Disease surveillance

Why it matters

Under Article 6 of the International Health Regulations (2005), each State Party must notify WHO of events that may constitute a public health emergency of international concern within 24 hours of assessing the information, using the decision instrument in Annex 2 [1][2]. That clock depends on how quickly a case recorded at a facility reaches the national level.

Key points

• National systems combine several approaches: integrated disease surveillance and response, syndromic surveillance, case based surveillance and event based surveillance.
• Paper reporting is slow and incomplete. In Sierra Leone, weekly paper IDSR reports had completeness and timeliness below 50% before the 2014 to 2015 Ebola outbreak; after mobile reporting from facilities, weekly reports from 2017 to 2023 averaged 97% completeness [3].
• Surveillance from the clinical record codes diagnoses, laboratory results and dispensing at source, so counts are computed rather than tallied by hand.
• The case definitions, thresholds and response structure remain the ministry's; the data source changes.

In Moana

MOANA Surveillance codes notifiable events at source, classifies syndromes, applies alert thresholds and presents national dashboards with reporting compliance.

Sources

1. International Health Regulations (2005), full text, World Health Organization (University of Oslo treaty library), 2005
2. Annex 2 of the International Health Regulations (2005), World Health Organization, accessed 2026
3. Implementing electronic IDSR at health facilities using mobile Android devices: a case study from Sierra Leone, DHIS2 Annual Conference abstract (Magoba), 2024