BACKGROUND
Malawi, Uganda, and Zimbabwe have recently adopted a universal 'test-and-treat' approach to the prevention of mother-to-child transmission of HIV (Option B+). Amongst a largely asymptomatic population of women tested for HIV and immediately started on antiretroviral treatment (ART), a relatively high number are not retained in care; they are labelled 'defaulters' or 'lost-to-follow-u...