Fatal pulmonary parafilaroidiasis in a free-ranging subantarctic fur seal (Arctocephalus tropicalis) coinfected with two gammaherpesviruses and Sarcocystis sp.

Abstract

A juvenile subantarctic fur seal (Arctocephalus tropicalis) found dead in Santa Catarina state, southern Brazil, presented with disseminated verminous pneumonia due to Parafilaroides sp. A concomitant infection with two different gammaherpesviruses was identified by PCR in different tissues; one of them possibly a novel species (tentatively named Otariid herpesvirus 7). Sarcocystis sp. DNA was identified molecularly in skeletal muscle samples with intrasarcoplasmic bradyzoites and no apparent tissue response. All analyzed samples (mandibular, laryngeal, tracheal, and mesenteric lymph nodes, and lung) were PCR-negative for Brucella spp. The most likely cause of death was severe pulmonary parafilaroidiasis. The pathogenic role of the gammaherpesviruses in several of the tissues was not evident. This study describes the pathogenicity of Parafilaroides sp. in a subantarctic fur seal, widens the host range of herpesvirus in pinnipeds, and reports the first molecular identification of Sarcocystis sp. in this species.

Verminotic pneumonia in South American fur seal (Arctocephalus australis) in Southern Brazil

“…The animals in this study, whose final diagnosis was determined to be starvation, and who also had verminotic pneumonia, did not present with any lung lesions that were severe enough to justify this as a cause of death. This is unlike what was found in the sub-Antarctic fur seal, as reported in SC state by Reisfeld et al (2019) which, despite being cachectic and carrying infections by Sarcocystis sp. and gammaherpesviruses, had pneumonia caused by Parafilaroides sp.…”

“…and these are affected by other aetiological agents. It is further suggested that this nematode is a host for Brucella pinnipedialis (Rhyan et al, 2018;Reisfeld et al, 2019). However, the South American fur seals studied by our team did not show immunohistochemical staining with anti-B.…”

“…Verminotic pneumonia caused by metastrongylids Parafilaroides spp. (Metastrongyloidea: Filaroididae) and Otostrongylus circumlitus (Metastrongyloidea: Crenosomatidae) is frequently reported in pinnipeds in different parts of the world (Onderka, 1989 ; Dailey, 2001 , 2009 ; Siebert et al ., 2007 ; Reisfeld et al ., 2019 ). While the nematode O. circumlitus affects different hosts, the genus Parafilaroides has several species that cause lung disease in pinnipeds from different regions (Dailey, 2006 , 2009 ; Jacobus et al ., 2016 ; Reisfeld et al ., 2019 ; Echenique et al ., 2020 ).…”

New host and geographical records for Parafilaroides normani (Nematoda: Filaroididae) Dailey, 2009 in South American fur seal, Arctocephalus australis, from southern Brazil

“…On the coast of Santa Catarina State, a recent study recorded lethal pneumonia caused by Parafilaroides sp. infection, associated with a g-herpes virus and Sarcocystis sp., in a juvenile A. tropicalis (Reisfeld et al ., 2019). In the present study, we recorded the presence of P. normani for the first time, but as the focus was to verify the prevalence of worms, it was impossible to be certain of the primary cause of death or to confirm if it was directly or indirectly associated with parasite infection.…”

“…The most common species are the South American sea lion ( Otaria flavescens ) and the South American fur seal ( A. australis ); these species are considered as being ‘of least concern’ by the IUCN (2008), although this classification needs updating. Previous studies performed in dead animals stranded along Brazilian coasts revealed lung lesions caused by parasites, but the morphological identification of the worms was not resolved to the species level (Ruoppolo, 2003; Reisfeld et al ., 2019).…”