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Treatment for sexually transmitted infections has a role in HIV prevention

Care aimed at the right people at the right time can reduce infections

The findings of a WHO/UNAIDS consultation presented at the XVI International AIDS Conference confirm that caring for sexually transmitted infections (STIs) at the right stage of an epidemic and targeting them at key population groups can reduce HIV transmission. The consultation, in mid-July 2006, was held to clarify the importance of treating STIs and the role of STI control programmes and services in HIV prevention. The main conclusion drawn by the experts at the meeting is that prompt and appropriate treatment for STIs reduce individual risk of HIV infection and that high-quality STI programmes are critical for controlling the HIV epidemic in key populations at higher risk of exposure to HIV.

Scientific evidence has been collected over the past two decades reinforcing the role of genital ulcer diseases and other STIs in facilitating the sexual transmission of HIV. In both men and women these STIs boost HIV shedding in the genital tract, which amplifies HIV infectiousness. The presence of STIs also increases susceptibility to HIV by recruiting HIV-susceptible inflammatory cells to the genital tract as well as by disrupting mucosal barriers to infection.

A number of community-based cluster randomized trials have been completed in Africa and give apparently conflicting outcomes on the impact of STI control interventions on the incidence of HIV. However, the trials were conducted in different settings and at different stages of the HIV epidemic and these factors must be taken into account in planning STI interventions.

The consultation concluded that STI treatment interventions have an impact on HIV transmission at the population level, but the effects differ according to the stages of HIV and STI epidemics. In low-level or concentrated HIV epidemics a considerable impact of STI treatment can be expected on HIV incidence at the population level. However, in a generalized epidemic, the population impact of STI treatment on HIV incidence is less but nevertheless important. Priorities must be set to target those pathogens that contribute most to the expansion of the HIV epidemic in specific settings.

"The opportunity is ripe for intensified STI primary prevention interventions working in collaboration with the move to intensify HIV prevention", says Joy Phumaphi, Assistant Director-General for Family and Community Health at WHO. "Primary prevention interventions should include behaviour-change communication, including reduction of the number and concurrency of sexual partners, correct and consistent condom use and delayed sexual debut for young adolescents. It is important", she added, "that any person with or suspecting an infection promptly seeks and has access to good quality STI care.”

Professor King Holmes, member of the WHO Expert Advisory Panel on Sexually Transmitted Infections including HIV, added “Services for STI patients provide access to individuals at high risk of HIV and provide a unique opportunity for prevention of STIs and HIV. In these settings, comprehensive STI services are important, especially prompt and correct treatment of STIs, safer-sex counselling, condom promotion, counselling and routine offer of testing for HIV, counseling about possible “acute” HIV infection, and partner notification and treatment."

"Optimizing STI control for people living with HIV (PLHIV) is a key part of "prevention for positives", " says Dr Tim Farley, Coordinator of the Sexually Transmitted and Reproductive Tract Infections team. "Among PLHIV, the natural history of HIV may be affected by the presence of other STIs such as HSV-2 which can increase the plasma HIV concentration. Thus, prompt and correct STI management can improve survival for PLHIV. "

"The link between STIs and the sexual spread of HIV is clear. If we are to achieve universal access to HIV/AIDS prevention, treatment and care we must invest in the expansion and quality of STI prevention and control services as an essential component of a comprehensive HIV response," said Teguest Guerma, Associate Director, Department of HIV/AIDS at WHO. "In its five-year HIV/AIDS plan for scaling up towards universal access, WHO includes STI prevention and control as a priority intervention, including integrating HIV and STI services, testing and counselling of STI patients and STI control in the prevention of people living with HIV/AIDS."

For more information contact:

In Toronto:
Tim Farley
Coordinator, Control of Sexually Transmitted Infections
Department of Reproductive Health and Research, WHO
Mobile phone: +41 79 254 68 32
E-mail: farleyt@who.int

In Geneva:
Christopher Powell
Communications Adviser
Family and Community Health, WHO
Telephone: +41 22 7912888
Mobile phone: +41 79217 3425
E-mail: powellc@who.int

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