First Occurrence of Eustrongylides spp. (Nematoda: Dioctophymatidae) in a Subalpine Lake in Northwest Italy: New Data on Distribution and Host Range

Abstract

The genus Eustrongylides includes nematodes that infect fish species and fish-eating birds inhabiting freshwater ecosystems. Nematodes belonging to the genus Eustrongylides are potentially pathogenic for humans; infection occurs after the consumption of raw or undercooked fish. In the two-year period 2019–2020, a total of 292 fish belonging to eight species were examined for the occurrence of Eustrongylides spp. from Lake San Michele, a small subalpine lake in northwest Italy. The prevalence of infestation was 18.3% in Lepomis gibbosus, 16.7% in Micropterus salmoides, and 10% in Perca fluviatilis. The other five fish species (Ameiurus melas, Ictalurus punctatus, Squalius cephalus, Carassius carassius, and Scardinius erythrophthalmus) were all negative for parasite presence. There were no significant differences in prevalence between the three fish species (Fisher’s exact test; p = 0.744). The mean intensity of infestation ranged from 1 (M. salmoides and P. fluviatilis) to 1.15 (L. gibbosus), and the mean abundance ranged from 0.1 (P. fluviatilis) to 0.28 (L. gibbosus). There were significant differences in the infestation site between the four muscle quadrants (anterior ventral, anterior dorsal, posterior ventral, and posterior dorsal) and the visceral cavity (Kruskal–Wallis test; p = 0.0008). The study findings advance our knowledge about the distribution and host range of this parasite in Italy.

Could Fish Feeding Behaviour and Size Explain Prevalence Differences of the Nematode Eustrongylides excisus among Species? The Case Study of Lake Garda

“…Planktivorous, benthivorous and pelagic fish, as well as amphibians and/or reptiles are second intermediate hosts. Eustrongylid nematodes have been described in 17 orders of fish worldwide to date [6][7][8][9][10]. Furthermore, predatory fish such as pikeperch (Sander lucioperca) and pike (Esox spp.…”

“…Eustrongylidosis occurs after the consumption of raw or undercooked fish products [10,14]; however, human infection has been rarely recorded to date [14,15]. The presence of larvae in the peritoneal cavity results in severe abdominal pain within 24 h after eating contaminated fish [16][17][18].…”

“…The occurrence of various zoonotic parasites in lacustrine fish species has been recently reported in Italy, mainly involving cestodes (Dibothriocephalus latus), trematodes (Clinostomum complanatum), and nematodes (E. excisus) [14,22,23]. Eustrongylides excisus was isolated in several fish species (i.e., Perca fluviatilis, Atherina boyeri, Micropterus salmoides) in central Italy [14,24,25], and in a subalpine lake in northwest Italy (P. fluviatilis, M. salmoides, L. gibbosus) [10]. On this path, it was noted a significant difference in prevalence values between such fish species [10].…”

ГЕМАТОЛОГИЧЕСКИЕ ПОКАЗАТЕЛИ ЕВРОПЕЙСКОГО ОКУНЯ (Perca fluviatilis Linnaeus, 1758) ПРИ ПАРАЗИТАРНОЙ ИНВАЗИИ

“…В России до настоящего времени P. fluviatilis считался сорной рыбой, малоценным объектом промысла. Во многом это объясняется тем, что в естественных водоемах окунь в значительной степени заражен различными паразитами, в особенности нематодами Eustongylides, Anisakis (6)(7)(8)(9)(10). Такая рыба часто остается бесплодной (11), отстает в росте и развитии, ее масса на 20-25 % ниже по сравнению с незараженными особями (12).…”

“…Нематод Eustrongylides spp. обнаруживают в мышцах, полостях тела и во внутренних органах рыб (25,26), в том числе у P. fluviatilis (9,27). Гистопатологические изменения, наблюдаемые у P. fluviatilis при инвазии этого паразита, включали дегенерацию и некроз мышц, распространяю-щиеся на саркоплазму, базальную пластинку сарколеммы, эндомизиальные клетки соединительной ткани и капилляры (27).…”