Designing text-messaging (SMS) in HIV programs : ethics-framed recommendations from the field - Martínez Pérez, Guillermo (Médicos Sin Fronteras/Doctors Without Borders Spain, Barcelona, Spain) ; Hwang, Bella (Doctors Without Borders South Africa, Johannesburg, South Africa) ; Bygrave, Helen (Southern Africa Medical Unit, Doctors Without Borders South Africa, Cape Town, South Africa) ; Venables, Emilie (Medical Department, Médecins Sans Frontières, Operational Centre, Brussels, Belgium)