Putting Out the Fire before it becomes an Inferno: Responding to an Outbreak of Diphtheria in Edo State, Nigeria

The recent outbreak of diphtheria in Nigeria, lasting over 18 months, is largely attributed to a lack of vaccination, but other factors may have been contributory. The study aims to describe the characteristics of cases and control measures of a localised outbreak of diphtheria in Edo State, Nigeria.

This was a descriptive study of patients who met the case definition for suspected diphtheria in Edo state between May and September 2024. A multidisciplinary management strategy was instituted for sample collection, integrated disease surveillance, contact investigation, awareness creation and standard treatment protocols. Data (age, gender, immunization status, signs and symptoms, receipt of Diphtheria Antitoxin (DAT), laboratory results and outcomes) were extracted from the case notes, entered into an Excel spreadsheet and exported into an SPSS spreadsheet for analysis. Continuous data were expressed as median (IQR), categorical data were summarized as proportions, and the level of immunity was categorized into adequate and inadequate. Ethical approval for the study was obtained from the University of Benin Health Research Ethics Committee with Protocol Number: ADM/22/A/VOL.VII/4831141825 and dated May 28^th 2025.

Of the19 suspected cases, 5(26.3%) were laboratory confirmed, and 4/5(80.0%) of the confirmed cases were older than 9 years. The commonest symptoms were catarrh12(63.2%), sore throat and neck swelling 11(57.9%) each, and fever and hoarseness 10(52.6%). The majority, 89.6% were vaccinated. Of the ten cases that had serology done, 7(70%) had inadequate immunity. No secondary cases were found on contact investigation.

A multidisciplinary team approach ensured this outbreak did not spread widely. With diphtheria occurring in almost 90% of previously vaccinated children, waned immunity was likely a major contributor to this outbreak. It is recommended that booster doses be included in the immunization schedule of Nigerian children.