Fatal systemic Mortierella wolfii infection in a neonatal calf in southern Brazil

This study described the pathological and microbiological aspects of a fatal systemic Mortierella wolfii infection in a neonatal calf in southern Brazil. The calf was born clinically normal, but on the third day of life it presented apathy, unilateral hypopyon, and neurological signs, and in the next day it was euthanized. At necropsy, multiple soft, and white-yellow nodules were observed in the liver, spleen, kidneys, mesenteric lymph nodes, heart, and lungs. In the brain, reddish, and friable areas were found. In the eye, there were anterior and posterior synechiae, diffuse thickening of choroid, and anterior chamber filled by whitish and friable material. Microscopically, areas of necrosis, pyogranulomatous inflammation, vasculitis, thrombosis, and intralesional fungal hyphae were observed, and the latter were better evidenced through Grocott Methenamine Silver technique. The fungus was identified as M. wolfii through mycological culture and molecular methods. To our knowledge, this is the first description of systemic disease caused by M. wolfii in a neonatal calf outside of Oceania.