A serious health condition caused by an advanced stage of HIV infection. The immune system becomes severely damaged by HIV and can no longer protect the body from infections.Rare “opportunistic” infections and cancers become more common.What is AIDS?In 2014, CDC revised its guidance around classifying AIDS Diagnoses. A stage system was developed. People that were traditionally diagnosed as having AIDS are now referred to as having HIV Stage 3 in surveillance data.CDC. Revised Surveillance Case Definition for HIV Infection — United States, 2014. MMWR 2014;63(No. RR-03):1-10.