Chlamydia diagnoses in England (thousands/year)
Overview
Bacterial sexually transmitted infections, principally Chlamydia trachomatis and Neisseria gonorrhoeae, are among the most preventable causes of male infertility globally. Both trigger localised inflammation in the epididymis and vas deferens — often completely silently — that can cause permanent scarring, partial or complete obstruction, and an oxidative environment hostile to sperm quality and DNA integrity. Critically, chlamydia infects sperm directly, impairing motility and increasing DNA fragmentation even when the overall sperm count remains normal on standard analysis. Post-COVID sperm impairment has emerged as a clinically significant concern, with multiple 2023–2025 studies documenting orchitis, elevated DNA fragmentation, and reduced count persisting for months after acute infection in a subset of men.
How It Affects Fertility
- Epididymal scarring from untreated chlamydia causing partial or complete ductal obstruction
- Direct chlamydial infection of sperm impairing motility and increasing DNA fragmentation
- Orchitis from viral infection (including SARS-CoV-2) causing direct testicular inflammation
- Oxidative environment from chronic genital infection damaging developing sperm
Symptoms to Watch For
- Chlamydia and many STIs are entirely asymptomatic in men — damage occurs invisibly
- Epididymal tenderness, swelling, or discomfort if epididymitis develops
- Scrotal pain or fever during acute orchitis
- Post-COVID: temporary or persistent changes in semen parameters
What You Can Do
- 1 Get tested for chlamydia and gonorrhoea annually if sexually active with multiple partners — most infections are asymptomatic in men
- 2 Treat promptly — early antibiotic treatment of chlamydia prevents the epididymal scarring responsible for long-term fertility damage
- 3 If you had COVID-19 and are experiencing fertility concerns, request a semen analysis — post-viral sperm impairment is real and worth quantifying
- 4 Use consistent barrier contraception to reduce STI transmission risk when not in a long-term monogamous relationship
- 5 Consider sperm banking before any treatment for serious infection that may involve testicular involvement
This content is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before making health decisions.