Alimentary mycosis in sloths

Abstract

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 Bradypus and Choloepus genera. In addition, panfungal polymerase chain reaction (PCR) targeting the ITS-2 gene was performed in all cases to determine a specific etiology. We retrieved 11 cases of alimentary mycosis in 3 sloth species: Bradypus variegatus (n = 1), Choloepus hoffmanni (n = 7), and Choloepus didactylus (n = 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 Trichosporon asahii infection in 45% (5/11) of the cases, from gastric, esophageal, and lingual lesions, and Penicillium sp. and Wallemia mellicola in a gastric lesion in 1 case each. Candida sp. infection was not confirmed in any of the cases. Trichosporon asahii has overlapping histological features with Candida 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.