Background:  Without early treatment, almost 50% of HIV-infected infants in Africa will die within 24 months; thus, early HIV diagnosis is critical. However, early diagnosis requires direct viral molecular assays. The ultrasensitive p24 antigen assay (Up24 Ag) is cheaper and easier to perform than HIV DNA polymerase chain reaction (PCR); and has proved useful for early infant diagnosis in some settings. However, it has not been studied among infants exposed to A and D subtypes, such as those in Uganda. The objective was to determine the sensitivity, specificity, and predictive values of the Up24 Ag assay to diagnose HIV infection among children 6 weeks to 18 months of age compared to the “gold standard” DNA PCR.

Methods:  We enrolled 210 HIV-exposed infants; mean age was 6.9 months (range 1.5 to 18 months), 118 (56.2%) were males, and 92 (43.8%) were HIV-infected. A cross-sectional study of HIV-exposed infants attending Mulago Paediatric Infectious Diseases and post-natal clinics was conducted. Demographic data and history were documented. With caretaker’s informed consent, each child had blood drawn for whole blood DNA PCR and Up24 Ag testing.

Results:  The table compares results of the Up24 Antigen Assay with DNA PCR.

Conclusions:  These findings are encouraging:  the Up24 Ag assay demonstrated high sensitivity, specificity, and positive (PPV) and negative predictive value (NPV) for diagnosing HIV infection in exposed Ugandan infants with subtype A and D infection when compared to DNA PCR.