Fatal gastric amebiasis in a Linnaeus's two-toed sloth associated with Naegleria australiensis infection

Here we describe a case of fatal amebic gastritis associated with Naegleria australiensis infection in an 11-mo-old Linnaeus's two-toed sloth (Choloepus didactylus). The sloth had a history of weight loss and intermittent diarrhea for 18 d, and subsequently died despite empirical treatment. Postmortem findings included emaciation, gastric dilation with fluid content, and fibrinonecrotic gastritis with intralesional amebic trophozoites and cysts in the glandular region of the fundus. Transmission electron microscopy ruled out Amoebozoa of the family Entamoebidae based on the presence of mitochondria in the amoeboid organisms. PCR for pan-free-living amebae followed by next-generation sequencing of the PCR product revealed 99% identity with Naegleria australiensis. Gastric amebiasis has been reported sporadically in macropods and in leaf-eating monkeys with a sacculated stomach. To our knowledge, gastric amebiasis has not been reported previously in a sloth, which also has a sacculated and multi-chambered stomach.