What exactly is chlamydia, and how do we treat it?
03 September 2019

Interview with 

Caroline Cooper, iCASH Cambridge


Chlamydia is one of the most prevalent sexually transmitted infections in the UK. To find out the scale of the problem, how it can be treated, and how far we might be from a vaccine, Chris Smith and Katie Haylor spoke to sexual health doctor Caroline Cooper from Cambridge. First up Chris asked Caroline how much of an issue STIs are in the UK in general...

Caroline - Well, certainly the rates of sexually transmitted infections are increasing year on year across the UK. I think it is an important issue. In particular, infections like chlamydia are becoming more common.

Chris - And when you say the rates are high, how high?

Caroline - For example chlamydia, there's about 220,000 new cases in the UK last year.

Chris - I did see some statistic of about 10% of 16 to 19 year old girls having it in this area. I mean that's quite high. Isn’t it?

Caroline - Yeah, certainly, it’s prevalence in the UK is somewhere between nine and eleven percent. And I think one of the challenges with chlamydia is that often people don't have any symptoms. About half of men and up to three quarters of women don't know they've got it. So they have no reason to go and be tested or go and seek help from a professional.

Katie - Also with us is Graham McKinnon. He's a sexual health doctor from Peterborough who specializes in HIV. Graham, what is the most common issue you see in your clinic?

Graham - I mean the most common issue is when you get someone coming in and they're worried that they've got something, they're worried that they've picked up an infection. They want to know what it is, they're worried whether it's going to affect them, maybe affect their partner. And you know they want to sort of get it sorted. And often they're quite embarrassed about things as well, we try to deal with that.

Chris - A very warm welcome to both of you. As Caroline alluded to, chlamydia is a major problem. So that's the first thing we're actually going to look at this week. Here's Phil Sansom with the quickfire signs of it.

Phil - Chlamydia is a bacterial infection. It's one of the most common sexually transmitted infections in the UK. It's easy to be infected with it without realizing, because many people with chlamydia have no symptoms. For those that do have symptoms, they can become apparent a few weeks after you're infected. You might experience a discharge from the vagina or penis, or a burning sensation while urinating. For women, there may also be bleeding after sex or between periods. For men, there might be painful testicles. The long term consequences can be varied and severe. For women, chlamydia can cause pelvic inflammatory disease which can affect fertility. In men, testicles can become inflamed and if not treated there could be a risk to fertility. It normally only takes a urine test or a swab of the relevant body parts to diagnose chlamydia and you can treat it with a course of antibiotics. It's a good idea to get checked regularly if you're sexually active. There is currently no vaccine for Chlamydia, but a group of Danish researchers are about to start the second stage of clinical trials on a possible candidate.

Chris - Interesting stuff. So Caroline, when someone has chlamydia, we've heard there that it can be asymptomatic, it can be smouldering away inside. What sorts of things actually happen when you get things like pelvic inflammatory disease, what are the consequences?

Caroline - Certainly chlamydia when untreated can lead to widespread pelvic infection. So this can lead to pelvic inflammatory disease, it can also lead to ectopic pregnancies where a woman will have a pregnancy outside of the uterus, most commonly in the fallopian tube, and in some women it can lead to infertility. So you know it's a potentially very serious condition.

Chris - What happens if someone contracts this when they are pregnant? Or if they’ve already got it and then they get pregnant. Because you've said it can be asymptomatic.

Caroline - Yes certainly. We would always encourage women to have treatment during pregnancy. It doesn't have any implications for the delivery, but for some of the babies born they can have eye infections. They can sometimes have quite a severe lung infection.

Chris - And is it relatively easy once you've got the diagnosis to actually treat it?

Caroline - Yes. So the treatment is very straightforward. We have extremely sensitive tests now. We have antibiotics that will treat chlamydia that are extremely effective.

Chris - Because with some of these infections we've seen that the bugs are becoming resistant to the drugs. That's not the case for chlamydia is it?

Caroline - It's not such a problem for chlamydia. Certainly the widespread resistance to treatment we're seeing with infections like gonorrhea, like Mycoplasma genitalium. But at the moment we're fairly confident with our chlamydia treatments.

Chris - Why do you think in recent years this has become such a big problem, because it wasn't such a big problem historically and it seems to have really grown. Why is that?

Caroline - Well I guess part of the reason is that people don't always know that they've got it. I suppose another reason is the changes culturally, in that people are having more sexual partners over their lifetime, and having more frequent change of partners. And once you've got the infection, up to 85% of your partners are likely to have it too.

Chris - So it's pretty easy to catch.

Caroline - Yes certainly it is. It generally would be caught through having either vaginal sex or anal sex with someone who's infected.

Katie - So if we take a step back, what is the main way of preventing getting a chlamydia infection?

Caroline - Well, I suppose it's the same as the ways that you would prevent getting any sort of STI. It would be having protected sex using a condom and having regular checks. Certainly, I think you mentioned at the beginning how common it is in young people. And we would encourage everyone under the age of 25 to have an annual checkup, or to have a check anytime they have a new partner.

Katie - The piece that we just heard also mentioned a vaccine for chlamydia, that's that's undergoing trials at the moment. So tell us about that. How does that work?

Caroline - This is potentially a very promising vaccine. The early trials were just on 35 women but they found that it was extremely successful in provoking an immune response. So the women produced antibodies to chlamydia both in their blood and in vaginal fluids. And certainly, the vaginal fluids would be the first line of defense against chlamydia. Obviously we now need much larger numbers of people to see if it will actually prevent chlamydia as well as producing the antibodies.

Chris - What's the nature of the vaccine, how do you administer that, is that an injection?

Caroline - In the trials it was a course of three injections and then two nasal sprays. But it's felt that continuing injections would be enough.

Katie - We were talking just a moment ago about the fertility implications for women. What about men?

Caroline - There is some suggestion that for men it can cause them to have inflammation, infections in the epididymis where the sperm is produced, and so that would have implications for their future fertility as well.

Chris - Is there any way for a person who gets treated, clears the infection, and now can be regarded as uninfected, to find out if it's had any long term consequence on them or do they have to wait and see?

Caroline - I think that is a real dilemma because there isn't a particularly easy test of someone's fertility after Chlamydia. You know, we can say statistically if you've had one episode you may be at risk of infertility. The more times you get it the higher your risk. But there's not really an easy test. So I think it is a bit of a dilemma for people.


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