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Out of Africa: Testing and treating all for eradication
By Dean L. Winslow, MD, FACP, FIDSA, Chief, Division of AIDS Medicine, Santa Clara Valley Medical Center; Clinical Professor, Stanford University, School of Medicine. Dr. Winslow serves as a consultant for Siemens Diagnostics, and is on the speaker's bureau for Boehringer-Ingelheim and GSK.
Synopsis: Mathematical models were used to explore the impact of universal voluntary HIV testing with immediate vs. delayed antiretroviral (ARV) therapy on HIV transmission. The findings suggest that this strategy could accelerate the transition of endemic HIV infection to an elimination phase in which most patients are receiving ARV in five years and reduce the prevalence of HIV infection to < 1% of the population within 50 years.
Source: Granich RM, et al. Universal voluntary HIV testing with immediate antiretroviral therapy as a strategy for elimination of HIV transmission: a mathematical model. Lancet. 2009;373:48-57.
Mathematical models (a case reproduction number/stochastic model and a long-term epidemic dynamics/deterministic transmission model) were used to explore the effect of testing for all people 15 or older for HIV and initiating ARV therapy immediately after diagnosis. Data from South Africa were used as a test case for a generalized epidemic, and it was assumed that all transmission was heterosexual. The studied strategy, as modeled, resulted in producing an epidemic elimination phase in which most HIV-infected patients were receiving ARV therapy within five years of initial infection. It could possibly reduce HIV incidence and mortality to < 1 case/ 100,000 people per year by 2016 (10 years) and reduce the prevalence of HIV to < 1% within 50 years. In 2032, the yearly cost of this strategy would be $1.7 billion; however, after that time, the cost would decrease.
Almost 10 million humans are infected with HIV worldwide, with the majority of these patients living in sub-Saharan Africa. At the end of 2007, only 3 million patients were receiving ARV therapy and 2.7 million became infected with HIV in 2007 alone. Arguably, the present haphazard and under-resourced approach to HIV testing and treatment will never result in eradication, or even significant reduction in both HIV incidence and prevalence. The current approaches to HIV prevention (abstinence, safe sex, use of condoms, etc.) have been largely ineffective, by themselves, in reducing the transmission of HIV in Africa. It is known from studies showing the effectiveness of ARVs in the prevention of vertical transmission and the relatively flat prevalence of HIV disease in North America and Western Europe since the mid-late 1990s, that effective ARV therapy can also significantly reduce sexual transmission of HIV.
This important paper uses straight forward mathematical modeling to demonstrate the theoretical effectiveness of widespread testing and treatment as a strategy to reduce transmission of HIV in the short term. With a steady commitment of resources, the models demonstrate that HIV could be almost eliminated within 50 years in areas where HIV infection meets the criteria for a generalized epidemic. Cost analysis shows that while the initial costs of this strategy of universal voluntary testing and ARV treatment are high, within a few years, as the numbers of HIV cases and deaths decline, the costs of this approach would be significantly less than continuing the present approach, which shows no promise of eliminating this scourge from the Earth. Granich et al sagely conclude that this approach merits further mathematical modeling, research, and consultation; however, their data are quietly compelling. I would argue from the perspective of a physician and scientist who has studied this disease and treated AIDS patients since 1981 (and watched as HIV has become the leading cause of death in Africa), that this approach in the absence of an effective vaccine is the only one with any chance of successfully eradicating HIV.