Sexually Transmitted Infections (STIs) in the ‘next’ era

By Professor Christopher Fairley, Director of Melbourne Sexual Health Centre and Central Clinical School, Monash University

Transcript from the interview with AFAO Deputy CEO Heath Paynter

Can you tell us about your role at Melbourne Sexually Health Centre?

I am the Director there, so I am responsible for everything, but a big part of my role is to direct the research program so that it is of most benefit to the population.

Today you spoke about STIs in our community, can you tell us what the most common STIs are in Australia?

I think numerically, probably chlamydia and herpes are the most common in some ways they are not as critical as we don’t know how to control them yet. But there are however a number of STIs that should be easy to control but we are not doing very well with, and they are gonorrhoea and syphilis and we need to do much better with those two.

You mentioned the “duration of infection” which is a really interesting concept. Could I ask you to explain what you mean but “duration of infection” in relation to prevention and detection of STIs?

When people see someone with an STI they think it is that person’s fault, they think they should have used a condom or they shouldn’t have had sex with that person. Whereas the biggest driver of STIs at a population level is how long they last in an individual. Not how many partners they have, it’s how long they (STI) last. That’s why penecilin was so effective in the 1940s because you saw this plummeting of syphilis – it went down 99-fold in women because you shortened the duration of infection.

I think people have forgotten that – even some public health people have forgotten that shortening the duration infection is the key to control of a STI. The reason we test people for HIV and then put them on treatment is because you shorten the duration of infection. For symptomatic STIs individuals who have access to healthcare quickly can get infections treated and can dramatically reduce the population level of those infection and that’s why there are free STI clinics. What need to do is makes sure these are accessible so that people with symptoms can come running in and get treatment and not pass the infection on.

You mentioned gonorrhoea as an STI that should be treated more efficiently and effectively in Australia and you spoke the role of saliva in transmission which is an interesting area that I don’t think people fully understand – could you tell us about your recent work in better understanding kissing as a pathway for transmission of gonorrhoea.

One question that has always puzzled me is why gay men get a lot more gonorrhoea than heterosexuals. When a man and woman have sex, the penis is always involved either with oral sex or vaginal sex almost all men get symptoms from the penis and women get symptoms so its easy to control. When gay men have sex its not always anal or oral sex, but you often get transmission to asymptomatic sites of infection and it’s possible the two partners can’t contact one another to tell each other that one has symptoms if the other doesn’t.

So, at a population level when a group of gay men have sex there’s lots more asymptomatic transmission of gonorrhoea than there is in heterosexuals. The key site that is the asymptomatic site is the throat because that is the only site where it can pass on to another asymptomatic site because when the anus is involved it doesn’t go to the throat, it goes to the penis and the penis gets treated straightaway. So, it’s the interaction between two throats that’s really important because you get one asymptomatic site transmitting to another asymptomatic site and no one actually know they have got the infection, so the duration is huge. That is the big driver of gonorrhoea in gay men as opposed to heterosexual people who always get symptomatic.

You’re involved in some research at the moment using mouth wash as a possible form of prevention. Can you tell us about that research?

No point in thinking about an idea unless you have a solution. We worked out that kissing might have a principle role but what can we do about it? If we test people frequently, it won’t be enough – you would have to test people every week for it to be enough. Then I suddenly thought about mouth wash one day which actually advertised in the 1800s as a treatment for gonorrhoea of the penis so we tried it out in the laboratory and it works really well in a laboratory experiment. So then we did a small randomised trial and it appears to have an effect on gonorrhoea in the throat and reduces its significance. I have a big randomised trail that is about to finish soon but if it works, if it reduces the duration of gonorrhoea significantly, you will see a whole population-level effect of a drop in gonorrhoea rates because the throat is the asymptomatic site that is driving all these infections.

It would be great to get that research when are you expecting it to be released?

We have the last few people being recruited into the study there in for 3 months, so they’ll go through to September. We’ll probably have it around October/November.