TETANUS

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DEFINITION
An infection of contaminated wounds, leading to rigid bodily muscular spasms (notably the jaw) and perhaps life threatening breathing complications, due to a nasty little bacteria.

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INCIDENCE

Incidence
Prevalence: 1,000,000 per year worldwide.
Age
Commonly neonates in developing countries.
Older pts (not immunised).
Sex
M>F ( occupational ).
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AETIOLOGY
Bacterial.
Clostridium tetani.
Anaerobic, spore-forming, gram -ve.
Common worldwide.
Likes guts (e.g. cows and small healthy humans) and soils.
Hardy, persists in environments for many years.
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BIOLOGICAL BEHAVIOUR

Natural History
Bacteria are introduced into a wound, e.g. through soil contact.
They multiply in a bit of dead tissue that's suitably anaerobic.
Incubation period of a few days to several months.
Longer for wounds far from the CNS.
Self resolving after possibly serious illness.

Pathogenesis
Produce exotoxin called tetanospasmin.
This is responsible for the illness.
It is carried up the axons of neurons and via the blood.
-> to the anterior horns of the spinal cord and medulla.
There it blocks the normal inhibitory input to the motor neurones.
There is a consequent increase in muscle tone, and an exaggeration of any movement into painful uncontrollable spasms.

Complications
Autonomic abnormalities accompany severe infection.
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MANIFESTATIONS

SYMPTOMS
Local
Muscular rigidity and spasms.
A normal level of consciousness.
Breathing is often impaired (as a direct result of the spasms or laryngeal spasms or because of inhalation of secretions).

SIGNS
Observe
Tense abdo, arched back (opisthotonos).
Clenched jaw (trismus).
And a fixed smile (risus sardonicus).
An unmistakable illness; ie if you get it wrong, you are an unqualified idiot.
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INVESTIGATIONS

Clinical and microbiological testing.

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MANAGEMENT

Medical
Penicillin and metronidazole used.
Unbound toxin must be eliminated by passive immunisation with human immune globulin.
Muscular spasms must be controlled and respiration protected by sedation, paralysis and artificial ventilation.
Spontaneous recovery occurs - typically after 1 or 2 weeks.

Surgical
Wound debridement as required.
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