Factors Associated with the Outcome of 2023 Diphtheria Outbreak in Jigawa State, Nigeria: A Retrospective Review of the Surveillance Data

Abstract

Objective: The objective of this study was to identify the factors associated with the outcome of the 2023 diphtheria outbreak in Jigawa State, Nigeria. Methods: A descriptive cross-sectional study was conducted amongst all line-listed diphtheria cases reported from Jigawa State, Nigeria, using the 2023 Integrated Disease and Surveillance Response line list of cases that met the World Health Organization case definition of diphtheria. A total of 245 line-listed cases from January 2023 to December 2023 met the criteria for inclusion in the study. Data were analysed using IBM SPSS version 22.0 with a P value set at ≤5%. Binary logistic regression was used to identify the independent predictors of the outcome of the 2023 outbreak. Results: The maximum age of the line-listed cases was 39 years, and the minimum was 1 year with a median of 8 (interquartile range = 5–8) years. More than two-thirds (68.2%) of the cases were ≥5 years of age. More than one-third of the cases (39.6%) were from the northeast senatorial zone of the state. Out of the total 245 cases, 14 died of the disease representing a case fatality rate of 6%, and an attack rate of 3.4 per 100,000 populations. The majority of the cases (95.5%) had fever, cough (81.2%), pharyngitis (86.9%), tonsillitis (96.7%) and laryngitis (82.0%). More diphtheria-related mortalities were recorded amongst cases <5 years of age (7.7%), female cases (5.9%), rural residence (7.7%) and cases from the northeast senatorial zone (8.2%) of the state. Significantly higher mortalities (8.8%, P = 0.003) were recorded amongst cases with nasopharyngitis. The odds of diphtheria-related mortality were higher amongst cases who presented clinically with nasopharyngitis and were 4 times more likely to die (adjusted odds ratio = 3.9; 95% confidence interval = 1.1–14.3) compared with those with no nasopharyngitis. Conclusions: Significantly higher mortalities were recorded amongst diphtheria cases whose samples were not taken, and those with nasopharyngitis. These findings underscored the importance of improved immunisation uptake, early and prompt case detection, investigation and proper management.