The outbreak, affecting 240 Local Government Areas across 30 states, is largely concentrated among children and adolescents, with low vaccination coverage fuelling transmission. WHO notes that more than two million Nigerian children remain under-immunised, including many who have received no doses of the Diphtheria, Tetanus, and Pertussis (DTP) vaccine.
Médecins Sans Frontières (MSF) reported scaling up emergency response operations in Borno, Kano, and Bauchi states since August, citing hundreds of suspected cases over the past three months that have strained health facilities and exposed gaps in treatment capacity and vaccine availability.
“Nigeria continues to report the highest number of diphtheria cases in the African region,” WHO confirmed. From 12,150 suspected cases, 8,587 were confirmed, with a case fatality rate of 7.2%. However, only 3% of cases were laboratory-confirmed, highlighting diagnostic limitations.
Reactive vaccination campaigns have been conducted in Imo, Kaduna, and Lagos states, targeting health workers and priority populations. WHO also emphasised that the outbreak overlaps with areas covered by the Big Catch-up immunisation initiative, but challenges remain, including delayed laboratory confirmation, poor infection prevention practices, limited public awareness, and vaccine shortages. Ongoing discussions with Gavi, the Vaccine Alliance, aim to secure additional support.
Diphtheria Across Africa
The outbreak is not confined to Nigeria. WHO reports a resurgence of diphtheria across multiple African countries, affecting vulnerable populations and raising serious public health concerns:
- Algeria: 13 suspected cases and 2 deaths in Skikda province, largely among unvaccinated individuals and refugees.
- Chad: 4,462 suspected cases and 47 deaths; only 4 laboratory-confirmed due to limited diagnostic capacity.
- Guinea: 476 suspected cases and 123 deaths, with transmission concentrated in Siguiri district, Kankan region.
- Mali: 430 suspected cases and 29 deaths across seven regions, with rapid geographic spread from three to 30 districts within six weeks.
- Mauritania: 849 suspected cases, 318 confirmed, and 33 deaths, mainly affecting children and adolescents aged 5–19 years.
- Niger: 1,926 suspected cases and 122 deaths, mostly in Agadez, Diffa, and Zinder regions.
- South Africa: 106 cases, including 66 confirmed respiratory infections and 37 asymptomatic carriers, predominantly in the Western Cape.
Across the WHO African Region, from January 1 to November 2, 2025, 20,412 suspected diphtheria cases were reported, resulting in 1,252 deaths (CFR 6.1%). Of these, 9,864 cases (48.3%) were confirmed through laboratory testing, epidemiological linkage, or clinical diagnosis.
Public Health Response and Challenges
WHO classifies the outbreak as a Grade 2 emergency, urging coordinated, multi-sectoral action to limit transmission and reduce fatalities. Effective control requires:
- Timely case detection and laboratory confirmation
- Access to diphtheria antitoxin (DAT) and antibiotics
- Strong infection prevention measures
- Sustained vaccination campaigns and routine immunisation
- Community engagement and strengthened health systems
WHO emphasises that immunity gaps extend beyond early childhood, affecting adolescents and young adults under 30, and warns that ongoing humanitarian crises, vaccine shortages, and limited laboratory capacity are exacerbating the outbreak.
Experts stress that strengthened surveillance, improved vaccine coverage, and emergency preparedness are essential to prevent further spread and safeguard public health across Africa.