Identification of the environmental source of infection for a domestic ferret with cryptococcosis

Abstract

Cryptococcosis, caused by the Cryptococcus gattii and C. neoformans species complexes, is an environmentally acquired mycosis affecting a broad range of host species. Among 9 communally housed ferrets, a 5-y-old castrated male ferret domiciled in an outdoor enclosure in Sydney, Australia was diagnosed with sinonasal cryptococcosis. Clinical signs resolved during 18 mo of itraconazole therapy, but the ferret was eventually euthanized because of splenic hemangiosarcoma. At postmortem, microscopic foci of persistent cryptococcosis were detected. The diagnosis raised concerns that the owners and other ferrets were exposed to a common environmental source of infection, thus prompting an investigation. Soil samples, swabs of a hollow eucalypt log (used for behavioral enrichment), and nasal swabs from 8 asymptomatic ferrets were collected. Nasal exudate (obtained at diagnosis) and tissues (collected at postmortem) were available from the clinical case. Bird seed agar culture resulted in a heavy growth of Cryptococcus spp. from one environmental site (the log), one nasal swab, and nasal exudate and tissues from the clinical case. All other samples were culture-negative. Sub-cultured isolates from the log were a mixture of C. gattii molecular type VGI and C. neoformans molecular type VNI. Ferret isolates were a similar mixture of C. gattii VGI (all disease isolates) and C. neoformans VNI (nasal-colonizing isolate). Multilocus sequence typing further revealed the ferret isolates as identical to environmental isolates collected from the log, confirming the log as the source of clinical disease and nasal colonization. The log was removed to prevent further exposure to a high environmental load of Cryptococcus spp.

Multilocus sequence typing of strains from the Cryptococcus gattii species complex from different continents

“…ST51 was also found in Colombia in clinical strains, but in lesser proportions 28 . Regarding ST154, our results agree with a recent study that collected this ST from a group of domestic ferrets and their environment (pot plants and garden beds to which ferrets had access) in western Sydney 29 . Among the other VGI strains, we identified one strain of ST106, one of the most virulent strains in the invertebrate model, Galleria mellonella 28 , and the dominant ST in Taiwan.…”

A severe case of disseminated cryptococcosis in a young French bulldog living in South‐East Queensland caused by Cryptococcus gattii VGII

“…C ryptococcosis is the most common systemic fungal disease in Australia, effecting a diverse array of hosts including cats, man, dogs, ferrets, horses, dolphins, rabbits, cattle, goats, rats, guinea pigs, kiwis, apes, cheetahs, cetaceans, kangaroos, and koalas. [1][2][3][4][5][6][7][8][9][10][11] Cryptococcus in the dog tends to occur in young largebreed dogs such as German Shepherds, Great Dane, Dobermans, Boxers and Border Collies, and this observation has been attributed to large breeds living more commonly outdoors, and greater exposure to contaminated environmental surfaces. 12,13 Clinical disease is most likely caused by the inhalation of basidiospores (reproductive spores) with the major virulence factors responsible for its pathogenicity being its large mucopolysaccharide capsule, production of melanin, urease, phospholipase, and the ability to survive and multiply at mammalian body temperature.…”

“…Cryptococcosis is the most common systemic fungal disease in Australia, effecting a diverse array of hosts including cats, man, dogs, ferrets, horses, dolphins, rabbits, cattle, goats, rats, guinea pigs, kiwis, apes, cheetahs, cetaceans, kangaroos, and koalas 1–11 . Cryptococcus in the dog tends to occur in young large‐breed dogs such as German Shepherds, Great Dane, Dobermans, Boxers and Border Collies, and this observation has been attributed to large breeds living more commonly outdoors, and greater exposure to contaminated environmental surfaces 12,13 .…”