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This retrospective cohort study analyzed 61 diphtheria cases admitted to a teaching hospital in Adamawa State, Nigeria between 2023-2026, revealing a 41.5% in-hospital fatality rate and a 580% increase in admissions over the study period. The case fatality rate declined from 60% in 2023 to 28.6% in 2025, coinciding with improved access to diphtheria antitoxin, though critical shortages of intravenous erythromycin persisted throughout. The study identified a distinct September-October seasonal peak and found that respiratory distress carried 80% mortality while cardiac complications were universally fatal.
Why it matters
This is the first facility-level epidemiological analysis of Nigeria's largest recorded diphtheria outbreak from a high-vulnerability region, identifying critical gaps in drug supply chains and seasonal patterns that differ from national trends. The findings support specific public health interventions including pre-positioning antitoxin and antibiotics before August-October peaks and accelerating childhood immunization campaigns in northeastern Nigeria.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Background Diphtheria caused by toxigenic Corynebacterium diphtheriae re-emerged in Nigeria from December 2022 as the country’s largest ever recorded outbreak, accumulating over 20,000 suspected cases and 872 confirmed deaths by December 2025. The Borno-Adamawa-Yobe (BAY) states zone in north-eastern Nigeria is a recognised high-vulnerability cluster, yet no facility-level, longitudinal epidemiological data from Adamawa State have been published. Methodology/Principal findings We conducted a retrospective cohort study of all patients admitted with diphtheria to the Isolation Ward of Modibbo Adama University Teaching Hospital (MAUTH), Yola — the sole federal university teaching hospital in Adamawa State — from January 2023 to April 2026, using prospective admission register records. Sixty-one patients were identified (17.9% of 330 total isolation admissions). Admissions escalated 580% from 5 (2023) to 34 (2025). Median age was 8.0 years; 91.8% were under 15 years. The overall in-hospital case fatality rate (CFR) was 41.5% (22/53 known outcomes; 95% confidence interval: 29.0-55.0%). Annual CFR declined from 60.0% (2023) to 28.6% (2025), temporally consistent with improving diphtheria antitoxin access. A critical operational finding was the persistent shortage of intravenous erythromycin — the mandated antibiotic for patients unable to swallow — compelling oral administration in patients with pharyngeal pseudomembrane and dysphagia. Respiratory distress at presentation carried an 80% CFR; cardiac complication, 100%. Age and sex were not statistically significant mortality predictors. Gombi local government area contributed 16.4% of cases — the highest burden among non-capital communities — consistent with its role as a population movement corridor from Borno State’s outbreak epicentre. A September-October seasonal peak (47.5% of admissions) was identified, diverging from the national January-April pattern. Conclusions/Significance This study provides the first peer-reviewed, facility-level diphtheria epidemiological dataset from Adamawa State. The in-hospital CFR substantially exceeds national surveillance averages due to referral bias and historical drug supply constraints. The declining CFR against rising admissions signals improving case management. Pre-positioning of diphtheria antitoxin and intravenous erythromycin before each August-October peak, accelerated childhood immunisation catch-up, and strengthened surveillance in Adamawa State are identified as urgent priorities.