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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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− | ===Pathogenesis===
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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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− | ===Diagnosis===
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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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− | ===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== |