Vaccínia Vírus: aspectos biológicos e epidemiológicos de um patógeno negligenciado no Brasil

Abstract

The orthopoxviruses (OPXV) comprise several emerging viruses of great importance to human and veterinary medicine, such as vaccinia virus (VACV). Zoonotic circulation of VACV was first reported in southeastern Brazil in 1999, since then, VACV infection has been associated with several outbreaks of exanthematous disease in rural areas of Brazil, mainly affecting dairy cattle and their milkers, in which the southeastern region is the epicenter of bovine vaccinia (VB) outbreaks. VACV outbreaks generate substantial impacts on public health and local economies in the affected regions. Despite the importance of VACV in the Brazilian epidemiological context, little is known about its origin, circulation and maintenance in the environment. The first chapter of this work performs the biological and molecular characterization of new Brazilian VACV samples (VACV-BR) isolated from clinical samples of humans suspected of OPXV infection and describes the serological profile of these populations affected by BV in the state of Minas Gerais. A total of five new samples of VACV- BR characterized as belonging to Group I were isolated, which present an 18-nucleotide deletion in the A56R gene encoding the viral hemagglutinin. The serological profile of the twenty patients showed overall positivity of 80% at high titers. The second chapter established the demographic profile, clinical profile and risk factors associated with OPXV infection in patients residing in several municipalities of Minas Gerais. The results obtained reinforce the occupational nature of BV, in which men residing in rural areas who work directly with cattle have a greater chance of exposure to BV. Furthermore, an epidemiological survey of the occurrence and distribution of VACV in Minas Gerais was carried out, describing the evolution of the distribution and numbers of cases of BV in the state during the last decades, using databases obtained from the partnership with the Secretaria de Saúde do Estado de Minas Gerais (SES), Fundação Ezequiel Dias (FUNED) and Instituto Mineiro de Agropecuária (IMA), in addition to data obtained from the scientific literature. These data demonstrate the increase in the area of occurrence and the number of cases in recent decades, especially in important regions of milk production in the state. The performance of the LV as a reference laboratory in studies of characterization and diagnosis of OPXV in Brazil is also described. The combination of these results contributes to the knowledge about circulating VACV variants, describes risks associated with OPXV infections in Brazil and the increase in the number of cases and distribution of this virus.