Trends and Geographical Distribution of Diphtheria in Nigeria: A Re-Emerging Disease

Diphtheria is a highly contagious and deadly vaccine–preventable bacterial infection that affects a person’s nose, throat, and occasionally the skin. Diphtheria is fatal in 5–10% of cases; however, the case fatality rate (CFR) can be as high as 20–40% among children and unvaccinated adults. Currently, the number of diphtheria cases reported globally has being increasing gradually. Nigeria ranks number six in the list of countries by population with about 42.54% of its population below 14 years of age. Despite the availability of the antitoxin vaccine in the country, only 41.7% of children under 15 years of age are fully vaccinated, making the country more vulnerable to the disease. The study, therefore, aimed to examine the spread and trend of diphtheria in Nigeria since the major outbreak of the disease in December 2022. Data for the study were sourced from secondary sources. From December 2022 to January 2023, Nigeria recorded a total of 111 (42.1%) confirmed cases and 22 deaths, with a case fatality rate for confirmed/probable cases of 19.8% in four states. Out of the 111 confirmed cases, only a small percentage (10.8%) were vaccinated with the diphtheria toxin-containing vaccine. Additionally, the majority (91.9%) of the confirmed cases occurred in children aged 2–14 years. Since then, there has been a constant number of reported cases. As of 31 July 2023, the country recorded a total of 1534 confirmed cases in 11 states and 137 deaths, with a CFR of 8.9%. The majority (66.4%) of the confirmed cases occurred among children aged 1–14 years, with only 18.1% of the 1534 confirmed cases previously vaccinated. In this era of globalization, if prompt action is not taken, diphtheria will become a major threat not only to Nigeria but also globally.