True about tetanus –
Pathogenicity 

Cl. tetani has little invasive property and is confined to the primary site of lodgment. Tetanus results from the action of the potent exotoxin it produces.
Toxin is released in the wound, it enters the axon of neurons and is transported to brain stern and spinal cord by regrograde intraneural transport where it presynaptically blocks release of glycine and GABA.

Tetanus 

Incubation period - is variable from two days to several weeks, but is commonly 6-12 days. Note : It is tetanus toxin not bacilli that spread along the nerve.
Tetanus bacilli can spread through blood
Spread along the nerves only
Requires oxygen
I.P. is variable