DBS collection, handling, processing, and tracking

Blood from each patient was collected in a 3-mL vacuum tube containing ethylene diamine tetra-acetic acid (EDTA) anticoagulant and used for preparation of two DBS cards at the ART clinics. DBS were made following a standardized protocol for ATCC kits by dropping of 100 μl of whole blood to each of the five pre-printed circles in the Whatman 903 card, dried overnight and then packaged with desiccants and a humidity indicator card. At the clinics, the dried and packaged DBS cards were kept in a dry and safe location at ambient temperature with no direct exposure to sunlight. The DBS cards were picked up biweekly from the ART sites by routine courier services and delivered to the storage facility in Nairobi or Dar es Salaam where they were stored at -80°C until shipment. Upon the completion of DBS collection, DBS were shipped at ambient temperature to the drug resistance genotyping laboratory at the International Laboratory Branch, U.S. CDC in Atlanta, Georgia for processing. Fig 1 is a schematic representation of the process for the Kenya surveys.