Scientists have been issuing increasingly urgent warnings about the dangers of antibiotic-resistant gonorrhea, but it seems that may not be the only thing we have to fear from “the clap”. A team at the Melbourne Sexual Health Center have found evidence saliva may play a role in transmitting the bacterium, which would open up the possibility that even kissing may be unsafe. If you thought that might ruin your day, the good news is that antiseptic mouthwashes may prevent the disease's spread.
The bacterium Neisseria gonorrhoeae has been interfering with people's sex lives for centuries. Some men, and about half of women, whose genitals become infected show no symptoms, greatly increasing the danger they will pass it on to others. Less fortunate women can suffer pelvic inflammatory disease and find sex becoming painful. For men, the most common symptom is a burning sensation during urination, but urinary infection also raises the risk of liver disease, some cancers and a range of other rare, but very nasty, outcomes.
Once a common disease, gonorrhea’s frequency dropped markedly with the invention of antibiotics but made a comeback to peak in the 1970s. Increased use of condoms to protect against HIV had the beneficial side effect of causing rates of other sexually transmitted infections, gonorrhea included, to plunge dramatically. However, we are once again seeing a rising trend.
Professor Kit Fairley of Monash University thinks our efforts to impede the bacterium's spread may have been hampered by misunderstanding how it is transmitted. He leads a team that has published a string of papers slowly building evidence that saliva is much more important than has been recognized, something we will need to come to grips with if we are to stop it.
As well as the urinary tract, gonorrhea can infect the throat or anus. Symptoms in both are rare, and it usually clears within a few months or year depending on the site. These infections are rarely a problem on their own, but represent a major transmission risk. Painful urinary infections quickly drive people to get treatment, but without symptoms, most infections in the throat and anus go untreated, and can then be transferred to others. However, Fairley thinks sexual health experts have been misunderstanding how this occurs.
Where conventional transmission models blame oral and anal sex for transmission, Fairley was struck by a surprising number of men coming to the clinic who said they had always used a condom during anal sex.
A single individual might be lying or forgetful but to Fairley, the cases were too common to ignore. Gonorrhea is often found in saliva, but in recent times this was not thought to be important for transmission. In the journals Emerging Infectious Diseases and Sexually Transmitted Infections, Fairley proposes this is wrong. He suggests the use of saliva as a lubricant during anal sex could account for much of the pattern of gonorrhea transmission the clinic has observed. Add in transmission from throat to throat through kissing, and to the genitals through oral sex, and the rest of the story falls into place.
Fairley told IFLScience a peck on the lips is unlikely to be a danger, but deep kissing with tongues in one another's mouths is a different matter. Unfortunately, studies on gonorrhea transmission seldom even ask how many partners someone has kissed.
Even before anti-retroviral drugs, many nations brought the AIDS crisis under control, not by persuading people not to have sex, but by boosting condom use. Fairley hopes mouthwash could be gonorrhea's equivalent. Listerine was initially marketed against gonorrhea, before gaining a more profitable application for bad breath, Fairley's co-author Dr Tim Read told IFLScience. The clinic is about to start a large-scale trial testing the effectiveness of mouthwash for preventing gonorrhea's transmission.
For reasons that are not fully understood, gonorrhea is most frequent in developed countries among men who have sex with men. However, rates of heterosexual transmission are rising, and the bacterium may soon be, once again, a much more widespread problem. If this combines with antibiotic-resistance, we could be facing the return of a disease thought to have been put behind us 60 years ago.