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Seroprevalência e fatores de risco associados à presença de Lentivírus dos pequenos ruminantes em 28 explorações no concelho de Bragança
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Resumo(s)
A designação Lentivirus dos Pequenos Ruminantes (SRLV) é atualmente utilizado para referir o que classicamente era conhecido por Maedi-Visna ovino e Artrite-Encefalite caprina, causadores de doenças de evolução lenta, multissistémica, progressiva e debilitante nestas espécies. As análises filogenéticas demonstram que estes dois vírus estão intimamente relacionados, ocorrendo infeção cruzada entre ovinos e caprinos. Atualmente, não há tratamento ou vacinas comerciais para Lentivirus de pequenos ruminantes, desta forma o diagnóstico torna-se fundamental para estabelecer um programa de controle eficaz da infeção e reduzir a sua prevalência. No nordeste de Portugal a maioria das explorações recorre a métodos tradicionais de produção animal, efetuando pastoreio de percurso o ano inteiro. Até ao momento, existe pouca informação sobre a seroprevalência de lentivirus de pequenos ruminantes em Portugal, tal como conhecimentos sobre os seus fatores de risco para a seropositividade dos animais e rebanhos. O objetivo deste trabalho foi determinar a seroprevalência de lentivírus dos pequenos ruminantes no distrito de Bragança e a existência de possíveis fatores de risco associados a estas explorações. Neste estudo, através de uma amostra por conveniência, foram colhidas amostras em 28 explorações, sendo 16 explorações de ovinos, 7 explorações de caprinos e 5 explorações mistas. Verificou-se que 27 (96,4%) das 28 explorações eram positivas aos SRLV, obtendo-se assim a prevalência aparente a nível de exploração. Das 514 amostras de animais, 238 eram positivas e 273 eram negativas. A prevalência aparente a nível animal obtida foi de cerca de 46,3%. A análise estatística de fatores de risco revelou que vários destes fatores, foram associados à infeção por SRLV. Destacamos que a realização da quarentena após introdução de novos animais na exploração (OR= 11,242; IC95%: 4,715-26,803), separação de animais doentes na exploração (OR= 5,961; IC95%: 3,226-11,013), o contacto interespécie na exploração (OR= 1,964; IC95%:1,303-2,959), contacto com outras explorações vizinhas (OR= 1,861; IC95%: 1,259-2,749), e partilha de bebedouros com outros animais que não os da exploração (OR= 1,562; IC95%: 1,057-2,306) revelaram uma associação significativa com a infeção.
ABSTRACT - Seroprevalence and risk factors associated with the presence of Small Ruminant Lentivirus in 28 farms in the municipality of Bragança - The designation “Small Ruminants Lentivirus” (SRLV) is currently used to refer to what was classically known as ovine Maedi-Visna and caprine Arthritis-Encephalitis, which cause slow, multisystemic, progressive and debilitating diseases in these species. Phylogenetic analyzes show that these two viruses are closely related, with cross-infection occurring between sheep and goats. Currently, there is no treatment or commercial vaccines for Lentivirus in small ruminants, so diagnosis is essential to establish an effective infection control program and reduce its prevalence. In the northeast of Portugal most breeders use traditional methods of animal production with grazing systems. Only a few studies about the seroprevalence of lentiviruses in small ruminants in Portugal are known, as well as the risk factors for the seropositivity of animals and herds. The purpose of this work was to determine the seroprevalence of lentiviruses in small ruminants in the district of Bragança and the existence of possible risk factors associated with these farms. In this study, through a convenience sample, samples were taken from 28 farms, 16 sheep farms, 7 goat farms and 5 mixed farms. It was found that 27 (96.4%) of the 28 farms were positive for SRLV, thus obtaining the apparent prevalence at the farm level. Of the 511 animal samples, 238 were positive and 273 were negative. The animal-level apparent prevalence obtained was around 46,3%. Statistical analysis of risk factors revealed that several of these factors were associated with SRLV infection. We highlight that the quarantine after the introduction of new animals on the farm (OR = 11.242; IC95%: 4.715-26.803), separation of sick animals on the farm (OR= 5.961; IC95%: 3.226-11.013), contact with other neighboring farms (OR= 1.861; IC:95%: 1.259-2.749), interspecies contact on the farm (OR= 1.964; IC:95%: 1.303-2.959), and sharing drinking fountains with animals other than those on the farm (OR= 1.562; IC95%: 1.057-2,306) revealed a significant association with infection.
ABSTRACT - Seroprevalence and risk factors associated with the presence of Small Ruminant Lentivirus in 28 farms in the municipality of Bragança - The designation “Small Ruminants Lentivirus” (SRLV) is currently used to refer to what was classically known as ovine Maedi-Visna and caprine Arthritis-Encephalitis, which cause slow, multisystemic, progressive and debilitating diseases in these species. Phylogenetic analyzes show that these two viruses are closely related, with cross-infection occurring between sheep and goats. Currently, there is no treatment or commercial vaccines for Lentivirus in small ruminants, so diagnosis is essential to establish an effective infection control program and reduce its prevalence. In the northeast of Portugal most breeders use traditional methods of animal production with grazing systems. Only a few studies about the seroprevalence of lentiviruses in small ruminants in Portugal are known, as well as the risk factors for the seropositivity of animals and herds. The purpose of this work was to determine the seroprevalence of lentiviruses in small ruminants in the district of Bragança and the existence of possible risk factors associated with these farms. In this study, through a convenience sample, samples were taken from 28 farms, 16 sheep farms, 7 goat farms and 5 mixed farms. It was found that 27 (96.4%) of the 28 farms were positive for SRLV, thus obtaining the apparent prevalence at the farm level. Of the 511 animal samples, 238 were positive and 273 were negative. The animal-level apparent prevalence obtained was around 46,3%. Statistical analysis of risk factors revealed that several of these factors were associated with SRLV infection. We highlight that the quarantine after the introduction of new animals on the farm (OR = 11.242; IC95%: 4.715-26.803), separation of sick animals on the farm (OR= 5.961; IC95%: 3.226-11.013), contact with other neighboring farms (OR= 1.861; IC:95%: 1.259-2.749), interspecies contact on the farm (OR= 1.964; IC:95%: 1.303-2.959), and sharing drinking fountains with animals other than those on the farm (OR= 1.562; IC95%: 1.057-2,306) revealed a significant association with infection.
Descrição
Dissertação de Mestrado Integrado em Medicina Veterinária, área científica Sanidade Animal
Palavras-chave
Lentivírus Maedi-Visna Artrite-Encefalite Caprina Seroprevalência Fatores de risco Bragança Lentivirus Maedi-Visna Caprine Arthritis-Encephalitis Seroprevalence Risk factors Bragança
Contexto Educativo
Citação
Martins VJR. 2022. Seroprevalência e fatores de risco associados à presença de Lentivírus dos pequenos ruminantes em 28 explorações no concelho de Bragança [dissertação de mestrado]. Lisboa: FMV-Universidade de Lisboa.
Editora
Universidade de Lisboa, Faculdade de Medicina Veterinária