Not to get too far off-topic, but I think that because it's impossible to have a perfect enclosure with 100% perfect husbandry, there is no way to guarantee this won't ever happen. Of course you can do your best to prevent it, but sometimes things just happen. I'm glad it was noticed quickly and treated the right way.. That's the most important part in this situation. Having husbandry that is "up to par" may greatly decrease this happening, but I don't think it will eliminate it. But, someone who knows more please correct me if I'm wrong.