Rising prevalence of HIV-1 non-B subtypes in Belgium: 1983-2001.

This study documented the HIV-1 subtype distribution in 2 Belgian hospitals and determined predictive demographics for non-B subtypes. Overall, subtype B was the most prevalent subtype in this population, followed by subtypes A and C. Several recombinants were detected, circulating recombinants as well as new ones. We found a rise in non-B subtypes from 0% in 1983 to 57% in 2001. The Cochran-Armitage trend test (P < 0.001) as well as the correlation analysis (R = 0.71, P = 0.0006) was highly significant. Recombinants were also increasing in this patient population from 0% in 1983 to 10% in 2001, with good support from the statistical analyses (trend test P < 0.001; correlation analysis R = 0.67, P = 0.0016). Heterosex- ual route of infection, black African race, African origin of the virus, and year of diagnosis were predictors for infection with non-B sub- types in multivariate analysis. This analysis indicates that the preva- lence of non-B subtypes and recombinants in this patient population is high and increasing. Gathering demographic and sequence informa- tion from newly diagnosed patients could be useful to further follow the spread of non-B subtypes in Belgium and Europe, but subtyping based on sequence information still remains the most reliable method.