Evaluation of diphtheria surveillance system in Kaduna State, Nigeria, July 2023 - December 2023

The re-emergence of the diphtheria outbreak in Nigeria raises concern about the surveillance system's capability to detect, prepare for and respond to outbreaks.

To evaluate the usefulness and attributes of the diphtheria surveillance system in Kaduna State, Nigeria.

Kaduna State, northwest Nigeria.

An observational study, using a mixed-method approach, was adopted. It comprised a survey, a record review of the 2023 outbreak and key informant interviews. A pre-tested semi-structured self-administered questionnaire and an interview guide, adapted from the Centres for Disease Control and Prevention (CDC) (2001) guidelines on surveillance evaluation, were utilised. Three stakeholders were interviewed, 21 surveillance officers were surveyed, and eight surveillance attributes were assessed.

The outbreak data had 67% (n = 382/573) missing values. Eighty-two per cent (n = 432/525) of cases had an investigation initiated within 48 hours. All 21 (100%) respondents reported ease in filling in forms and a willingness to continue participating in the system, which could correctly identify cases. Twelve (57%) of the 21 respondents stated that private health facilities submitted their reports. Of the 12 respondents who reported modifications in the system, six (50%) stated < 1 month for implementation. Nineteen (90%) of the 21 respondents reported inadequate resources, while six (67%) of the nine respondents who reported receiving stipends indicated these were provided by partner organisations.

The system was acceptable to stakeholders, useful in detecting outbreaks, simple in data collection, flexible in accommodating changes and sensitive in identifying cases. However, resource constraints pose a threat to its stability. We recommend providing adequate resources, improving data quality and reporting from private health facilities.

The study underscores areas for improvement in the diphtheria surveillance system, highlighting the potential for targeted interventions to overhaul the system.