Nigeria is facing a growing diphtheria outbreak, with more than 10,000 confirmed cases recorded this year, according to the Nigeria Centre for Disease Control (NCDC).
At a press briefing on 28 August 2026, the NCDC said recorded cases are concentrated in Kano, Borno and Bauchi.
Diphtheria is one of the most feared childhood diseases, marked by devastating outbreaks, according to the World Health Organization (WHO).
As cases continue to rise, this factsheet looks at the situation and what the authorities are doing to slow down the increase.
What is diphtheria?
Diphtheria is a highly contagious bacterial infection that can be fatal in up to 10% of cases. It is caused by Corynebacterium diphtheriae, with humans as its only natural host. It can affect people of all ages but primarily affects young children and is more common in countries with low immunisation rates.
The disease spreads through respiratory droplets and secretions, particularly in closed and crowded settings. The bacteria produce toxins that can destroy tissue in the respiratory system, forming a membrane in the throat that can make breathing and swallowing difficult. Severe cases can lead to airway obstruction, while the toxin can also damage the heart, nerves and kidneys, according to the U.S. Centre for Disease Control and Prevention
Diphtheria has been reported across several regions, including Eastern Europe, Southeast Asia, South America and the Indian subcontinent. According to WHO data, 30,206 cases were reported globally in 2025.
How is diphtheria transmitted and what are its symptoms?
Diphtheria is transmitted through respiratory secretions, or by breathing in droplets from an infected person when they cough or sneeze.
Some people may become infected and have no symptoms. For those who do, symptoms usually start two to five days after someone becomes infected.
Infection of the skin can also occur, particularly where hygiene is poor, and may cause open sores or ulcers, scaling rashes, redness and swelling.
The CDC notes that “people can also get sick from touching infected open sores or ulcers”.
Who is at risk from diphtheria?
There is a higher risk of spread of the disease in closed and crowded spaces. Communities with high vaccination rates have a lower risk.
Healthcare workers are also at increased risk in endemic settings and during outbreaks, the WHO says.
According to the world health body, diphtheria is treated with an antitoxin. Antibiotics are also given to eliminate bacteria and toxin production and to prevent transmission.
CDC says people with respiratory diphtheria are usually no longer contagious 48 hours after starting antibiotics, although follow-up testing is needed to confirm elimination of the bacteria.
Children should also be vaccinated against diphtheria. The NCDC recommends three doses during infancy, given at six, 10 and 14 weeks. Diphtheria-containing vaccines have been part of WHO’s Expanded Programme on Immunisation (EPI) since the programme was launched in 1974.
In Nigeria and many other countries, diphtheria vaccination is included in the pentavalent vaccine, which protects children against five diseases: diphtheria, pertussis, tetanus, hepatitis B and Hib disease.
Why are cases concentrated in northern Nigeria?
According to the NCDC, gaps in vaccination coverage have contributed to Nigeria’s diphtheria outbreak. The agency’s data covering epidemiological week 19 of 2022 to week three of 2026 showed that only 5,974 (14.3%) of 40,460 confirmed cases had received a diphtheria toxoid-containing vaccine. Children aged 5–9 years recorded the highest proportion of unvaccinated cases.
The NCDC says children need three doses of a diphtheria-containing vaccine during infancy, given at six, 10 and 14 weeks of age, to build protection against the disease. In Nigeria, the diphtheria vaccine is included in the pentavalent vaccine, which also protects against pertussis, tetanus, hepatitis B and Hib disease.
However, vaccination coverage has remained low in parts of northern Nigeria. Data from the 2024 Nigeria Demographic Health Survey showed that only 53% of children had received the third dose of the pentavalent vaccine. Coverage was lowest in the north-west at 39.7%, followed by 48.2% in the north-central and 53% in the north-east region.
The current surge in diphtheria cases reflects the large number of children who remain unvaccinated or under-vaccinated in Nigeria, Oladimeji Bolarinwa, a professor of Epidemiology and Public Health, told The ICIR.
“More than two million children have received no routine vaccines at all, while many others do not complete the recommended immunisation schedule. As a result, preventable diseases such as diphtheria will continue to affect vulnerable children because the population has not achieved sufficient herd immunity,” he said.
Diphtheria immunity can decline without adequate booster doses
“It is obvious that our vaccination programme is below par,” renowned virologist Prof. Oyewale Tomori told The ICIR.
“According to the WHO, Nigeria’s DPT (diphtheria, tetanus, and pertussis) vaccination coverage remains suboptimal,” Tomori said.
He also explained that vaccination does not provide lifelong protection against diphtheria, as immunity can wane over time. While babies and children need to complete the recommended primary vaccination series and childhood booster doses to develop and maintain strong immunity, protection against diphtheria can wane over time, which is why booster doses are recommended after the primary childhood vaccination series.
What health agencies are doing?
The NCDC says it is strengthening vaccination coverage and rapidly identifying and managing cases, and that reactive vaccination is currently being conducted in affected areas. It also said essential treatment and laboratory commodities are continuously being provided.
The agency urged state and local governments to identify communities with low vaccination coverage and intensify routine and targeted vaccination in affected underserved areas.
Governments must also ensure that children missing routine immunisation doses are reached and vaccinated.
“To curtail this surge, more children at risk need to be reached with diphtheria-containing vaccines, which provide the best protection against the disease,” Bolarinwa said.
“Appropriate public health strategies such as community mobilisation, mass vaccination, case finding and surveillance among populations with extremely low immunisation coverage are crucial.
Understanding the socio-cultural factors responsible for low coverage and the surge in diphtheria cases is important. Building trust in government and strengthening its presence in underserved communities can enhance acceptance of public health strategies,” he added.