Background:  We have previously identified sexually transmitted disease (STD) clinics in Malawi as sites with high proportions of acute HIV infection and thus of high public health concern. We therefore conducted a prospective study to evaluate methods of detecting STD patients who are acutely co-infected with HIV.

Methods:  After obtaining informed consent, all clients with acute STD at Lilongwe Central Hospital in Lilongwe, Malawi, were offered voluntary HIV counseling and testing using 2 rapid tests, Unigold and Determine. Western blot was used as a rapid test tie-breaker, and all rapid test negative (^–/^–) or discordant (⁺/^–) specimens were tested for p24 antigen (Perkin-Elmer) and also pooled 1:10:50 for Roche Monitor, version 1.5 RNA testing. Initial results were given at a 1-week follow-up visit. Patients with possible acute HIV infection were followed at frequent intervals for 4 months to confirm seroconversion.

Results:  A total of 1440 clients (33% female, 67% male) agreed to testing, of whom 555 (38.5%) had established HIV infection and 20 (1.4%) had acute infection; the remainder were uninfected. Median baseline viral load for the 20 acute cases was 599,994 copies/mL, vs 65,899 copies/mL for 84 cases with established infection. Considering all detectable infections, sensitivity of 2 rapid tests was only 96.2%. However, of 22 clients with discordant rapid test results (17 Determine⁺, 5 Unigold⁺), 7 (32%) were acutely infected and 2 had established infection. To detect additional HIV infections among rapid test negative/discordant clients, p24 antigen identified 13 of 16 (81%) cases but gave 4 instances of false positive results. RNA tests were 100% sensitive and 99.5% specific.

Conclusions:  These results suggest that a substantial number of people seeking care for acute STD in Malawi have acute HIV co-infection that would be undetected by standard testing. Real-time pooled RNA testing for detection of acute HIV and quality control is feasible at centers of excellence in sub-Saharan Africa; however, parallel rapid testing and p24 antigen testing are technologically simple approaches that together may detect as much as 80% of acute cases. Acutely infected patients are likely to be extremely contagious, and thus deserve special prevention and treatment efforts.

Keywords: diagnosis ; pooled RNA; resource poor setting