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Diphtheria is a dangerous bacterial infection that can damage a person’s nose, throat, and occasionally skin. Corynebacterium species are the cause of it, primarily the toxin-producing Corynebacterium diphtheriae, but also, infrequently, strains of C. ulcerans and C. pseudotuberculosis.
An adhesive membrane covering the tonsils, throat, and/or nose is linked to the condition, which might present as laryngitis, pharyngitis, or tonsillitis.
About 25% of patients may experience heart issues (myocarditis) in addition to respiratory symptoms. Diphtheria antitoxin (DAT) and antibiotics are the cornerstones of diphtheria treatment.
Over the past five decades, the incidence of diphtheria has reduced dramatically worldwide because of widespread immunisation using a diphtheria toxoid-containing vaccine.
The number of Diphtheria cases reported to the World Health Organization (WHO) declined from about 100,000 cases in 1980 to less than 10,000 cases in 2021. Diphtheria is primarily controlled by the prevention of infection through high vaccination coverage.
This edition of Athena Perspectives brings to scene a data-driven analysis of diphtheria outbreak in Nigeria. It identifies the cause, mode of transmission, Symptoms and key challenges. while drawing from global best practices to recommend urgent policy reforms. The fight against diphtheria requires a quick and unified approach; one that prioritises early detection and equitable access to treatment.
Cause of Diphtheria
Corynebacterium diphtheriae: The primary cause of diphtheria is the bacterium Corynebacterium diphtheriae. This bacterium produces a toxin that can lead to the characteristic symptoms of the disease.
Mode of Transmission
The mode of transmission of diphtheria is the transfer of bacterium from an infected person to others. below are the key modes of transmission related to diphtheria:
• Human-to-Human Transmission: Diphtheria is primarily spread through respiratory droplets when an infected person coughs, sneezes, or talks. Close contact with an infected person can lead to the transmission of the bacterium.
• Contaminated Objects: Diphtheria bacteria can also survive on surfaces for a period, and touching contaminated objects or surfaces and then touching one’s mouth, nose, or eyes can lead to infection.
• Low Vaccination Rates: diphtheria is a major public health concern, but widespread vaccination efforts have significantly reduced it. Low vaccination rates or lack of access to vaccines can contribute to diphtheria outbreaks.
• Crowded and Unsanitary Conditions: Diphtheria is more likely to spread in overcrowded and unsanitary living conditions where close contact among individuals is common.
• Weakened Immune System: People with weakened immune systems due to underlying medical conditions, malnutrition, or certain medications may be more susceptible to diphtheria.
Diphtheria rarely occurs in the United States and Western Europe, where children have been vaccinated against the condition for decades. However, diphtheria is still common in developing countries where vaccination rates are low.
In the European Union/European Economic Area (EU/EEA) where diphtheria vaccination is usual, the disease is mainly a threat to unvaccinated people who travel internationally or have contact with people with diphtheria.
In Niger, as of March, 2024, Niger reported 4,273 suspected cases and 196 deaths. Of the confirmed cases, 191 (5%) were laboratory confirmed, 102 (2%) by epidemiological linkage, and 3,900 (93%) by clinical compatibility. A total of 59% of confirmed cases are female, 31% are vaccinated, and 64% are under 15 years old.
However, Mauritania reported 20 suspected cases, all confirmed by clinical compatibility, resulting in 6 deaths.
Recently, Gabon reported 29 suspected cases (20 in 2024), with 3 deaths, including two lab-confirmed cases. but regular monitoring and active case-finding are necessary. These associated low cases are attributed to a combination of vaccine coverage, Early recognition and laboratory confirmation, and the presence of antitoxin and antibiotics for treatment.
In Nigeria, there was an outbreak of diphtheria in Borno in 2011 with a total of 98 cases, and 21 deaths. However, a total of 1870 and 2289 cases were reported in the year 2018 and 2019, respectively, with an incidence rate of 9.4% and 11.3% per 1,000,000 total population.
In Katsina state, a total of 5–6 monthly cases of diphtheria were recorded between July and December in the year 2020. however, these cases were seen to be lower than those recorded in Borno.
However, From May 2022 to February 2025, A total of 41,978 suspected cases were reported from 37 states. Kano (24,062), Yobe (5,330), Katsina (3,939), Bauchi (3,066), Borno (3,035), Kaduna (777) & Jigawa (364) accounted for 96.6% of suspected cases reported.
Of the 41,978 suspected cases reported, 25,298 (60.3%) were confirmed cases (394 lab confirmed; 215 epid linked; 24,717 clinically compatible), 7,769 (18.5%) were discarded, 3,561 (8.5%) are pending classification & 5,350 (12.7%) were unknown.
Majority [16,125 (63.7%)] of the confirmed cases were among children aged 1 – 14 years. Only 4,981 (19.7%) out of the 25,326 confirmed cases were fully vaccinated with a diphtheria toxoid-containing vaccine. A total of 1,279 deaths were recorded among confirmed cases.
The confirmed cases were distributed across 26 states with Kano (17,931), Bauchi (2,334), Yobe (2,408), Katsina (1,276), Borno (1,139), Jigawa (53), Plateau (31) & Kaduna (44) accounting for 99.4% of confirmed cases reported and 99% death among confirmed cases.
This outbreak and the associated high case fatality were due to a combination of low vaccination coverage, delayed clinical recognition and laboratory confirmation, and the absence of antitoxin and antibiotics for treatment.
This, if not given immediate attention would escalate and put to a halt the activities of each affected state. Diphtheria is dangerous.
Symptoms
The most common type of diphtheria is classic respiratory diphtheria. The onset of signs and symptoms is usually from 2-5 days after exposure. Initial symptoms may be mild and include fever, runny nose, sore throat, cough, and red eyes (conjunctivitis). In severe cases, the bacteria produce an exotoxin that causes a thick grey or white patch (pseudo-membrane) on the tonsils and/or at the back of the throat. This can block the airway making it hard to breathe or swallow and causing a barking cough.
The exotoxin produced by the bacteria may also enter the bloodstream causing complications such as inflammation and damage of the heart muscle, inflammation of nerves, kidney problems, and bleeding problems due to decreased blood platelet count. The infection can also affect the skin.
Complications due to diphtheria usually occur in the second and third week following infection.
This includes corneal scarring, encephalitis, diarrhoea, pneumonia and subacute sclerosing panencephalitis. Case fatality ratios up to 10% have been reported in diphtheria outbreaks and are higher in settings where diphtheria antitoxin (DAT) is unavailable.
Key Issues and Challenges
• Low Vaccination Coverage
• In some regions, lack of access to vaccines, misinformation, or refusal to vaccinate leads to outbreaks.
• Booster doses are necessary for long-term protection, but many people miss them.
• Delayed Diagnosis and Treatment
• Symptoms resemble common throat infections, causing misdiagnosis or delayed medical intervention.
• Limited access to diagnostic facilities in rural areas worsens the issue.
• Antitoxin and Antibiotic Shortages
• Diphtheria antitoxin (DAT) is essential for treatment but is often in short supply, which has helped speed up the outbreak’s spread.
• Antibiotics like penicillin and erythromycin are necessary, but resistance and limited availability pose challenges.
• Outbreaks in Crowded and Poor Sanitation Areas
• Refugee camps, slums, and Crowded Areas face frequent outbreaks due to close contact and poor hygiene.
• Carrier Transmission
• Some people can carry Corynebacterium diphtheriae without symptoms and unknowingly spread the infection.
• Lack of routine screening makes it hard to detect and control carriers.
• Weak Healthcare Systems
• Some healthcare systems in Nigeria lack infrastructure, trained personnel, and resources to handle outbreaks effectively.
• Misinformation and Public Hesitancy
• Misinformation about vaccines, fear of side effects, and mistrust in healthcare systems hinder vaccination efforts.
Recommendations
The resurgence of diphtheria across Nigeria highlights the urgent need for comprehensive public health interventions. To effectively combat this outbreak in Nigeria, a multi-faceted approach is essential.
Strengthening vaccination campaigns, ensuring access to critical medical supplies, improving surveillance systems, fostering community engagement, and promoting regional collaboration will be key to controlling the spread. By implementing these strategies, Federal Ministry of Health, NCDC and National Health Care Development Agency can protect vulnerable populations and prevent future outbreaks.
• Enhance Vaccination Efforts: Low immunization coverage is a significant factor in the spread of diphtheria. vaccination rates are as low leaving many especially children, vulnerable. Prioritizing mass vaccination campaigns targeting unvaccinated populations is crucial.
• Ensure Access to Medical Supplies: Effective diphtheria treatment requires timely administration of diphtheria antitoxin (DAT) and antibiotics. Collaborative actions with international health organizations are essential to secure and distribute these critical supplies.
• Strengthen Surveillance and Response Systems: Robust disease surveillance is vital for early detection and containment. Enhancing laboratory capacities and training healthcare workers can improve case management and infection control.
• Foster Community Engagement: Addressing vaccine hesitancy and misinformation through community outreach and education can promote acceptance of vaccination and timely medical intervention.
Conclusion
Nigeria is at a crucial moment in its fight against the rise of diphtheria. The country can significantly improve the health of her citizens by making diphtheria vaccine mediately for children and diphtheria treatment available at healthcare centre across local government areas. Learning from successful global models (EU-EEA etc.) where the number of diphtheria cases are minimal or not in existence as a result of constant availability of vaccine, Federal Ministry of Health, NCDC and National Health Care Development Agency can implement policies that ensure early detection and treatment. The time to act is now.
Author:
Dede Oghenevwede
Data Analyst, Athena Centre for Policy and Leadership