Research and analysis

Spotlight on sexually transmitted infections in the South East: 2025 data

Updated 8 October 2026

Applies to England

Summary

Trends in STI diagnoses

This report presents data on sexually transmitted infection (STI) diagnoses among South East residents. It includes new data from 2025, with historical trends going back to 2016. Any data from 2020 and 2021 should be interpreted with caution, because the COVID-19 pandemic affected both sexual behaviour and STI testing rates.

Of all the UK Health Security Agency (UKHSA)’s regions, the South East has the third lowest rate of new STI diagnoses in England. However, STIs remain an important public health issue in the South East.

In 2025, 38,320 new STIs were diagnosed in the South East, a rate of 410 diagnoses per 100,000. Rates across upper tier local authorities ranged from 240 per 100,000 on the Isle of Wight to 1,001 per 100,000 in Brighton and Hove.

The number of STI diagnoses in the South East decreased (-6%) between 2024 and 2025. Decreases were seen in 4 of the 5 main STIs: syphilis (-11%), gonorrhoea (-4%), chlamydia (-9%), and genital warts (-9%). Genital herpes diagnoses increased by +5%.

UKHSA recommends that local areas should be working towards a chlamydia detection rate of at least 3,250 per 100,000 women and girls aged 15 to 24 years, as a measure of screening effectiveness. This detection rate is an indicator in the Public Health Outcomes Framework. The South East did not achieve this target in 2025, with 1,082 detections per 100,000 (down from 1,287 per 100,000 in 2024).

Health inequalities

Rates of STI diagnoses differ between men and women (435 and 356 per 100,000, respectively). Gay and bisexual men are one of the groups disproportionately impacted by STIs. Where gender and sexual orientation were known, 19% of the South East STI diagnoses in 2025 were among gay and bisexual men. The proportions were higher for syphilis (66%) and gonorrhoea (57%).

STIs also disproportionately affect young people. People aged between 15 and 24 years accounted for 38% of the South East STI diagnoses in 2025. A steep decline has been seen in genital warts diagnoses in young people aged 15 to 19 following the 2008 introduction of HPV (human papillomavirus) vaccination for girls and the 2019 extension to boys. Between 2016 and 2025, there was a 97% decrease in diagnoses in females in this age group and a 95% decrease in males.

The White ethnic group had the highest number of STI diagnoses in 2025: 24,702 (76% of all diagnoses). Although only 2% of diagnoses were among the Black Caribbean ethnic group, this group had the highest rate: 1,604 per 100,000 (5.2 times the rate in the White ethnic group). Where country of birth was known, 76% of the South East population diagnosed with an STI in 2025 were UK born. The rate of STI diagnoses among people who live in the most deprived areas of South East (635 per 100,000) was more than double that in the least deprived areas (289 per 100,000), although more deprived areas tend to have higher proportions of young people, who also have higher STI rates.

Prevention messages

The key preventions messages are:

• sexual health clinics are free, confidential and available to everyone. They provide testing, post-exposure prophylaxis and treatment for STIs and HIV, as well as vaccination and contraception
• using condoms consistently and correctly with new or casual partners protects against HIV and other STIs
• testing is recommended if you have had sex without a condom with a new or casual partner in the last 3 months, or if a partner has tested positive for an STI. In addition:
  • women and other people with a womb aged under 25 who are sexually active should have a chlamydia test after sex with a new partner or annually
  • gay and bisexual men with new or casual partners should test for HIV and STIs annually or every 3 months if having sex without condoms with new or casual partners
• prevention medications (known as pre- and post-exposure prophylaxis) can prevent HIV and some STIs:
  • doxycycline post-exposure prophylaxis (doxyPEP) is recommended to people at risk of syphilis to reduce their chance of infection – doxyPEP is available at specialist sexual health clinics
  • HIV pre-exposure prophylaxis (PrEP) reduces an individual’s risk of getting HIV – PrEP is available from specialist sexual health clinics
  • HIV post-exposure prophylaxis (PEP) can be taken after sex to reduce the risk of getting HIV – PEP is available for free from most sexual health clinics and most emergency departments
• vaccination can prevent some STIs and blood-borne viruses:
  • gay and bisexual men can get the hepatitis A and hepatitis B vaccines from specialist sexual health clinics – these vaccines are also available for other people with a higher risk of exposure to these viruses
  • gay and bisexual men aged 45 years and younger can get the human papillomavirus (HPV) vaccine from specialist sexual health clinics – this protects against genital warts and some forms of cancer
  • gay and bisexual men who have recently had multiple sexual partners or an STI and other people at higher risk are eligible for a meningococcal B disease vaccine (4CMenB) which can protect against gonorrhoea
  • mpox vaccination is available for people at increased risk, including gay and bisexual men who have recently had multiple sexual partners
  • hepatitis B and HPV vaccines are also part of the routine childhood vaccination program – catch-up vaccines are available for people who missed them at school

STIs in South East

Overview

Figure 1. New STI diagnosis rates by UKHSA region of residence, England, 2025

Data sources: GUMCAD, CTAD, ONS Census 2021 mid-year estimates.

Figure 1 is a column chart which shows the rate of new diagnoses of STIs by region for 2025. This rate is per 100,000 residents and is not adjusted.

For 2025, the rate of new STI diagnoses in the South East was 410 per 100,000 residents. The rate of new STI diagnoses in the South East was the seventh highest by region and was broadly in line with rates observed in most other regions. The rate of new STI diagnoses was considerably higher in London than in other regions.

Figure 2. Number of diagnoses of the 5 main STIs (South East, 2016 to 2025): A) all 5 STIs; B) excluding chlamydia (expanded scale)

Data sources: GUMCAD, CTAD.

It is important to consider whether there have been any changes to testing practices when interpreting increases or decreases in chlamydia.

Figure 2A is a line chart which shows the trend in the number of new diagnoses of the 5 main STIs between 2016 and 2025. Figure 2B is similar but excludes chlamydia so that the trends for the 4 other STIs can be seen more clearly.

Figure 2A shows that the most commonly diagnosed STI in residents in the South East is chlamydia, with 17,043 diagnoses in 2025. The second most commonly diagnosed STI in 2025 in the South East was gonorrhoea (5,702), followed by genital herpes (4,094) and genital warts (3,317). The least commonly diagnosed STI of the 5 main STIs in 2025 was syphilis (837).

Since 2016, there has been a reduction in the number of new diagnoses of chlamydia, genital herpes and genital warts in South East residents. During this time period, there has been an increase in the number of diagnoses of gonorrhoea and syphilis. While the number of chlamydia diagnoses has increased overall between 2016 and 2025, it has declined in recent years, with a reduction in numbers between 2023 and 2025.

Furthermore, despite the overall reduction in the number of genital herpes diagnoses between 2019 and 2025, there has been an increase in the number of diagnoses over the period since 2020, following the reduction in numbers during the COVID-19 pandemic.

Table 1. Percentage change in new STI diagnoses, South East

Diagnosis	2019	2024	2025	Percentage change 2019 to 2025	Percentage change 2024 to 2025
Chlamydia	28,939	18,688	17,043	-41%	-9%
Genital herpes	4,675	3,891	4,094	-12%	+5%
Genital warts	7,621	3,657	3,317	-56%	-9%
Gonorrhoea	6,549	5,957	5,702	-13%	-4%
Syphilis	834	938	837	<0.5% change	-11%
Other	8,962	7,605	7,327	-18%	-4%
All new STIs	57,580	40,736	38,320	-33%	-6%

Data sources: GUMCAD, CTAD.

See notes for Figure 2. See New STIS section for a list of diagnoses that are included in the other STIs.

Table 1 shows the percentage change in the number of new diagnoses of STIs between both 2019 and 2024, and 2025 in South East residents.

The total number of new STI diagnoses declined by 33% between 2019 and 2025, and by 6% between 2024 and 2025. The proportional decline in the number of new diagnoses of STIs is largely driven by the decline in the number of cases of chlamydia in the South East, which has declined by 41% between 2019 and 2025.

Between 2019 and 2025, 4 of the 5 main STIs declined in terms of new diagnoses in the South East. Genital warts had the highest proportional decline (56%), followed by chlamydia (41%) and ‘all other new STIs’ outside of the 5 main STIs (18%).

From 2024 to 2025, the highest proportional decline in the number of diagnoses was in syphilis, which saw an 11% decline in the number of diagnoses in South East residents. The only STI which saw a proportional increase in the number of new diagnoses in the South East was genital herpes (+5%).

Figure 3. Rates of new STIs per 100,000 by age group (for those aged 15 to 64 years only) and gender, South East, 2025

Data sources: GUMCAD, CTAD, ONS Census 2021 mid-year estimates.

Figure 3 is a pyramid chart which shows the rate of diagnosis of new STIs by age group and gender in 2025. Rates are per 100,000 population in each age group for each gender and for residents in the South East aged 15 to 64.

In the youngest age groups (15 to 19 and 20 to 24) in the South East, rates of new STI diagnoses were higher in females. This largely reflects higher chlamydia diagnoses, which are in part due to targeted screening of young females by the National Chlamydia Screening Programme (1). In older age groups (25 to 34, 35 to 44 and 45 to 64), new STI diagnosis rates were higher among males.

Figure 4. Rates of new STIs per 100,000 by ethnic group, South East, 2025

Data sources: GUMCAD, CTAD, ONS Census 2021.

Figure 4 is a column chart which shows the rate of new STIs among South East residents by ethnic group in 2025. This chart shows rates and therefore takes into account the underlying size of the population for each ethnic group.

Ethnic group is not a proxy for country or world region of birth, it is a complex concept and is self-identified and reported within the limitations of the available options provided. It may incorporate cultural, religious and linguistic differences as well as differences in physical attributes and world region of origin. People may identify their ethnic group differently in different contexts or over time.

Rates are calculated regardless of age, but age distributions differ across ethnic groups. For example, the White ethnic group has the oldest age distribution, which will depress its rate, as numbers of STI diagnoses are lower in the oldest age groups. Other important determinants, such as deprivation and issues of stigma, also vary by ethnic group. Charts and tables by ethnic group should always be interpreted in the wider context of determinants and never in isolation.

This chart shows that, in 2025, the highest rate of new STI diagnoses was in people who reported their ethnicity as Black Caribbean (1,604 per 100,000), followed by Black African (1,333 per 100,000). The lowest rates of new STI diagnoses were in people who reported their ethnicity as White (308 per 100,000) followed by Asian or Asian British (316 per 100,000).

Table 2. Percentage of new STI diagnoses by ethnic group, South East, 2025

Ethnic group	Number	Percentage (excluding unknown)
Asian or Asian British	2,056	6%
Black African	2,006	6%
Black Caribbean	698	2%
All other Black ethnic groups combined	279	1%
Mixed or Multiple ethnic groups	2,023	6%
White	24,702	76%
Other ethnic groups	747	2%
Unknown	5,809

Data sources: GUMCAD, CTAD and ONS Census 2021.

Table 2 provides a breakdown of the percentage of new STIs by ethnic group. This table displays crude numbers as opposed to rates, which are seen in Figure 4.

In 2025, the highest number of new STI diagnoses was in people who reported their ethnicity as White (24,702), making up 76% of the total number in the South East. This highlights how the differences in the underlying size of the population have a high impact on the rates seen in Figure 4, as the total number of new STIs are considerably higher in the White ethnic group than all other groups combined. A significant proportion of the new STI diagnoses were made in people whose ethnicity is unknown (5,809 diagnoses).

Figure 5. Percentage of new STI diagnoses by world region of birth [note ], South East, 2025

Data source: GUMCAD data only.

Note: data on country of birth is not collected by CTAD. All information about world region of birth is based on diagnoses made in specialist and non-specialist services which report to GUMCAD.

Figure 5 is a column chart which shows the proportion of new STI diagnoses in South East residents by world region of birth in 2025. World region of birth differs from ethnicity, and the separate indicators should not be used as proxies for each other.

In the South East, 76% of the total number of diagnoses of new STIs in 2025 were in people who were born in the UK. The second highest proportion of new STIs were in people who were born in the European Union (EU) (7%).

It should also be noted that migrants are more likely to be of working age population and are therefore more likely to be diagnosed with an STI than older adults.

Figure 6. Rates of new STIs per 100,000 by decile of deprivation [note], South East, 2025

Data sources: GUMCAD, CTAD, ONS Index of Multiple Deprivation and Census 2021 mid-year estimates.

Note: deciles run from 1 to 10 in order of decreasing deprivation, with 1 being the decile for the most deprived area. Deprivation is based on 2021 LSOAs which are available for 96% of GUMCAD data reported in 2025.

Figure 6 is a column chart which shows the new STI diagnosis rate by 100,000 population for each deprivation decile in the South East in 2025. These deciles run from 1 to 10 in descending levels of deprivation, with 1 referring to the people living in the 10% most deprived LSOAs. The Index of Multiple Deprivation (IMD) includes several metrics to provide an overall ranking of deprivation and is not adjusted for differences in the demographics of the underlying population, such as age (2). IMD includes 7 domains: education, employment, housing, health, crime, income and living environment.

This chart shows that the rate of diagnosis of new STIs is highest among the most deprived populations. In the South East population living in the 10% most deprived LSOAs, the new STI diagnosis rate was 635 per 100,000. In comparison, in the 10% least deprived LSOAs, the new STI diagnosis rate was 289 per 100,000. The new STI diagnosis rate was significantly higher for the more deprived areas and lower for the less deprived areas.

Figure 7. Diagnoses of the 5 main STIs among gay and bisexual men [note], South East, 2016 to 2025

Data source: GUMCAD data only.

Note: data on sexual orientation is not collected by CTAD. All information about gay and bisexual men is based on diagnoses made in specialist and non-specialist services which report to GUMCAD and exclude chlamydia diagnoses via online services.

Figure 7 is a line chart which shows the trend in the number of new diagnoses of the 5 main STIs in the South East among gay and bisexual men from 2016 to 2025.

In 2025, gonorrhoea was the most frequently diagnosed STI among gay and bisexual men (3,079 diagnoses), followed by chlamydia (1,623 diagnoses). Of the 5 main STIs, the least frequently diagnosed among gay and bisexual men in the South East was genital warts, with 178 new diagnoses in 2025. Between 2024 and 2025, diagnoses of gonorrhoea and genital herpes increased in gay and bisexual men in the South East. Diagnoses of chlamydia declined during this time period.

Table 3. Percentage change in new STI diagnoses among gay and bisexual men [note], South East

Diagnosis	2019	2024	2025	Percentage change 2019 to 2025	Percentage change 2024 to 2025
Chlamydia	2,348	1,866	1,623	-31%	-13%
Genital herpes	195	228	249	+28%	+9%
Genital warts	417	232	178	-57%	-23%
Gonorrhoea	2,739	3,099	3,079	+12%	-1%
Syphilis	582	657	529	-9%	-19%
Other	1,066	1,031	923	-13%	-10%
All new STIs	7,347	7,113	6,581	-10%	-7%

Data source: GUMCAD data only.

See notes for Figure 7 (including asterisk). See New STIS section for a list of diagnoses that are included in the other STIs.

Table 3 shows the percentage change in the number of new diagnoses of each of the 5 main STIs among gay and bisexual men between 2019 and 2025, and between 2024 and 2025.

Across all new STIs in gay and bisexual men, there has been a 10% decrease between 2019 and 2025. The largest percentage reduction between 2019 and 2025 was in genital warts (57%). There was also a notable reduction (31% decrease) in the chlamydia between 2019 and 2025. During the same time period, there has been an increase in the number of new cases of other STIs, including genital herpes (28% increase) and gonorrhoea (12% increase).

The number of new STIs has also declined between 2024 and 2025. During this period, there was a 7% reduction in the number of all new STIs. There have been notable reductions in several STIs, including genital warts (23% decrease), syphilis (19% decrease), chlamydia (13% decrease) and Other STIs (10% decrease). The only STI that increased between 2024 and 2025 was genital herpes (9% increase). The number of diagnoses of genital herpes is small, and therefore small changes in the crude number of diagnoses has a greater impact on the percentage changes reported.

Figure 8. Diagnoses of the 5 main STIs among heterosexual men and all women [note], South East, 2016 to 2025

Data source: GUMCAD data only.

Note: data on sexual orientation is not collected by CTAD. All information here is based on diagnoses made in specialist and non-specialist services which report to GUMCAD and exclude chlamydia diagnoses via online services. Diagnoses are defined here as GUMCAD records where gender is specified as male and sexual orientation is specified as heterosexual, or gender was specified as female, or gender was not specified but orientation was specified as heterosexual. GUMCAD records where sexual orientation was not specified for males or unknown gender individuals are excluded.

Figure 8 is a line chart which shows the number of new diagnoses of each STI among women and heterosexual men in the South East between 2016 and 2025.

In 2025, the most commonly diagnosed STI in women and heterosexual men in the South East was chlamydia, with 11,815 diagnoses. The second most commonly diagnosed STI in this population was genital herpes (3,736), followed by genital warts (3,022 new diagnoses). This is different to what is seen in gay and bisexual men, where gonorrhoea was the most common STI, and only the fourth most commonly diagnosed STI among heterosexual men and women in the South East.

Table 4. Percentage change in new STI diagnoses among heterosexual men and all women [note], South East

Diagnosis	2019	2024	2025	Percentage change 2019 to 2025	Percentage change 2024 to 2025
Chlamydia	22,531	12,649	11,815	-48%	-7%
Genital herpes	4,444	3,573	3,736	-16%	5%
Genital warts	7,092	3,312	3,022	-57%	-9%
Gonorrhoea	3,467	2,579	2,321	-33%	-10%
Syphilis	205	233	270	32%	16%
Other	7,670	6,323	6,194	-19%	-2%
All new STIs	45,409	28,669	27,358	-40%	-5%

Data source: GUMCAD data only.

See notes for Figure 8 (including asterisk). See New STIS section for a list of diagnoses included in the other STIs.

Table 4 summarises what is shown in Figure 8 and shows the percentage change in the number of new STIs diagnosed in heterosexual men and all women in the South East between 2019 and 2025, and separately between 2024 and 2025.

Between 2019 and 2025, there has been a percentage reduction of 40% in the number of new STIs diagnosed. The number of diagnoses of STIs continued to decline between 2024 and 2025 with a 5% reduction during this period.

From 2019 to 2025, there has been a decline in the number of new diagnoses across many STIs in the South East. Notably, there was a significant reduction in the number of new diagnoses of chlamydia (48% decrease), genital warts (57% decrease), gonorrhoea (33% decrease) and genital herpes (16% decrease). The only STI with an increase during this period was syphilis, which saw a 16% increase between 2019 and 2025. It should be noted that the number of diagnoses of syphilis is small, which means small changes in numbers can appear large proportionally.

Figure 9. Rate of new STI diagnoses per 100,000 by upper tier local authority, South East, 2025

Data sources: GUMCAD, CTAD, ONS Census 2021 mid-year estimates.

Figure 9 is a column chart which shows the breakdown of new diagnoses of STIs in 2025 by local authority of residence in the South East. Local authorities are shown in descending order, with the local authority with the highest rate of new STIs on the left of the chart. Confidence intervals are shown by the yellow brackets on each bar. The rate for the whole of the South East (410 per 100,000) is shown by the dashed orange line. The rate for England is shown by the solid grey line (570 per 100,000).

The highest rate of new STI diagnoses was in Brighton and Hove (1,001 per 100,000), followed by Reading (670 per 100,000) and Portsmouth (626 per 100,000). The significantly higher rate of new STI diagnoses in Brighton may reflect the underlying population demographics of Brighton and Hove. Slough (618 per 100,000) and Southampton (589 per 100,000) also had a higher rate of new STI diagnoses than England (570 per 100,000).

The lowest rate of new STI diagnoses was in the Isle of Wight (240 per 100,000), followed by Wokingham (242 per 100,000) and Hampshire (297 per 100,000).

Figure 10. Rate of new STI diagnoses (excluding chlamydia diagnoses among people aged under 25 years [note]) per 100,000 by upper tier local authority, South East, 2025

Data sources: GUMCAD, CTAD, ONS Census 2021 mid-year estimates.

Note: chlamydia diagnoses in the target group for the National Chlamydia Screening Programme (those aged 15 to 24 years) are excluded as these diagnoses may reflect local implementation of screening.

Figure 10 is a column chart which shows the new STI diagnoses rate by upper tier local authority, excluding new cases of chlamydia made in the under 25 population. The dashed orange line shows the rate for the South East (316 per 100,000) and the solid grey line is the national rate (441 per 100,000).

The rate for the South East (316 per 100,000) in 2025 was lower than the national rate. Similarly to Figure 9, the highest rate of new diagnoses of STIs in this population was in Brighton and Hove (860 per 100,000), followed by Slough (539 per 100,000) and Reading (522 per 100,000). These 3 local authorities had rates of new diagnoses higher than the England rate. The lowest rates of new STI diagnoses were in Wokingham (188 per 100,000), the Isle of Wight (195 per 100,000) and West Berkshire (214 per 100,000).

Figure 11. Map of new STI rates per 100,000 by upper tier local authority, South East, 2025

Data sources: GUMCAD, CTAD, ONS Census 2021 mid-year estimates.

Figure 11 is a map which shows the new STI diagnostic rate for each local authority. Local authorities with higher new STI diagnostic rates are shaded in a darker colour.

This figure provides a visual representation of what is presented in Figure 9. It shows that the highest rate of new STI diagnoses in 2025 was in Brighton. Local authorities which border London, such as Slough and other unitary authorities such as Reading and Portsmouth, also report comparably high rates of new STI diagnoses in comparison to other local authorities in the South East.

Figure 12. Map of new STI rates per 100,000 by middle super output area (MSOA21), South East, 2025

Data sources: GUMCAD, CTAD, ONS Census 2021 mid-year estimates.

Figure 12 is a map of new STIs per 100,000 by middle super output area for 2025.

This map shows a similar picture to Figure 11, and highlights that there are higher rates of new STIs concentrated in cities and towns across the South East. Rates of new STI diagnoses tended to be lower in rural areas across the South East.

Figure 13. STI testing rate (excluding chlamydia in under 25 year olds [note]) per 100,000, South East, 2012 to 2025

Data sources: GUMCAD, CTAD, ONS Census 2021 mid-year estimates.

Note: chlamydia diagnoses in the target group for the National Chlamydia Screening Programme (those aged 15 to 24 years) are excluded as these diagnoses may reflect local implementation of screening.

Figure 13 is a line chart which shows the STI testing rate per 100,000, excluding tests conducted for chlamydia in people aged under 25, from 2012 to 2025. The red line shows the testing rate in the South East, and the blue line shows the testing rate in England (which is particularly affected by the higher testing rate in London).

Testing for chlamydia in people aged under 25 is excluded in this chart, as this population is specifically targeted as part of the National Chlamydia Screening Programme (1). In 2025, the STI testing rate in the South East (3,174 per 100,000) was lower than the STI testing rate seen nationally (4,012 per 100,000).

A high STI testing rate can reflect a higher number of symptomatic individuals accessing tests, but it can also reflect awareness of the need to undertake STI screening and is a good indicator of access to sexual health services. Both nationally and in the South East, STI testing rate dropped in 2020 due to the COVID-19 pandemic. Since 2020, rates have gradually increased year on year in the South East but not yet returned to pre-pandemic levels.

Figure 14. STI testing positivity rate (excluding chlamydia in under 25 year olds [note]), South East, 2012 to 2025

Data sources: GUMCAD, CTAD.

Note: chlamydia diagnoses in the target group for the National Chlamydia Screening Programme (those aged 15 to 24 years) are excluded as these diagnoses may reflect local implementation of screening.

Figure 14 is a line chart which shows the proportion of STI test results which were positive for both England and the South East, from 2012 to 2025. The red line indicates the positivity rate for the South East and the blue line England. In 2025 STI positivity for the South East was 5%. This means that 5% of the total STI tests performed for residents in the South East were positive for an STI. This is lower than the positivity rate nationally, which was at 6% in 2025. Both nationally and in the South East, the positivity rate has been declining year on year since 2022 after a prolonged rise since 2012.

Table 5. Number of diagnoses of new STIs by UKHSA region of residence, data source and Sexual Health Service Type, 2025

UKHSA region of residence	GUMCAD: specialist SHSs	GUMCAD: non-specialist SHSs [note]	CTAD	Total
East Midlands	13,724 (61%)	4,076 (18%)	4,711 (21%)	22,511
East of England	17,420 (68%)	2,042 (8%)	6,139 (24%)	25,601
London	79,241 (72%)	10,529 (10%)	19,826 (18%)	109,596
North East	9,111 (70%)	1,703 (13%)	2,264 (17%)	13,078
North West	31,340 (77%)	4,738 (12%)	4,816 (12%)	40,894
South East	28,757 (75%)	1,649 (4%)	7,914 (21%)	38,320
South West	14,333 (64%)	3,777 (17%)	4,360 (19%)	22,470
West Midlands	20,450 (74%)	4,133 (15%)	2,877 (10%)	27,460
Yorkshire and Humber	18,720 (72%)	1,636 (6%)	5,467 (21%)	25,823

Data sources: GUMCAD, CTAD.

Note: diagnoses from enhanced GPs reporting to GUMCAD are included in the ‘Non-specialist sexual health services (SHSs)’ total.

Table 5 is a summary of the number of new STI diagnoses for each UKHSA region of residence in 2025 broken down by the reporting surveillance system. In addition, GUMCAD data is broken down by the location in which the test was performed ie, whether this was a specialist or a non-specialist sexual health service. CTAD provides data on chlamydia testing only.

The majority of new diagnoses of STIs in the South East were made in specialist sexual health services (75%), this is higher than in most other regions. Only 4% of the total number of new STIs diagnosed in the South East were made in non-specialist sexual health services. The remainder of the positive STI diagnoses were reported through the CTAD system, which is responsible for collating the number of new chlamydia diagnoses made through online testing.

Table 6. Number of diagnoses of the 5 main STIs by STI, data source and Sexual Health Service type, South East, 2025

STI	GUMCAD: specialist SHSs	GUMCAD: non-specialist SHSs [note]	CTAD	Total
Chlamydia	8,894 (52%)	235 (1%)	7,914 (46%)	17,043
Genital herpes	4,074 (100%)	20 (<1%)	-	4,094
Genital warts	3,300 (99%)	17 (1%)	-	3,317
Gonorrhoea	4,547 (80%)	1,155 (20%)	-	5,702
Syphilis	835 (100%)	2 (<1%)	-	837

Data sources: GUMCAD, CTAD.

Note: diagnoses from enhanced GPs reporting to GUMCAD are included in the ‘Non-specialist sexual health services (SHSs)’ total.

Table 6 provides a summary of the number of diagnoses of the main STIs in the South East for 2025 broken down by the reporting surveillance system.

The majority of diagnoses of genital herpes (100%), genital warts (99%), gonorrhoea (80%) and syphilis (100%) are reported by specialist sexual health services. For chlamydia, the availability of testing through a variety of settings including online postal means that a higher proportion of diagnoses are made outside of sexual health services, with 52% of new diagnoses of chlamydia made through testing at specialist sexual health services.

Figure 15. Consultations by service medium, South East, 2016 to 2025

Data sources: GUMCAD, NHS Fingertips.

Figure 15 is a column chart which shows the number of consultations each year in the South East from 2016 to 2025, broken down by the medium of consultation.

In 2025, the majority of consultations in the South East were made face-to-face (324,352), followed by consultations conducted online (221,607). The fewest number of consultations were made via telephone (28,552). The number of consultations that were conducted face-to-face has declined from over 410,000 in 2017 to approximately 325,000 in 2025. This is likely due to the rise in the number of online consultations, with an increase from 10,000 in 2017 to 220,000 in 2025. This highlights the changing ways in which people in the South East are accessing sexual health services and implies that the availability of digital services has widened access as the total number of consultations has increased significantly.

Figure 16. All consultations by age group, South East, 2016 to 2025

Data sources: GUMCAD, NHS Fingertips.

Figure 16 is a line chart which shows the rate of consultations per 100,000 in each year from 2016 to 2025, broken down by age group.

In 2025, the highest rate of consultations in the South East was in people aged 20 to 24 (7,502 per 100,000) followed by people aged 25 to 34 (5,686 per 100,000) and people aged 15 to 19 (3,146 per 100,000). The lowest rates of consultations were in the older age groups: people aged 45 to 64 (1,191 per 100,000) and people aged 35 to 44 (3,090 per 100,000).

Between 2023 and 2025, the rate of consultations declined in the younger populations, aged 15 to 19, 20 to 24 and 25 to 34. During the same time period, there was an increase in the rate of consultations in the older age groups (35 to 44 and 45 to 64).

Chlamydia

Figure 17. Number of chlamydia diagnoses, South East, 2016 to 2025

Data sources: GUMCAD, CTAD.

It is important to consider whether there have been any changes to testing practices when interpreting increases or decreases in chlamydia.

Figure 17 is a line chart which shows the number of new chlamydia diagnoses in South East residents between 2016 and 2025.

Chlamydia, caused by the bacteria Chlamydia trachomatis, is the most commonly diagnosed STI in England (1). Chlamydia can often be present without symptoms, which can contribute to transmission. Long-term complications of untreated chlamydia can include chronic pelvic inflammatory disease in females and issues with fertility. The National Chlamydia Screening Programme promotes screening for chlamydia to ensure that it is detected and treated. The focus of this screening program is females aged under 25, to reflect the fact that this group of the population is most at risk of long-term complications of untreated chlamydia.

There were 17,043 diagnoses of chlamydia in South East residents in 2025. This graph shows that diagnoses of chlamydia declined significantly in 2020 and 2021 as a result of the COVID-19 pandemic. Diagnoses subsequently started to increase again in 2022, but since 2023, there has been a year-on-year decline in the number of diagnoses of chlamydia.

Figure 18. Rates of chlamydia per 100,000 by age group (for those aged 15 to 64 years only), South East, 2016 to 2025

Data sources: GUMCAD, CTAD, ONS Census 2021 mid-year estimates.

Figure 18 is a line chart which shows the differences in the rate of chlamydia diagnoses in South East residents between 2016 and 2025, with each line representing a different age group.

In 2025, the highest rate of chlamydia diagnoses in the South East was in people aged between 20 and 24 years of age (1,159 per 100,000). This was followed by people aged 15 to 19 (549 per 100,000), and people aged 25 to 34 (427 per 100,000). The lowest rate of new chlamydia diagnoses was in people aged 45 to 64 (50 per 100,000). In younger age groups, the rate of new diagnoses of chlamydia has fallen since 2023.

Figure 19. Rates of chlamydia per 100,000 by age group (for those aged 15 to 64 years only) and gender, South East, 2025

Data sources: GUMCAD, CTAD, ONS Census 2021 mid-year estimates.

Figure 19 is a pyramid chart which shows the rate of new chlamydia diagnoses by age group and gender. This graph does not include people aged 65 and over, or people younger than 15.

In the younger populations, the graph is skewed towards the right. This indicates that among 15 to 19 year olds and 20 to 24 year olds, the rate of new diagnoses of chlamydia is higher among females. This is a result of the National Chlamydia Screening Programme (1), which concentrates efforts on improving chlamydia screening of females aged 15 to 24 due to the impact that undiagnosed asymptomatic chlamydia infections can have in females.

Among people aged 35 to 44 and 45 to 64, the graph is skewed to the left indicating that there is a higher rate of new chlamydia diagnoses in males in these age groups.

Figure 20. Chlamydia detection rate per 100,000, females aged 15 to 24 years by upper tier local authority of residence, South East, 2025

Data sources: GUMCAD, CTAD, ONS Census 2021 mid-year estimates.

Figure 20 is a column chart which shows the rate of new chlamydia detection in females aged between 15 and 24 broken down by upper tier local authority for 2025. The dashed orange line is the rate for the South East (1,082 per 100,000), and the solid grey line is the rate for England (1,348 per 100,000).

UKHSA recommends that local areas should be working towards achieving a chlamydia detection rate no lower than 3,250 per 100,000 female population aged 15 to 24 years. The detection rate is a measure of chlamydia control activity, aimed at reducing the incidence of reproductive sequelae of chlamydia infection and interrupting transmission. An increased detection rate is indicative of increased control activity; it is not a measure of morbidity. The chlamydia detection rate is an indicator in the Public Health Outcomes Framework.

With the exception of Portsmouth, the chlamydia detection rate in 2025 for the whole of the South East was lower than the national rate and in all areas considerably lower than the target. For 2025, the highest rates of chlamydia detection were in Portsmouth (1,593 per 100,000) and Kent (1,296 per 100,000). The lowest rates of chlamydia detection were in Wokingham (668 per 100,000), Windsor and Maidenhead (673 per 100,000), and the Isle of Wight (723 per 100,000).

  Gonorrhoea

Figure 21. Number of gonorrhoea diagnoses, South East, 2016 to 2025

Data source: GUMCAD.

Figure 21 is a line chart which shows the number of gonorrhoea diagnoses in the South East between 2016 and 2025.

Gonorrhoea is a sexually transmitted infection, caused by the bacterium Neisseria gonorrhoeae (3). It is often transmitted through unprotected sex and is not always associated with symptoms but can lead to issues with fertility and, in females, chronic pelvic inflammatory disease (3, 4).

There were 5,702 new diagnoses of gonorrhoea in the South East in 2025. Cases of gonorrhoea in the South East peaked in 2023, following the fall during the COVID-19 pandemic, but have since declined year on year.

Figure 22. Rates of gonorrhoea per 100,000 by age group (for those aged 15 to 64 years only), South East, 2016 to 2025

Data sources: GUMCAD, ONS Census 2021 mid-year estimates.

Figure 22 is a line chart which shows the rate of new gonorrhoea diagnoses in each year between 2016 and 2025, broken down by age group.

In 2025, the highest rate of gonorrhoea diagnoses was in people aged 20 to 24 (225 per 100,000), followed by people aged 25 to 34 (161 per 100,000). The lowest rates of gonorrhoea diagnoses in 2025 were in 45 to 64 year olds (41 per 100,000), 15 to 19 year olds (84 per 100,000) and 35 to 44 year olds (96 per 100,000). The rate of gonorrhoea diagnoses has declined between 2023 and 2025 in the younger age groups while in older age groups it has plateaued.

Figure 23. Rates of gonorrhoea per 100,000 by age group (for those aged 15 to 64 years only) and gender, South East, 2025

Data sources: GUMCAD, ONS Census 2021 mid-year estimates.

Figure 23 is a pyramid chart which shows the rate of new gonorrhoea diagnoses per 100,000, broken down by age group and gender.

In most age groups, the chart is skewed towards the left. This indicates that among these age groups, the rate of gonorrhoea diagnoses is higher among males. The exception is the youngest age group (15 to 19) where rates of diagnoses were higher in the female population.

Figure 24. Rate of gonorrhoea diagnoses per 100,000 by upper tier local authority, South East, 2025

Data sources: GUMCAD, ONS Census 2021 mid-year estimates.

Figure 24 is a column chart which shows the rate of gonorrhoea diagnoses per 100,000 in each upper tier local authority in the South East in 2025. The dashed orange line shows the rate across the South East, while the solid grey line represents the rate across England.

In 2025, the rate of gonorrhoea diagnoses in England (109 per 100,000) was higher than the rate in the South East (61 per 100,000). The rate was significantly higher in Brighton and Hove (228 per 100,000) than in the other South East local authorities and is an outlier. Reading (115 per 100,000) and Southampton (111 per 100,000) also had higher rates of gonorrhoea diagnoses than the national average. The lowest rates of gonorrhoea diagnoses were in the Isle of Wight (21 per 100,000), Hampshire (36 per 100,000) and West Berkshire (38 per 100,000).

Genital warts

Figure 25. Number of genital warts diagnoses, South East, 2016 to 2025

Data source: GUMCAD.

Figure 25 is a line chart which shows the number of genital warts diagnoses in the South East between 2016 and 2025. Genital warts are an STI and typically appear as small painless lumps, often around the anus, penis or vagina (5). They are caused by a virus, the Human Papillomavirus (HPV). Some specific HPV serotypes are also responsible for causing cervical cancer (5, 6).

There were 3,317 diagnoses of genital warts in the South East in 2025. Diagnoses of genital warts saw a large decline in 2020 during the COVID-19 pandemic, and this has been sustained since then, with diagnoses continuing to fall. This is likely a result of the HPV vaccination programme, which was extended to boys in 2019, and helps to protect against genital warts (6).

Figure 26. Rates of genital warts per 100,000 by age group (for those aged 15 to 64 years only), South East, 2016 to 2025

Data sources: GUMCAD, ONS Census 2021 mid-year estimates.

Figure 26 is a line chart which shows the differences in the rate of diagnoses of genital warts per 100,000 by age group in South East residents.

In 2025, the highest rate of genital warts diagnoses was in people aged between 25 and 34 (119 per 100,000). This marks a change from the trend prior to 2022 and is likely explained by the continued effect of the introduction of HPV vaccination (6), which will have affected younger age groups first (7, 8) The second highest rate of genital warts diagnoses was in people aged 20 to 24 (78 per 100,000), followed by people aged 35 to 44.

From 2020, the rates of genital warts diagnosed in older age groups has largely stayed relatively similar.

Figure 27. Rates of genital warts per 100,000 aged 15 to 19 and 20 to 24 years by gender, South East, 2016 to 2025

Data sources: GUMCAD, ONS Census 2021 mid-year estimates.

Figure 27 is a line chart which shows the changes in the rate of diagnoses of genital warts per 100,000 in younger cohorts. Trends are broken down into male and female and also by age, into 15 to 19 year olds and 20 to 24 year olds.

This chart demonstrates the impact of the HPV vaccination programme on the rate of new genital warts in the younger population. Since the introduction of the HPV programme for boys in 2019 (6), there has been a rapid and sustained decrease in the rate of genital warts diagnoses in both males and females aged 15 to 19 and aged 20 to 24 years old. Diagnosis rates in 2020 and 2021 will also have been affected by the COVID-19 pandemic

Figure 28. Rates of genital warts per 100,000 by age group (for those aged 15 to 64 years only) and gender, South East, 2025

Data sources: GUMCAD, ONs Census 2021 mid-year estimates.

Figure 28 is a pyramid chart which shows the rates of genital warts per 100,000 by age group, for those aged between 15 and 64.

This chart shows that for people across each age group between 20 and 64, the graph is skewed to the left. This signifies that the rate of new diagnoses of genital warts is higher in males in these age groups. The only exception to this is in people aged 15 to 19, where the rate of new diagnoses of genital warts is higher among females.

Syphilis

Figure 29. Number of syphilis diagnoses, South East, 2016 to 2025

Data source: GUMCAD.

Figure 29 is a line chart which shows the number of syphilis diagnoses in South East residents between 2016 and 2025.

Syphilis is an STI which is caused by the bacterium Treponema pallidum and is treatable with antibiotics (9). The presentation of syphilis often follows a standard pattern, with distinct stages known as primary, secondary and tertiary syphilis. Primary syphilis is typically characterised by a small ulcer or sore, which typically does not cause any pain. Secondary syphilis is a more advanced stage and corresponds with the sore disappearing, followed by symptoms such as tiredness, swollen glands and a rash appearing, often on the palms of the hands, which is not itchy. Following this, symptoms can resolve for some time. Some people who are infected with syphilis will later go on to develop serious symptoms, which may affect different organs in the body, and this is known as tertiary syphilis.

In 2025, there were 837 diagnoses of syphilis in South East residents. This was a decline in the number of diagnoses since 2024 following an upward trend since 2016.

Figure 30. Rates of syphilis per 100,000 by age group (for those aged 15 to 64 years only), South East, 2016 to 2025

Data sources: GUMCAD, ONS Census 2021 mid-year estimates.

Figure 30 is a line chart which shows the rate of syphilis diagnoses per 100,000 each year between 2016 and 2025, and this is broken down by age group.

In 2025, the highest rate of diagnoses of syphilis in the South East was in people aged between 25 and 34 (22 per 100,000), followed by people aged 35 to 44 (16 per 100,000) and people aged 20 to 24 (15 per 100,000). The lowest rate of diagnoses of syphilis was in people aged 45 to 64 (11 per 100,000) and people aged 15 to 19 (4 per 100,000). In most age groups, rates have remained relatively constant over recent years. The exception was the 25 to 34 age group which had the highest rate and a significant rise between 2016 and 2024.

Figure 31. Rates of syphilis per 100,000 by age group (for those aged 15 to 64 years only) and gender, South East, 2025

Data sources: GUMCAD, ONS Census 2021 mid-year estimates.

Figure 31 is a pyramid chart which shows the rate of syphilis diagnoses for 2025 broken down by age group and gender.

Across each age group for the population aged 20 to 64, the chart is skewed towards the left. This reveals that the rate of diagnoses of syphilis is significantly higher in males than in females. The exception to this is in people aged 15 to 19, where the rate of diagnoses of syphilis was higher in females in the South East in 2025. Nationally, rates of syphilis are highest in gay and bisexual men (10).

Genital herpes

Figure 32. Number of genital herpes diagnoses, South East, 2016 to 2025

Data source: GUMCAD.

Figure 32 is a line chart which shows the number of diagnoses of genital herpes made in South East residents between 2016 and 2025.

Genital herpes is a sexually transmitted infection which causes genital sores. It is caused by the herpes simplex virus, namely HSV-1 and HSV-2 (11, 12) HSV-1 primarily causes cold sores but can also cause genital infections, caught via oral sex. HSV-2 is almost exclusively associated with genital infection.

Since a decline in the number of diagnoses of genital herpes in the South East in 2020, diagnoses have increased year on year. Diagnoses of genital herpes continued to increase between 2024 and 2025. In 2025, there were 4,094 diagnoses of genital herpes in the South East.

Figure 33. Rates of genital herpes per 100,000 by age group (for those aged 15 to 64 years only), South East, 2016 to 2025

Data sources: GUMCAD, ONS Census 2021 mid-year estimates.

Figure 33 is a line chart which shows the trend in the rate of genital herpes diagnoses between 2016 and 2025. This is broken down by age group.

In the South East in 2025, the highest rate of diagnoses of genital herpes was in people aged 20 to 24 (179 per 100,000), followed by people aged 25 to 34 (118 per 100,000), people aged 15 to 19 (67 per 100,000) and people aged 35 to 44 (58 per 100,000). The lowest rate of diagnoses of genital herpes was in people aged between 45 to 64 (27 per 100,000). In older age groups, the rate of diagnoses of genital herpes has increased marginally each year since 2020, whereas in the 2 youngest groups it has fallen since 2022.

Figure 34. Rates of genital herpes per 100,000 by age group (for those aged 15 to 64 years only) and gender, South East, 2025

Data sources: GUMCAD, ONS Census 2021 mid-year estimates.

Figure 34 is a pyramid chart which shows the rate of diagnoses of genital herpes for 2025 broken down by age group and gender.

Across all age groups, the chart is skewed towards the right, highlighting that in each age group between 15 and 64, the rate of diagnoses of genital herpes was higher in females than in males. The highest rate of diagnoses of genital herpes was in females aged 20 to 24, followed by females aged 25 to 34.

Information on data sources

Find more information on local sexual health data sources in the UKHSA guide.

The gender and age group chart is restricted to those aged 15 to 64 years as information about STIs in those aged under 15 years is considered highly sensitive. Analyses specific to this group are not provided in routine outputs. Rates for those aged 65 or older are withheld to ensure that no deductive disclosure is possible for the under 15 years age group. The proportion of STIs in those aged under 15 years or older than 64 years is very low.

GUMCAD surveillance system

This disaggregate reporting system collects information about attendances and diagnoses at specialist (Level 3) and non-specialist (Level 2) sexual health services. Information about the patient’s area of residence is collected along with demographic data and other variables. GUMCAD superseded the earlier KC60 system and can provide data from 2009 onwards. GUMCAD is the main source of data for this report.

Due to limits on how much personally identifiable information sexual health clinics are able to share, it is not possible to deduplicate between different clinics. There is a possibility that some patients may be counted more than once if they are diagnosed with the same infection (for infection specific analyses) or a new STI of any type (for new STI analyses) at different clinics during the same calendar year.

CTAD surveillance system

CTAD collects data on all local authority and NHS or NHS-commissioned chlamydia testing carried out in England. CTAD is comprised of all chlamydia (NAATs) tests for all ages (with the exception of conjunctival samples), from all venues and for all reasons. CTAD enables unified, comprehensive reporting of all chlamydia data, to effectively monitor the impact of the NCSP through estimation of the coverage of population screening, proportion of all tests that are positive and detection rates.

For services which report to GUMCAD and for which CTAD does not receive data on the patient’s area of residence (for example, SHSs), information about chlamydia diagnoses is sourced from GUMCAD data.

CTAD does not collect information about sexual orientation or country of birth. Reports from CTAD are excluded from figures in this report which relate to analyses by sexual orientation or world region of birth.

New STIs

New STI diagnoses comprise diagnoses of the following:

• chancroid
• Lymphogranuloma venereum (LGV)
• donovanosis
• chlamydia
• gonorrhoea
• genital herpes (first episode)
• HIV (acute and AIDS defining)
• Molluscum contagiosum
• non-specific genital infection (NSGI)
• non-specific pelvic inflammatory disease (PID) and epididymitis
• chlamydial PID and epididymitis (presented in chlamydia total)
• gonococcal PID and epididymitis (presented in gonorrhoea total)
• scabies
• pediculosis pubis
• syphilis (primary, secondary and early latent)
• trichomoniasis and genital warts (first episode)
• Mycoplasma genitalium
• shigella

Calculations

Confidence Intervals were calculated using Byar’s method for numerators >= 10. For small numerators Byar’s method is less accurate and so an exact method based on the Poisson distribution is used.

ONS mid-year population estimates for 2024 were used as a denominator for rates (other than by ethnic group) for 2025. ONS estimates of population by ethnic group for the year 2021 were used as a denominator for rates by ethnic group for 2025. This is the first time that new estimates of population by ethnic group have been available since 2011. This must be considered if comparing rates for 2025 in this report with rates by 2024 in last year’s report, as the rates in the last report used the 2011 estimates.

Interpreting trends

When interpreting trends in the number of STI diagnoses it is important to consider the potential impact of changes to testing, vaccination programmes and the availability of interventions (such as prophylaxis). Specifically, diagnostic testing for gonorrhoea and genital herpes now includes in some areas highly sensitive testing using nucleic acid amplification tests. Additionally, there is some screening of gay and bisexual men at extra-genital sites. Where in place, both will have led to increased case ascertainment of gonorrhoea and genital herpes. Local testing practices for all STIs may vary.

Further information

As of 2020, all analyses for this report include data from non-specialist (Level 2) SHSs and enhanced GP services as well as specialist (Level 3) SHSs.

For further information, see the online Sexual and Reproductive Health Profiles.

For more information on HIV data, see the separate HIV Spotlight report.

For more information on local sexual health data sources, see the UKHSA guide.

Local authorities have access to The Summary Profile of Local Authority Sexual Health (SPLASH) Reports (accessible from the Sexual and Reproductive Health Profiles) and the SPLASH supplement reports via the HIV and STI Data exchange.

About the Field Services

The Field Services was established in 2018 as a national service comprising geographically dispersed multi-disciplinary teams integrating expertise in Field Epidemiology, Real-time Syndromic Surveillance and Public Health Microbiology to strengthen the surveillance, intelligence and response functions of UKHSA.

You can contact your local FS team at FES.SEaL@ukhsa.gov.uk

Acknowledgements

We would like to thank the following:

• local SHSs for supplying the SHS data
• local laboratories for supplying the CTAD data
• UKHSA Blood Safety, Hepatitis, Sexually Transmitted Infections (STI) and HIV Division for collection, analysis and distribution of data

References

1. UK Health Security Agency. NCSP: programme overview (accessed 17 August 2026)

2. Ministry of Housing, Communities and Local Government. ‘English indices of deprivation 2025: statistical release’ (accessed 17 August  2026)

3. UKHSA. Gonorrhoea: guidance, data and analysis (accessed 17 August 2026)

4. NHS. Conditions A to Z. Gonorrhoea (accessed 17 August 2026)

5. NHS. Conditions A to Z. Genital warts (accessed 17 August 2026)

6. UKHSA. HPV vaccination programme (accessed 17 August 2026)

7. UKHSA. ‘Ten years on since the start of the HPV vaccine programme – what impact is it having?’ (accessed 17 August 2026)

8. UKHSA. ‘What is HPV and how effective is the vaccine that protects against it?’ (accessed 17 August 2026)

9. WHO. Syphilis (accessed 17 August 2026)

10. UKHSA. ‘What is syphilis? A quick guide to its symptoms and treatment’ (accessed 17 August 2026)

11. UKHSA. ‘How do you catch genital herpes and is there a cure?’ (accessed 17 August 2026)

12. WHO. Herpes simplex virus (accessed 17 August 2026)