Global control of sexually transmitted infections

Summary

Sexually transmitted infections other than HIV are important global health issues. They have, however, been neglected as a public-health priority and control efforts continue to fail. Sexually transmitted infections, by their nature, affect individuals, who are part of partnerships and larger sexual networks, and in turn populations. We propose a framework of individual, partnership, and population levels for examining the effects of sexually transmitted infections and interventions to control them. At the individual level we have a range of effective diagnostic tests, treatments, and vaccines. These options are unavailable or inaccessible in many resource-poor settings, where syndromic management remains the core intervention for individual case management. At the partnership level, partner notification and antenatal syphilis screening have the potential to prevent infection and re-infection. Interventions delivered to whole populations, or groups in whom the risks of infection and onward transmission are very high, have the greatest potential effect. Improvements to the infrastructure of treatment services can reduce the incidence of syphilis and gonorrhoea or urethritis. Strong evidence for the effectiveness of most other interventions on population-level outcomes is, however, scarce. Effective action requires a multifaceted approach including better basic epidemiological and surveillance data, high quality evidence about effectiveness of individual interventions and programmes, better methods to get effective interventions onto the policy agenda, and better advocacy and more commitment to get them implemented properly. We must not allow stigma, prejudice, and moral opposition to obstruct the goals of infectious disease control.

Introduction

“…nice people don't talk about syphilis, nice people don't have syphilis, and nice people shouldn't do anything about those who do have syphilis.”¹

This 1937 analysis of the barriers to syphilis control in the USA by Thomas Parran, a former Surgeon General, helps us to understand why the control of this and other sexually transmitted infections continues to fail worldwide. The responses of governments and societies to sexually transmitted infections often seem to be affected more by moral judgments and social attitudes towards sexual behaviour than the degree of death, disease, and distress caused by the medical conditions. Cultural meanings and prejudices become attached to infected people, who become stigmatised as being wicked, dirty, and not deserving of care,² even though sexually transmitted infections are often acquired through consensual, pleasurable, and legal sexual intercourse.

For HIV infection, governments have been convinced to invest in HIV programmes mainly by macroeconomic arguments about the negative effect of poor health on economic growth.³ Combating HIV infection is now one of the Millennium Development Goals (MDGs) and international commitment is guaranteed. Even so, some world leaders would not allow a UN declaration to openly specify that men who have sex with men, sex workers, and injecting drug users needed specific interventions.⁴ All other sexually transmitted infections, which were high on the international policy agenda in the 1990s,⁵ now receive little attention, and are not named in the MDGs. Although diagnosis and treatment of sexually transmitted infections are now officially recognised as a low cost, neglected intervention by the Disease Control Priorities Project, they are considered only as a means of reducing the risk of HIV transmission.⁶

Sexual and reproductive tract infections other than HIV are important global health priorities in their own right,⁷ but their impact is often unrecognised. Human papillomaviruses (HPV) cause almost all cervical cancers but the 3·3 million disability adjusted life years (DALYs) that they cause are included in estimates of mortality and morbidity due to cancer rather than sexually transmitted infection.⁸ Syphilis, responsible for 4·2 million DALYs, can be fatal, and infection in pregnant women causes stillbirth, prematurity, and congenital syphilis. Effective screening programmes could prevent up to 492 000 stillbirths and perinatal deaths every year,⁹ with a cost per DALY that is lower than prevention of a case of perinatal HIV infection.9, 10 Chlamydia and gonorrhoea (7 million DALYs) cause tubal infertility and, potentially fatal, ectopic pregnancy. Vaginal discharge prompts women to seek frequent care, which is expensive, often ineffective, and sometimes harmful.¹¹ Candida and bacterial vaginosis, which are the most common reproductive tract infections in women, and cause distressing symptoms that are frequently misdiagnosed as sexually transmitted infections, are not included in the burden of disease calculations.¹² Women are disproportionately physically affected by all these infections. Transmission rates from men to women are higher than from women to men, in part because of the exposure of columnar epithelium.¹³ Signs of infection in women, however, can remain hidden until it is too late to reverse the damage. Furthermore, women are more vulnerable to infection because of gender-based power inequalities.¹⁴ Women who manage to overcome these barriers and get diagnosed with a sexually transmitted infection might then be blamed for being the reservoir of infection and face judgment, stigma, and possibly violence from their partners.¹³

We need to renew our commitment to controlling all sexually transmitted infections. Parran,¹ in his call for dispassionate public-health action to replace “moral prophylaxis” in the control of syphilis, proposed a thoroughly modern agenda. This action included location, reporting, and treatment of all cases and contacts, ensuring that there were enough money, drugs, and doctors to provide the service; education of the public, and demanding that public-health agencies and private physicians used “scientific methods”.¹ In today's words, we should take an evidence-based public-health approach to treatment and prevention. This approach should also include sustainable implementation of preventive policies and effective integration of sexual and reproductive health services, in addition to the traditional focus on case management of the individual.¹⁵

We focus on strategies for the control of sexually transmitted infections other than HIV. There is, however, an important biological interaction between HIV and other sexually transmitted infections that affects control strategies.¹⁶ Sexually transmitted infections, especially those that cause genital ulceration, increase the risk of acquisition and transmittal of HIV infection, and the treatment of sexually transmitted infections reduces the shedding of HIV in genital secretions and plasma.17, 18 Therefore, we also discuss interventions in which control of sexually transmitted infection is used to prevent HIV infection. We present our key messages in panel 1.