Sexually transmitted diseases STDs are increasingly common and service providers working in STD prevention are often asked about the chance of getting an STD from a one-time heterosexual sexual encounter. What do studies tell us about how commonly an STD results from one-time sex? How can we interpret the results? Males and females are equally likely to contract most sexually transmitted infections, but females are at higher risk of acquiring some of them.
It is not easy for researchers to calculate the risk of contracting HIV through sex between heterosexual couples. Studies have produced a wide range of numbers that differ on the basis of factors like the type of sexual act, the serologic status of each partner positive or negative , and how many times the partners have had sex.
Most studies suggest that a person is more likely to contract HIV through anal sex than vaginal sex. And oral sex carries the lowest risk. We know that there is more risk for the receptive sex partner the person in whom the penis is inserted, anally or vaginally than for the insertive sex partner the person inserting the penis. A person can become infected with HIV from bodily fluids exchanged during anal sex. Such fluids include blood, semen, pre-seminal fluids lubricating fluids before semen appears , and even rectal fluids.
Researchers have found that female partners receptive partners in vaginal sex have a slightly higher risk of getting HIV. The risk of HIV transmission through receptive vaginal sex ranges from 0. The risk to male partners was found to be slightly lower, 0. The risk of transmission through oral sex whether penile—oral or vaginal—oral is much lower than through anal or vaginal sex. This is because the oral cavity contains a thick epithelial layer, a low number of CD4 target cells, and antiviral antibodies.
A meta-analysis by Baggaley and others of 10 studies aimed at calculating the risk of HIV transmission through oral sex found that only 4 of the studies reported a non-zero estimate of risk from unprotected oral intercourse. We know that most cases of genital herpes are caused by the herpes simplex virus type 2 HSV A person who has genital herpes may have sores in multiple parts of the body.
