Human immunodeficiency virus infection and acquired immunodeficiency syndrome ( HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Near normal life expectancy with treatment ġ1 years life expectancy without treatment ĥ5.9 million – 100 million total cases Safe sex, needle exchange, male circumcision, pre-exposure prophylaxis, post-exposure prophylaxis Unprotected anal or vaginal sex, having another sexually transmitted infection, needle sharing, medical procedures involving unsterile cutting or piercing, and experiencing needlestick injury Later: Large lymph nodes, fever, weight loss The red ribbon is a symbol for solidarity with HIV-positive people and those living with AIDS.