Background: UNAIDS aims for 90% of HIV-positive individuals to be diagnosed by 2020, but few attempts have been made in developing countries to estimate the fraction of the HIV-positive population that has been diagnosed.
Methods: To estimate the rate of HIV diagnosis in South Africa, reported numbers of HIV tests performed in the South African public and private health sectors were aggregated, and estimates of HIV prevalence in individuals tested for HIV were combined. The data were integrated into a mathematical model of the South African HIV epidemic, which was additionally calibrated to estimates of the fraction of the population ever tested for HIV, as reported in three national household surveys.
Results: The fraction of HIV-positive adults who were undiagnosed declined from more than 80% in the early 2000s to 23.7% [95% confidence interval (95% CI) 23.1-24.3] in 2012. The undiagnosed proportion in 2012 was substantially higher in men (31.9%, 95% CI 29.7-34.3) than in women (19.0%, 95% CI 17.9-19.9). Projected probabilities of experiencing disease progression (CD4 cell count <350 cells/μl) without diagnosis are more than 50% for most HIV-positive adults over the age of 40. The fraction of HIV-positive adults who are undiagnosed is projected to decline to 8.9% by 2020 if current targets (10 million tests per annum) are met.
Conclusion: South Africa has made significant progress in expanding access to HIV testing, and at current testing rates, the target of 90% of HIV-positive adults diagnosed by 2020 is likely to be reached. However, uptake is relatively low in men and older adults.