Bovine papular stomatitis affecting dairy cows and milkers in midwestern Brazil

Abstract

Bovine papular stomatitis virus (BPSV) is a parapoxvirus associated with papular and erosive lesions on the muzzle, lips, and oral mucosa of cattle. Teats of milking cows are occasionally affected, and the infection is frequently transmitted to human beings. The present report describes an outbreak of BPSV infection affecting cows in midwestern Brazil, with human involvement. The disease was observed in neighboring small hand-milking farms, affecting 20 milking cows. The signs included painful reddish papules, ulcers, and scabby proliferative lesions on the teats, with a clinical course of 7-12 days. Affected cows presented severe local pain, not allowing the completion of milking. Histologically, acanthosis, spongiosis, and parakeratotic hyperkeratosis with adjacent focally extensive ulcers and multifocal inflammatory infiltrate were observed in the epidermis. Eosinophilic inclusion bodies were noted in the cytoplasm of epithelial cells. Personnel milking the affected cows developed lesions on the hands, painful papules that progressed to ulcerative and scabby lesions in 4-7 days. A polymerase chain reaction using a set of pan-parapoxvirus primers for the B2L gene performed on DNA extracted from scabs amplified a 590-bp product, which when sequenced, revealed similarities of 99%, 85%, and 84% with BPSV, Pseudocowpox virus, and Orf virus, respectively. A phylogenetic tree based on the B2L sequence was constructed, showing that the virus clustered with BPSV isolates. Although clinical cases compatible with BSPV infection have been frequently described in Brazil, the present report identifies the agent associated with cattle and human disease in the country.