possible Causative Agent of Cercarial Dermatitis

Abstract

Several species of avian schistosomes are known to cause dermatitis in humans worldwide. In Europe, this applies above all to species of the genus Trichobilharzia. For Austria, a lot of data are available on cercarial dermatitis and on the occurrence of Trichobilharzia, yet species identification of trematodes in most cases is doubtful due to the challenging morphological determination of cercariae. During a survey of trematodes in freshwater snails, we were able to detect a species in the snail Physella acuta (Draparnaud, 1805) hitherto unknown for Austria, Trichobilharzia physellae; this is also the first time this species has been reported in Europe. Species identification was performed by integrative taxonomy combining morphological investigations with molecular genetic analyses. The results show a very close relationship between the parasite found in Austria and North American specimens (similarity found in CO1 ≥99.57%). Therefore, a recent introduction of T. physellae into Europe can be assumed.

Morphological, Behavioral, and Molecular Characterization of Avian Schistosomes (Digenea: Schistosomatidae) in the Native Snail Chilina dombeyana (Chilinidae) from Southern Chile

“…This outbreak was associated with "Trichobilharzia sp. "; however, this taxon was not properly described and did not include all measurements nor molecular characterizations, which are required to determine the identity of furcocercariae [2,10,11,21,25].…”

“…All infected snails came from the same lagoon, Laguna Chica de San Pedro, where Valdovinos & Balboa [ 23 ] reported an outbreak of swimmer’s itch. This outbreak was associated with “ Trichobilharzia sp.”; however, this taxon was not properly described and did not include all measurements nor molecular characterizations, which are required to determine the identity of furcocercariae [ 2 , 10 , 11 , 21 , 25 ].…”

“…We support that suggestion, because the measurements for both schistosomes (see Table 1 , Szidat [ 18 ]) are included in the range of measurements for Lineage II from the present study, with the exception of tail stem length and total length, which were slightly longer. These morphometric differences could be due to the constriction of worms because different fixatives, environmental temperatures, or host size, or they may be a result of their morphometric variability [ 14 , 25 ].…”

“…The description of cercarial behavior is important for the delineation of taxa in the fluke identification process [ 3 , 25 ]. Thus, this study describes, for first time, the behavior and response to different stimuli of these schistosomes shared with Argentina, except for Lineage III.…”

Somatic Dimorphism in Cercariae of a Bird Schistosome

“…franki haplotype “peregra” sensu Jouet et al [ 43 ] based on molecular characterization of specimens from two of these four snails [ 82 ] or that cercariae obtained from the remaining two snails come from the same sampling conducted in September 2013 and only one schistosome so far occurred in the lake [ 44 , 45 , 82 ]. However, given the current knowledge of Trichobilharzia systematics with Trichobilharzia franki Müller & Kimmig, 1994 parasitizing its type snail host Radix auricularia (Linnaeus, 1758) [ 43 , 83 , 84 , 85 ], T . franki haplotype “peregra” in R .…”