sexually transmitted infections

The prevalence of sexually transmitted infections is not insignificant; according to data on the website there were over 300,000 STI’s diagnosed in 2021 in England alone.

Globally, the prevalence of male genital tract infection related infertility varies between 10 and 20% and in some larger studies it is as high as 35%.

The impact of infections

Our bodies are very adept at dealing with pathogens whether it be bacterial or viral infections, either way our immune system will jump straight into action.

For particularly strong infections our response may be equally as strong including a fever, malaise, loss of appetite and just generally feeling a bit pants for a few days. Then we will either recover naturally or may need a course of treatment to help us get on top of things. Either way, things usually improve.

With sexually transmitted infections, of course, symptoms may be a little more unpleasant with localised rashes, itching, discharge, pain and more. All in all, not a pleasant experience but also with the risk of direct transmission to your sexual partner.  

It may be the case that you are carrying an infection and are completely oblivious to it. This is known as an asymptomatic or silent infection.

Unfortunately, even an asymptomatic infection could be causing issues, and this is why it is a big problem when trying to conceive. If a pregnant woman becomes infected, this can have negative implications on her pregnancy with the disease potentially being transmitted to the baby.

There are 3 main aspects to consider when thinking about the effects of an infection on fertility. They are:

  1. The increase in oxidative stress
  2. The increase in localised inflammation
  3. The direct interaction of the pathogen with the sperm

A leukocyte and cytokine storm!

One of the key responses to infection is of course the activation of the immune system. When the immune system picks up a pathogen, it produces additional white blood cells (leukocytes) in order to fight off the infection. A further off shoot of this immune response is the production of cytokines, another key player in our bodily defence system.

This raised level of activity by the immune system and the battle that ensues within your body results in the production of additional reactive oxygen species (ROS) which increases oxidative stress. Oxidative stress is a condition where the balance between reactive oxygen species (sometimes referred to as free radicals) and antioxidants (substances that neutralize the free radicals) is shifted towards higher levels of ROS.

Higher levels of oxidative stress are known to be detrimental to our health and are particularly troublesome when it comes to sperm quality as sperm are incredibly vulnerable to ROS. Consequently, spermatogenesis and sperm function are compromised leading to sub- or infertility with raised oxidative stress levels also leading to sperm DNA fragmentation which is linked to IVF failure and recurrent miscarriage.

Long term damage?

The other key player in response to bacterial and viral infections is inflammation. Again, a perfectly normal immune response that can have serious and long-lasting effects.

Any localised infection in the male urogenital tract has the potential to cause serious damage. Male urogenital tract infections can affect the testis (orchitis), epididymis (epididymitis), prostate (prostatitis) or urethra (urethritis). All these areas play a key role in sperm production, storage and / or ejaculation.

Whilst an infection is present, there may be very immediate effects to the physiology in the urogenital tract causing a decline in sperm quality and problems ejaculating. However, the bigger concern is whether any inflammation in this area causes permanent damage to the delicate structures responsible for sperm production, storage and ejaculation leading to chronic sub fertility.

The silent problem

As mentioned above, not all infections will lead to symptoms and many men will go undiagnosed. Infection screening is not a routine part of a male fertility assessment and often will not be considered until a couple is further down the line of trying to conceive. It is not uncommon for a man to be carrying a low-level infection that is completely asymptomatic but may still have an impact on his sperm quality. Chronic or inadequately treated infections seem to be more relevant to infertility than acute infections most likely because they remain undetected or do not get treated properly. Whereas with a raging STI you are far more likely to see a physician and get the correct treatment sooner.  

Giving the gift of an STI

The other issue that comes with asymptomatic infections is that they can easily be passed between partners. Hence, although we are talking about the impact on male fertility, this subject is just as relevant for women, too. If you are having unprotected sex, which of course you will be, it is highly likely that any current infections will be passed between the two of you. A fact that must also be considered in reverse when the woman has a silent genital tract infection which she can transmit to her male partner.

Any previous infections from previous relationship should not be discounted either. For the exact reason that infections can lurk undetected, it is always worth getting checked. You may have been aware of a previous infection and in fact had it treated, nonetheless, it could still be lingering and causing problems.

Get checked, get treated

Ideally, we would like to see all men (and couples for that matter) being offered an infection screen as part of a standard fertility assessment. Unfortunately, this is not happening.

Therefore, it is important that a man takes control of his fertility and looks to get these things checked. In an ideal world, both he and his partner should look to get fully checked for any infections before trying to conceive. The fact that you could be passing infections between you completely unaware means it is well worth getting checked early.

Much as going to your GP or sexual health clinic may allow you to get some of the relevant tests done. It may be worth booking an appointment with a Urologist / Andrologist so that you can get a proper comprehensive screening carried out on your urine and semen. It is usually then advisable to also get your partner checked (and possibly treated) just to be sure that you are both in the clear.

If you come back with an infection, then you will be put on the appropriate course of treatment depending on the type and location of the infection. It may be that both you and your partner will need treatment and it is imperative that you complete the full course of treatment before a likely re-test.

If after the course of treatment, there are still issues, a Urologist / Andrologist may want to run further checks.


Semen culture and the assessment of genitourinary tract infections: Solomon M, Henkel R (2017); Semen culture and the assessment of genitourinary tract infections. Indian J Urol 33: 188-193

Infection in infertility: Henkel R (2020); Infection in Infertility. In: Parekattil SJ, Esteves SC, Agarwal A (eds.) Male Infertility: Contemporary Clinical Approaches, Andrology, ART and Antioxidants, 2nd Edition, Springer Nature, Cham, Switzerland; pp. 409-424

The role of infections and leukocytes in male infertility : Henkel R, Offor U, Fisher D (2020); The role of infections and leukocytes in male infertility. Andrologia. 2020 Jul 21;e13743. doi: 10.1111/and.13743. Online ahead of print.

Long-term consequences of sexually transmitted infections on men’s sexual function: A systematic review : Henkel R (2021); Long-term consequences of sexually transmitted infections on men’s sexual function: A systematic review. Arab J Urol 19: 411-418