In MSM, PrEP Stops HIV, Not Other STIs. Does It Matter?

Not so long ago, preventing HIV and other sexually transmitted infections (STIs) came down to the same basic safer sex choice: avoid risky sexual behavior or use condoms. But in recent years, much has changed. Improved antiretroviral therapy has turned treatment into prevention, because many people living with HIV have undetectable viral loads and cannot spread the virus. Meanwhile, increased testing rates have led some people to make decisions about partners and practices based on real (or assumed) test results.

Perhaps most notable, however, is the growing use of pre-exposure prophylaxis (PrEP) by those who are HIV negative but at risk of contracting the virus. In 2012, the U.S. Food and Drug Administration (FDA) approved Truvada (tenofovir/FTC), a once-daily pill, for use as PrEP. Studies show that when taken consistently it can reduce the risk of contracting HIV by over 90%. Both the U.S. Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) now recommend PrEP for those at high risk of infection, which includes men who have sex with men (MSM) who have had sex without a condom in last six months.

While the introduction of a new prevention method is great news, not everyone in the public health world is excited about Truvada -- in part because it only addresses HIV and does not provide protection against other STIs that are common among MSM, like gonorrhea and syphilis. AIDS Healthcare Foundation went so far as to launch a public campaign against Truvada because it feared that those using Truvada would give up condoms altogether.

The evidence is mixed. While initial studies showing that PrEP worked for gay men didn't show a drop-off in self-reported condom use, some subsequent research suggests that men taking Truvada use condoms less frequently than before they were on the blue pill -- but it is still too soon to tell what the impact will be on a large scale.

In the meantime, it may be time for gay men to take a look at the other STIs out there, when considering whether or not to use condoms. STIs can cause health issues ranging from the unpleasant to the life-threatening, and most of them also increase the likelihood of transmission of HIV. While this last point might not be directly relevant to men who are protected from HIV by Truvada, they may have partners who are not using PrEP -- so increasing that partner's risk could in turn lead to HIV infections among gay men and other MSM.

Do MSM Have Those "Other" STIs?

At the risk of sounding too much like your high school health teacher, there are many STIs out there that MSM should be at least a little worried about. Let's start with HPV (or human papillomavirus), which can infect the genitals, throat and anus. MSM are at high risk for anal HPV in particular. Researchers estimate that 60% of MSM have anal HPV compared to just 15% of men who only have sex with women.

MSM are also at high risk of hepatitis A, B and C -- all of which infect the liver. Approximately 15% to 25% of all new hepatitis B virus infections in the U.S. are among MSM; it's frequently transmitted via sex. (Hepatitis A and B, however, can be prevented through vaccination.)

When we talk about chlamydia and gonorrhea -- the two most common bacterial infections -- we often talk about women and the possibility that an untreated infection can lead to pelvic inflammatory disease (PID) and subsequently to infertility. But MSM should be aware of these STIs as well, as they can infect the penis, throat and anus. Studies have found that between 3% and 10.5% of MSM screened for rectal chlamydial infection were positive, as were between 0.5% and 2.3% of MSM screened for chlamydial infection of the throat. As for gonorrhea, the rate among women decreased by 2% between 2012 and 2013, but the rate among men (all men, not just MSM) increased by over 20%.

Finally, we have to talk about syphilis. In the late 1990s, when there were fewer than 7,000 cases each year, the CDC declared that the U.S. was on the verge of eliminating this ancient disease that was historically known for causing blindness and insanity. Since that time, unfortunately, the number of cases has increased considerably, particularly in gay men. In 2013, there were 17,375 cases of primary and secondary syphilis. Almost 75% of the cases were seen in MSM. Over the past several years, there have also been local outbreaks of syphilis among MSM in various cities and areas including Chicago, Seattle, San Francisco, Southern California, Miami and New York City.

How Are They Related to HIV?

STIs and HIV often occur together. For example, one study found that 77% of MSM with HIV were also infected with anal HPV while another study found that over 90% of MSM with HIV were infected with at least one strain of HPV. And, in the outbreaks of syphilis mentioned earlier, between 20% and 70% of the men involved were also found to have HIV.

The presence of another STI makes HIV easier to transmit and acquire. For example, herpes sores are known to provide an entry point for HIV. The CDC estimates that during a herpes outbreak there is a two- to four-fold increase in the risk of acquiring HIV.

But Are STIs Really a Problem by Themselves?

It is tempting to look at these STIs as merely nuisance infections that come and go, especially when comparing them to HIV, which can be a life-altering diagnosis. But we can't just dismiss STIs as unimportant, as all of these infections cause significant health issues. HPV, for example, is responsible for a dramatic rise in the incidence of cancer of the head, neck, throat and anus. Herpes causes outbreaks of painful sores that can recur at any time.

Syphilis, if left untreated, can still cause symptoms like blindness and dementia. In the primary phase of the infection, sores called chancres appear at the site of infection. These usually go away on their own within a few weeks. If undetected and untreated, however, syphilis can progress to the secondary stage, which often starts with a whole body rash and can also include flu-like symptoms such as fever, aches and swollen lymph nodes. When these symptoms disappear, the infection enters its latent phase during which it can cause damage to the internal organs despite no outward symptoms. If left untreated, syphilis can cause difficulty coordinating muscle movements, paralysis, numbness, gradual blindness, dementia and eventually even death.

But Don't Antibiotics Solve the Problem?

We have become used to the idea that antibiotics can cure a lot of STIs easily. While this is still true of those infections caused by bacteria, it is important to get tested and diagnosed quickly so that treatment can start before any health issues occur.

And, you should be aware that some bacteria, most notably the one that causes gonorrhea, are evolving in ways that make antibiotics less effective. Today, the only class of antibiotics that remains effective against gonorrhea are cephalosporins, but the bacterium's susceptibility to these drugs is declining rapidly in the U.S. Other countries have already seen cephalosporin-resistant cases.

So What Should We Do?

The most effective ways to prevent these STIs are the same as always: avoid risky sexual behavior and use condoms. Latex condoms are highly effective at preventing STIs that are caused by bodily fluids, like gonorrhea and chlamydia, and can also reduce the risk of transmitting those caused by skin-to-skin contact such as HPV and syphilis.

Still, we know that many MSM choose not to use condoms all the time. Though consistent condom use is the gold standard of STI prevention, there are other things that MSM can do to protect themselves and their partners. One of the first and easiest steps is to get vaccinated for both HPV and hepatitis B. Another important move for sexually active MSM is to get tested for syphilis, gonorrhea, chlamydia and hepatitis B and C regularly. Men who have had oral or anal sex should be sure to ask for tests of the anus and throat. Just like with HIV, diagnosing STIs early and treating them quickly can prevent the spread of these diseases and make sex safer for everyone.

The rest of prevention comes down to personal decisions about risk. Limiting the number of partners (especially multiple partners at the same period in your life) can lower risk. Limiting the use of recreational drugs can lower risk. Talking openly and honestly about STIs with partners and committing to getting tested (ideally before having sex) can also bring your risk down.

As you make your decisions, just keep in mind that HIV is not the only STI around.