No risk for contracting HIV by rimming or being rimmed. But there are other things you can contract.
An anus is an anus no matter what you do and you can't sterilize it.
No amount of cleaning will fully protect you from a variety of STDs and parasites if they are present in your partner's mouth or anus.
Parasites may cause symptoms of upper abdominal pain, bloody diarrhea and fever, but there have been no known cases of HIV transmission through rimming.
But Hepatitis A, gonorrhea, herpes, shigella, e-coli and salmonella
can all be transmitted through rimming.
I would strongly advise having an STD panel done as well as a fecal test for parasites.
Anytime there is a wound visible around the anus, be safe and always use a condom.