I was curious to what could get passed on through ass-licking so I google'd and found an interesting website.
http://www.collegesexadvice.com/lick-ass.shtml
I copied n pasted this:
Dear RSA,
I love licking girls' assholes as well as their pussies. Is this normal/healthy?
Matt, U.S.
Matt,
Licking ass (aka tossing her salad) is perfectly normal, although a lot of people don't do it because of taboos about the butt, squeamishness, cleanliness issues, fear of disease, etc. However, asses are hot, the anal area is full of sensitive erotic nerve endings, and eating out a nice, clean asshole can be very pleasurable for both the giver and the receiver.
When you ask whether analingus (ass eating) is healthy, I'm not sure if you mean, like, healthy sexually and psychologically, or healthy like, can you get sick from it? If it's the former, I think I already answered that above -
it is within the normal and healthy range of sexual behaviors. If you're concerned about what you might catch from licking your lover's ass, well, that's another story. Yes,
it is possible to contract communicable diseases from anal-oral contact. By eating ass, you're exposing yourself to any disease that person might have that could be transmitted through their poop, including hepatitis A, food-poisoning type illnesses, and intestinal parasites like Cryptosporidium and Giardia. These are relatively rare, but if you are concerned about protecting yourself, you can use a latex barrier such as a dental dam or an unlubricated condom (unroll it, cut off the end and slice the tube lengthwise to make a square). Plastic kitchen wrap may also work.
To use a barrier, dab some water-based lube or saliva on your friend's asshole for better sensation, then place the barrier over their butthole and hold it in place with both hands as you lick against it with your tongue.