Abstract
As the epidemic matures, accurate information about where new infections are occurring, and in which populations, is becoming increasingly critical in designing effective, targeted interventions relevant to current epidemiological trends. Although the quality and accuracy of HIV surveillance data and methodology have improved, in many cases the second generation WHO/UNAIDS surveillance system has not been fully implemented at the national level. National surveillance systems in many low and middle-income countries often do not collect disaggregated data on some most at risk populations, which is critical to developing targeted prevention interventions.While the majority of new infections occur in low- and middle-income countries, the dynamic situation in high-income countries demands renewed attention.