A.16.Rapid, real time diagnosis of acute HIV infection in Malawi
Mapanje C, Hoffman I, Chilongozi D, Martinson F , Krysiak R, Gama S, Pilcher C, Miller W, Cohen M, Fiscus S
Objectives: We previously identified the STD clinic at KCH in Lilongwe, Malawi as a site with a high proportion of acute HIV infection (AHI). Persons with AHI are in the “window phase”, HIV antibody negative, and highly infectious. We conducted a prospective study to evaluate real time methods of detecting STD patients that test antibody negative but have AHI.
Methods: All patients with an STD were offered HIV VCT using two rapid tests (RT), Unigold and Determine. Western Blot was used as a RT tiebreaker, and all RT negative (-/-) or discordant (+/-) specimens were tested for p24 Antigen and also pooled 1:10:50 for viral load RNA testing. Baseline specimens from all acute cases and 102 negative cases were also later tested by ultrasensitive p24 Ag (Up24). Results were given at a one week follow-up visit. Patients with possible AHI were followed at frequent intervals for 4 months to confirm seroconversion.
Results: 1440 STD patients (33% female, 67% male) were tested. 555 (38.5%) had established HIV infection and 20 (1.4%) had AHI. Sensitivity of the two antibody RT was only 96.2%. Of the 22 patients with discordant RT results (17 Determine+, 5 Unigold +), 7 (32%) had AHI and 2 (9%) had established infection. Among RT neg/discordant clients, p24 Ag identified 12 of 16 (75%) cases and was 99.5% specific. Up24 detected 16 of 19 cases (84.2%) and was 100% specific. RNA tests were 100% sensitive and 99.5% specific.
Conclusions: These results show a substantial number of patients with STDS in Malawi have AHI. Real-time pooled RNA testing for detection of AHI is feasible at centers of excellence in sub-Saharan Africa. Parallel rapid testing and p24 Ag testing are technologically simple approaches that together may detect up to 85% of acute cases.