Systemic Mucormycosis in a Hooded Seal (Cystophora cristata)

Abstract

A 4-yr-old male captive hooded seal (Cystophora cristata), previously diagnosed as hypothyroid, died after a 3-wk period of lethargy and inappetance despite treatment that included intramuscular administration of antibiotics and multivitamins. Gross pathologic findings included extensive muscle necrosis over the left flank, an underlying necrotic iliac lymph node, two necrotic pulmonary masses and a necrotic bronchial lymph node. Routine cultures yielded a number of bacterial isolates and a heavy pure fungal growth from the necrotic iliac lymph node; wet preparations of which revealed sporangiophores typical of Mucor sp. Histopathology of necrotic muscle, pulmonary lesions and bronchial and iliac lymph nodes revealed necrosis with a marked pyogranulomatous and eosinophilic inflammatory cell infiltrate and fungal hyphae consistent with a Zygomycete species. This is believed to be the first report of systemic mucormycosis in a pinniped likely to have originated from an injection site reaction.

Fungal infections in animals: a patchwork of different situations

“…[60][61][62][63] Cases in wild living animals have been described, for example, in dolphin, bison, and seal. 64,65…”

The Emergence of Mucormycosis in Free-Ranging Marine Mammals of the Pacific Northwest

“…Huckabone et al (2015), reported only two cases in over 7000 marine mammal necropsies conducted in California, and a single case was documented in 444 examined harbor porpoises (Phocoena phocoena) in the Baltic Sea (Wunschmann et al, 1999). Affected captive animals include killer whales (Orcinus orca), finless porpoise (Neophocaena phocaenoides), bottlenose dolphins (Tursiops truncatus), Pacific white-sided dolphins (Neophocaena phocaenoides), a harp seal (Pagophilus groenlandicus), and a hooded seal (Cystophora cristata) (Kaplan et al, 1960;Robeck and Dalton, 2002;Naota et al, 2009;Barnett et al, 2011;Abdo et al, 2012a,b). Isolated cases in wild stranded marine mammals have been described in a Southern right whale (Eubalaena australis) (Best and McCully, 1979), a bottlenose dolphin (Eubalaena australis) (Isidoro-Ayza et al, 2014), an Atlantic spotted dolphin (Stenella frontalis) (Cerezo et al, 2018), a harbor porpoise (Wunschmann et al, 1999), a harbor seal (Phoca vitulina) and a California sea lion (Zalophus californianus) (Huckabone et al, 2015).…”

Mycotic encephalitis in a grey seal (Halichoerus grypus) pup associated with Rhizomucor pusillus infection

“…Zygomycetes are also opportunists in marine mammals (Reiderson and others 2001, pp 337–338) and immunosuppression associated with organic pollutants has been suggested as a possible additional risk factor (Wu˝nschmann and others 1999, Barnett and others 2011) but further investigation of this possibility was outside the scope of this study. Antibiotics had been used in nearly every published case considered in one review (Ribes and others 2000) and antibiotics also had been administered to this seal pup within a few hours of being picked up.…”

“…Cases include pulmonary mucormycosis in a captive female harp seal ( Pagophilus groenlandicus ) (Kaplan and others 1960), systemic mucormycosis in a captive hooded seal, Cystophora cristata (Barnett and others 2011), systemic Rhizopus microsporus infection in a grey seal (Sosa and others 2013) and an unspecified disseminated zygomycete infection also in a hooded seal (Reiderson and others 2001, p 346). Zygomycete infections of the CNS have been rarely reported in marine mammals as a whole, with reported cases to date being confined to cetaceans (Wu˝nschmann and others 1999, Reiderson and others 2001, pp 345–347, Robek and Dalton 2002).…”