DOI: 10.1017/s0031182026102601 ISSN: 0031-1820
Molecular identification, life cycle and histopathology of Contracaecum rudolphii infecting Phalacrocorax carbo sinensis in northern Italy
Bahram Sayyaf Dezfuli, Flavio Pironi, Luca Bellini, Letizia Marangon, Serena Cavallero, Stefano D'Amelio, Luisa GiariAbstract
Six freshly dead adult great cormorant Phalacrocorax carbo sinensis (Blumenbach, 1798) were collected during the winter season of 2025 from the coast of Canneviè lagoon (Northern Adriatic Sea, Italy). All 6 P. carbo sinensis (prevalence 100%) were infected with nematodes of the genus Contracaecum Raillet and Henry, 1912, with the intensity of infection ranging from 39 to 550 worms per host (212.8 ± 80.7; mean ±
s.e.
). From the same lagoon, 41 European seabass,
Dicentrarchus labrax
(L.), were examined for helminths and in 27 specimens (65%) L3 larvae of
C. rudolphii
were encountered in extraintestinal sites of the seabass. In this study, 40 adults and 30 larvae of
C. rudolphii
from cormorants and 40 nematode larvae from seabass were characterized at species level using the diagnostic key based on the Restriction Fragment Length Polymorphism of 2 ribosomal regions, the nuclear ITS and the mitochondrial rrnS (12S). Adult nematodes from cormorants were identified as
Contracaecum rudolphii
B 83.8% (31/37) and the remaining 16.2% (6/37) were
C. rudolphii A
. Of the 30 larvae recovered from bird stomach 84.2% (16/19) appeared to be
C. rudolphii B
and 15.7% (3/19) were
C. rudolphii A
and all parasites from the seabass were third stage larvae of
C. rudolphii A
. Histological sections of cormorant alimentary canal showed that the nematodes went into the depth of the gastric folds and induced detachment of epithelial cells and secretion of excessive mucus. Furthermore, near the worm site of attachment, different types of innate immune cells were documented.