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Larvae (metacestodes) of gryporhynchid tapeworms (Cestoda: Cyclophyllidea) are reported for the first time from the liver of tilapia hybrids (Oreochromis aureus × O. niloticus) reared in earth ponds in northeastern Israel (along the Jordan River). This is the first record of Amirthalingamia macracantha (Joyeux & Baer, 1935), a parasite of cormorants (Phalacrocoracidae), outside Africa and outside the tropics. Larvae found in the liver of tilapias (Cichlidae) were identified to species level because they possessed 20 massive rostellar hooks of 3 types, with the 4 largest hooks measuring almost 500 µm. Molecular data confirmed species identification. The possible route of introduction to Israel of this African parasite, which is large (length up to 2 cm) and potentially pathogenic for cultivated tilapias, is discussed.

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Some fish parasites constitute severe management problems as they may cause mortality of their fish host or are important zoonoses of humans. Parasite assessments are therefore critical to keep track of infections. If conventional sampling techniques can be simplified, parasite assessments might be easier to obtain, less time-consuming and more extensive. In this study, we compare the assessed number of Diphyllobothrium spp. cysts (CYST) with the counted number of Diphyllobothrium spp. plerocercoid larvae recovered using a conventional digestive technique (LARV). The aim was to determine the potential of using CYST as a simplified methodology for assessing Diphyllobothrium spp. infection in salmonids. In total, 365 brown trout and 424 Arctic charr were sampled from nine lakes in subarctic Norway. Strong correlation, significant linear relationship and large amount of explained variation were found between log10 CYST and log10 LARV in both fish species. The method had a slight, but not significant tendency to work better in charr compared to trout. In addition, absolute difference between CYST and LARV increased at parasite intensities >100 indicating that the method has reduced functionality when estimating parasite intensity in heavily infected salmonid populations. However, overall, using this simplified and less time-consuming methodology, a good indication of Diphyllobothrium spp. intensity, abundance and prevalence was obtained. We suggest that this method provides a sound proxy of the Diphyllobothrium spp. burden and have the potential to be used in parasite assessment during fish monitoring and fisheries management surveys, particularly if the time and resources for detailed parasite studies are not available.

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In recent years there has been a re-emergence of diphyllobothriasis by Diphyllobothrium latum (Cestoda: Diphyllobothriidae) in Italy, France and Switzerland, where in the past this fish-borne zoonosis was widespread and then virtually disappeared. A change in eating habits such as the consumption of raw/undercooked freshwater fish, has led to an increased risk for consumers of ingesting infective larvae of D. latum. A survey on the factors responsible for the re-emergence of human diphyllobothriasis in Italy was carried out from March 2013 to December 2014. The aim of this study was to assess the diffusion of D. latum plerocercoids in the fish populations of the sub-alpine lakes of Maggiore, Como, Iseo and Garda, updating the scarce historical data and assessing a preliminary "risk level" of the lacustrine environments and fish species under investigation. A total of 2228 fish belonging to 5 species, 690 from Lake Maggiore, 500 from Lake Como, 655 from Lake Iseo and 383 from Lake Garda were submitted to parasitological examination. The presence of D. latum plerocercoid larvae was detected in 6.6%, 25.4% and 7.6% of perch (Perca fluviatilis) from Lakes Maggiore, Como and Iseo respectively. The parasite was also present in pike (Esox lucius) with prevalence values ranging from 71.4 to 84.2% and in 3.6-3.8% of burbot (Lota lota) from Lakes Iseo and Como. Fish from Lake Garda were negative as well as sampled whitefish (Coregonus lavaretus) and shad (Alosa fallax lacustris). The results of this survey showed a widespread presence of D. latum plerocercoid larvae in Maggiore, Como and Iseo fish populations. Urban fecal contamination of water is still a key issue to be resolved, together with the improvement of communication with consumers regarding the best dietary habits and the most effective processes of parasite inactivation, required for the consumption of raw/undercooked fish caught in high-risk areas.

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The occurrence of the plerocercoid larva, Sparganum of Sparganum spp. in two Russell's viper snakes maintained in Chennai snake park trust, Chennai is reported for the first time from Southern India. The cestode larvae were found in the sub cutis and were flat, solid, wrinkled, ribbon like creamy white in colour with peudosegmentation with anterior end possessing bothria. The cuticles, subcuticular cells and parenchymatous tissue stained by acetic alum carmine further confirmed the cestode larvae.

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Histopathological lesions caused by plerocercoids of Triaenophorus nodulosus within the liver of perch, Perca fluviatilis, from Lake Trasimeno were studied. Livers harbored 1-3 parasite larvae and pathological alterations were more marked in those with 3 plerocercoids. In the liver, larvae were encysted, surrounded by a capsule of host tissue; two of 14 plerocercoids were necrotic. In infected livers, some hepatocytes showed degenerative changes, i.e. swelling and hydropic degeneration, notably those in close proximity to larvae. By comparison, hepatocytes in uninfected livers or in regions away from the point of infection appeared normal. The occurrence of macrophage aggregates (MAs) distributed among the mast cells (MCs) was observed around the encysted larvae. The cellular elements involved in the immune response within liver were assessed by immunohistochemical techniques and by the use of antibodies against the antimicrobial peptides piscidins 3 and 4, which revealed a sub-population of positive MCs. In infected livers, numerous MCs that were immunopositive to P4 and a few that were positive to P3 were found around T. nodulosus larvae. Histological sections of both uninfected and infected liver were immunostained with proliferative cell nuclear antigen (PCNA) antibody. Within the capsule and in close proximity to the parasite larvae, various cell types (i.e., MCs, fibroblasts and epithelioid cells) and a significantly higher number of PCNA-positive hepatocytes that were immunoreactive to PCNA were found compared to uninfected livers (ANOVA, P<0.05). No parasites of any type were found in gill, spleen, kidney or gonad of P. fluviatilis and the intestine of 3 perch were infected with few specimens of Acanthocephalus lucii.

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