Mycotic Infections in Free-Ranging Harbor Porpoises (Phocoena phocoena)

Abstract

Studies on the occurrence of fungal communities in the marine environment are still scarce, but mycotic infections in cetaceans are increasingly reported. Fungal disease following infection with Aspergillus species is most frequently reported, with the respiratory tract commonly affected in cetaceans and other taxa, like humans and birds. Infection with Aspergillus spp. is dependent on the characteristics of the fungus as well as the hosts immune status, with dissemination into other organs being relatively common. Along the southern North Sea, harbor porpoise (Phocoena phocoena) strandings increased significantly since 2005 and necropsies to determine causes of death have been conducted since 2008. Here we describe the post-mortem findings in stranded, free-ranging harbor porpoises on the Dutch coast which were diagnosed with fungal disease, to determine the prevalence of mycotic infections, and to compare them to those described in other species. A total of 18/754 (2.4%) harbor porpoises showed lesions compatible with localized or disseminated fungal disease as confirmed by histological examination. The respiratory tract was most commonly affected (67%), followed by the central nervous system (CNS, 33%), and auditory system (AS, 17%). Aspergillosis was confirmed for 11/18, by fungal growth (as A. fumigatus species complex, n = 9) and PCR (as Aspergillus spp., n = 1, and as A. fumigatus sensu strictu by sequence analysis, n = 1). One live stranded and euthanized animal presented partial hemiplegia of the blowhole and therefore an MRI was conducted, which resulted in a unique image of the extensive, fungus-induced lesion in the left cerebellar hemisphere, deforming and displacing the brainstem, and additionally affected the AS. The gross-and histologic lesions in the 18 porpoises diagnosed with fungal disease were similar to changes described in other mammalian species. The prevalence of fungal disease in free-living harbor porpoises is lower than seen in captive and rehabilitated animals, suggesting that captivity increases the

Fatal aspergillosis and evidence of unrelated hearing loss in a harbor porpoise (Phocoena phocoena) from the German Baltic Sea

“…Leger et al, 2018), infections with morbilliviruses and thus coinfections are rare in harbor porpoises (Kennedy et al, 1991;Jepson et al, 2000). So far, only a few cases of aspergillosis have been detected in harbor porpoise stranding schemes: Kapetanou et al (2020) found 11 out of 754 porpoises (i.e., 1.5%) from the Dutch North Sea to be infected. In contrast, a higher frequency of aspergillosis (9/61, 14.7%) was detected by van Elk et al (2019) in porpoises from Dutch, Belgian, and German coastlines, whereas all those animals died during attempted rehabilitation, which might have favored infection (Kapetanou et al, 2020).…”

Pathological findings in stranded harbor porpoises (Phocoena phocoena) with special focus on anthropogenic causes

“…Several infectious agents have, however, been targeted and published separately, including on the prevalence of Brucella spp. (Maio et al, 2014), mycoses, specifically Aspergillus fumigatus (Kapetanou et al, 2020), herpesvirus (van Beurden et al, 2015), and Toxoplasma gondii (van de Velde et al, 2016;Morell et al, 2021).…”

Postmortaal onderzoek van bruinvissen (Phocoena phocoena) uit Nederlandse wateren, 2020 : Biologische gegevens, bgezondheidsstatus en doodsoorzaken

“…De platen werden om de dag beoordeeld op schimmelgroei door een microbioloog. Verdachte kolonies werden geïdentificeerd op basis van fenotypische kenmerken en microscopisch onderzoek (Kapetanou & IJsseldijk et al, 2020). Mycologisch onderzoek werd tevens uitgevoerd bij het VMDC.…”