Sexually transmitted infections (STIs) and blood borne viruses (BBVs)

STIs and BBV share sexual, blood borne and vertical transmission routes and are strongly associated with HIV infection.  Because of shared routes of transmission, it makes sense to include HIV testing whenever testing for STI, and when testing for BBVs (hepatitis B & C), to also include HIV.  In opt-out settings (in universal testing, such as ED opt-out, as well as targeted opt-out in prisons and Alcohol and Drug Recovery Services (ADRS)), testing for HIV, hepatitis B and hepatitis C in all cases is recommended.  

If testing is not done simultaneously, STI and BBV diagnoses are strongly associated with undiagnosed HIV. In conjunction with this project, NHS inform now advises those diagnosed with gonorrhoea, syphilis and anogenital warts that they should be tested for HIV. 

Note that this toolkit does not recommend systemic approaches to HIV testing for everyone diagnosed with chlamydia. NHS Inform does not recommend to people diagnosed with chlamydia that they are routinely tested for HIV. This is because: 

• Chlamydia is an endemic infection in sexually active young people and is not strongly associated with particular risk behaviours or other STI or BBV. The evidence for chlamydial infection as an IC is relatively weak – the evidence for association is stronger in men than for women but this is compounded by the inclusion of gay, bisexual and other men-who-have-sex-with-men (GBMSM), who have much higher rates of both HIV and chlamydial infection than heterosexual men or women.
• The international approach to chlamydial infection is changing, with a reduction and withdrawal of screening programmes in some countries, and a recognition of the lack of evidence of benefit of widespread testing and treatment of asymptomatic chlamydial infection in both men and women.  
• Management of chlamydial infection has been simplified and protocolised in Scotland, with remote testing and treatment using electronic vouchers in some areas. Implementation of HIV testing for all positive cases would involve significant resource for a relatively low probability of identifying undiagnosed HIV. 
• Working to ensure that, wherever possible, STI testing at the point of offer includes syphilis and HIV tests, is a more efficient system-wide option.  

• Review STI testing offer across sexual health and other services to ensure that HIV testing is routinely included.
• Where test offer does not include HIV (for example gonorrhoea (GC)/ Chlamydia trachomatis (Ct) postal or express testing services), implement routine HIV testing in those diagnosed with STI.
• Ensure that laboratory test sets routinely include HIV and syphilis along with Ct and Neisseria gonorrhoea (NG)
• Prompt HIV testing when GC and Ct ordered in isolation.
• Include HIV testing in local pathways, treatment guidelines and guidance on management of STI.
• Audit and report on HIV testing rates by GC/Ct test and HIV testing rates per Hepatitis B and C test (work is underway nationally to report on these parameters as part of a programme management approach) 

Prompts will depend on whether it is possible to stratify according to whether an HIV test was included with the original test, and/or testing has occurred in the last year, the patient has already been recorded as living with HIV or the patient is taking HIV PrEP. Final recommended wording of laboratory prompts is in development; example: 

• Gonorrhoea is an Indicator Condition for HIV. This patient should be tested for HIV. 

In the HIDES 2 study¹², Hepatitis B and C co-infection was associated with a 10% prevalence of undiagnosed HIV, the highest rate observed in any condition in the study. In HIDES 115, STIs (pooled) were associated with a prevalence of HIV infection of 4.1% overall. STIs were not included in HIDES 2.  In the HeLP study³, syphilis, gonorrhoea infection, chlamydia in men and anogenital warts were all independently associated with a high prevalence of infection and this persisted in a stringent sensitivity analysis which included only HIV diagnoses made after the STI diagnosis (ie correcting for the possibility of higher rates of STI in people living with HIV and excluding those cases where HIV was diagnosed concurrently with one or more STI – see below). Chlamydial infection in women, herpes simplex and trichomoniasis were associated with HIV, but at a much lower prevalence. Notably, the prevalence of HIV in STI diagnosed in men is much higher than in women, and in the case of chlamydial infection and herpes simplex, the lower 95% CI for HIV prevalence in women falls below the threshold of 0.1%. The extent to which chlamydia (and other STI) diagnoses in GBMSM (who have a significantly higher prevalence and incidence of HIV as a population than heterosexual men) affect the data in men is unknown because the study did not collect data on partner gender or sexual orientation, but it seems likely to be significant. It could therefore be argued that chlamydial infection is an indicator condition for HIV in cis males but not females and the associations in Trans and non-binary people have not been explored. The association between HIV in diagnosis in the year after an STI diagnosis is also seen in an UK General Practice based case-control study², so is not confined to those attending sexual health services. 

Table: HIV Prevalence/incidence in the HeLP study³ 

STI prevalence/incidence in multiple sensitivity analyses as summarised below. Noting that in the case of STI, analysis IV is likely to significantly underestimate the prevalence of HIV in each STI; due to the routine nature of testing for HIV as part of STI testing, particularly in specialist sexual health clinics, HIV is commonly diagnosed concurrently with one or more other STIs -these diagnoses would be excluded in analysis IV.  

Table: Overview of sensitivity analyses used in the HeLP Study³ 

For chlamydial infection, the lower 95% confidence interval for HIV prevalence/incidence was significantly below the 0.1% threshold for females in the primary analysis (Males: sample no 1855; 7.06% (5.88–8.25), Females: sample no 4165; 0.1 % (0.02–0.19)).   See reference for further detail.

Information on Indicator Conditions is included in pages on NHS Inform: HIV

• Hepatitis B 
• Hepatitis C 
• Sexually transmitted infections including gonorrhoea and syphilis

Example text: Hepatitis B is a health condition that occurs more often in people living with HIV. If you have been diagnosed with hepatitis B, you should be offered an HIV test. If you have been diagnosed with hepatitis B but you haven’t been offered an HIV test, you can: 

• speak to your healthcare provider about getting tested for HIV 
• get a free test using one of these options 

Testing for HIV when you have hepatitis B can help with early diagnosis, treatment and preventing passing it on.