Number of adults (ages 15-49) newly infected with HIV. Development relevance: Despite the existence of effective medications and treatment, HIV/AIDS is still a leading cause of death and public health threat in the world. Low and middle income countries continue to bear a disproportionate share of the global burden of HIV/AIDS. The incidence rate provides a measure of progress toward preventing onward transmission of HIV. Also, the identification of newly infected persons will allow for interventions to reduce the risk of HIV transmission.