"It is very unlikely, but possible. Some people, for example, are born with HIV, which they can pass to other people later in life when they start having sex. People can also pick up herpes through casual kissing — even from friends and family. Their herpes infections can then be passed on sexually. The chances of this happening are rare, so it’s not something to spend time worrying about. On the other hand, it’s another one of the many good reasons to always use condoms when you have sexual intercourse."
"Let's say you had sex with someone who is HIV infected and the condom broke, or you found out only after unprotected sex that your partner had HIV. Can you reduce your risk of getting HIV from sex--or from a needlestick--by taking medications afterward? Yes. This is called postexposure prophylaxis, or PEP. The medications that are given are the same types that are used to treat HIV (antiretrovirals, or ARVs), and they usually are given as a combination of 3 medicines for 1 month. To work best, these ARVs should be taken as soon as possible after the exposure, and…"
"Yes. Syphilis is a sexually transmitted disease. A person with syphilis can spread the infection during the first two stages of the disease. If you come in contact with an open sore (first stage) or skin rash (second stage), you can pick up the bacteria that cause the infection. If the bacteria enter your body through an opening such as the penis, anus, vagina, mouth, or broken skin, you can get syphilis. If a person has had syphilis for more than two years, it's unlikely that he or she can spread the disease. Don't take a chance. Use a lubricated…"