<p>We established a call desk with five phones and toll-free lines maintaining a 24/7 operation. Data collected were name, age, sex, telephone contact, and residential address. Others were signs and symptoms and date of onset; travel to a hotspot; attendance of burial of, or physical contact with, a probable or confirmed case; visiting a healthcare facility, Church or traditional healer where a probable or confirmed case had been; all within the previous 21 days. Desk verifiers decided whether an alert case is evacuated, discarded or further assessed by field verifiers. We used the WHO and CDC evaluation guidelines to assess the system for validity, timeliness, representativeness, usefulness and stability.</p>