Bovine Vaccinia in dairy cattle and suspicion of vesicular disease on milkers in Brazil

EnglishBovine vaccinia (BV) is a vesicular disease induced by the Vaccinia virus (VACV) that affects milk production and is an occupational zoonosis. This research had the following objectives: (i) detection of VACV by qPCR in cattle with clinical suspicion of vesicular disease; (ii) symptoms characterization in animals and milkers with clinical suspicion of the disease and virus detection in humans; and (iii) identification of risk factors for infections of VACV in herds from several Brazilian states. A total of 471 bovine epithelial samples from dairy farms, in 15 Brazilian states, were evaluated between 2007 and 2012. The samples were tested by quantitative PCR (qPCR) using SYBR Green® reagents, validated with a lower limit of detection of 100TCID50/50µL (1.7x100 viral particles), and 45.1% of VACV positive samples were detected. Using official forms for epidemiological investigation (FORM-IN), the risk factors for VACV infections in cattle were determined to be farms with a lack of technological facilities (P= 0.029) and the presence of rodents (P= 0.001). There was an effect of seasonality in cattle with a higher occurrence of BV during the dry season. A total of 420 epidemiological questionnaires were applied at public health care centers, where 100% of the milkers had vesicular lesions on their hands (98.1%) and on their arms (6.9%). The most frequent clinical symptoms in humans were: local swelling (74.2%), headache (20.7%), fever (10.4%) and inguinal lymphadenopathy (74.2%). Only 19.98% of milkers aged between 39 and 58 years were seroreactive to VACV and were immunized with the human anti-smallpox vaccine. There was an increase in the frequency of BV in older individuals due to their natural decrease in specific immunity. It has been shown that the implementation of zootechnical management techniques and health planning are important for the prevention of BV in animals and humans. Key words: Orthopoxvirus; Poxviridae; quantitative PCR; risk factor; VACV; zoonosis portuguesVaccinia bovina (VB) e uma doenca vesicular induzida pelo Vaccinia virus (VACV) que afeta a producao de leite e e uma zoonose ocupacional. Este trabalho teve os seguintes objetivos: (i) deteccao de VACV por qPCR em bovinos com suspeita clinica de doenca vesicular; (ii) caracterizacao dos sintomas apresentados por animais e ordenhadores com suspeita clinica da doenca e deteccao do virus em humanos; e (iii) identificacao de fatores de risco para infeccao por VACV em rebanhos de varios estados brasileiros. Um total de 471 amostras de epitelio bovino de fazendas leiteiras, em 15 estados brasileiros, foram avaliados entre 2007 e 2012. As amostras foram testadas por PCR quantitativa (qPCR) usando reagentes SYBR Green®, validados com um limite inferior de deteccao de 100TCID50 / 50μL (1,7x100 particulas virais) e 45,1% das amostras positivas de VACV foram detectadas. Usando formularios oficiais de investigacao epidemiologica (FORM-IN), os fatores de risco para infeccoes por VACV em bovinos foram determinados como fazendas com falta de instalacoes tecnologicas (P= 0,029) e presenca de roedores (P= 0,001). Houve um efeito da sazonalidade no gado com maior ocorrencia de VB durante a estacao seca. Um total de 420 questionarios epidemiologicos foram aplicados nos centros publicos de saude, onde 100% dos ordenhadores apresentaram lesoes vesiculares nas maos (98,1%) e nos bracos (6,9%). Os sintomas clinicos mais frequentes em humanos foram: inchaco local (74,2%), cefaleia (20,7%), febre (10,4%) e linfadenopatia inguinal (74,2%). Apenas 19,98% dos produtores de leite com idade entre 39 e 58 anos foram sororreagentes ao VACV e foram imunizados com a vacina contra a variola humana. Houve um aumento na frequencia de BV em individuos mais velhos devido a sua diminuicao natural na imunidade especifica. Demonstrou-se que a implementacao de tecnicas de gestao zootecnica e planejamento sanitario sao importantes para a prevencao da VB em animais e seres humanos. Palavras-chave: Poxviridae; quantitative PCR; risk factor; VACV; zoonosis