Background:

Acute (antibody-negative) HIV infection is associated with high transmission potential but is rarely recognized.

Design:

Cross-sectional study.

Methods:

We examined the prevalence and predictors of acute HIV infection among 1361 consecutive male outpatients attending sexually transmitted disease (STD; n= 929) and dermatology (n= 432) clinics in Lilongwe, Malawi. Serum specimens negative for HIV antibodies were screened by HIV RNA PCR using a highly specific pooling/resolution testing algorithm.

Results:

Five-hundred and fifty-three men (40.6%) were HIV antibody positive and 24 (1.8%) had acute HIV infection; 23 of 24 acutely infected men were from the STD clinic, where they represented 4.5% of all HIV antibody-negative men and 5.0% of all HIV infections. HIV RNA levels for acutely infected men were significantly higher [median (interquartile range), 6.10 (5.19–6.54) log 10 HIV RNA copies/ml] than for 58 HIV antibody-positive men [4.42 (3.91–4.95) log 10 copies/ml; P< 0.0001]. The factor most strongly associated with acute HIV infection was STD clinic attendance:(odds ratio, 15.2; 95% confidence interval, 2.04–113.0). In multivariate analysis considering only STD patients, factors associated with acute HIV infection included inguinal adenopathy, genital ulceration and age 24–26 years, the age stratum associated with peak incidence of HIV infection among Malawian men.

Conclusions:

Traditional HIV antibody tests alone are not sufficient to exclude HIV infection among men with acute STD in Malawi due to a surprising proportion of acute HIV infections in this population. Alternative screening methods are required for diagnosis of acute HIV infection; such screening could be important for research and for prevention of the sexual transmission of HIV in select populations.