Sexually transmitted

Evidence brief

More than 1 million sexually transmitted infections occur every day.

Key facts `` More than 1 million sexually transmitted infections (STIs) occur every day. `` An estimated 376 million , gonorrhoea, and infections occur each year. `` More than 500 million people have genital with a (HSV1 or HSV2). `` Approximately 300 million women have a human papillomavirus (HPV) infection and this- number is likely similar in men. `` The majority of STIs occur without symptoms. `` Some STIs can increase the risk of HIV acquisition three-fold or more. `` STIs can have serious consequences beyond the immediate infection itself, through mother- to-child of infections or conditions such as infertility and cervical . `` Drug resistance for gonorrhoea is a major threat to controlling this STI worldwide.

What are sexually transmitted include , urethral discharge in men, infections and how are they genital ulcers, and . transmitted? Eight of the more than 30 known to be transmitted through sexual contact have been linked to STIs are caused by more than 30 different , the greatest incidence of illness. Of these eight infec- and parasites and are spread predominantly by tions, four are currently curable: syphilis, gonorrhoea, sexual contact, including vaginal, anal and oral . chlamydia and trichomoniasis. The other four are viral Many STIs – including chlamydia, gonorrhoea, infections and are incurable, but can be mitigated or B, HIV, HPV, HSV2 and syphilis – can also be modulated through treatment: , herpes, HIV, transmitted from mother to child during and HPV. and . The organisms causing STIs can also be spread through non-sexual means such as Scope of the problem products and tissue transfer. STIs have a profound impact on sexual and A person can have an STI without having obvious worldwide. More than 1 million symptoms of disease. Therefore, the term “sexually sexually transmitted infections occur every day. Each transmitted infection” is a broader term than “sexually year, an estimated 376 million infections occur with one transmitted disease” (STD). Common symptoms of STIs of four curable STIs: chlamydia, gonorrhoea, syphilis and trichomoniasis. More than 500 million people are living with infection. Approximately 300 million women have HPV infection and numbers among men are likely as high.

Estimated new cases of curable sexually transmitted infections (gonorrhoea, chlamydia, syphilis and trichomoniasis) by WHO region, 2016

STIs can have serious consequences beyond the as well as against unintended . These immediate impact of the infection itself. include: •• Some STIs such as HSV2 can increase the risk of HIV •• comprehensive sexuality education, STI and HIV acquisition three-fold or more. pre- and post-test counselling; •• Mother-to-child transmission of STIs can result •• safer sex/risk-reduction counselling, in stillbirth, neonatal death, low birth weight promotion; and and prematurity, sepsis, pneumonia, infant eye •• interventions targeted at key and vulnerable infections, and birth defects. Syphilis in pregnancy populations, such as adolescents, sex workers, men leads to approximately 200 000 fetal and neonatal who have sex with men and people who inject deaths every year and leaves over 150 000 infants drugs. at increased risk of dying from prematurity, low birth weight or congenital disease. In addition, counselling can improve people’s ability to recognize the symptoms of STIs and increase •• HPV infection causes 570 000 cases of cervical the likelihood they will seek care or encourage a cancer and over 300 000 deaths sexual partner to do so. Unfortunately, lack of public each year. awareness, lack of training of health workers, and •• STIs such as gonorrhoea and chlamydia are major long-standing, widespread stigma around STIs remain causes of pelvic inflammatory disease, adverse barriers to greater and more effective use of these pregnancy outcomes and infertility. interventions. Barrier methods Prevention of STIs When used correctly and consistently, offer Counselling and behavioural approaches one of the most effective methods of protection Counselling and behavioural interventions offer against STIs, including HIV. Female condoms are primary prevention against STIs (including HIV), effective and safe but are not used as widely by national programmes as male condoms. Diagnosis of STIs resistant organism. resistance for other STIs, though less common, also exists, making Accurate diagnostic tests for STIs are widely used in prevention and prompt treatment critical. high-income countries. These are especially useful for the diagnosis of asymptomatic infections. However, STI case management in low- and middle-income countries, diagnostic tests Low- and middle-income countries rely on syndromic are largely unavailable. Where testing is available, it is management, which is based on the identification of often expensive and geographically inaccessible; and consistent groups of symptoms and easily recognized patients often need to wait a long time (or need to signs (syndromes) to guide treatment, without the return) to receive results. As a result, follow up can be use of laboratory tests. This approach, which often impeded and care or treatment can be incomplete. relies on clinical algorithms, allows health workers to Both an inexpensive rapid dual HIV/syphilis diagnose a specific infection on the basis of observed and single rapid test for syphilis are currently available. syndromes. These tests are already in use in some resource-limited Syndromic management is simple, assures rapid, settings. These tests are accurate, can provide results same-day treatment, and avoids expensive or in 15 to 20 minutes, and are easy to use with minimal unavailable diagnostic tests. However, incorrect training. Rapid syphilis tests have been shown to diagnoses occur and this approach misses infections increase the number of pregnant women tested for that do not demonstrate any symptoms or syndromes syphilis. However, increased efforts are still needed in - the majority of STIs globally. most low- and middle-income countries to ensure that all pregnant women receive a syphilis test. and other biomedical Several rapid tests for other STIs are under interventions development and have the potential to improve STI diagnosis and treatment, especially in resource-limited Safe and highly effective vaccines are available for settings. two STIs: human papillomavirus (HPV) and hepatitis B. These vaccines represent major advances in STI prevention. Treatment of STIs Eighty-five countries, mostly high- and middle- Effective treatment is currently available for several income, include HPV vaccination as part of their STIs. routine immunization programmes. HPV vaccination •• Three bacterial STIs (chlamydia, gonorrhoea and could prevent the deaths of more than 4 million syphilis) and one parasitic STI (trichomoniasis) are women over the next decade in low- and middle- generally curable with existing, effective single- income countries, where most cases of cervical cancer dose regimens of . occur, if 80% vaccination coverage can be achieved. •• For herpes and HIV, the most effective The against hepatitis B is included in infant available are antivirals that can modulate the immunization programmes for more than 95% of course of the disease, though they cannot cure the countries and global coverage for the 3 dose infant infection. HBV vaccine is currently 84% (unchanged between •• For hepatitis B, modulators and 2015 and 2017) with global targets of 90% vaccine antiviral medications (tenofovir) can help to fight coverage and 90% reduction in incidence by 2030. the virus and slow damage to the . Research to develop vaccines against herpes and HIV Resistance of gonorrhoea – to antibiotics has have advanced with several vaccine candidates in increased rapidly in recent years and has reduced clinical studies. Research into vaccines for chlamydia, treatment options. The emergence of decreased gonorrhoea, syphilis and trichomoniasis are at earlier susceptibility of gonorrhoea to the “last line” treatment stages of development. option (oral and injectable cephalosporins) together Other biomedical interventions to prevent some STIs with already shown to include adult male circumcision and microbicides. penicillins, sulphonamides, tetracyclines, quinolones •• Male circumcision reduces the risk of and macrolides make gonorrhoea a multidrug- heterosexually acquired HIV infection in men by approximately 60% and provides some protection WHO response against other STIs, such as herpes and HPV. WHO develops global norms and standards for STI •• Vaginal microbicides have the potential to allow treatment and prevention, strengthens systems for women to actively avert HIV acquisition. surveillance and monitoring, including those for drug- resistant gonorrhoea, and leads the setting of the global research agenda on STIs. Current efforts to contain the spread Our work is guided by the Sustainable Development of STIs are not sufficient Goals, the Global Health Sector Strategy on STIs adopted by the World Health Assembly in 2016 and Behaviour change is complex the 2015 United Nations Secretary-General’s Global Despite considerable efforts to identify simple Strategy for Women’s Children’s and Adolescents’ interventions that can reduce risky sexual behaviour, Health, which highlights the need for a comprehensive, behaviour change remains a complex challenge. integrated package of essential interventions, including Research has demonstrated the need to focus on information and services for the prevention of HIV and carefully defined populations, consult extensively with other sexually transmitted infections the identified target populations, and involve them in WHO works with countries to: design, implementation and evaluation. •• Scale-up effective STI services including: Health services for screening and treatment of STIs –– STI case management and counseling; remain weak –– syphilis testing and treatment, in particular for People seeking screening and treatment for STIs face pregnant women; numerous problems. These include limited resources, stigmatization, poor quality of services, and little or no –– HPV and hepatitis B vaccination. follow-up of sexual partners. •• Promote strategies to enhance STI-prevention •• In many countries, STI services are provided impact including: separately and are not available in primary health –– integrate STI services into existing health care, antenatal care, family planning and other systems; routine health services. –– promote sexual health; •• In many settings, services are often unable to provide screening for asymptomatic infections and –– measure the burden of STIs; lack trained personnel, laboratory capacity and –– monitor and respond to STI antimicrobial adequate supplies of appropriate antibiotics for the resistance. treatment of STIs, e.g. benzathine penicillin for the treatment of syphilis. •• Support the development of new technologies for STI prevention such as: •• Marginalized populations with the highest rates of STIs – such as sex workers, men who have sex –– point-of care diagnostic tests for STIs; with men, people who inject drugs, prison inmates, –– additional drugs for gonorrhoea and syphilis. mobile populations and adolescents – often do not –– STI vaccines and other biomedical interventions. have access to adequate health services.

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