By Liz Highleyman

"Test-and-treat" as an HIV prevention strategy has garnered increasing attention in recent years, with mathematical models indicating that widespread voluntary testing and treatment of everyone infected could lower HIV incidence (new cases). A recent report by World Health Organization (WHO) researchers, for example, suggested that implementing test-and-treat could halt the global epidemic within 50 years.

Most new HIV infections are transmitted from people who are not aware they carry the virus, so they have not started ART and may not adopt safer sex and needle use practices. Once people start treatment and achieve undetectable viral load, however, the risk of transmission falls dramatically.

The National Institute of Allergy and Infectious Diseases (NIAID) supports universal testing and linkage to care, and recently allocated $26 million for a partnership with the Washington, DC, Department of Health that includes a pilot test-and-treat study.

But test-and-treat is not without controversy, due to concerns about involuntary testing, difficulties with long-term adherence, development of antiretroviral drug resistance, and worry that people will be treated for the sake of public health rather than their own individual benefit.

Rochelle Walensky and fellow investigators with the Cost-Effectiveness of Preventing AIDS Complications (CEPAC) study team sought to forecast outcomes of a universal test-and-treat approach in DC. The district has one of the worst local HIV/AIDS epidemics in the U.S. -- in particular among African-Americans -- and prevalence is now so high that people outside defined high-risk groups (such as gay/bisexual men and injection drug users) are at significant risk of becoming infected.