For monitoring of the measles program, serum specimens from patients with suspected measles are collected and transported from the health facilities to the NRL. The samples are analyzed for viral antibodies by ELISA. The results are given to EPI for their use in determining a timely response. The results are shared with WHO-AFRO on a monthly basis. Serum specimens also are sent to UVRI on a quarterly basis for external quality control. In addition, the NRL receives quality control panels every quarter from UVRI.