Parasitic Granulomatous Dermatitis Caused by Pelodera spp. in Buffalo on Marajó Island, Pará

Abstract

This is the first report of parasitic granulomatous dermatitis caused by Pelodera spp. in a buffalo. The affected buffalo was about seven years old, was a female of the Murrah breed and belonged to a property located on Marajó Island in the State of Pará. During the clinical examination, the animal was in a standing position and presented several multifocal nodular and placoid masses throughout the body, mostly on the forelimbs, hindlimbs, abdomen, mammary glands, perineum, vulva and tail. These masses were also observed on the nasal mucosa, head, neck, back and chest. On macroscopic examination, the skin had several multifocal-to-coalescent sessile nodular and placoid lesions. Histopathology of the skin showed a marked reduction in the number of hair follicles. In the superficial dermis, there was significant multifocal-to-coalescent inflammatory infiltration, consisting of macrophages, epithelioid macrophages, lymphocytes, plasma cells and multinucleated giant cells. In the remaining hair follicles, there were numerous cross and longitudinal sections of small rhabditoid nematodes characterized by a thin cuticle, platymyarian musculature, an intestinal tract, a rhabditiform esophagus and lateral alae (morphologically compatible with Pelodera spp.). The diagnosis of parasitic dermatitis was confirmed by histopathological skin lesions associated with the presence of intralesional rhabditiform larvae morphologically compatible with Pelodera spp.

Keywords: Amazon biome; Bubalus bubalis; parasitic disease; rhabditoid nematodes.

Figure 1

Parasitic granulomatous dermatitis caused by Pelodera spp. in buffalo; (A) multifocal to coalescing, well-delimited and sometimes ulcerated nodular skin lesions of varying size were distributed across several regions of the body; (B) same aspect of the lesions with an emphasis on the posterior region.

Figure 2

Parasitic granulomatous dermatitis caused by Pelodera spp. in buffalo; (A) ultrasound image of skin nodules characterized by ovoid structures located in the subcutaneous tissue, with a multifocal and sometimes coalescent distribution delimited by a capsule. Sometimes, these nodules were thicker and sometimes they were delimited by a thin hyperechoic line, with heterogeneous contents in echogenic areas and hypoechogenic liquid content tending to anechoic in shapeless hyperechoic areas. (B) Ulcerated, well-delimited, multifocal to coalescing skin lesions with irregular borders and of varying sizes distributed along the ventral region of the tail.

Figure 3

Parasitic granulomatous dermatitis caused by Pelodera spp. in buffalo: (A) cut surface of the multifocal to coalescing, yellowish, caseous skin granulomas, surrounded by fibrous connective tissue. (B) Osteophytic proliferation of rough-to-irregular appearance on the periosteal surface of the metacarpal and on the carpal bones after maceration. Concavities where the granulomas exerted more pressure are seen on the caudomedial side of the diaphysis. (C) X-ray image showing mild spiculate periosteal reactions, mainly on the proximal third of the metacarpal and on the bones of the adjacent carpal. Medullary canal of the metacarpal with a heterogeneous appearance and radiopaque circumscribed areas. A large area of osteolysis is seen on the proximal third of the metacarpal. Reduced intracarpal and carpometacarpal joint space.

Figure 4

Parasitic granulomatous dermatitis caused by Pelodera spp. in buffalo: (A) Inflammatory infiltrate in the superficial dermis, absence of hair follicles and evident acanthosis and epidermal hyperkeratosis. HE, 40×. (B) Inflammatory infiltrate rich in multinucleated giant cells in the dermis. HE, 100×. (C) Granulomatous inflammation around a hair follicle full of parasitic structures. HE, 200×. (D) Several sections of rhabditiform parasites inside the hair follicle. HE, 400×.