Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche ''Togo Rosati''

Authors      Agnetti F, Sgariglia E, Maresca C, Lo Vaglio G, Serva D, Veronesi F, Ghittino C, Fioravanti M L

Abstract     Eustrongylidosis is a parasitic disease of waterfowl and freshwater fish, caused by the genus Eustrongylides (Nematoda, Dioctophymatidae), also known as Big Red Worm Disease. The recognized valid species, E. tubifex, E. ignotus and E. excisus, can be responsible for large birds' deaths, in particular juveniles of herons and cormorants, which represent the definitive host. The life cycle of the parasite requires as intermediate hosts firstly aquatic oligochaetes and then benthonic fish, in which the 4th stage larvae develops. In the definitive host, adults colonize and reproduce in the thickness of the proventriculus wall. The interest of the scientific community in this parasite has developed in recent years, in addition to its high pathogenicity in birds, especially as a result of some reports of human cases that have highlighted the potential zoonotic role. The presence of large and reddish larvae in fish can represent a health risk for the consumer in case of food preparations at risk such as raw or undercooked fish products. Therefore, it was extremely interesting to study the epidemiology and biology of Eustrongylides sp. in the Umbrian lakes; this in order to be able to understand the mechanisms of diffusion and transmission and to make suitable surveillance actions and/or possible containment measures, also to the light of current legislation regarding the consumption of raw and/or undercooked fish products. In total, 125 samples were examined (105 fish pools weighing around 1kg each, 18 birds and 2 crustaceans). With regard to fish, n. 18 pools were positive at inspection due to the presence of larvae referable to Eustrongylides spp. Within the various fish species sampled, the smelt fish was found to be the most parasitized one. Among the birds, n. 12 out of 18 were positive at necropsy, for the presence of parasitic elements referable to Eustrongylides spp. in the gastro-enteric tract. The most parasitized specimens were found to be cormorant. As regards the fecal samples of waterfowl, no eggs referable to Dioctophymatidae were found in them. With regard to the morphological identification of larvae and adults found in fish and birds, a total of 56 specimens belonging to Eustrongylides spp. were identified, including 5 larvae from fish hosts and 51 adults from avian hosts. On the basis of the morphological characters described and the PCR amplification, the sampled adults were identified as E. excisus. Globally, the data obtained allow us to place the parasite Eustrongylides sp. in the context of Trasimeno Lake (Italy). The presence of the parasite has been demonstrated both in fish and avian samples, in the larval and/or adult stage.

Publish Date    2019

Volume   114

ISSN   1592-1581

DOI    no

URL    https://spvet.it/archivio/numero-114/696.html

Journal   Sanità Pubblica Veterinaria

Pages   no

PMID  no