Avaliação de rotas alternativas de transmissão do Vaccinia Virus (Vacv) em áreas urbanizadas do Estado de Minas Gerais, Brasil

Abstract

Bovine vaccinia (BV) is an emerging viral zoonosis associated with the vaccinia virus (VACV), characterized mainly by the presence of ulcerative lesions on the skin and mucous membranes of cattle and milkers. In the rural environment, VACV is transmitted through direct contact between workers and infected animals. Twenty years after the emergence of BV in Brazil, aspects related to the origin and transmission of VACV are still unknown and little is known about the potential viral circulation in an urban environment.In this study, the hypothesis of human exposure through the consumption of artisanal cheese produced in Minas Gerais (MG) was evaluated. The analysis of 71 artisanal cheeses produced in different regions of the state, between 2015 and 2018, detected the genetic material of the VACV in 28,1% of the cheeses, whose sampling included every year of collection and all milk basins. In the urban area of the Serro-MG dairy basin, a population study was carried out to assess human exposure factors. A total of 372 individuals were sampled, whose molecular investigation of the virus in an oropharyngeal swab detected VACV in 25 samples (6.7%). A seroepidemiological survey was carried out which detected an overall prevalence of 16.9% (63/372) of neutralizing antibodies, with a titer between 100 and 800 UN/mL. IgG-type antibodies were detected in 26 individuals (7%), while the IgM was detected in 2.7% of the studied population (10/369). The presence of IgG and neutralizing antibodies were statistically correlated with age > 40 years. The occupations of “retiree” and “rural worker” were associated as a risk factor with the presence of neutralizing antibodies, while for the presence of IgG, only “rural worker” showed an association. In this study, individuals vaccinated against smallpox were approximately four times more likely to have neutralizing antibodies, IgG and IgM, compared to those who were not vaccinated; handling raw milk during the production of dairy products also behaved as a risk factor for detection of neutralizing antibodies (OR=2.45; 95% CI = 1.17-5.16) and IgG- type antibodies (OR=3.6; 95% CI = 1.18-9.8) . These data are indicative of exposure to VACV in urban areas, outside the context of an outbreak and classical transmission, and reinforce the hypothesis of the existence of alternative routes for the transmission of VACV in Brazil.