A SURVEY ON CESTODES IN ITALIAN LACUSTRINE FISH.

AIM: Data concerning the presence of cestodes in wild fish populations in Italian Lakes are scarce and fragmentary. In the framework of a Research Project funded by the Ministry of Health on zoonotic helminths in freshwater fish, a parasitological survey aimed to update the existing data on the presence of Diphyllobothrium spp. (Cestoda: Diphyllobothriidea) in Italy has been carried out in fish populations from Italian lakes, widening data collection also to the presence of not zoonotic tapeworms. During the period January-November 2013, from 5 Italian lakes (Maggiore, Como, Iseo, Garda, Piediluco), 775 fish belonging to 6 species have been sampled by professional fishermen: 553 perch (Perca fluviatilis), 91 shad (Alosa fallax lacustris), 66 whitefish (Coregonus lavaretus), 46 burbot (Lota lota), 10 pike (Esox Lucius) and 9 tench (Tinca tinca). Fish were weighted, measured and submitted to parasitological examination. Parasites were isolated, washed in saline solution and fixed in 70° ethanol for morphology. Plerocercoid larvae were also submitted to molecular identification. Prevalence (P%) values, Mean Intensity (MI) and Abundance (A) have been calculated according to Bush et al,. 1997, J. Parasitol., 83: 575-583. Concerning Diphyllobothriid plerocercoid larvae positivities were found in perch from Maggiore Lake (P%=10.53, MI=1.00, A=0.11), Como Lake (P%=23.97, MI=1.34, A=0.32) and Iseo Lake (P%=12.79, MI=1.68, A=0.17); pike from Como (P%=40.00, MI=6.00, A=2.40) and Iseo Lakes (P%=100, MI=3.50, A=2.33); burbot from Como (P%=17.39, MI=5.75, A=1.00) and Iseo Lake (P%=19.05, MI=6.75, A=1.29). All the fish from Garda and Piediluco lakes and all the shad and whitefish were negative for diphyllobothriid plerocercoid larvae. All the larvae found in perch, pike and burbot are identified as Diphyllobothrium latum by morphology and confirmed by PCR and sequencing. Concerning adult cestodes found in fish intestine, Proteocephalus percae has been isolated from perch, pike and burbot, confirming perch as definitive host and pike and burbot as post-cyclic hosts. Proteocephalus longicollis has been isolated from whitefish, representing the most suitable host besides salmonids and from shad in which the major part of parasites were subadult. In tench from Piediluco lake the adult cestodes has been identified as the caryophyllidean Monobotrhium wageneri, commonly observed in tight clusters of parasites and causing a huge inflammatory reaction in massive infections. Data collected represent a contribute to the knowledge on diffusion of cestodes in wild freshwater fish in Italy. Concerning D. latum plerocercoid larvae, perch, pike and burbot are the only hosts reported in Italy so far and lakes Maggiore, Como and Iseo confirm to be endemic environments, instead of Garda Lake which seems to be D. latum free, but more fish from additional sampling areas have to be investigated to confirm these data.