Bacterial neurological diseases Flashcards
List some bacterial diseases affecting the neurological system
- Listeriosis
- Anthrax
- Tetanus
- Botulism
- Thromboembolic meningoencephalitis
What species cause listeriosis?
MAINLY LISTERIA MONOCYTOGENES
When does listeriosis most commonly occur?
At the end of winter or beginning of spring when the animals have a reduced immunity
How is listeriosis transmitted?
- Food contamination
- Congenital infection of offspring - aspiration of infected amniotic fluid
In what secretions may you find listeria?
- Urine
- Milk
- Genital discharge
- Foetal faeces
Describe the pathogenesis of listeriosis
- Reaches the organs via the lymphatic and haematogenous routes
- Goes to the CNS and genital organs
What are the different forms of listeriosis?
- Septicaemic form
- Encephalitic form
- Abortive form
What are the clinical signs of the septicaemic form?
- Weakness
- Inappetence
- Fever
- Serous ocular and nasal discharge
- Offspring die within 24-48 hours of lung oedema and diarrhoea
What are the clinical signs of the encephalitis form?
- Stiff gait and twisting movements
- Circling
- Head pressing
- Paralysis of throat and facial muscles
- Unilateral limb paralysis and swimming movements
- Coma and death within 3-10 days
How do we diagnose listeriosis?
- Clinical signs
- PM lesions
- Microscopy - gram staining (G+)
- Culture - blood agar
- PCR or ELISA
How do we treat listeriosis?
- ATB treatment
- Penicillin and tetracycline
- Ampicillin
- Gentamycin
- Ceftofur
- Erythromycin
- TMPS
- Dexamethasone
- Electrolyte therapy
- Supplemental feeding
What is the aetiological agent of tetanus?
Clostridium tetani
How is tetanus transmitted?
Inoculation into deep skin wounds from contaminated soil or pasture (spores)
What toxins are produced in tetanus?
- Tetanospasmin
- Tetanolysin
What does tetanospasmin do?
- Neurotoxin that attacks the nervous system and provokes stroke spasms in striated muscle
- Ascending paralysis
- Blocks release of GABA and gylcine
What does tetanolysin do?
Necrotising haemolysin causing tissue lysis
What are the clinical signs of tetanus?
- Lockjaw
- Rigidity
- Spasms of skeletal muscle
- Protrusion of third eyelid
- Dilated nostrils
- Unsteady gait
- Sawhorse stance
- Collapse and death
How do we treat tetanus?
- High doses of IV ATB
- Metronidazole
- Tetanus anti-toxin
- Sedatives
- Muscle relaxants
- Cleaning with H2O2
- Surgical debridement of wound
What causes botulism?
Clostridium botulinum
How is botulism transmitted?
- Ingestion of toxins
- Inoculation of skin wound
- Inhalation
Waht is the pathogenesis of botulism?
- Toxin production - exotoxin
- Release of neurotoxins B, C and D
- Inhibits release of ACh from pre-synaptic nerve endings at neuromuscular junctions
What are the clinical signs of botulism?
- Incoordination
- Paralysis of tongue
- Hypersalivation and dysphagia
- Sternal recumbency
- Muscle tremors
- Inability to stand
- Death due to respiratory and cardiac muscle paralysis
How do we treat botulism?
MUST OCCUR BEFORE TOXIN ADHERES TO MOTOR END PLATE
- Anti-toxin serotherapy
- Supportive therapy - gastric lavage
- Symptomatic
- Emetic
- Purgatives
- Diuretics
- ATB
What is the aetilogical agent of anthrax?
Bacillus anthracis
How is anthrax transmitted?
- Ingestion of spores
- Cutaneous - rare
- Inhalation - rare
- Blood sucking insects
Describe the pathogenesis of anthrax
- Ingestion of spores
- Transported to lymph nodes - lymphangitis and lymphadenitis
- Fatal septicaemia due to toxin production
What toxins are produced during anthrax?
- Factor 1 - oedema factor
- Factor 2 - protective factor
- Factor 3 - lethal factor
What are the clincial signs of anthrax in ruminants?
- Per-acute systemic disease
- Sudden death
- Fever
- Staggering, trembling, incoordination, disorientation
- Convulsions
- Cyanosis
- Bleeding from all origices
What are the typical PM findings during anthrax?
- Blackberry jam spleen
- Tarry blood
- Absent rigor mortis
What samples should be taken when anthrax is suspected?
- Blood
- Ear
How do we diagnose anthrax?
- Culture - blood smear - medusa head
- Ascoli thermoprecipitation test
- Penicillin susceptibility
- Animal inoculation
How do we treat anthrax?
ONLY EFFECTIVE IN VERY EARLY STAGES
- ATB - penicillin
- Supportive
What causes thromboembolic meningoencephalitis?
Histophilus somni
What is the pathogenesis of thromboembolic meningoencephalitis?
- Severe vasculitis caused by bacterial attachment to the endothelial cells
- Endotoxin/exotoxin release
- Cell destruction
What are the clinical signs of TME?
SUDDEN DEATH
