PrEP services could enhance STI control, says World Health Organization

Jason Ong presenting at IAS 2019. Photo by Roger Pebody.

The roll-out of pre-exposure prophylaxis (PrEP) provides an opportunity to bring down the incidence of sexually transmitted infections (STIs), provided that PrEP and STI programmes are better co-ordinated and integrated, representatives from the World Health Organization (WHO) said yesterday at the 10th International AIDS Society Conference on HIV Science (IAS 2019) in Mexico City.

While much of the debate and research on the relationship between PrEP and STIs has focused on gay men in high-income countries, the greatest gains in STI control could be achieved in low- and middle-income countries, the conference was told.

The high rates of STIs in people using PrEP should spur policy makers, healthcare providers and activists to create better services, speakers suggested. As people who could benefit from PrEP most are also likely to be at increased risk of STIs, PrEP can be an entry point to comprehensive sexual and reproductive health services, including STI screening and treatment. Equally, clinics testing and treating STIs should offer PrEP to those who would benefit.


middle income countries

The World Bank classifies countries according to their income: low, lower-middle, upper-middle and high. There are around 50 lower-middle income countries (mostly in Africa and Asia) and around 60 upper-middle income countries (in Africa, Eastern Europe, Asia, Latin America and the Caribbean).

point-of-care test

A test in which all stages, including reading the result, can be conducted in a doctor’s office or a community setting, without specialised laboratory equipment. Sometimes also described as a rapid test.


A sexually transmitted infection caused by the bacterium Treponema pallidum. Transmission can occur by direct contact with a syphilis sore during vaginal, anal, or oral sex. Sores may be found around the penis, vagina, or anus, or in the rectum, on the lips, or in the mouth, but syphilis is often asymptomatic. It can spread from an infected mother to her unborn baby.


Chlamydia is a common sexually transmitted infection, caused by bacteria called Chlamydia trachomatis. Women can get chlamydia in the cervix, rectum, or throat. Men can get chlamydia in the urethra (inside the penis), rectum, or throat. Chlamydia is treated with antibiotics.

low income countries

The World Bank classifies countries according to their income: low, lower-middle, upper-middle and high. While the majority of the approximately 30 countries that are ranked as low income are in sub-Saharan Africa, many African countries including Kenya, Nigeria, South Africa and Zambia are in the middle-income brackets. 

Dr Jason Ong of Monash University conducted a systematic review for WHO on STI incidence and prevalence in PrEP programmes, with 88 studies.

STI prevalence was already high in people seeking PrEP, with 24% having chlamydia, gonorrhoea and/or early syphilis at baseline. Prevalence was comparable in low- and middle-income countries (a third of the studies) and in high-income countries. It was only a little lower in studies involving populations other than men who have sex with men (MSM) (a third of the studies) than in studies exclusively involving MSM.

And incidence was extremely high while people were on PrEP: for chlamydia, compared to a global average incidence of around 3%, it was 21% in PrEP users.

WHO has outlined a series of interventions needed to address STIs within PrEP programmes. Some can already be delivered: condoms and lubricant supplies, partner notification services, and culturally sensitive services for specific communities.

STI diagnostics and treatment already exist, but WHO says that policy and funding changes are needed. In many lower- and middle-income countries, STI services rely on ‘syndromic management’ – in other words, people who present with symptoms are offered presumptive treatment without any testing being done. This can result in inappropriate or unnecessary treatment being offered, but most of all leads to massive under-treatment of STIs.

Dr Sinéad Delany-Moretlwe of the Wits Reproductive Health and HIV Institute said that syndromic management served young women particularly poorly. Many vaginal infections are asymptomatic or cause mild symptoms that adolescents may not recognise as being due to an STI.

Services rely on syndromic management because diagnostic assays – both nucleic acid amplification tests (NAATs) performed in laboratories and point-of-care tests – are prohibitively expensive. What’s more, many point-of-care tests perform poorly, missing up to half of infections. WHO say advocacy and policy work is needed to drive down prices and to develop more accurate point-of-care tests as well as assays that can detect multiple infections.

Other future interventions needed for improved STI services but which may need policy work to come into being are the development of new STI vaccines (in addition to HPV and hepatitis B) and monitoring of antimicrobial resistance (such as gonorrhoea which does not respond to first- or second-line antibiotics).

“PrEP programmes can be a gateway for empowering comprehensive sexual health services,” said Jason Ong. PrEP is attracting people with behaviours that put them at high risk for STIs, so providing screening and treatment is a priority.

However, provision is highly varied. It ranges from the ‘Rolls Royce’ of 56 Dean Street in London where point-of-care testing for STIs is integrated with PrEP provision; to several middle- and high-income countries in which the only STI test offered by PrEP services is the syphilis blood test; and to some PrEP services in Thailand which refer clients to another clinic for STI management. Rectal and throat samples are often not tested.

The low priority that governments and donors have put on STIs, as well as the separate funding streams, make it harder to develop high quality, integrated services. Dr Rachel Baggaley of WHO said that advocacy was needed to push the issue up the agenda. “We need community to demand better STI services,” she said.


Ong J et al. STIs incidence and prevalence in PrEP programmes – highlights from a systematic review. 10th International AIDS Society Conference on HIV Science (IAS 2019), Mexico City, session SUSA07, 2019.

View the session details on the conference website.

World Health Organization Prevention and control of sexually transmitted infections (STIs) in the era of oral pre-exposure prophylaxis (PrEP) for HIV. 2019.

Update: Following the conference presentation, this research was published in a peer-reviewed journal:

Ong J et al. Global epidemiologic characteristics of sexually transmitted infections among individuals using preexposure prophylaxis for the prevention of HIV infection - a systematic review and meta-analysis. JAMA Network Open, 2: e1917134, 2019.