What question this study addressed. This study conducted the first comprehensive nationwide evaluation of Cameroon’s IDSR system to assess its core functions, structure, and operational gaps in the face of global infectious threats. What this study adds to our knowledge. While regional levels show strong data analysis and 95% DHIS2 integration, the system faces critical operational failures due to poor reporting timeliness, low local data analysis, and severe shortages in guidelines, funding, and logistical support. How this is relevant to practice, policy or further research. To optimize the IDSR system, Cameroon must decentralize resource allocation and technical support to the district level to improve reporting timeliness and ensure sustainable outbreak preparedness. This publication is available in full in Health Research in Africa.