Disseminated blastomycosis in a rhesus monkey (Macaca mulatta)

Area of Science:

• Veterinary Pathology
• Mycology
• Primate Medicine

Background:

• Blastomycosis is a systemic fungal infection caused by *Blastomyces dermatitidis*.
• It primarily affects dogs and humans, with distinct clinical and pathological presentations.
• Nonhuman primates are rarely studied for susceptibility to this dimorphic fungus.

Observation:

• An 8-year-old male rhesus monkey presented with acute respiratory distress, anorexia, and depression.
• Necropsy revealed severe granulomatous pneumonia, splenitis, and multifocal cerebral abscesses.
• Histopathology identified broad-based budding yeast forms consistent with *Blastomyces* within pyogranulomatous lesions.

Findings:

• The pathological findings, including extrapulmonary lesion distribution, were intermediate between canine and human blastomycosis.
• This case represents the first documented instance of blastomycosis in a nonhuman primate.
• The causative agent was identified as *Blastomyces dermatitidis* based on morphology.

Implications:

• This discovery expands the known host range for *Blastomyces dermatitidis*.
• It underscores the importance of considering blastomycosis in nonhuman primates with compatible clinical signs.
• Further research is warranted to understand the epidemiology and transmission dynamics in primate populations and potential zoonotic implications.