Diagnosis and clinic-pathological findings of influenza virus infection in Brazilian pigs

Influenza A virus (IAV) is a respiratory pathogen of pigs and is associated with the porcine respiratory disease complex (PRDC), along with other respiratory infectious agents. The aim of this study was to diagnose and to perform a clinic-pathological characterization of influenza virus infection in Brazilian pigs. Lung samples from 86 pigs in 37 farrow-to-finish and two farrow-to-feeder operations located in the States of Minas Gerais, São Paulo, Paraná, Rio Grande do Sul, Santa Catarina, and Mato Grosso were studied. Virus detection was performed by virus isolation and quantitative real time reverse-transcription PCR (qRT-PCR). Pathologic examination and immunohistochemistry (IHC) were performed in 60 lung formalin-fixed paraffin-embedded tissue fragments. Affected animals showed coughing, sneezing, nasal discharge, hyperthermia, inactivity, apathy, anorexia, weight loss and growth delay, which lasted for five to 10 days. Influenza virus was isolated from 31 (36.0%) lung samples and 36 (41.9%) were positive for qRT-PCR. Thirty-eight (63.3%) lung samples were positive by IHC and the most frequent microscopic lesion observed was inflammatory infiltrate in the alveoli, bronchiole, or bronchi wall or lumen (76.7%). These results indicate that influenza virus is circulating and causing disease in pigs in several Brazilian states

Diagnosis and clinic-pathological findings of influenza virus infection in Brazilian pigs Diagnóstico, achados clínicos e patológicos da infecção pelo vírus influenza em suínos no Brasil

Influenza A virus (IAV) is a respiratory pathogen of pigs and is associated with the porcine respiratory disease complex (PRDC), along with other respiratory infectious agents. The aim of this study was to diagnose and to perform a clinic-pathological characterization of influenza virus infection in Brazilian pigs. Lung samples from 86 pigs in 37 farrow-to-finish and two farrow-to-feeder operations located in the States of Minas Gerais, São Paulo, Paraná, Rio Grande do Sul, Santa Catarina, and Mato Grosso were studied. Virus detection was performed by virus isolation and quantitative real time reverse-transcription PCR (qRT-PCR). Pathologic examination and immunohistochemistry (IHC) were performed in 60 lung formalin-fixed paraffin-embedded tissue fragments. Affected animals showed coughing, sneezing, nasal discharge, hyperthermia, inactivity, apathy, anorexia, weight loss and growth delay, which lasted for five to 10 days. Influenza virus was isolated from 31 (36.0%) lung samples and 36 (41.9%) were positive for qRT-PCR. Thirty-eight (63.3%) lung samples were positive by IHC and the most frequent microscopic lesion observed was inflammatory infiltrate in the alveoli, bronchiole, or bronchi wall or lumen (76.7%). These results indicate that influenza virus is circulating and causing disease in pigs in several Brazilian states.<br>O vírus influenza A (IAV) é um patógeno respiratório comum de suínos e faz parte do complexo de doenças respiratórias do suíno (PRDC) junto com outros agentes infecciosos. O objetivo deste estudo foi diagnosticar e realizar a caracterização clínica e patológica de casos/surtos de influenza em suínos brasileiros. Foram utilizadas amostras de tecido pulmonar de 86 suínos de 37 granjas de ciclo completo e duas unidades produtoras de leitões localizadas em Minas Gerais, São Paulo, Paraná, Rio Grande do Sul, Santa Catarina e Mato Grosso. A detecção viral em fragmentos pulmonares frescos foi realizada através do isolamento viral e da transcrição reversa-PCR em tempo real quantitativa (qRT-PCR). Exame patológico e imuno-histoquímica (IHQ) foram realizados em 60 amostras de pulmão fixadas em formalina 10% e embebidas em parafina. As amostras eram de animais apresentando tosse, espirros, secreção nasal, hipertermia, prostração, apatia, anorexia, perda de peso e ganho de peso reduzido, com duração entre cinco e 10 dias. O vírus influenza foi isolado de 31 (36,0%) amostras e 36 (41,9%) foram positivas na qRT-PCR. Na IHQ, 38 (63,3%) amostras foram positivas e a lesão mais frequentemente observada foi a presença de infiltrado inflamatório na parede e lúmen de vias aéreas (76,7%). Estes resultados indicam que o vírus influenza está circulando e causando lesões e doença respiratória em suínos de diversos Estados do Brasil