A small number of people never become infected with HIV despite years
of exposure to the virus. For example, they may have repeated, unprotected sex
with an infected person. These people are said to be HIV-resistant. These people are never infected, so they can't spread HIV.
The most common way people are infected with HIV is by having sex with an infected person. You can't tell by looking at a person whether they have HIV, so you have to protect yourself -- and your sex partner.
and HIV Prevention
Don't have unprotected sex outside marriage or a committed relationship. If you or your partner has ever had unprotected sex -- or if either of you uses injected drugs -- the only way to be sure you don't have HIV is to get tested. Have two...