Monitoring for multi-drug resistant TB is done by the NRL, and some specimens are subsequently referred to the external laboratory at the Institute of Tropical Medicine (IMTA) in Antwerp, Belgium for quality control (QC) testing. The QC panel samples for epidemic bacteria, malaria and TB microscopy, CD4 counts, HIV ELISA and Western Blot are received from the National Institute of Public Health (NIPH) in South Africa every quarter. The QC panels for assessing PCR capacity are received from CDC in Atlanta, USA.