Cutaneous Mucormycosis in Buffalos in the Brazilian Amazon Biome

Abstract

This is the first description of cutaneous mucormycosis in buffalo in the Brazilian Amazon biome. All buffalo showed apathy, inappetence, weight loss, reluctance to move, and prolonged sternal decubitus. Of the four affected animals, two died 15 and 30 days after the appearance of clinical signs. In the initial phase, the skin lesions were rounded areas with dry central regions, sensitive to palpation, with protruding edges and diameters ranging from 8 cm to 15 cm. These areas of necrosis were isolated or coalescing and present mainly on the limbs and sides. In an advanced stage of the disease, there was detachment of the skin from the necrotic areas with extensive wound formation, which sometimes exposed the subcutaneous tissue. The histopathology of the skin showed a multifocal inflammatory infiltrate composed of intact and degenerated eosinophils surrounded by epithelioid macrophages. At the center of these areas was a focally extensive area of epidermal ulceration characterized by intact and degenerated neutrophils, the necrosis of epithelial cells, and the accumulation of fibrin and erythrocytes. The mycological culture was positive for Rhizopus sp. The diagnosis of cutaneous dermatitis caused by Rhizopus sp. was based on clinical signs, macroscopic and histopathological findings, and the identification of the fungus by mycological and molecular techniques.

Keywords: Brazil; Bubalus bubalis; Rhizopus sp.; fungal infection; skin diseases.

Figure 1

Cutaneous mucormycosis in buffalo in the Brazilian Amazon biome. Buffalo 1: skin lesions characterized by rounded, isolated-to-coalescing areas, with dry and depressed central regions and protruding and irregular borders with varying diameter, Castanhal, Pará state.

Figure 2

Cutaneous mucormycosis in buffalo in the Brazilian Amazon biome. (a) Buffalo from Figure 1, at a closer view, focusing on lesions on the hind limbs; (b) cut surface of the skin biopsy of Buffalo 1, performed in the transition area between healthy and lesioned tissues and an area of necrosis involving the epidermis and dermis is shown.

Figure 3

Cutaneous mucormycosis in buffalo in the Brazilian Amazon biome. (a,b) Histological section of the skin with marked necrosis of the vascular wall and pyogranulomatous inflammatory infiltrate with unstained hyphae. Hematoxylin and eosin staining, obj. 10 and 40; (c,d) Tubular, irregular in diameter, thick hyphae (arrows) with dichotomous branching and an unstained interior, and a characteristic of the order Mucorales, stained with Grocott–Gomori’s methenamine silver, obj. 20 and 40.