View
44
Download
0
Category
Tags:
Preview:
DESCRIPTION
Objectives for NS 3:. You should be able to define, describe pathogenesis, list lesions and know how to diagnose the following conditions:. Infectious diseases of CNS. Portal of entry. Blood Nerves Paracranial and paravertebral infections (sinuses, ear, bones et cet). Meningitis. - PowerPoint PPT Presentation
Citation preview
Objectives for NS 3: You should be able to define, describe pathogenesis,
list lesions and know how to diagnose the following
conditions:
•Meningitis
•ITEME
•Listeriosis
•TSE
•Rabies
•Distemper
•West Nile Viral encephalitis
•Equine protozoal encephalomyelitis
Infectious diseases of CNS
BloodNervesParacranial and paravertebral infections(sinuses, ear, bones et cet)
Portal of entry
Meningitis
• Et: E. coli, Streptococcus, Haemophilus
Cryptococcus, 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
Encephalomyelitis
• Viral• Bacterial• Mycotic• Protozoal• Parasitic (nematodes)• Prion
There are many infectious agents
Infectious thrombotic (thromboembolic) meningoencephalitis
• Et: Haemophilus somnus • Pneumonia, arthritis, heart abscess….in Bo• Pathogenesis:
H. somnus invades circulationDamages endothelium of CNS venulesSubendothelial collagen exposedThrombosis, infarction, & vasculitisCNS hemorrhage, necrosis and inflammation
Bacterial infections - H. somnus
Diagnosis
• Gross and histologic lesions
• Bacterial culture
Bacterial infections - H. somnus
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
Bacterial infections - Listeriosis
Diagnosis
• Histologic lesions (with Gr + bacteria)
• Bacterial culture
Bacterial infections - Listeriosis
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
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
TSE
PrPcPrPc
PrPc
PrPres PrPc
PrPres PrPresConformational
change
PrPres
InoculationTransmissionMutationInheritance
TSE
Diagnosis
• Histology• IHC
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 protectionDecapitate the animal and send the head
Rabies
• Rabies virus can 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
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
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
Viral infections - Rabies
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)
Viral infections - Distemper
Infection (inhalation)Replication in tonsils/lungsOther lymphoid tissues >> immunosuppressionCNS & Epithelia (~ 8-9 days after infection)
Death due toSevere viral infection +/- 2o bacterial infect.
Recovery
CNS infection1o demyelination due to direct viral damage 2o demyelination due to inflammatory reaction
PathogenesisViral infections - Distemper
Diagnosis
• Histology• IHC
Lesions in CNS:Demyelination (primary and secondary)
Non suppurative encephalitis with I/N and I/C inclusion bodies
Viral infections - Distemper
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
Viral infections - in utero
In utero viral infections
• Cerebellar hypoplasia Feline panleukopniavirus
• Cerebellar hypoplasia, hydranencephaly and/or hypomyelination
Bovine viral diarrhea virusHog cholera virusBlue tongue virusBorder disease virus
Protozoal infections
• Equine protozoal encephalomyelitis
Sarcocysis neurona (defin. host - opasum)
Lesions: necrosis/malacia, inflammation
most frequently in the spinal cord
Diagnosis: Histological lesions
IHC
Neoplasia
Neoplasia
• Meningioma• Astorcytoma• Oligodendroglioma• Ependymoma
Diagnosis
Histology
Recommended