Casualties of Diphtheria have been rising steadily since its outbreak was first recorded this year. African Health Report (AHR)’s Juliet Jacob Ochenje spoke with eminent Professor of Virology and infectious diseases expert, educationist and ex-Regional Virologist for the WHO, Africa Region, Oyewale Tomori, on issues surrounding diphtheria in Nigeria.
Diphtheria cases in Nigeria have risen significantly since the beginning of 2023, with about 21 out of the 36 States and the Federal Capital Territory recording a total of 557 cases, according to the World Health Organisation (WHO).
During the initial outbreak in February this year, eminent Professor of Virology and infectious diseases expert, educationist and ex-Regional Virologist for the WHO, Africa Region, Oyewale Tomori, spoke exclusively with Africa Health Report (AHR) on all that’s to know about the disease. Read here
As more people fill up healthcare facilities in search in search for medical attention, AHR spoke with Prof. Tomori again, this time on efforts that have been made so far to address the outbreak of the disease and its spread can be stopped.
Unvaccinated children responsible for outbreak…
The Professor explained that the outbreak of the disease started in May, 2022 with isolated cases of the disease in different parts of the country which were not captured. According to him, because new cases are now being reported in health centres with better facilities and laboratory support, there is more awareness of its existence.
He attributed the rising cases to children who did not take vaccines for the disease in past years, saying even if the first set of reported cases had been immunised after the incident, there will still be infections because many more did not get immunised and remain susceptible to the disease.
Prof. Tomori, therefore, expressed hope that President Bola Ahmed Tinubu and his advisers will provide adequate funding for the health sector and ensure that it is disbursed with ”accountability and transparency.”
Quoting data from the Nigeria Centre for Disease Control (NCDC), Prof. Tomori said ”indeed, the diphtheria outbreak actually started way back in May 2022.”
According to NCDC, Epi-week 19 2022 – Epi-week 09 2023 record show that a total of 1,064 suspected cases of diphtheria were reported from 21 states.
The breakdown of the outbreak according to states are Kano 843, Yobe 86, Katsina 46, Lagos 22, Sokoto 14 and Zamfara 13.
The record also show that out of the 1,064 suspected cases reported, 389 (36.6%) were confirmed as 45 were lab confirmed, 343 clinically compatible and 1 was epidemiologically linked.
About 322 (30.3%) were discarded, 201 (18.9%) are pending classification and 152 (14.3%) unknown.
The confirmed cases were distributed across 24 LGAs in six (6) states, while majority of 305 [78.4%]) of the confirmed cases occurred among children aged 2 – 14 years.
A total of 62 deaths were recorded among all confirmed cases (CFR: 15.9%) and only 60 (15.4%) out of 389 confirmed cases were fully vaccinated with a Diphtheria toxin-containing vaccine.
Protection against diphtheria
Tomori explained that the disease is everywhere, or rather the causative agent – Corynebacterium diphtheriae – is everywhere available to infect the vulnerable and unprotected.
He explained that “the disease is usually spread between people by direct contact, through the air, or through contact with contaminated objects.
“Human-to-human transmission of diphtheria typically occurs through the air when an infected individual coughs or sneezes. Breathing in particles released from the infected individual leads to infection.”
The virology expert added that contact with any lesions on the skin can also lead to transmission of diphtheria, but this is uncommon.
He, therefore, advised everyone to “avoid contact with an infected person. However, since it can be spread also through the air through the coughing of an infected person, the best method of prevention is by vaccination with the diphtheria vaccine which is effective for prevention and available in a number of formulations.”
Three or four doses, given along with tetanus vaccine and pertussis vaccine, are recommended during childhood, he further said, adding that “further doses of diphtheria–tetanus vaccine are recommended every ten years.”
Age group at risk of diphtheria
Prof. Tomori also disclosed that diphtheria develops mostly in children under 15 years old or in people over 40 years old.
According to him, there is 5% to 10% fatality in children under five years and in adults over 40 years, the fatality rate may be as much as 20%.
World Health Organisation (WHO) risk assessment
According to World Health Organisation (WHO), diphtheria cases are under-reported in Nigeria, with few reports of outbreaks in the past. This corroborates the earlier disclosure by Prof. Tomori that cases of the disease existed in several parts of the country but were not being recorded.
It said, “The last outbreak was reported between February and November 2011 in the village of Kimba and its surrounding settlements in Borno State, north-eastern Nigeria, where 98 cases were reported.”
The WHO added that “the diphtheria toxoid-containing vaccine third dose coverage in Nigeria is suboptimal. According to the 2021 Nigeria Multiple Indicator Cluster Survey (MICS) and National Immunisation Coverage Survey (NICS), the third dose of pentavalent vaccine coverage was 57% in 2021.”
WHO also added that the country is currently faced with several public health emergencies such as Lassa fever, cholera, mpox, meningitis and a humanitarian emergency in the northeast of the country but due to insecurity, especially in north-eastern Nigeria, vaccination coverage remains suboptimal, especially in the areas controlled by non-state armed groups.
Therefore, the outbreak of diphtheria further complicates and strains the already overstretched resources. The global supply of diphtheria antitoxin (DAT) is limited, and this may affect the availability of the required doses in a timely manner.
The overall risk of diphtheria in Nigeria was assessed as high at the national level, low at the regional level, and low at the global level.
WHO advice on diphtheria
WHO, however, recommended that epidemiological surveillance ensuring early detection of diphtheria outbreaks should be in place in all countries, and all countries should have access to laboratory facilities that allow for the reliable identification of toxigenic C. diphtheriae.
WHO further recommended early reporting and management of suspected diphtheria cases to initiate timely treatment of cases and follow-up of contacts and ensure the supply of diphtheria antitoxin.
As vaccination is key to preventing cases and outbreaks, high-risk populations such as children under five years of age, schoolchildren, close contact of diphtheria cases, and healthcare workers, should be vaccinated with diphtheria-containing vaccines on a priority basis. A coordinated response and community engagement can support control of the ongoing outbreak.
