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Estudo de circovirose em explorações intensivas de suínos
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Resumo(s)
O agente etiológico da circovirose é um vírus de pequenas dimensões, sem envelope, de
simetria icosaédrica, contendo um genoma DNA de cadeia circular simples, ao qual se deu o
nome de Porcine circovirus (PCV). O PCV é considerado um vírus ubiquitário, que causa
doença exclusivamente em suínos e já foi isolado em todos os continentes. Este vírus é
responsável por várias afecções, sendo a mais comum e responsável por maiores perdas
económicas no sector, a síndrome de emagrecimento pós-desmame (PMWS).
Existem diversos factores de risco para que se verifique manifestação clínica de doença,
nomeadamente deficiências de maneio, a presença de co-infecções, estatuto imunitário das
reprodutoras contra o PCV e imuno-estimulação por diferentes causas. As lesões e sinais
clínicos associados a infecção por PCV sugerem que este seja um agente imunossupressor /
imunomodulador. O controlo e prevenção das PCVD passam pela minimização do efeito dos
factores de risco e pela vacinação contra o PCV.
Neste contexto, o presente estudo tem como objectivos:
1. Identificar explorações intensivas de suínos com suspeita de ocorrência de PCV2.
2. Caracterizar diferentes explorações intensivas de suínos com base na avaliação de medidas
gerais de maneio, biossegurança, vacinação e outros tratamentos.
3. Identificar animais com suspeitas de doença nas explorações avaliadas e proceder ao seu
diagnóstico.
4. Avaliar a transferência de imunidade contra PCV2, por reprodutoras vacinadas para leitões.
5. Implementar medidas correctivas das anomalias identificadas.
No trabalho I foram seleccionadas diversas explorações intensivas de suínos onde se procedeu
ao diagnóstico de PMWS através de avaliação de sinais clínicos, lesões microscópicas e
detecção do vírus por hibridação in situ. Em quatro das sete explorações avaliadas obtiveramse
resultados positivos, mas em apenas uma delas foi aconselhada a implementação de
medidas de controlo da infecção por PCV, nomeadamente através de vacinação.
No trabalho II foram seleccionadas duas explorações intensivas de suínos onde se realizava a
vacinação das reprodutoras com CIRCOVAC®. Realizaram-se provas de serologia, segundo
protocolo da MERIAL, para avaliar a transferência de imunidade das reprodutoras para a sua
descendência. Em oposição à homogeneidade observada nos títulos de anticorpos das porcas
da exploração 2, na exploração 1, 20% das reprodutoras apresentavam títulos baixos de
anticorpos vacinais. Por tal motivo, aconselhou-se a reavaliação do plano de vacinação de
modo a minimizar as falhas vacinais e maximizar a imunidade pós-vacinal.
ABSTRACT - STUDY OF CIRCOVIROSIS IN INTENSIVE PIG FARMS - The etiological agent of circovirosis is a small icosahedral, non-enveloped vírus, containing single-stranded, circular DNA genome, which was named porcine circovirus (PCV). The PCV is considered a ubiquitous virus, that causes disease only in pigs and has been isolated on all continents. This virus is responsible for various diseases, with the most common and responsible for major economic losses of them being, the post- weaning multisystemic wasting syndrome (PMWS). There are several risk factors for which there is manifestation of clinical disease, including deficient management, presence of co-infections, immune status of the sow against PCV and immune-stimulation by different causes. The clinical signs and lesions associated with PCV infection suggest that this agent is an immunosuppressant / immunomodulator. The control and prevention of PCVD is focused in the minimization of the effect of risk factors and vaccination against PCV. In this context, this study aims to: 1. Identify intensive pig farms with suspicion of PCV2. 2. Characterize different intensive pig farms based on management, biosecurity, vaccination and other treatments. 3. Identify animals suspected of disease on evaluated farms and proceed to diagnosis. 4. Evaluate the transfer of immunity against PCV2 by vaccinated sows to breeding. 5. Implement corrective action of deficiencies identified. In work I several intensive pig farms were selected and diagnosed to PMWS through evaluation of clinical signs, microscopic lesions and detection of virus by in situ hybridization. In four of the seven farms evaluated, positive results were obtained, but only one was advised to implement measures for the control of PCV infection, particularly through vaccination. In Work II two intensive pig farms were selected, where the sows were vaccinated with CIRCOVAC ®. Serology was made, by blocking ELISA, according to Merial’s protocol, to evaluate the transfer of immunity from sows to their offspring. In contrast to the homogeneity observed in the antibody titers of sows of farm 2, in farm 1, 20% of the sows had low antibody titres from vaccine. Therefore a reassessment of the vaccination program was advised to minimize the vaccine failures and to maximize immunity post-vaccination.
ABSTRACT - STUDY OF CIRCOVIROSIS IN INTENSIVE PIG FARMS - The etiological agent of circovirosis is a small icosahedral, non-enveloped vírus, containing single-stranded, circular DNA genome, which was named porcine circovirus (PCV). The PCV is considered a ubiquitous virus, that causes disease only in pigs and has been isolated on all continents. This virus is responsible for various diseases, with the most common and responsible for major economic losses of them being, the post- weaning multisystemic wasting syndrome (PMWS). There are several risk factors for which there is manifestation of clinical disease, including deficient management, presence of co-infections, immune status of the sow against PCV and immune-stimulation by different causes. The clinical signs and lesions associated with PCV infection suggest that this agent is an immunosuppressant / immunomodulator. The control and prevention of PCVD is focused in the minimization of the effect of risk factors and vaccination against PCV. In this context, this study aims to: 1. Identify intensive pig farms with suspicion of PCV2. 2. Characterize different intensive pig farms based on management, biosecurity, vaccination and other treatments. 3. Identify animals suspected of disease on evaluated farms and proceed to diagnosis. 4. Evaluate the transfer of immunity against PCV2 by vaccinated sows to breeding. 5. Implement corrective action of deficiencies identified. In work I several intensive pig farms were selected and diagnosed to PMWS through evaluation of clinical signs, microscopic lesions and detection of virus by in situ hybridization. In four of the seven farms evaluated, positive results were obtained, but only one was advised to implement measures for the control of PCV infection, particularly through vaccination. In Work II two intensive pig farms were selected, where the sows were vaccinated with CIRCOVAC ®. Serology was made, by blocking ELISA, according to Merial’s protocol, to evaluate the transfer of immunity from sows to their offspring. In contrast to the homogeneity observed in the antibody titers of sows of farm 2, in farm 1, 20% of the sows had low antibody titres from vaccine. Therefore a reassessment of the vaccination program was advised to minimize the vaccine failures and to maximize immunity post-vaccination.
Descrição
Dissertação de Mestrado Integrado em Medicina Veterinária
Palavras-chave
Suíno Circovírus Diagnóstico Sistema imune Maneio Vacinação Swine Circovirus Diagnosis Immune system Management Vaccination
Contexto Educativo
Citação
Lopes, J.A.C. (2009). Estudo de circovirose em explorações intensivas de suínos. Dissertação de Mestrado, Universidade Técnica de Lisboa, Faculdade de Medicina Veterinária, Lisboa
Editora
Universidade Técnica de Lisboa. Faculdade de Medicina Veterinária