Reducing Transmission
The efficiency of HIV transmission is directly proportional to the viral load in the transmitting individual (Quinn et al., 2000) i.e. the higher the viral load, the easier it is to transmit HIV. Acute HIV infection, lasting weeks or months, may account “for a substantial proportion of HIV-1 transmission worldwide. Viral burden is particularly high during this brief period, resulting in individuals being highly infectious” (Powers et al., 2008: 560). Acute HIV infection usually evolves, in the absence of treatment, into a state of chronic HIV infection that can remain relatively constant for years. While this period is associated with a much lower risk of transmission compared with that of acute HIV infection, because the period following acute HIV infection can last a median duration of eight years, the cumulative risk of transmission during these eight years can be substantial (Granich et al., 2009).
Treatment May Be A Successful Strategy in Reducing Transmission
“Given the dramatic effect of ART on viral load, it is reasonable to consider using treatment of individuals infected with HIV as a means of preventing HIV transmission” (Dieffenbach and Fauci, 2009: 2380). However, “…there is insufficient evidence to formulate guidance on the role of ART in HIV prevention, both at the level of the individual and the population” (Attia et al, 2009: 1402). Emerging evidence shows that “reducing virus levels with antiretroviral therapy…reduces the risk of HIV transmission in a variety of settings” (IAS, 2010: 3). Results are awaited from HPTN 052, an ongoing, prospective, two-arm, randomized, controlled, multi-center study with 1,750 HIV-positive people and their HIV-negative sexual partners, started in 2008, with results in five years. In the study, the HIV-positive partner goes on treatment when CD4 counts go below 200; the study endpoint is seroconversion of the HIV-negative sexual partner (Godbole et al., 2008).
Though ARV treatment can reduce transmission through reduced viral load (Attia et al., 2009; Vernazza et al., 2008), condom use is still necessary to increase protection for both HIV-positive and HIV-negative sexual partners. “While the use of HIV treatment as prevention is emerging as an exciting component of scaled up AIDS programmes, further research and clarification is needed. The reliability of projections developed from mathematical models is limited by the accuracy of the assumptions on which a model is built and by the realities of implementation. Additional areas of uncertainty range from questions regarding the accuracy of mathematical models used in recent publications to questions regarding the acceptability and impact of massive scale up of HIV testing, and of long-term treatment in people where HIV treatment may not yet [be] medically indicated but is being prescribed to prevent HIV transmission. Many of these questions will be addressed by studies planned or underway” (IAS, 2010: 6).
Treatment Alone Will Be Insufficient in Reducing Transmission
Given the unknowns and the inadequate availability of medications, treatment alone is insufficient in reducing and preventing HIV transmission. Additional factors must be addressed to bridge the divide that exists between HIV prevention and treatment activities in order to reduce transmission of the virus, as well as to meet the SRH needs and fertility desires of women. “The historical separation of treatment and prevention and the focus of prevention on uninfected individuals are counterproductive in a setting [such as South Africa] where more than 30% of the sexually active population is infected with HIV” (Abdool Karim et al., 2009: 931). The new standard of care for all people living with HIV should include counseling, support, condom negotiation skills, and provision of male and female condoms to reduce transmission. In addition to antiretroviral therapy “all treatment programs should provide patients with routine risk-reduction counseling, access to condoms and other prevention tools, and other prevention services in their clinical settings” (Global HIV Prevention Working Group, 2008: 23).
Non-judgmental, non-stigmatizing interventions to reduce HIV transmission to sexual partners are urgently needed (Collins et al., 2008). Other interventions both within the health sector and outside the health sector, for example, those that transform norms, reduce violence against women, promote legal rights, etc, also need to be implemented in order to support safer sexual behavior once someone knows his/her positive serostatus. [See also Chapter 11. Strengthening the Enabling Environment] Transmission can also occur in the attempt to become pregnant: “In the absence of artificial insemination technologies, effectively unavailable in most low- or low-to-middle income countries, conception requires unprotected sexual intercourse; this means risk of either HIV transmission (in serodiscordant couples) or HIV super-infection (in couples where both couples are positive” (London et al., 2008: 14). [See also Chapter 9. Safe Motherhood and Prevention of Vertical Transmission]
“Treatment cannot replace the use of condoms. The proper use of condoms remains a reliable means of enabling everyone, without knowing the serologic status of their partners, to keep control on protecting themselves and others during sexual intercourse…. Treatment should be thought of as a tool providing regular condom users valuable extra safety. Moreover, condoms remain the only way to protect oneself against other STIs” (Bourdillon et al., 2008: 11).
Further research is critical to assess “what works” in reducing transmission. Randomized evaluations of different behavioral intervention models, including clinician-initiated communication are needed (Bunnell et al., 2006b). “When discussions of ongoing STD-related risk behavior do occur, they are infrequent and often initiated at the patient’s request. At best, the lack of these discussion in HIV-related care settings is unfortunate; at worst, it indirectly contributes to escalating rates of STDs among HIV-infected persons and of new HIV acquisition among others at risk” (Hall and Marrazzo, 2007: 518.)