“Finally, someone is talking about this.” I heard this refrain frequently at the recent International Conference on HIV/AIDS and Sexually Transmitted Infections in Africa (ICASA) in Addis Ababa, Ethiopia, after telling people about the satellite session hosted by Médecins Sans Frontières (MSF). The difficult topic: false positive HIV tests.
In resource limited settings, HIV diagnosis is done with rapid diagnostic tests (RDTs). Two or three different RDTs are used in either a serial or parallel algorithm (according to national guidelines). RDTs allow scale-up and decentralisation of treatment, both of which are essential to saving lives. Yet RDTs are screening tests—they were not designed for definitive diagnosis. They work well for screening blood transfusions and identifying people who need further tests, but are known to yield false positive results owing to serological cross reactivity (or inadequate quality control and human error, e.g. mislabelling of specimens). I first came across this unpleasant reality in Bukavu, Democratic Republic of the Congo, while working as a medical coordinator for MSF in 2005. We were running the first programme offering antiretroviral therapy to the province and had tested nearly 6000 people. But late in 2004 we realised that some people in our programme did not have HIV, so we retested a number of them—and identified almost 50 who we suspected had a false positive HIV diagnosis. This news was devastating, considering the consequences a false diagnosis can have on people’s lives. more…