Surveillance for HIV-1 incidence using tests for recent infection in resource-constrained countries.

Over the past few years, several assays have been developed for the purpose of estimating HIV-1 incidence from cross-sectional population surveys. The tests detect features of the evolving virological or immunological response to HIV-1 infection that distinguish recent from established infection. Surveillance programmes that collect specimens from population surveys for HIV-1 prevalence can apply some of these tests to the same specimen sets to estimate incidence. We describe these tests and discuss the principle and strategy for implementation of a testing programme for recent infection in surveillance settings. Test-specific prerequisites, such as calibration, validation, and quality assurance, and other test-specific performance characteristics that may influence interpretation, epidemiological considerations that may guide application, and practical operational considerations for implementation in surveillance settings are considered. When properly and judiciously applied, the capacity to estimate incidence from existing programmes that conduct surveillance for prevalent HIV-1 infection will enhance the capacity for more precise and timely analysis of the dynamics of the epidemic and the effectiveness of public health interventions.