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Estudo retrospetivo sobre a prevalência de paratuberculose em efetivos de bovinos de carne do Alentejo
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A Paratuberculose é uma enterite granulomatosa crónica incurável em ruminantes provocada pela micobactéria Mycobacterium avium subespécie paratuberculosis caracterizada por um longo período de incubação e síndrome de má absorção com perda de peso gradual, diarreia intermitente, hipoproteinémia e desenvolvimento de edema submandibular. A transmissão ocorre por via fecal-oral e transplacentária, sendo o agente também excretado no colostro e leite. A disseminação da doença e as perdas económicas associadas (refugo precoce, menor produtividade animal) terão tendência a aumentar na inexistência de controlo, no entanto este é difícil. Os objetivos do presente trabalho são evidenciar, através de um estudo retrospetivo e cálculo de prevalência, a presença da doença nos efetivos de bovinos de carne em extensivo na área de ação do Hospital Veterinário Muralha de Évora nos distritos de Évora e Beja entre 2008 e 2022. A prevalência individual verdadeira foi de 20%, superior aos valores estimados para os bovinos de carne. Das explorações incluídas, 42% foram consideradas infetadas e a maioria das prevalências aparentes nos efetivos testados encontraram-se perto ou dentro de valores considerados moderados (6 a 19%). Foram incluídos 7 dos 14 concelhos do distrito de Évora onde 6 foram positivos. A primavera foi associada a uma maior chance de positividade para Paratuberculose nos casos suspeitos, porém os anos de seca revelaram uma redução da mesma chance nos casos gerais. A média de idade dos animais positivos foi de 5,9 anos, onde as idades destes e dos animais não positivos foram significativamente diferentes, com uma maior chance de positividade com o avançar da idade. Os sinais clínicos predominantes nos animais testados foram a diarreia crónica e caquexia. As idades e quadros clínicos apresentados foram compatíveis com a doença e a existência de animais positivos com menos de 3 anos sugere uma elevada pressão de infeção. O ELISA indireto em soro sanguíneo, teste mais utilizado, é imperfeito e insuficiente para alcançar o controlo. Por não existir um plano de controlo oficial foi realizado um inquérito aos produtores de modo a perceber o seu interesse num plano desta natureza. Os produtores mostraram-se interessados, tendo como principal motivo para o controlo a Saúde Animal. Elaborou-se uma sugestão de plano de controlo para a Paratuberculose, encontrando-se este dividido em três fases: caracterização da exploração e testagem do efetivo, avaliação de risco e criação do plano sanitário. Os resultados sugerem um cenário de subdiagnóstico de Paratuberculose e uma necessidade de mais estudos de prevalência em bovinos de carne
ABSTRACT - RETROSPECTIVE STUDY OF THE PREVALENCE OF PARATUBERCULOSIS IN BEEF CATTLE HERDS IN ALENTEJO - Paratuberculosis is an uncurable chronic granulomatous enteritis in ruminants caused by Mycobacterium avium subspecies paratuberculosis. The disease is characterized by a long incubation period and a malabsorption syndrome with gradual weight loss, intermittent diarrhea, hypoproteinemia, and development of submandibular edema. Transmission occurs through the fecal-oral and transplacental routes. This pathogen is also excreted in colostrum and milk. The spread of the disease and associated economic losses (early culling, lower animal productivity) will tend to increase in the absence of control measures, but control can be challenging. The objectives of the present work are to highlight, through a retrospective study and prevalence calculation, the presence of the disease in beef cattle in pasture-based production systems herds in the area of action of the Hospital Veterinário Muralha de Évora in the districts of Évora and Beja between the years 2008 and 2022. The true individual prevalence was 20%, higher than the estimated values for beef cattle. Of the included farms, 42% were considered infected, and most of the apparent prevalences for the herds tested were close or within the moderate values (6 to 19%). Farms from 7 of the 14 municipalities in the Évora district were investigated, where 6 out of these 7 municipalities were positive. Spring was associated with a higher chance of positivity of suspected animals, but in the years of drought a decrease in the chance of positivity of general cases was observed. The mean age of the positive animals was 5,9 years, and the ages of positive and non-positive animals were significantly different, with a greater chance of positivity at an older age. The predominant clinical signs in tested animals were chronic diarrhea and cachexia. The ages and clinical signs were compatible with the disease. The existence of positive animals under 3 years old suggests a high pressure of infection. Indirect ELISA in blood serum was the most common test, but it is imperfect and insufficient to achieve control. Due to the lack of an official control plan, a survey was carried out to determine farmers’ interest in the matter. Farmers were interested and the main reason for control was Animal Health. A suggestion for a Paratuberculosis control plan was elaborated, divided into three phases: herd characterization and herd testing, risk assessment, and creation of a health plan. These results are suggestive of an underdiagnosis scenario of Paratuberculosis and a need for further prevalence studies in beef cattle
ABSTRACT - RETROSPECTIVE STUDY OF THE PREVALENCE OF PARATUBERCULOSIS IN BEEF CATTLE HERDS IN ALENTEJO - Paratuberculosis is an uncurable chronic granulomatous enteritis in ruminants caused by Mycobacterium avium subspecies paratuberculosis. The disease is characterized by a long incubation period and a malabsorption syndrome with gradual weight loss, intermittent diarrhea, hypoproteinemia, and development of submandibular edema. Transmission occurs through the fecal-oral and transplacental routes. This pathogen is also excreted in colostrum and milk. The spread of the disease and associated economic losses (early culling, lower animal productivity) will tend to increase in the absence of control measures, but control can be challenging. The objectives of the present work are to highlight, through a retrospective study and prevalence calculation, the presence of the disease in beef cattle in pasture-based production systems herds in the area of action of the Hospital Veterinário Muralha de Évora in the districts of Évora and Beja between the years 2008 and 2022. The true individual prevalence was 20%, higher than the estimated values for beef cattle. Of the included farms, 42% were considered infected, and most of the apparent prevalences for the herds tested were close or within the moderate values (6 to 19%). Farms from 7 of the 14 municipalities in the Évora district were investigated, where 6 out of these 7 municipalities were positive. Spring was associated with a higher chance of positivity of suspected animals, but in the years of drought a decrease in the chance of positivity of general cases was observed. The mean age of the positive animals was 5,9 years, and the ages of positive and non-positive animals were significantly different, with a greater chance of positivity at an older age. The predominant clinical signs in tested animals were chronic diarrhea and cachexia. The ages and clinical signs were compatible with the disease. The existence of positive animals under 3 years old suggests a high pressure of infection. Indirect ELISA in blood serum was the most common test, but it is imperfect and insufficient to achieve control. Due to the lack of an official control plan, a survey was carried out to determine farmers’ interest in the matter. Farmers were interested and the main reason for control was Animal Health. A suggestion for a Paratuberculosis control plan was elaborated, divided into three phases: herd characterization and herd testing, risk assessment, and creation of a health plan. These results are suggestive of an underdiagnosis scenario of Paratuberculosis and a need for further prevalence studies in beef cattle
Descrição
Dissertação de Mestrado Integrado em Medicina Veterinária, área científica de Clínica
Palavras-chave
Bovino de carne Mycobacterium avium subespécie paratuberculosis Paratuberculose Plano de controlo Prevalência Beef cattle Control programme Mycobacterium avium subspecies paratuberculosis Paratuberculosis Prevalence
Contexto Educativo
Citação
Pereira AFT. 2024. Estudo retrospetivo sobre a prevalência de paratuberculose em efetivos de bovinos de carne do Alentejo [dissertação de mestrado]. Lisboa: FMV-Universidade de Lisboa
Editora
Universidade de Lisboa, Faculdade de Medicina Veterinária