Recent data from the Manicaland HIV/STD Prevention Project, a general-population open HIV cohort study, suggested that
between 2004 and 2007 HIV prevalence amongst males aged 15–17 years in eastern Zimbabwe increased from 1.20% to
2.23%, and in females remained unchanged at 2.23% to 2.39%, while prevalence continued to decline in the rest of the
adult population. We assess whether the more likely source of the increase in adolescent HIV prevalence is recent sexual HIV
acquisition, or the aging of long-term survivors of perinatal HIV acquisition that occurred during the early growth of the
epidemic. Using data collected between August 2006 and November 2008, we investigated associations between
adolescent HIV and (1) maternal orphanhood and maternal HIV status, (2) reported sexual behaviour, and (3) reporting
recurring sickness or chronic illness, suggesting infected adolescents might be in a late stage of HIV infection. HIV-infected
adolescent males were more likely to be maternal orphans (RR = 2.97, p,0.001) and both HIV-infected adolescent males and
females were more likely to be maternal orphans or have an HIV-infected mother (male RR = 1.83, p,0.001; female RR = 16.6,
p,0.001). None of 22 HIV-infected adolescent males and only three of 23 HIV-infected females reported ever having had
sex. HIV-infected adolescents were 60% more likely to report illness than HIV-infected young adults. Taken together, all
three hypotheses suggest that recent increases in adolescent HIV prevalence in eastern Zimbabwe are more likely
attributable to long-term survival of mother-to-child transmission rather than increases in risky sexual behaviour. HIV
prevalence in adolescents and young adults cannot be used as a surrogate for recent HIV incidence, and health systems
should prepare for increasing numbers of long-term infected adolescents.