Serological study of vaccinia virus reservoirs in areas with and without official reports of outbreaks in cattle and humans in São Paulo, Brazil

Abstract

Vaccinia virus (VACV), the etiological agent of an exanthematic disease, has been associated with several bovine outbreaks in Brazil since the end of the global vaccination campaign against smallpox. It was previously believed that the vaccine virus used for the WHO global campaign had adapted to an unknown wild reservoir and was sporadically re-emerging in outbreaks in cattle and milkers. At present, it is known that Brazilian VACV is phylogenetically different from the vaccinia virus vaccinal strain, but its origin remains unknown. This study assessed the seroprevalence of orthopoxviruses in domestic and wild animals and farmers from 47 farms in three cities in the southwest region of the state of São Paulo with or without official reports of outbreaks in cattle or humans. Our data indicate a low seroprevalence of antibodies in wild animals and raise interesting questions about the real potential of wild rodents and marsupials as VACV reservoirs, suggesting other routes through which VACV can be spread.

Ticks infesting wild small rodents in three areas of the state of São Paulo, Brazil

“…Rodents were captured as part of a study on the wild cycle of the Vaccinia viruses, in which rodents were evaluated as potential reservoirs of the virus (PeReS et al, 2013). Rodent captures were performed with Sherman and pitfall intercepts traps, as previously described (PeReS et al, 2013).…”

Experimental infection of horses with Vaccinia virus

“…Vaccinia virus (VACV) belongs to family Poxviridae, genus Orthopoxvirus, and is associated with exanthematic and vesicular disease mainly in cattle, but also in man and, possibly in wild and peridomestic rodents (TRINDADE et al, 2007;ABRAHÃO et al, 2009;BORGES et al, 2013;PERES et al, 2013). Natural infection by VACV in horses was reported in Brazil, yet it seems to be a rare event (BRUM et al, 2010;MATOS et al, 2013).…”

“…The natural cycle of VACV infection is not completely known, yet the participation of wild/peridomestic rodents as reservoirs had been suggested (ABRAHÃO et al, 2009;BORGES et al, 2013;PERES et al, 2013). If this were the case, peridomestic rodents could transmit the virus to farm animals and then to man (ABRAHÃO et al, 2009).…”

“…The disease was characterized by ulcerative, scabby, and hemorrhagic lesion in the muzzle and mucocutaneous junction of mouth and nostrils (BRUM et al, 2010). Furthermore, serological and epidemiological studies in Brazilian equine herds showed the presence of antibodies anti-OPV in animals from Midwest Brazil (BORGES et al, 2013;PERES et al, 2013). Recently, another VACV outbreak in horses was identified in Minas Gerais (MATOS et al, 2013), with clinical course similar to the VACV outbreak reported in Southern Brazil (BRUM et al, 2010).…”

Vaccinia Virus: It’s Use in Smallpox Vaccine and Epidemiology

“…It is believed that some species of Rodent Order act as VACV natural reservoirs [4,17]. Accordingly, a serological study was conducted in areas with and without official VACV zoonotic outbreak, and the statistical analysis show low likelihood of wild rodents studied are acting as VACV reservoirs in this area [18]. Although, studies has demonstrated the possible of transmission of VACV from mice experimentally infected to cow [4,19,20].…”