People with high rates of HIV infection include sexually promiscuous or sex workers, people who share needles for intravenous drug use, and men who have sex with men, all of whom are at high risk for HIV infection. Sexual transmission, blood transmission and vertical transmission from mother to child are the three ways of transmission of HIV infection, among which sexual transmission is the main way of transmission. Because of the sharing of needles for intravenous drug use, if one of them carries HIV, it will be transmitted to others through the sharing of needles. Gay men: Gay men usually have anal sex because the mucous membrane of the anus is easy to break, and if the mucous membrane of the rectum is broken during sexual intercourse, HIV will infect the partner through the broken mucous membrane.