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| − | ==Tetanus== | + | ==[[Tetanus]]== |
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| − | * In a pathological context, '''"tetanus" is an infectious disease caused by the bacterium [[Clostridium tetani|''Clostridium tetani'']]'''.
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| − | ** Physiologically, the term "tetanus" refers to continuous sustained muscle contraction.
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| − | *** The disease caused by [[Clostridium tetani|''Clostridium tetani'']] is characterised by this feature.
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| − |
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| − | ===Pathogenesis===
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| − |
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| − | * [[Clostridium tetani|''Clostridium tetani'']] generally cause infection via wound contamination.
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| − | ** Cuts or deep puncture wounds are most commonly infected.
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| − | * [[Clostridium tetani|''Clostridium tetani'']] produces tetanospasmin, a neurotoxin.
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| − | ** Tetanospasmin inhibits the release of the neurotransmitters GABA and glycine from interneurons in the spinal cord and brain.
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| − | * Without the usual inhibitory influence of glycine and GABA, there is increased excitation of the brainstem and motor neurons.
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| − | ** This leads to unopposed muscle contraction.
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| − | *** The frequency of action potentials at the neuromuscular junctions increases above a threshold.
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| − | *** Above this threshold, muscle fibres enter a state of tetanus.
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| − | **** Muscle spasm is initially present in the muscles of the jaw.
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| − | **** This is followed by a difficulty in [[Deglutition|swallowing]].
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| − | **** General muscle stiffness and spasms then develop in other parts of the body.
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| − | ** Other effects may include:
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| − | *** Seizures
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| − | *** Effects on the autonomic nervous system
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| − |
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| − | ===Diagnosis===
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| − |
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| − | * Diagnosis is made by taking into account the animal's:
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| − | ** History
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| − | ** Clinical signs
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| − | * Very rarely a wound where the bacteria may have entered may be seen.
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| − |
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| − | ===Treatment===
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| − | * Wound debridement
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| − | ** Surgical removal of dead and infected tissue from the wound.
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| − | * Antibiotic treatment.
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| − | ** Metronidazole
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| − | *** Treatment with metronidazole decreases the number of bacteria but has no effect on the bacterial toxin.
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| − | *** Metronidazole is particularly active against anaerobic bacteria, and so is a good choice for use against [[Clostridium tetani|''C. tetani'']]
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| − | ** Penicillin
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| − | *** Penicillin is becoming a less favoured treatment for tetanus, since there is a theoretical risk of increased spasms.
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| − | * Muscle relaxants
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| − | ** Diazepam
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| − | ** Midazolam
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| − | * Supportive therapy, for example:
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| − | ** Administering fluids
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| − | ** Providing appropriate nutrition
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| − | ** Maintaining a quiet environment with dimmed light.
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| − | * Remission take several weeks to months
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| | ==Tetany== | | ==Tetany== |