Alterações no encéfalo de bovinos submetidos à vigilância das encefalopatias espongiformes transmissíveis

• Autor(a) principal: Rech, Raquel Rubia
• Data de Publicação: 2007
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Manancial - Repositório Digital da UFSM
• dARK ID: ark:/26339/001300000kdpx
• Texto Completo: http://repositorio.ufsm.br/handle/1/4035
• topic: Doenças de bovinos; Neuropatologia veterinária; Diseases of cattle; Veterinary europathology; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA

This study stems from the findings during the gross and histopathological exam of 3,338 cattle brains as part of the bovine spongiform encephalopathy (BSE) active surveillance program of the Brazilian Ministry of Agriculture, Livestock and Supply (MAPA) from 2001-2005. The work was carried out in the Veterinary Pathology Laboratory (LPV) of the Federal University of Santa Maria (UFSM) which is the national reference laboratory for the diagnosis of BSE and other transmissible spongiform encephalopathies. This work is presented in four parts. Initially the key events about the significance, etiology, epidemiology, clinical signs, pathology, and control of BSE are presented in order to provide the reader with the background that led the MAPA to develop this surveillance program for BSE. In the second part, the mechanics of the surveillance program are explained in detail and most of the written rules and ordinances issued by MAPA in order to strength the surveillance for BSE are included as annexes. The third part deals with the gross and histopathological examinations of the 3,338 cattle brains. Both gross and histopathological methodologies are described. Gross exam considered distribution, color, form, size, consistency and other general aspects of any particular change. Gross examinations included also non-lesions (anatomical normal structures that may be interpreted as lesions), lesions of limited or no clinical significance, postmortem changes and other artifacts. All these are considered pitfalls in the examination of the central nervous system (CNS). Accordingly equivalent pitfalls were described in the histopathological examination; additionally the normal CNS components are described together with their general reactions to injury. In the fourth part of the work, copies of papers that resulted from the systematic examination of 3,338 cattle brains during the BSE active surveillance program are included. The papers are allotted to two groups: the first group includes those primary papers that are a direct part of this thesis and in which the thesis author is the senior author. These papers are: 1) Rech R.R. et al. 2004. Granulomatous meningoencephalitis in cattle grazing vetch (Vicia spp). Pesq. Vet. Bras. 24:169-172, 2) Rech R.R. et al. 2005. Malignant catarrhal fever in cattle in Rio Grande do Sul, Brazil: Epidemiology, clinical signs and pathology. Pesq. Vet. Bras.25:97-105, 3) Rech R.R. et al. 2006. Histomorphology of the Gasserian ganglion, carotid rete mirabile and pituitary gland in cattle: A study of 199 cases. Pesq. Vet. Bras. 26:105-111, 4) Rech R.R. et al. 2006. Poisoning by Solanum fastigiatum (Solanaceae) in cattle: Epidemiology, clinical signs and morphometry of cerebellar lesions. Pesq. Vet. Bras., 26:183-189, 5) Rech et al. 2006. Rabies in herbivores: 27 cases. Proceedings of the Annual National Meetings Veterinary Diagnostic Labs in Brazil, March 2006 (Abstract) and 6) Rech R.R. et al. 2007. Poisonous plants affecting the central nervous system (CNS) of cattle in Brazil, p. 238- 243. In: Panter K.E.; Wierenga T.L. & Pfister J.A. (ed.). Poisonous Plants: Global Research and Solutions. Wallingford: CAB International. The second group of papers includes those that derived from the surveillance BSE program but were developed by another Graduate Student of the LPV/UFSM and in which this thesis author (RR) is a co-author. These papers are: 1) Rodrigues A. et al. 2005. Cerebral babesiosis in cattle: 20 cases. Ciência Rural.35:121-125, 2) Barros R.R. et al. 2006. Ocular squamous cell carcinoma in a cow with cerebral invasion through cranial nerves. Ciência Rural 36:1651-1654, 3) Barros R.R. et al. 2006. Poisoning by Ramaria flavo-brunnescens (Clavariaceae) in cattle. Pesq. Vet. Bras. 26:87-96 and 4) Rissi D.R. et al. 2006. Epidemiology, clinical signs and distribution of the encephalic lesions in cattle affected by meningoencephalitis caused by bovine herpesvirus-5. Pesq. Vet. Bras. 26:123-132. During part of the Graduate Program that led to this Thesis the author stayed for 10 months in a CAPES-Sandwich-Fellowship in The University of Georgia at Athens, USA where a protocol for immunohistochemistry (IHC) for detection of rabies antigen in formalin fixed paraffin blocks from bovine brain was established under the supervision of Prof. Corrie Brown. The description of this protocol and the partial results of the IHC diagnosis for rabies in cattle are included in the text of this Thesis. Most of the conclusions drawn from the work presented here are detailed in the papers listed above. Additionally conclusions are that the MAPA design and implemented an adequate system for BSE surveillance. Weak points in the program are that not enough samples from cattle that tested negative in the official laboratories for rabies diagnosis in Brazil, from imported cattle and from cattle submitted to emergence slaughter in abattoirs under federal Meat Inspection are arriving at the LPV/UFSM. From the material examined, it was also concluded that the more frequent inflammatory diseases in the brain of cattle are rabies, meningoencephalitis by bovine herpesvirus 5 and malignant catarrhal fever and the more frequent degenerative diseases are hepatic encephalopathy and poisoning by Solanum fastigiatum.