Gastrointestinal helminths and related histopathological lesions in black-necked swans Cygnus melancoryphus from the Carlos Anwandter Nature Sanctuary, Southern Chile / Helmintos gastrintestinais e lesões histopatológicas relacionadas em cisnes de pescoço negro Cygnus melancoryphus do Santuário da Natureza Carlos Anwandter, Sul do Chile

Abstract Black-necked swans are distributed across South America and face conservation problems in Chile according to data of the State institution SAG. The aim of this study was to identify helminths and to assess associated tissue damage via histopathology. A total of 19,291 parasites were isolated from 21 examined birds; 17 species were identified, including nematodes, flukes, and tapeworms. Of these, 12 were new host records, 13 were reported for the first time in Chile, and 5 were new records for the Neotropical region. Further, the flukes Schistosomatidae gen. sp. and Echinostoma echinatum are of zoonotic concern. Regarding histopathology, an inflammatory response was found along the birds' entire digestive tract. Nevertheless, it is difficult to declare that there is a clear association between such lesions and isolated parasites, as other noxa could be responsible as well. Although in some cases there was an evident association, such inflammatory responses and necrosis were minimal, as occurred with Capillaria, Retinometra, Catatropis, Echinostoma, and Schistosomatidae gen. sp. Nevertheless, Epomidiostomum vogelsangi caused granulomatous injuries, an important inflammatory response, and necrosis, but it always circumscribed to superficial layers of the gizzard. Conversely, Paramonostomum was not associated with an inflammatory response despite a high parasitic load.

Resumo O cisne de pescoço negro é distribuído por toda a América do Sul, e enfrenta problemas de conservação no Chile, sendo protegido pela Lei Estadual de Caça. O objetivo deste estudo foi identificar helmintos em cisnes e avaliar o dano tecidual por meio de histopatologia. Um total de 19.291 parasitas foi isolado de 21 aves examinadas, sendo 17 espécies identificadas, entre nematóides, trematódeos e tênias. Destes, 12 são novos registros de hospedeiros, 13 são reportados pela primeira vez no Chile, e 5 são novos registros para a região Neotropical. Além disso, os trematódeos Schistosomatidae gen. sp. e Echinostoma echinatum detectados têm importância zoonótica. Em relação à histopatologia, uma resposta inflamatória foi encontrada em todo o trato digestivo. Entretanto, é difícil estabelecer uma associação estrita de tais lesões com parasitas isolados, porque outros fatores também poderiam ser responsáveis. Em alguns casos, houve uma associação óbvia entre parasitas e lesões, embora a resposta inflamatória e a necrose fossem mínimas, como foi o caso dos gêneros Capillaria, Retinometra, Catatropis, Echinostoma e Schistosomatidae gen. sp. Entretanto, Epomidiostomum vogelsangi causou lesões granulomatosas com importante resposta inflamatória e necrose, mas sempre circunscrita às camadas superficiais da moela. Por outro lado, Paramonostomum não foi associado com uma resposta inflamatória óbvia apesar da alta carga parasitária.

Gastrointestinal helminths and related histopathological lesions in black-necked swans Cygnus melancoryphus from the Carlos Anwandter Nature Sanctuary, Southern Chile.

Black-necked swans are distributed across South America and face conservation problems in Chile according to data of the State institution SAG. The aim of this study was to identify helminths and to assess associated tissue damage via histopathology. A total of 19,291 parasites were isolated from 21 examined birds; 17 species were identified, including nematodes, flukes, and tapeworms. Of these, 12 were new host records, 13 were reported for the first time in Chile, and 5 were new records for the Neotropical region. Further, the flukes Schistosomatidae gen. sp. and Echinostoma echinatum are of zoonotic concern. Regarding histopathology, an inflammatory response was found along the birds' entire digestive tract. Nevertheless, it is difficult to declare that there is a clear association between such lesions and isolated parasites, as other noxa could be responsible as well. Although in some cases there was an evident association, such inflammatory responses and necrosis were minimal, as occurred with Capillaria, Retinometra, Catatropis, Echinostoma, and Schistosomatidae gen. sp. Nevertheless, Epomidiostomum vogelsangi caused granulomatous injuries, an important inflammatory response, and necrosis, but it always circumscribed to superficial layers of the gizzard. Conversely, Paramonostomum was not associated with an inflammatory response despite a high parasitic load.