1 / 22

Infectious Diseases of CNS: Pathogenesis, Lesions, Diagnosis

This learning objective covers the pathogenesis, lesions, and diagnosis of various infectious diseases affecting the central nervous system, including meningitis, encephalomyelitis, and transmissible spongiform encephalopathy (TSE). It includes information on bacterial infections such as Listeriosis, TSE pathogenesis, and viral infections like Rabies and Distemper.

norina
Download Presentation

Infectious Diseases of CNS: Pathogenesis, Lesions, Diagnosis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Objectives for NS 3: You should be able to define, describe pathogenesis, list lesions and know how to diagnose the following conditions:

  2. Infectious diseases of CNS Portal of entry Blood Nerves Paracranial and paravertebral infections (sinuses, ear, bones et cet)

  3. Meningitis • Et: E. coli, Streptococcus, HaemophilusCryptococcus, FIP virus etc. • Most common in young animals (Bo, Po) • Often as part of polyserositis • Lesions: inflammatory exudate • Diagnosis: • Gross (impression smear) and histology • Bacterial/fungal culture

  4. Encephalomyelitis There are many infectious agents • Viral • Bacterial • Mycotic • Protozoal • Parasitic (nematodes) • Prion

  5. Bacterial infections - H. somnus Infectious thrombotic (thromboembolic) meningoencephalitis • Et: Haemophilus somnus • Pneumonia, arthritis, heart abscess….in Bo • Pathogenesis: H. somnus invades circulation Damages endothelium of CNS venules Subendothelial collagen exposed Thrombosis, infarction, & vasculitis CNS hemorrhage, necrosis and inflammation

  6. Bacterial infections - H. somnus Diagnosis • Gross and histologic lesions • Bacterial culture

  7. Bacterial infections - Listeriosis Listeriosis • Et: Listeria monocytogenes • Abortion, septicemia, CNS in Bo, Ov, (Ho) • Pathogenesis: • Invasion of oral mucosa • Cetnripetal intraaxonal migration • Infection of Trigeminal gang. and brainsteam • Multifocal suppurative meningoencephalitis

  8. Bacterial infections - Listeriosis Diagnosis • Histologic lesions (with Gr + bacteria) • Bacterial culture

  9. TSE Transmissible spongiform encephalopathy • Unique and very unusual dz!!!??? • Scrapie in sheep and goats • Bovine Spongiform Encephalopathy in cattle • Chronic Wasting Disease in elk, white-tailed deer, black-tailed deer and mule deer • Transmissible Mink Encephalopathy • Several forms in humans • Recent reports in other species

  10. TSE Pathogenesis • Normal prion protein PrPc is present in • neurons and it has helix conformation • Abnormal prion protein PrPres or PrPsc has •  sheet conformation • PrPres can induce conformational change in • PrPc to become PrPres • Accumulation of PrPres in neurons causes dz. • Interspecies transmission depends on in each • PrPc species

  11. TSE Inoculation Transmission Mutation Inheritance PrPc PrPc PrPc PrPres PrPres PrPc Conformational change PrPres PrPres

  12. TSE What to do if …? • Submit the animal to a diagnostic lab and indicate that it is “TSE suspect” • If diagnostic lab is far away: • Wear double gloves, mask and eye protection • Decapitate the animal and send the head Diagnosis • Histology • IHC

  13. Viral infections - Rabies Rabies • Rabies viruscan infect all mammals • Maintained in nature in reservoir host • (skunks (prairies); foxes (ON), raccoons, bats) • Pathogenesis: • Transmitted by bite • Centripetal intraaxonal migration to CNS • Infects many neurons incl. Lymbic system • Centrifugal migration to salivary gl. • Death is due to progressive paralysis

  14. Viral infections - Rabies Lesions • Clin. phases: prodromal, excitatory (furious or dumb form), & paralytic • Non suppurative encephalitis • and ganglioneuritis • Intracytoplasmatic inclusion bodies Diagnosis • Fluorescence antibody test • Mouse or tissue culture inoculation • Histology & IHC

  15. Viral infections - Rabies What to do if…? • Label: “RABIES SUSPECT” and submit • to diagnostic lab • If you are doing necropsy yourself: • Should be vaccinated against rabies • Use double gloves, mask and eye protection • Never use power tools for brain removal • Avoid, contact with saliva, brain and CSF • Submit half brain (frozen) to CFIA • Other half in formalin

  16. Viral infections - Distemper Distemper • Distemper virus, morbillivirus, Paramyxov. • Dogs, fox, wolf, hyena, ferret, raccoons, etc • Rarely seen in dogs due to vaccination • Multisystemic dz (lung, skin, CNS, urinary,lymphoid tissue immunosuppression)

  17. Viral infections - Distemper Pathogenesis Infection (inhalation) Replication in tonsils/lungs Other lymphoid tissues >> immunosuppression CNS & Epithelia (~ 8-9 days after infection) Death due to Severe viral infection +/- 2o bacterial infect. Recovery CNS infection 1o demyelination due to direct viral damage 2o demyelination due to inflammatory reaction

  18. Viral infections - Distemper Lesions in CNS: Demyelination (primary and secondary) Non suppurative encephalitis with I/N and I/C inclusion bodies Diagnosis • Histology • IHC

  19. Viral infections - WNV West Nile Virus • Arthropod-borne flavivirus in birds, Eq, Ho • Usually no clinical signs in birds • However, fatal CNS dz. WAS PRESENT in various birds in the recent US outbreak. • Lesions: non suppurative encephalitis • Diagnosis: IHC, PCR, • Serology in live

  20. Viral infections - in utero In utero viral infections • Cerebellar hypoplasia • Feline panleukopniavirus • Cerebellar hypoplasia, hydranencephaly and/or hypomyelination • Bovine viral diarrhea virus • Hog cholera virus • Blue tongue virus • Border disease virus

  21. Protozoal infections • Equine protozoal encephalomyelitis • Sarcocysis neurona (defin. host - opasum) • Lesions: necrosis/malacia, inflammation most frequently in the spinal cord • Diagnosis: • Histological lesions • IHC

  22. Neoplasia Neoplasia • Meningioma • Astorcytoma • Oligodendroglioma • Ependymoma Diagnosis Histology

More Related