Epidemiological trend and clinical features of diphtheria in Hajjah Governorate, Yemen: a seven-years retrospective analysis (2018–2024)

BACKGROUND: Diphtheria is a contagious infection caused by the bacterium Corynebacterium diphtheriae and is most prevalent in populations lacking effective vaccination programs. The Hajjah Governorate has limited recent epidemiological data on diphtheria outbreaks. Therefore, this retrospective analysis aimed to assess the epidemiological trends and clinical characteristics of diphtheria in Hajjah Governorate over a seven-year period from 2018 to 2024. METHODS: This retrospective study in Hajjah Governorate relied on secondary data from diphtheria cases clinically diagnosed only in accordance with WHO definitions. The data were statistically analyzed to identify the demographic characteristics, temporal and seasonal trends, and clinical symptoms associated with diphtheria infection. RESULTS: A total of 1,722 probable cases of diphtheria were enrolled in this analysis, with a higher rate recorded among females (970, 56.3%), individuals aged 5–9 years (418, 24.3%), in 2018 (394, 22.9%), and in autumn (565, 32.8%). The total incidence rate of the diphtheria burden was 73.12 cases per 100,000 inhabitants in Hajjah Governorate, with a higher incidence rate reported among females (80.3), the 5–9-year-old age group (172.3), in 2018 (18.7), and in the Al Miftah district (296.6). Regarding clinical presentation, 97.6% of cases suffered from laryngitis/pharyngitis, 99.3% showed pseudomembranous diphtheria, and 98.6% had difficulty swallowing. CONCLUSION: In this analysis, the high number of diphtheria cases and incidence rates pose a significant burden on the health system and disproportionately affect children and vulnerable populations. These outcomes emphasize the importance of targeting interventions at the most vulnerable groups and critical times of the year, implementing immediate medical interventions, and targeting high-risk districts to effectively control and reduce diphtheria outbreaks in the study area in the future. CLINICAL TRIAL NUMBER: Not applicable.