Abstract:
Annual mortality events in Nile crocodiles (Crocodylus niloticus) in the Olifants River Gorge in
Kruger National Park, South Africa, were experienced between 2008 and 2012, during which at least 216
crocodiles died. Live crocodiles were lethargic. Necropsy examination of 56 affected crocodiles showed dark
yellow-brown firm nodules in both somatic fat and the abdominal fat body. In all of the 11 crocodiles submitted
for histology, degenerative, necrotic, and inflammatory changes supported a diagnosis of steatitis in both fat types.
Crocodiles are apex predators in this anthropogenically changed aquatic ecosystem that is used by humans
upstream and downstream from the park for domestic, agricultural, fishing, and recreational purposes. This
pathologic review of pansteatitis in crocodiles in the Olifants River system was part of a broad multidisciplinary
research program. To date, no definitive causative agent has been identified. Epidemiologic evidence suggests that
this event may have been a one-time event with long-standing repercussions on the health of the crocodiles.
Pathologic findings are rarely documented in wild crocodilians. This study also reports on other conditions,
including the presence of coccidian oocysts, capillarid and filaroid nematodes, digenetic trematodes, and
pentastomes.
