Chlamydia is a bacterial infection that is caused by a type of bacterium called Chlamydia trachomatis and transmitted through sexual intercourse. As such, it is classified as a bacterial STI, and is also undoubtedly the most common STI in the UK with more than 200.000 new cases being reported to the health authorities every year. In total, chlamydia cases amount for roughly 50% of all STI cases in the United Kingdom.

In this article, we will try to bust some myths regarding chlamydia transmission and provide our readers with the reliable info on how you can catch this disease.

What’s on this page:

For starters, we will debunk the claim that chlamydia can only be passed on through penetrative sex – this is far from true as there are many other transmission routes, including:

  • Unprotected vaginal, anal or oral sex
  • Sharing of sex toys
  • Non-penetrative genital contact
  • Contact between genital fluids and the eyes

Chlamydia doesn’t necessarily produce symptoms in those affected. As mentioned on our chlamydia symptoms page, roughly 7 in 10 women and half of men affected will develop no noticeable signs. However, just because the conditions remains asymptomatic it doesn’t mean it is any less contagious or any less likely to cause more severe health complications.

Chlamydia trachomatis

Although there is little talk about it, there are several strains of bacteria from Chlamydia family and a majority of them doesn’t live in the human body nor can it be considered to be an STD. In fact, only Chlamydia trachomatis can cause this condition. In infected person, colonies of bacteria will first form at the site where the transmission took place. This is always on a mucous membrane – a soft, red tissue in the body which is not protected by the skin and that can be found in the inside of the mouth, vagina, urethra or rectum.

Mucous membranes naturally emit fluids which in turns carry the bacteria throughout the body or outside of it as in semen, vaginal fluid or rectal mucous membrane secretions. These fluids are usually the main vehicle of transmission.

Chlamydia transmission routes

As a consequence of the life cycle of bacteria within the human body, chlamydia can be transmitted from one person to the other in several different routes.

Unprotected vaginal sex

Chlamydia can pass from male to female partner or vice versa during unprotected vaginal sex. This can happen via vaginal fluid, sperm or just contact between genital tissues. It is important to note that this means that ejaculation doesn’t have to occur for the transmission of chlamydia as the bacteria causing the condition is present in the mucous membranes, so just contact between those two during unprotected vaginal sex is enough to pass on the infection.

Unprotected anal sex

The mechanism of transmission during unprotected anal sex is the same as is the case with vaginal sex, since mucous membranes are also exposed within the rectum.

Unprotected oral sex

Chlamydia can also be transmitted via oral sex, either through infected sperm or via infected tissue in the mouth. However, this route of transmission is very rare since tissue in the genital area is far more susceptible to bacterial infections, as opposed to mucous membranes in the mouth. But, this also means that it is more likely, for example, for a woman to get infected by receiving oral sex from a partner who has chlamydia in the mouth already. In other words, vagina-to-mouth or anus-to-mouth transmissions are possible but much rarer than mouth-to-vagina or mouth-to-anus transmissions.

Chlamydia transmission through sex toys

Chlamydia infection can also be transmitted through sharing of sex toys if fluids of the person affected find their way onto the surface of the sex toy which is then used by their partner. In other words, the contact between mucous membranes in this case is mediated in a way by the sex toy.

Chlamydia transmission to eyes

Chlamydia can be passed on through mucous membranes of the eye where it will cause conjunctivitis. The symptoms include reddening of the tissue surrounding the eye, inflammation and sometimes discharge.

Can chlamydia be passed on from mother to the baby?

If a pregnant woman is infected with chlamydia, the infection can be passed on to the baby during childhood. If this occurs, the baby can get conjunctivitis or other infections. On top of that, chlamydia has been known to cause significant complications during pregnancy.

How likely am I to get chlamydia?

Everybody who is sexually active is at risk of getting infected. Of course, if you are in a monogamous relationship with a long-term partner who knows he or she doesn’t have any STIs, the chances of contracting chlamydia are, for all intents and purposes, non-existent.

However, if you are sexually active and don’t have long-term partner, the risk is exceptionally higher. If you have any reasons whatsoever to suspect you might have been infected, it is crucial to get tested as soon as possible, so that you can get diagnosed and commence your treatment. If the diagnosis is confirmed, you should avoid sexual activities until you get confirmation that the infection has been successfully eliminated.

Despite this, if someone had unprotected sex with an infected person, it doesn’t mean that the transmission had definitely occurred. As was discussed before, the rates of transmission vary according to different factors, including the nature of sexual acts performed. It is estimate that single unprotected exposure will result in a transmission in roughly 25% of cases.

In addition to that, it would seem that male-to-female transmission rates are somewhat higher with 40% as compared to female-to-male transmission rates which reach around 32%. Repeated exposure, as is evident, will dramatically increase the odds of getting infected. However, even then, barrier protection can be used as a reliable precaution – when used properly, barrier contraceptives are effective in 99% of cases when it comes to preventing the transmission of STIs.