How to steralise wooden saw handle without twisting it?

Hello, so i bought cheap old saw handle. After i got it i found holes made by some bugs in it. How to steralise it?

I dont mind boiling it, but im afraid that it will make wood twist, so handle would loose its shape. Same thing with baking it in oven.

Freezing is not enough.

Greatful for any suggestion

Edit: problem solved. I have desinfected handle in bath of denatured alcohol and bleach. I reccomend binding rather hard the part of the handle with the gap for the blade, with a plastic string, in order to keep it from twisting apart once its being dried.