I really dont think parasites live inside your tooth! yes there are but those you cannot see with the naked eye.
I think its an cavity wich formed in between the teeth, a tooth can be eaten from the inside out once the little f***ers reach the dentin, you will not see it for yourself untill you got pics like you do and the teeth exploded.
In My Opinion the tooth was eaten from the inside out after a little unnoticable cavity gave acces to the dentin.