16.1 STI Epidemiology, Prevention, Services, Sexual History, HIV Testing, ART & PrEP/PEP
Key Takeaways
- Chlamydia is the most frequently reported bacterial STI in the EU/EEA, and reported gonorrhoea and syphilis have risen markedly over the past decade, especially among men who have sex with men.
- A fourth-generation HIV antigen/antibody test detects most infections by about 4 weeks, and a negative result 6 weeks after the last exposure is widely used to exclude infection.
- European (EACS) guidance recommends antiretroviral therapy for everyone with HIV as soon as possible, regardless of CD4 count, and a sustained undetectable viral load prevents sexual transmission (U=U).
- Event-driven HIV PrEP with tenofovir disoproxil/emtricitabine (two tablets 2 to 24 hours before sex, then one at 24 and 48 hours) is recommended only for men who have sex with men.
- HIV post-exposure prophylaxis should start as soon as possible and within 72 hours of exposure, and it consists of a 28-day course of three antiretroviral drugs.
16.1 STI Epidemiology, Prevention, Services, Sexual History, HIV Testing, ART & PrEP/PEP
The official venereology syllabus starts with epidemiology of STIs including HIV, prevention and control including partner notification, organisation of STI services, and sexual history-taking and genito-anal examination, and it includes HIV infection and its management. In many continental European countries, venereology is part of dermatology training, so dermatologists run STI clinics.
Epidemiology in the EU/EEA
The European Centre for Disease Prevention and Control (ECDC) collects national surveillance data.
| Infection | Recent European Pattern |
|---|---|
| Chlamydia | The most frequently reported bacterial STI; highest rates in young women and men under 25 |
| Gonorrhoea | Marked rise over the past decade; many cases in men who have sex with men (MSM), with increases in young heterosexuals in some countries; growing antimicrobial resistance |
| Syphilis | Rising, mostly among MSM; congenital syphilis is rare but has increased in some countries |
| Lymphogranuloma venereum | Mostly MSM, often with HIV, presenting as proctitis |
| HIV | Roughly 20,000–25,000 new diagnoses a year across the EU/EEA in recent years, with about half diagnosed late (CD4 count below 350 cells/µL) |
Reporting of syphilis, gonorrhoea, and HIV to national authorities is mandatory in most European countries. Rising rates are linked to changes in sexual behaviour, dating apps, chemsex, lower condom use, and better testing.
Prevention and Control
| Level | Measures |
|---|---|
| Primary (prevent infection) | Sex education; condoms; vaccination against HPV, hepatitis B, and hepatitis A (and mpox for at-risk groups); HIV PrEP; treating people with HIV to an undetectable viral load |
| Secondary (find and treat early) | Screening of at-risk groups; rapid diagnosis and treatment; partner notification; test of cure where recommended |
| Tertiary (limit complications) | Prevent PID, infertility, neurosyphilis, congenital infection, and cancer |
Doxycycline post-exposure prophylaxis (doxy-PEP, 200 mg within 72 hours after condomless sex) reduces syphilis and chlamydia in MSM and transgender women with recurrent STIs. European bodies are cautious because of the risk of resistance in gonorrhoea and other bacteria, and they suggest limited, individual use rather than routine use.
Organisation of STI Services
Good STI care is open access, confidential, often free at the point of use, and ideally one-stop (testing, treatment, partner notification, vaccination, contraception, and PrEP in one place). Models include specialist dermato-venereology and sexual health clinics, express testing for people without symptoms, online and home-sampling services, and outreach to MSM, sex workers, migrants, and people who inject drugs. Services need links to HIV care, gynaecology, urology, paediatrics, and safeguarding teams.
Sexual History
A structured history makes sure the right tests are taken from the right sites:
- Symptoms: discharge, dysuria, ulcers, rash, anal or pharyngeal symptoms, and their duration.
- Last sexual contact and previous partners in the relevant window: gender, regular or casual, and whether they can be contacted.
- Sites and practices: oral, vaginal, and anal (insertive or receptive) sex, and condom use.
- Previous STIs and HIV tests, vaccination status, and PrEP use.
- Contraception and possible pregnancy.
- Risk factors: drug use and chemsex (GHB/GBL, mephedrone, methamphetamine), sex work, travel, partners from high-prevalence areas.
- Safeguarding: age, coercion, sexual exploitation, and intimate partner violence.
Genito-Anal Examination and Sampling
- Explain the examination, obtain consent, and offer a chaperone.
- Examine the skin, mouth, and lymph nodes. In men, retract the foreskin and inspect the urethral meatus, scrotum, and perianal skin. In women, examine the vulva and use a speculum (cervix, vaginal walls), with bimanual examination if PID is suspected. Use proctoscopy after receptive anal sex with symptoms.
| Test | Best Sample |
|---|---|
| Gonorrhoea and chlamydia NAAT | Men: first-void urine; women: vulvovaginal swab (self-taken is acceptable); rectal and pharyngeal swabs according to exposure (routine for MSM) |
| Gonorrhoea culture | Urethral, cervical, rectal, or pharyngeal swab before treatment, for susceptibility testing |
| Herpes simplex virus | PCR swab from an ulcer |
| Syphilis | Serology; PCR or darkfield microscopy of a lesion |
| HIV and hepatitis | Blood: HIV antigen/antibody, hepatitis B (HBsAg, anti-HBc), and hepatitis C antibodies where there is risk |
HIV Testing
- Fourth-generation laboratory tests detect p24 antigen and antibody. They pick up most infections by about 4 weeks, and a negative result 6 weeks after the last exposure is widely used to exclude infection. Rapid point-of-care and self-tests mostly detect antibody only and have a longer window.
- A reactive result is confirmed with a second assay (and viral load). Give results in person with support.
- Offer testing widely. Opt-out testing in STI clinics and antenatal care, and testing whenever an HIV indicator condition is present. European initiatives recommend testing for conditions where undiagnosed HIV prevalence exceeds about 0.1%. Dermatological examples include any STI, herpes zoster (especially multidermatomal or in younger adults), severe or recalcitrant seborrhoeic dermatitis or psoriasis, oral candidiasis, oral hairy leukoplakia, Kaposi sarcoma, hepatitis B or C, a mononucleosis-like illness, lymphoma, and cervical or anal dysplasia.
Principles of Antiretroviral Therapy (ART)
- The European AIDS Clinical Society (EACS) recommends ART for everyone with HIV as soon as possible, regardless of CD4 count. Same-day starts are possible.
- First-line regimens usually combine an integrase inhibitor (dolutegravir or bictegravir) with two nucleoside reverse transcriptase inhibitors (tenofovir with emtricitabine or lamivudine). Dual therapy with dolutegravir and lamivudine suits selected patients. Long-acting injectable cabotegravir with rilpivirine is an option for people who are already suppressed.
- U=U (undetectable = untransmittable): people with a sustained undetectable viral load do not transmit HIV sexually.
- Dermatology-relevant points: abacavir hypersensitivity (screen for HLA-B*57:01 first); rashes with nevirapine and some other drugs; drug interactions with boosters (ritonavir, cobicistat), for example inhaled or injected corticosteroids causing Cushing syndrome, and interactions with azoles, ciclosporin, and some biologics or small molecules; and immune reconstitution inflammatory syndrome after starting ART (herpes zoster, Kaposi sarcoma flares, folliculitis).
HIV Pre-Exposure Prophylaxis (PrEP)
| Aspect | Key Points |
|---|---|
| Who | People at substantial risk: MSM and transgender women with condomless anal sex, partners of people with detectable HIV, and others at high risk |
| Oral daily PrEP | Tenofovir disoproxil/emtricitabine once daily; suitable for all genders |
| Event-driven ("2-1-1") PrEP | Two tablets 2–24 hours before sex, then one at 24 hours and one at 48 hours; only for MSM, and not for people with hepatitis B |
| Long-acting PrEP | Injectable cabotegravir every 2 months is approved in the EU |
| Before starting | Exclude HIV (including acute infection), check kidney function and hepatitis B status |
| Follow-up | HIV and STI testing every 3 months, kidney function, adherence, hepatitis B vaccination |
HIV Post-Exposure Prophylaxis (PEP)
- Start as soon as possible, ideally within hours and no later than 72 hours after exposure.
- A 28-day course of three antiretroviral drugs (for example tenofovir/emtricitabine plus an integrase inhibitor).
- Indications depend on the exposure and the source. For example, PEP is recommended after receptive anal sex with a partner with HIV and a detectable or unknown viral load. It is usually not needed if the source has a confirmed undetectable viral load.
- Test for HIV at baseline and again after the course, and consider hepatitis B vaccination or immunoglobulin and emergency contraception.
A 29-year-old man had condomless receptive anal sex 36 hours ago with a new partner who has just told him he has HIV and is not on treatment. What is the recommended action?
A woman who has sex with men asks about "on-demand" (event-driven) HIV PrEP instead of daily tablets. What is the correct advice?
A man had a possible HIV exposure 2 weeks ago. A fourth-generation HIV antigen/antibody test today is negative. How should this be interpreted?
A 35-year-old man who has sex with men attends an STI clinic without symptoms. He reports receptive and insertive anal sex and oral sex. Which samples should be taken for gonorrhoea and chlamydia NAAT?