Occurrence and Spatial Distribution of Dibothriocephalus Latus (Cestoda: Diphyllobothriidea) in Lake Iseo (Northern Italy): An Update

Abstract

Dibothriocephalus latus (Linnaeus, 1758) (Cestoda: Diphyllobothriidea; syn. Diphyllobothrium latum), is a fish-borne zoonotic parasite responsible for diphyllobothriasis in humans. Although D. latus has long been studied, many aspects of its epidemiology and distribution remain unknown. The aim of this study was to investigate the prevalence, mean intensity of infestation, and mean abundance of plerocercoid larvae of D. latus in European perch (Perca fluviatilis) and its spatial distribution in three commercial fishing areas in Lake Iseo (Northern Italy). A total of 598 specimens of P. fluviatilis were caught in 2019. The total prevalence of D. latus was 6.5%. However, there were significant differences between areas (10.2% North; 7.3% Center; 1.5% South) (Chi-square test, p = 0.0018). The mean intensity of infestation ranged from 1 larva in southern area to 1.2 larvae in both the central and northern (Pisogne) areas. In addition, the mean abundance ranged from 0.02 in the southern area to 0.26 in the northern area (Pisogne). The total number of larvae (anterior dorsal—AD = 21; anterior ventral—AV = 1; posterior dorsal—PD = 15; posterior ventral—PV = 5) differed significantly between the four anatomical quadrants (Kruskal–Wallis test; p = 0.0001). The prevalence of D. latus plerocercoid larvae in European perch from Lake Iseo has long been investigated, but without an appropriate sampling design. With the present study, a broader analysis in spatial distribution has been added to the existing literature, revealing new information about D. latus distribution and occurrence in Lake Iseo, with new data that will be useful for health authorities and future studies.

Low prevalence of Contracaecum third-stage larvae parasitizing Sea of Galilee fisheries: 1-year survey after 57 years of no information

“…In the laboratory, fish were measured, weighed, sexed, and then subjected to visual inspection of the abdominal cavity, internal organs, and musculature for the presence of zoonotic parasites following the procedure for fish premarketing control (Israeli Veterinary Services, 2017 ). Moreover, each filet was cut into thin slices (5 mm) and carefully inspected using a white light transilluminator as described by Menconi et al (2020) . Nematodes were isolated with a dissecting needle, counted, and preserved in 70% ethanol for both morphological and molecular analyses.…”

Relationship between the prevalence of Dibothriocephalus latus (Cestoda: Diphyllobothriidea) and the load of Escherichia coli: New findings in a neglected fish‐borne parasitic zoonosis

“…Lake Iseo is located within the endemic area of D. latus (Borroni & Grimaldi, 1973;Gustinelli et al, 2016;Parona, 1887). In their recent study, Menconi et al (2020) reported on the distribution of D. latus in P. fluviatilis from Lake Iseo and found a decreasing gradient from north (10.2%) to centre (7.3%) to south (1.5%). The prevalence was highest in the northern area, which is closest to a wastewater treatment plant (WWTP) on the lake.…”

“…Predatory fish (i.e. P. fluviatilis) acting as a second intermediate host ingest an infected copepod, and the parasite migrates from the gut to the flesh of the fish where it develops further into the plerocercoid (Menconi et al, 2020).…”

“…The resistance of D. latus eggs to external factors is low, and they cannot hatch unless they reach a suitable water body quickly (Bylund, 2003). The discharge from faulty sewage treatment plants can lead to faecal contamination of a water body, thus facilitating the parasite's life cycle (Menconi et al, 2020). The water body may be contaminated and continuously re-contaminated (Perdek et al, 2003).…”

Unique genetic structure of the human tapeworm Dibothriocephalus latus from the Alpine lakes region – a successful adaptation?

“…Diphyllobothriosis has persisted in ALR despite great efforts to eliminate the further spread of the disease, mainly due to eating habits and the proliferation of restaurants serving raw fish, insufficient disinfection of wastewater and the many yachters and fishermen using the lakes (Dupouy-Camet and Peduzzi, 2004;Jackson et al, 2007). Since 2000, diphyllobothriosis has been diagnosed in human patients from Switzerland, Italy and France and D. latus has also been frequently detected in fish from various subalpine lakes (Wicht et al, 2010a(Wicht et al, , 2010bDupouy-Camet et al, 2015;Menconi et al 2020Menconi et al , 2021.…”