STI Measures

Knowledge of the epidemiology of STIs in the UK is largely based on cases reported by genito-urinary medicine (GUM) to the Health Protection Agency (HPA). Diagnoses have been increasing over the last decade. However, routine surveillance gives only part of the picture of STI epidemiology. It does not measure the true extent of STIs in the population or the prevalence of asymptomatic infections and only limited socio-demographic and behavioural information is collected.

We have collected urine samples from a proportion of Natsal-3 respondents. These samples will be tested for five infections that may be transmitted sexually: Chlamydia trachomatis, Neisseria gonorrhoeae, mycoplasma genitalium, human papillomavirus and HIV. We have collected urine samples from around 5,000 men and women aged 16-44 years and remaining urine is being stored for future testing.

Analysis of these samples will allow us to:

  • measure the population prevalence of these five STIs
  • identify demographic and behavioural factors and clinical symptoms associated with each infection

Testing of urine samples in Natsal-2 for Chlamydia trachomatis informed the strategy of the National Chlamydia Screening Programme, which initially focussed on women aged 16-25 years, but was then extended to include young men.