Bugs.

THEY'RE UNDER MY SKIN-

But seriously, the insects are extremely infectious. Almost every living creature in vanilla minecraft can be converted to bug. There were issues trying to make them infect modded entities sadly, so this is the best you get.

Along with this, another insect mod that is hard also exists, although you'll just need to see it.

Phases?

There are phases to the spawn rate of the bugs, which start with infected spooders. It'll end with cows.

These phases will be changed with similarity to Spore And Ruins when things like festered mobs. Expect updates, I guess.

Future Additions

More bug mods will be added soon, especially something like Infectum or Wyrms Of Nyrus when they finally get updated to newer versions. I'm debating about gigeresque, but eh.