Question

When someone has tetanus disease, they are infected with bacteria that release a harmful toxin. What are the symptoms of tetanus disease? And exactly how does the toxin cause these symptoms (be specific)?

Answer 1

Tetanus is causes by bacteria clostridium tetani.

It produces two types of toxins

1.tetanolysin : a hemolysin - not relevant in pathogenesis of tetanus.

2. Tetanospasmin : a neurotoxin

Symptoms:characterised by tonic painful muscle spasm which leads to following symptoms

1.lock jaw(trismus): 1st symptom.

2.difficulty in swallowing

3.stiffness of abdominal muscles.

Pathogenesis of disease due to tetanospasmin:

Toxin is absorbed by local nerve endings and transported to central nervous system intra axonally.

It blocks synaptic inhibition in spinal cord(inhibits terminals that uses gaba or glycine as neurotransmitter).

The toxin acts presynaptically .

The abolition of inhibition leads to uncontrolled release of impulses results in uncontrolled muscle rigidity and spasms.