How do I change the infection level on a Terraria server using the console?

There are two ways to change the infection level but not in console

First is Journey mode difficulty is a place where you can increase, decrease or stop the infection.

Second is if you're not using Journey mode difficulty you can just go to the File then select tshock then select config.json, then go find "AllowCrimsonCreep" and if you type "true" it will allow the server to spread the inspection of the world and "false" otherwise.

AllowCrimsonCreep is for "CRIMSON"

AllowCorruptionCreep is for "CORRUPTION"

Allow hollow creep is for "HOLLOW"