Alimentary mycosis in sloths

Alimentary mycosis is seldom reported in sloths. Through a multi-institutional retrospective study, we described the histological features of fungal infections within the digestive tract of sloths of the <i>Bradypus</i> and <i>Choloepus</i> genera. In addition, panfungal polymerase chain reaction (PCR) targeting the <i>ITS-2</i> gene was performed in all cases to determine a specific etiology. We retrieved 11 cases of alimentary mycosis in 3 sloth species: <i>Bradypus variegatus</i> (<i>n</i> = 1), <i>Choloepus hoffmanni</i> (<i>n</i> = 7), and <i>Choloepus didactylus</i> (<i>n</i> = 3). Eight were free-ranging, whereas 3 were held in captivity. Nine were females and 8 were juveniles (ranging from 2 weeks to 2 years old). In 64% of the cases, the lesions were gastric in the muscular portion of the prepyloric stomach. In the other animals, the lesions were located in the tongue and/or esophagus. Pustules, erosions, ulcers, and hyperkeratosis within the keratinoid layer with intralesional yeast, pseudohyphae, and hyphae characterized alimentary mycotic infections. Panfungal PCR identified <i>Trichosporon asahii</i> infection in 45% (5/11) of the cases, from gastric, esophageal, and lingual lesions, and <i>Penicillium</i> sp. and <i>Wallemia mellicola</i> in a gastric lesion in 1 case each. <i>Candida</i> sp. infection was not confirmed in any of the cases. <i>Trichosporon asahii</i> has overlapping histological features with <i>Candida</i> and poses a diagnostic challenge when conventional culture or molecular methods are unavailable. Trichosporonosis is a differential diagnosis in cases of fungal alimentary lesions in sloths. Predisposing factors for alimentary mycosis in sloths include age (younger animals), canine distemper virus co-infection, late pregnancy, and chronic antibiotic use.