Pathology associated with larval Eustrongylides sp. (Nematoda: Dioctophymatoidea) infection in Galaxias maculatus (Actinopterygii: Galaxiidae) from Patagonia, Argentina

Abstract

Helminth infections within tissues tend to be subjected to a host response that can include encapsulation and melanization to isolate the parasite. The effectiveness of this response depends on the host species. During a survey of parasites of the native fish, Galaxias maculatus , we found conspicuous, strongly melanized exterior cysts located in the caudal peduncle of the fish. Dissection of these cysts exposed larval nematodes whose morphometrical features allowed their identification as Eustrongylides sp. Species of this genus are distributed worldwide. Galaxias maculatus was previously reported as second intermediate host to Eustrongylides sp. larvae, and the aquatic bird Podiceps major was cited as definitive host of Eustrongylides tubifex in Andean Patagonian lakes. The site of infection in the fish, and the host's response are unique among infections by larvae of Eustrongylides sp. in fishes, so the objective of this study was to describe the histological injury caused by larvae of the genus Eustrongylides parasitizing G. maculatus . Samples of fish were taken near the shore of Gutiérrez lake, in northwestern Patagonia. Some larval morphometric features were described to confirm the identity of larvae to generic level. Histopathological analysis (tissues sectioned at 5–7 μm, stained with Hematoxylin and Eosin, and Masson's Trichrome) of the caudal peduncle revealed almost complete disappearance of the epaxial musculature due to compressive atrophy and a chronic inflammatory response, associated mainly with a dense fibrotic capsule and an intense melanic deposit. This is the first description of the histopathology of an external cyst caused by Eustrongylides sp. larvae in fishes.

One Health in The Brazilian Western Amazon: Helminths in Native Fish and The Food Change of The Puruborá People

“…in the musculature of jeju, traíra and tucunaré, fish that are very popular in the region. This parasite has been reported in several parts of the world, in Europe 13 , in Asia 14 and in the Americas 15,16 .…”

“…Larvae of Eustrongylides sp. have been described mainly in traíra and jeju in several states in northern Brazil 8,[15][16][17][18] .…”

Co‐exposure of iron oxide nanoparticles and glyphosate‐based herbicide promote liver toxicity in guppy (Poecilia reticulata): A histochemical and ultrastructural approach

“…When investigating the hepatocyte‐matrix relationship, special importance is given to connective tissue, which is part of the matrix and has collagen fibers as its fundamental composition, the supporting framework of this tissue. Collagen fibers are fundamental in understanding tissue reactions in several organs of various species, changes in collagen content and arrangement, whether in natural physiological modifications, such as gonadal maturation in Mullus barbatus , 28 or in modifications arising from nematode infection in the species Galaxias maculatus , 29 or even in exposure of Variola louti to heavy metals present in contaminated water, 30 show that connective tissue maintains an intimate relationship with blood tissue, being elucidated complementary by Disse space analysis. This latter is rarely studied in fish species, but explored in the present study.…”

Sensitization with Eustrongylides sp. (Nematoda: Dioctophymatidae) antigens induce production of specific IgG and IgE in murine model

“…include multiple hosts; piscivorous birds serve as the terminal host and oligochaetes and small predatory fish act as intermediate hosts (Moravec, 1998;Knoff et al, 2013). Species of the genus Eustrongylides Jägerskiöld, 1909 have been observed parasitizing fish in the United States (Choudhury et al, 2004;Mitchell et al, 2009;Bauer & Whipps, 2013;McAllister et al, 2016a, b;Muzzall & Hessenauer, 2018), Mexico (Salgado-Maldonado et al, 2004;Rosas-Valdez et al, 2007;Martínez-Aquino et al, 2012;Pinacho-Pinacho et al, 2014;García-López et al, 2016;Bautista-Hernández et al, 2019;Mosqueda-Cabrera et al, 2019), Argentina (Brugni & Viozzi, 1999Guagliardo et al, 2019), Turkey (Aydoğdu et al, 2011;Çolak, 2013), Italy (Dezfuli et al, 2015;Branciari et al, 2016), Poland (Mierzejewska et al, 2012), Bulgaria (Nachev & Sures, 2009), Romania (Urdes et al, 2015), Iceland (Kristmundsson & Helgason, 2007), Serbia (Bjelić-Čabrilo et al, 2013;Djikanović et al, 2018), China (Moravec et al, 2003), Japan (Abe, 2011;Moravec & Nagasawa, 2018) and Australia (Chapman et al, 2006). In Brazil, Eustrongylides sp.…”