Poxviruses diagnosed in cattle from Distrito Federal, Brazil (2015-2018)

A retrospective study of officially diagnosed poxvirus infections in cattle in Distrito Federal (DF), Brazil, between 2015 and 2018 was performed. All cases were investigated by the DF Official Veterinary Service. In the most cases, samples of oral, cutaneous (teats, udder) or foot lesions were submitted to molecular diagnosis by PCR. In approximately 70% of the cases, additional samples were also submitted for histopathology. Ninety-three out of 2,467 clinically examined cattle (from 385 farms) presented suggestive and/or compatible lesions with poxviruses. Fifty-two out of these 93 cases were confirmed as poxviruses: 27 vaccinia virus (VACV), 9 pseudocowpox virus (PCPV), 8 bovine papular stomatitis virus (BPSV), 5 coinfection by PCPV and BPSV and 3 unidentified parapoxvirus. The clinical cases were observed in farms with different exploration (beef, dairy or mixed) from 9 out of 30 administrative regions of DF. Gross findings consisted of papules, vesicles, ulcers, scabs and scars and varied of type, severity and affected tissue, according to the detected virus. A single human case was observed associated with a BPSV infection. Histologically, the lesions were very similar, independently of the detected poxvirus, and included mild to moderate, superficial, multifocal inflammatory infiltrate of lymphocytes, plasma cells, macrophages and/or neutrophils, with acanthosis and parakeratotic hyperkeratosis, usually associated with serous content, cellular debris and spongiosis. In the ulcerated lesions, there were focally extensive areas of necrosis with severe infiltrate of neutrophils in the adjacent connective tissue. Few to moderate amount of 4- to 8-µm eosinophilic inclusion bodies were observed in the cytoplasm of keratinocytes in 6 cases (2 of VACV, 2 of PCPV and 2 of PCPV/BPSV coinfection). Data of the current study demonstrate the wide circulation of different poxviruses in cattle from DF.