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Microbial agents of neurological dz [Major] - Coggle Diagram
Microbial agents of neurological dz [Major]
Rabies
Source
Rhabdoviridae
Stable in cold, dark places
Australian bat lyssavirus (ABLV)
Sensitive to drying + UV light
Broad mammalian host range
Distinct genotypes / strains
Direct inoculation - infectious saliva
Bite wound / abrasian
Rabid animal
Pathogenesis
Viral replication in peripheral tissue
Nerve migration --> CNS
Replication within brain
Centrifugal spread
Various organs
Salivary glands :!:
Diagnosis
Clinical signs
Temperament change
Dumb (paralytic)
LMN paralysis
Vocalisation change :musical_note: ; dropped jaw
Dull; coma; respiratory failure :skull_and_crossbones:
Furious (psychotic)
Aggression :explode:
Hyperaesthesia
Self-trauma
Seizures; restless; hypersalivation; pica
Pruritus; licking at wound;
Incubation period: 2wks to 3months
Viral antigen in brain tissue
Direct immunofluorescence
Immunohistochemistry
Histology: Negri Bodies
Not always present
RT-PCR
Brain tissue
Saliva, urine less sensitive
Treatment / control
Vaccination
Pre-exposure prophylaxis
3 months old
Anti-rabies Ig
Quarantine / euthanasia
Not vaccinated: 6 months
Vaccinated: 90d
Canine Distemper virus
Source
Paramyxoviridae
Canine parainfluenza virus 5
Droplets
Conjunctival ; nasal exudates
Faces, urine, saliva
Pathogenesis
Replicate in oropharynx (tonsils)
Spread via cell mediated viraemia
7d: Lymphoid tissue proliferation
1st fever peak
Viraemia
14d: Generalised
Polysystemic - epithelial sites + CNS
Viral shedding
21d: Death; CNS disease
Good immunity: subclinical dz
No / Low Ab response
Diagnosis
Clinical signs
Acute
Biphasic fever
Second peak T = 41degC
Respiratory disease :!:
Catarrhal inflammation
Larynx, bronchi, tonsils, nasal passages
GIT; Conjunctivitis (purulent)
Vomiting, watery D+
CNS
Behavioural changes; spasms; ataxia; paresis
Subacute neurological form
Encephalitis; seizures
Late / chronic
Old dog encephalitis
Slow progressive motor function loss
Hard pad disease
Hyperkeratosis
Nasal planum + pads
IFA ; immunohistochemistry
Ocular ; nasal discharges
Early onset
Biopsy
Inclusion bodies
Footpads; conjunctiva; bladder
RT-PCR
Acute
Buffy coat; conjunctival swab
Chronic
Urine; whole blood; serum; CSF
Treatment / control
Vaccination (C3)
Cell-mediated + humoural immunity
Stable surface glycoproteins
Antigenic drift :arrow_down:
Puppy --> booster (adult)
Listeria
Source
Eoxgenous
Contaminated food sources
High protein Eg. cheese
Poorly quality silage
Endogenous
Septicaemia
Localisation
Cleared by macrophages
Trigeminal nerves migration
Pathogenesis
Visceral form
Septicaemia
Abortion
Foetus with CNS deficits
Neural form
Meningoencephalitis
"Circling disease" :arrows_counterclockwise:
Microabscessation of brain stem
Cross BBB
Haematogenously / trigeminal nerve
Virulence factors
Bind to cells wall
Internalin
Evade phagocytosis
Haemolysin
Facultative Intracellular survival
Invade adjacent epithelial cells
Cell-mediated immunity
Underlying host immunosuppression
Advanced pregnancy :!:
Diagnosis
Clinical signs
Neural
Circling in 1 direction
Unilateral facial paralysis; head tilt
Difficulty swallowing
Paralysis; recumbency; death
Fever; blindness
Keratoconjunctivitis; nystagmus
Histopathology
Post mortem
Mononuclear pleocytosis
Wide tissue range - dissemination
Gram +ve short rods
Unreliable
Treatment / control
Beta lactam antibiotics
Narrow spectrum Penicillin
Acute cases - localised infections
Aminopenicillin Eg. amoxicillin
Trimethroprim / sulfonamides ; rifampin