The link between HIV infection and other sexually transmitted diseases (STDs) has now been clearly established. The Centers for Disease Control and Prevention (CDC) is applying new research to prevent all of the major STDs, including HIV infection, and to ensure that communities have the information they need to design, implement, and evaluate comprehensive approaches to HIV/STD prevention programming.
In addition, researchers have long recognized that the behaviors which place individuals at risk for other STDs also increase their risk of becoming infected with HIV. STD surveillance can provide important indications of where HIV infection may spread, and where efforts to promote safer sexual behaviors should be targeted.
a)Increased susceptibility -- Other STDs increase the number of HIV target cells (CD4+ cells) in cervical secretions, thereby probably increasing HIV susceptibility in women who have an HIV-positive sex partner.
b) Increased infectiousness -- Studies have demonstrated that when HIV-infected individuals are also infected with other STDs, they are more likely to shed HIV in genital secretions, and shed HIV in greater amounts. For example, in African studies, coinfection with gonorrhea and HIV more than doubles the proportion of HIV-infected individuals with HIV genetic material detectable in genital secretions compared with men infected with HIV alone. Furthermore, the median concentration of HIV genetic material in semen is dramatically increased in coinfected men compared with men infected with HIV alone.
a)STD treatment reduces the frequency and magnitude of HIV shedding-- Treatment of gonorrhea in HIV-infected men returns the concentration of HIV genetic material in semen to baseline levels. These levels are comparable to the levels found in HIV-infected men who do not have other STDs. Treatment of gonorrhea also reduced the proportion of the coinfected men who had detectable levels of HIV genetic material in semen.
b)STD treatment reduces the spread of HIV infection in communities -- A landmark community-level, randomized trial in a rural African community in Tanzania demonstrated a 42% decrease in new, heterosexually transmitted HIV infections in communities with improved STD treatment as compared to communities with minimal STD services. An ongoing randomized trial in Uganda is exploring alternative approaches, such as mass treatment for STDs, to further examine the impact of STD control on HIV prevention. The results of these studies will be crucial to validating the findings of the Tanzanian trial and to providing a range of intervention models for reducing the spread of HIV infection in communities with high rates of other STDs, both in the developing world and in industrialized countries.
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