HIV incidence declines have been slower than expected during the roll-out of antiretroviral treatment (ART) services in subSaharan African populations suffering generalised epidemics. Using data from a general population, open-cohort, HIV serosurvey (2004-2013), we found evidence for initial reductions in sexual activity and multiple sexual partnerships followed by
increases in the period of ART scale-up, in high HIV-prevalence areas in Manicaland, east Zimbabwe. Recent populationlevel increases in condom use were also recorded but reflected largely high use by the rapidly growing proportion of HIVinfected individuals on treatment. Sexual risk behaviour increased in susceptible uninfected individuals and in untreated – and
therefore more infectious – HIV-infected men, which may have slowed the decline in HIV incidence in this population.
Intensified primary HIV prevention programmes, together with strengthened risk screening, referral and support services
following HIV testing, could help to maximise the impact of ‘test-and-treat’ programmes in reducing new infections.