Can the Crimson and Corruption in Terraria spread through background walls? [duplicate]

The title is basically my question.

I've use TEdit to remove all of the stone and dirt Crimson in my world, but the background walls don't seem to be removed by TEdit.

Will these wall blocks make the Crimson spread in my world still, or am I safe?

Solution 1:

No, walls cannot spread anything. Blocks of certain types within a small enough range (3 or less blocks I believe) can be converted by Crimson/Corruption/Hallow, with a handful of special exceptions related to flora in the Corruption, and the beginning of Hardmode.

In the next section on that same link one can also find this relevant gem:

Each time an Altar is destroyed, there is a 66% chance that a single random tile in the caverns layer will be converted to Ebonstone/Crimstone or Pearlstone, facilitating the spread of underground Hallow or Corruption/Crimson. Only stone blocks can be converted in this way.

So ensure you either kill all Altars in your world that you don't plan on keeping (protect the one(s) you want to keep, it is important to have at least one) or ensure you scour your entire caverns layer each time to kill an Altar.