April 24, 2009— -- Life is short. Have an affair, urges AshleyMadison.com, a social networking site for married people looking for extracurricular love. Visit for an "erotic chat" or meet up for "anything goes."
On gay.com, check out "Cronic-Candy," a 22-year-old California man who is looking for a hook-up and insists, "I'm not gay, guys just like sleeping with me."
On Craigslist.org, sex-seekers can go "preference shopping" for sex with or without a condom on the site's "casual encounters" or "men seeking men" pages, where escorts and sex workers cruise the Internet's so-called "erotic underbelly."
Social networking sites connect friends, serve special interest groups and make it easier than ever before to stay in touch.
But when the Internet is used for anonymous and unprotected sex -- that touch can turn toxic.
Such was the case with Brett, now a 21-year-old college student who met up with men at a party through a connection his friend had made online.
"It was one of the few times I had unprotected sex," Brett, who asked that his last name not be used for this story, told ABCNews.com. "But my friend and I were still in high school and these guys were older and we had been drinking."
Today, after Brett's reckless encounter he is HIV positive.
"A lot of people don't like to use protection," said Brett, who lives in Chicago and was diagnosed when he was 18.
Some fear that online chat rooms and dating sites are becoming today's virtual bathhouses, where HIV/AIDS first percolated among gay men in the 1980s.
On April 28, the Kaiser Family Foundation will release a report that finds the number of Americans who list the disease as "the most urgent health problem" is at its lowest levels ever -- only 6 percent, compared to 44 percent in 1995.
That report comes on the heels of one from the Centers for Disease Control and Prevention that found the number of Americans newly infected with HIV/AIDS is 40 percent higher than previously reported -- 56,300.
More than 1 million in the U.S. are living with the disease, and 14,000 to 15,000 die annually.
"The epidemic has been roughly stable since the late 1990s," according to the CDC, though the numbers remain "unacceptably high."
More than one-quarter of HIV-infected people are unaware of their infections, according to the CDC. And more new infections occur among young people ages 13 to 29 than any other age group -- precisely the demographic that uses the Internet for social networking.
An estimated 16 million people say they have used Web sites to meet other people, according to report prepared by the Pew Internet and American Life Project.
Gay men, in particular, have benefited from the "privacy" of the Internet, with 40 percent reporting they use it to find sex partners, according to studies cited by the University of California San Francisco AIDS Research Institute.
Their studies reveal that people who use the Internet to meet sexual partners engage in more risky behavior: they have more partners and are more likely to report sexually transmitted diseases than those who seek sex in more traditional ways.
"These sites are a great temptation for those who suffer from sexual addiction," said Dr. Kristen Ries, an infectious disease specialist from University of Utah Hospitals and Clinics. "I am especially worried about some of the younger generations who are so Internet savvy, but who seem nonchalant about the seriousness of HIV/AIDS."
"Remember that HIV positive people who are in denial about their HIV, or who are fearful of abandonment if they disclose their HIV positive status, are more apt to seek anonymous sex at such sites," she told ABCNews.com.
With that in mind, many public health agencies are using the Internet to change people's attitudes and educate them about the possible dangers of risky sex.