Concurrent Fowlpox and Candidiasis Diseases in Backyard Chickens with Unusual Pox Lesions in the Bursa of Fabricius.

Concurrent fowlpox and candidiasis diseases occurred in a backyard chicken flock. Four deceased chickens (one Nagoya breed and three white silkie chickens) were examined for diagnosis. At necropsy, white curd-like plaques were observed in the crop. Fungal elements that stained positive for Candida albicans with immunohistochemistry were distributed throughout the tongue, choanal mucosa, esophagus, and crop. Typical fowlpox lesions, composed of proliferating epithelial cells with ballooning degeneration and viral intracytoplasmic inclusions, were observed in the conjunctiva, nasal mucosa, and skin around the cloaca. Interestingly, hyperplastic interfollicular epithelium with rare virus inclusions was observed in the bursa of Fabricius (BF). Some bursal follicles were replaced by proliferating epithelial cells. These proliferating cells immunohistochemically stained positive for cytokeratin. PCR and subsequent genetic sequencing detected the C. albicans gene in the crop, and fowlpox virus genes in the BF. These results indicate that this outbreak was a rare presentation of fowlpox in spontaneously infected chickens, with unusual pox lesions in the BF.