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Listeriose em pequenos ruminantes: apresentação de um caso clínico
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Advisor(s)
Abstract(s)
A Listeriose é uma doença infeciosa de carácter zoonótico causada pela bactéria Listeria monocytogenes. Esta afeta tanto o ser humano como os animais domésticos, nomeadamente os ruminantes, sendo os pequenos ruminantes mais afetados.
L. monocytogenes é uma bactéria intracelular, gram-positiva, com distribuição ubiquitária e com características de organismo anaeróbio facultativo, tolerando e proliferando em condições hostis de temperatura e pH.
Em ruminantes, casos de listeriose estão diretamente relacionadas com a ingestão de silagem contaminada. Isto deve-se ao facto de a silagem estar indevidamente condicionada, proporcionando um meio favorável ao crescimento da bactéria.
A Listeriose manifesta-se principalmente através de três formas da doença: a forma encefálica, septicémica e a abortiva. A forma encefálica ou “Circling Disease” é considerada uma das mais prevalentes e será abordada nesta dissertação.
O ciclo intracelular da bactéria é conhecido, contudo a forma como a L. monocytogenes afeta o sistema nervoso central (SNC), ainda merece maior compreensão.
Os borregos referentes ao presente caso clínico, apresentavam sinais clínicos compatíveis com a forma encefálica. Os sinais mais comuns nesta infeção do SNC são: hipertermia, prostração e inapetência, anorexia, incoordenação, torneio e cabeça inclinada.
O tratamento é pouco eficaz e após o aparecimento dos primeiros sinais neurológicos, normalmente ocorre morte dos animais. A terapêutica mais indicada passa pelo uso de antimicrobianos e para complementar, hidratação endovenosa e corticoterapia.
O diagnóstico é baseado na história, sinais clínicos e na deteção da bactéria. Um diagnóstico definitivo apenas pode ser realizado post mortem e, na forma encefálica, a amostra mais indicada a ser recolhida é o encéfalo.
Listeriosis is an infectious and zoonotic diseases caused by Listeria monocytogenes. It can affect humans as well as domestic animals, including ruminants in which small ruminants are more commonly affected. L. monocytogenes are intracellular, gram-positive bacteria, with a ubiquitous distribution and facultative anaerobic characteristics, allowing the bacteria to tolerate and proliferate under hostile conditions of temperature and pH. In ruminants, listeriosis is often linked to consumption of contaminated silage, this is due to poor fermentation that provides a unique environment for the bacteria. Listeriosis manifestations include three main forms: encephalitic, septicaemic and abortive. Encephalitic form or Circling Disease is one of the most frequently form of listeriosis and will be described in this dissertation. The intracellular life cycle of the L. monocytogenes has been known for long, yet it is still necessary to understand how it affects the central nerve system (CNS). The lambs in this clinical case revealed clinical sings compatible with the encephalitic form. Signs common to CNS infection include hyperthermia, prostration, lack of appetite, anorexia, incoordination, circling and head tilt. Treatment is seldom successful and after the first neurologic signs, animals frequently die despite treatment. The therapeutic options include the use of antimicrobials with a supportive therapy like hydration intravenous and corticotherapy. Diagnosis is based on history, clinical signs and the detection of the bacteria. A definitive diagnosis of the encephalitic form can only be achieved post mortem by histopathology examination of bran tissues.
Listeriosis is an infectious and zoonotic diseases caused by Listeria monocytogenes. It can affect humans as well as domestic animals, including ruminants in which small ruminants are more commonly affected. L. monocytogenes are intracellular, gram-positive bacteria, with a ubiquitous distribution and facultative anaerobic characteristics, allowing the bacteria to tolerate and proliferate under hostile conditions of temperature and pH. In ruminants, listeriosis is often linked to consumption of contaminated silage, this is due to poor fermentation that provides a unique environment for the bacteria. Listeriosis manifestations include three main forms: encephalitic, septicaemic and abortive. Encephalitic form or Circling Disease is one of the most frequently form of listeriosis and will be described in this dissertation. The intracellular life cycle of the L. monocytogenes has been known for long, yet it is still necessary to understand how it affects the central nerve system (CNS). The lambs in this clinical case revealed clinical sings compatible with the encephalitic form. Signs common to CNS infection include hyperthermia, prostration, lack of appetite, anorexia, incoordination, circling and head tilt. Treatment is seldom successful and after the first neurologic signs, animals frequently die despite treatment. The therapeutic options include the use of antimicrobials with a supportive therapy like hydration intravenous and corticotherapy. Diagnosis is based on history, clinical signs and the detection of the bacteria. A definitive diagnosis of the encephalitic form can only be achieved post mortem by histopathology examination of bran tissues.
Description
Keywords
Forma Encefálica Listeria monocytogenes Listeriose Ovinos Encephalitic form Listeriosis Ovine