Stigma, squeamishness and misunderstanding of anal sex is leading to research gaps and inaccurate information about the risks of this common sexual behaviour, and hindering effective HIV/AIDS prevention strategies, experts say. A move towards "sex positive" approaches could enhance social acceptance and increase protection.
"If we look at historical art depictions and carvings, heterosexual anal sex has been part of the human sexual repertoire for a long time. Not discussing anal sex and its relationship to HIV transmission leads people to making wrong assumptions about its risks," Jim Pickett, director of prevention advocacy and gay men's health at the AIDS Foundation of Chicago, told IRIN.
In 2011 the UN General Assembly issued its "Political Declaration on HIV/AIDS" which, among other goals, set the target of reducing sexual transmission of HIV by 50 percent by 2015.
According to the Joint UN Programme on HIV/AIDS (UNAIDS), the number of new HIV infections among adults in low- and middle-income countries in 2012 was 30 percent lower than in 2001, which the agency attributes in its 2013 global report as: "primarily represent[ing] a reduction in sexual transmission."
However, some experts warn, even with this decreased infection rate, the HIV response remains harmfully incomplete unless it begins to acknowledge a range of sexual behaviours, including those that are stigmatized, misunderstood, or deemed disgusting.
Mixed messages cause risky oversight
The risk of HIV transmission for anal intercourse is 18 times higher than for vaginal intercourse because the anus has thinner membranes and does not self-lubricate like the vagina - making it more prone to tears and lesions.
Historically interventions that mention anal sex have focused on men who have sex with men (MSM) and transgender women, who are often (wrongly, many argue) categorized as male for public health purposes. Research focused on MSM populations has uncovered some important facts about anal sex, including dangerous gaps in personal lubricant availability around the world.
Pickett argued that anti-sodomy laws further add to the stigmatization of anal sex and also link it to being something only MSM do.
However, new evidence is emerging that the MSM focus may lead to assumptions that heterosexual intercourse does not include anal penetration and therefore sends the wrong message about who needs to protect themselves.
A study on the practice of heterosexual anal sex in five communities in Kenya, Tanzania and Uganda found that it is widely practiced for a variety of reasons including the preservation of virginity, contraception, economic gain and maintaining fidelity.
The 2009 National Survey of Sexual Health Promotion and Behavior by Indiana University in the US showed that among the men and women surveyed, around 45 percent admitted to having anal sex.
However, despite it being relatively common behaviour, there is a dearth of accurate information on it.
"Even though most people who have anal sex engage in it only occasionally, anal sex is a fairly common practice. And if people are going to engage in a sexual behavior, then they deserve enough information to help make that behavior as safe, pleasurable and satisfying as possible," wrote Debby Herbenick, one of the authors of the 2009 survey, which was published in The Journal of Sexual Medicine.
Other experts agree, and argue that part of the reason anal sex gets overlooked is the reluctance to explore the behaviour in studies.
"We're not asking, so people are not telling," said Pickett who attributes this disinclination to stigma around the anus as a body part.
"We have been conditioned to think of it as filthy and unclean so we do not talk about it," said Pickett, who coordinates the International Rectal Microbicide Advocates (IRMA), a global network that works to create "safe, effective, acceptable and accessible rectal microbicides for the women, men, and transgender individuals around the world who engage in anal intercourse."
"If we cannot talk about all sex acts and what is risky and less risky, people cannot really make intelligent choices," said Pickett.
Going "sex positive" with HIV messages
"Anal sex is one of the last taboos of the HIV world. It is not mentioned in campaigns targeting straight couples and leads to informal messaging that it is actually safe or there is no need to wear a condom," said Anne Philpott, founder of The Pleasure Project, an organization that works with NGOs, sex counsellors and erotic film producers on incorporating "sex-positive" approaches to sex education.
A 2014 study published in the British Medical Journal revealed that the first experience of anal sex among teenagers was often painful and coercive. Many of the study's participants, however, perceived anal sex as "safer" because they did not think it was possible to get sexually transmitted infections from it.
Easy access to pornography featuring anal sex scenes among heterosexual couples also contributes to the expectation that anal sex is part of the "standard sex routine", the study suggested.
"About four percent of websites are now pornographic. We need to be proactive about creating more safe porn, and models of sex that do not legitimize unsafe sex," added Philpott who explained that in countries where there is little or no sexuality education, pornography can become a default information source.
Philpott pointed out that unprotected anal sex also has a higher rate of infection for the receptive partner - in heterosexual couples, the woman. During anal sex without a condom, an insertive partner has about a one in 909 chance of HIV infection compared to a one in 154 chance for the receptive partner.
A 2008 National Health Statistics Report in the US showed that of the more than 13,000 respondents 36 percent of women and 44 percent of men reported having anal intercourse with the opposite sex.
However, a related study indicates that only 13 percent of receptive women used condoms during their past 10 anal intercourse events, compared to 44 percent of receptive men - a significant behavioural gap in heterosexual intercourse.
"Not even mentioning this risk to straight couples is a huge mistake. Not giving them tips and information on how to make anal sex safe is a huge loss," said Philpott.