Have they been wormed? If you used an avermectin, then it wont be lice, unless this has worn off. If they haven't been treated against parasites, they could have lice or mange. Are they scratching a lot? Have you noticed any hair loss.
I have had lice with my OSB's, and I generally noticed the eggs which looked like little white dots in areas like: Under the chin, top of the legs. And then if you look, lots of little crabs are running all around the dry skin.
Sorry I couldn't give you a direct answer.
HTH