Rapid #risk #assessment, acute event of potential public health concern: #Diphtheria, #Africa Region (#WHO, March 20 '26)

{Summary)

Risk statement

-- This WHO Rapid Risk Assessment (RRA, v2) aims to assess the risk of diphtheria at the regional level, considering the public health impact, the risk of geographical spread and the risk of insufficient control capacities with available resources. 

-- Diphtheria is a major public health problem in the WHO African Region (AFR) despite significant efforts on immunization in the past decades (e.g. introduction of DTP vaccine in the Expanded Program on Immunisation in 1974). 

-- Between 2000 and 2024, 75 789 diphtheria suspected cases were reported across the Region with an average 3 500 cases per year.    

-- Between the beginning of 2025 and as of 1 March 2026, over 29 000 suspected diphtheria cases with 1 420 deaths (CFR 4.9%) have been reported across these eight countries: Algeria, Chad, Guinea, Mali, Mauritania, Niger, Nigeria and South. 

-- This represents a 67% increase in the number of suspected cases (11 749 additional cases) and a 59.4% increase in the number of deaths (529 additional deaths) reported since the last WHO RRA (v1) conducted in October 2025, Nigeria continues to account for the majority of suspected cases (62.6%) and deaths (66%) in the Region. 

-- Of the 18 130 total confirmed cases (clinically compatible, laboratory-confirmed and epidemiologically linked) across the eight affected countries, 752 (4%) cases were recorded as laboratory-confirmed: Algeria (8), Chad (1), Guinea (48), Mali (66), Mauritania (12), Niger (313), Nigeria (211) and South Africa (93).     

-- Case data trends from 2026 have been difficult to interpret, with extremely delayed case reporting from countries (both to the national and regional levels), and instances of under-reporting also being notified, particularly from humanitarian settings. 

-- However, a lower number of cases are being consistently reported than earlier in the outbreak and thus it appears that new cases continue to decline or plateau, as seen in half of the affected countries (Chad, Mali, Mauritania, and Nigeria).    

-- Since the first WHO RRA (v1) conducted in October 2025, the regional CFR remains around 5%. 

-- While Guinea continues to report among the highest CFRs in the region at 19%, South Africa’s CFR has increased since the last WHO RRA (v1) to 19%.  

-- Children aged 5–14 yrs (57%) and females (63%) are the most affected; where information is available on the vaccination status of cases, most cases are unvaccinated, under-vaccinated, or with unknown vaccination status.   

-- While the overall risk was previously assessed as “HIGH” at the regional level in October 2025, it is now considered “MODERATE” due to:  

• Overall declining trend in number of weekly cases regionally, with country-specific trends also declining in half of the affected countries (Chad, Mali, Mauritania and Nigeria), and only sporadic cases reported from South Africa. 

• Strengthened coordination of public health response through the activation of an Incident Management System (IMS) in most of the affected countries. A joint Regional Office for Africa (AFRO) and WHO headquarters (HQ) IMS structure was activated to support the regional coordination of the response, with high-level ministerial commitment to controlling the outbreaks in the affected countries.  

• Implementation of immunization activities as part of the outbreak response in most of the affected countries. 

• Strengthening of surveillance, case management, community sensitization, through capacity building activities, and the provision of diphtheria antitoxin (DAT), antibiotics, laboratory supplies, etc.  

-- Nonetheless, some challenges continue to prevent the effective containment of these outbreaks:  

• The complex humanitarian situation in many of the affected countries continues to contribute to poor access to immunization and healthcare services for internally displaced persons (IDPs), nomads, miners, and migrants. Unsanitary living conditions (in displacement camps) are also favouring the transmission of diphtheria. These increase the exposure risk of vulnerable groups (particularly women and children) to diseases.   

• Limited laboratory confirmation due to lack of reagents, sample transportation challenges and limited available of laboratory capacity.  

• In most of the affected countries, the annual coverage for routine diphtheria vaccination remains below the national targets thereby contributing to the resurgence of cases and outbreaks.  

• Global scarcity of DAT for the treatment of affected persons. 

• High internal and cross-border movements of susceptible individuals (unvaccinated or not fully vaccinated). 

• Persistent funding challenges across most affected countries exacerbated by the current challenging international funding landscape.  

-- The overall risk at the global level remains ‘’LOW’’ due to: 

- The global risk of diphtheria outbreaks from the ongoing multi-country diphtheria outbreak in the African region is assessed as low, given the existence of routine immunization programs in most countries. 

- Nonetheless, the risk posed by international travel of susceptible populations from the WHO African Region cannot be overlooked, highlighting the need to strengthen risk communication, demand generation and reactive immunisation, as well as the need for enhanced data sharing and surveillance globally. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---diphtheria--african-region-v.2

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#Diphtheria - #Africa Region (#WHO, D.O.N., Nov. 21 '25)

{Excerpt}

Diphtheria is a major public health problem in the WHO African Region despite substantial efforts on immunization activities over the past three decades. 

Between 2000 and 2024, 75 789 suspected diphtheria cases were reported in the Region, with the majority reported from 2023 to 2024, when Algeria, Chad, Gabon, Guinea, Mali, Mauritania, Nigeria, Niger, and South Africa reported a resurgence of diphtheria outbreaks with approximately 57 000 suspected cases and 2 000 deaths (case fatality ratio (CFR) of 3.5%) recorded. 

The countries most affected were Guinea, Nigeria and Niger. 

Most cases reported were in children under fifteen years and female. 

Over 50% of suspected cases were non-vaccinated or with unknown vaccination status. 

In 2025, as of 19 October 2025, over 17 000 suspected diphtheria cases and about 900 deaths with an average CFR of 5.1% have been reported across eight Member States in the African Region; Algeria, Chad, Guinea, Mali, Mauritania, Niger, Nigeria, and South Africa.

Of these suspected cases, 7 886 were confirmed through laboratory testing, epidemiological linkage, or clinical compatibility. 

Laboratory-confirmation has been conducted in 6.8% (n=1181) of the suspected cases. 

Women, children aged between 5 and 18 years and young adults less than 30 are the most affected groups. 

The situation seems to have worsened in Mali, Mauritania and Niger in recent weeks with increasing trends and geographic expansion of the outbreaks reported in these countries. 

In addition, high CFRs (up to 24%) have been reported across all affected countries.   

The overall public health risk posed by the diphtheria event in the African Region is classified as ‘’high’’ due to:

-- Significant risks of further widescale spread:

- The humanitarian profile of some of the affected countries (Chad, Mali, Niger, Nigeria): fragile, conflict-affected and vulnerable settings, with low vaccination coverage often recorded among displaced populations.

- Outbreak hotspots are sometimes located in hard-to-reach areas with security constraints. 

- Crowded, unsanitary living conditions in displacement camps in humanitarian settings.

- Low routine immunization coverage in most affected countries and important heterogeneity in coverage at subnational level in a number of countries - with pockets of under-vaccination leading to outbreaks (e.g. Nigeria, Chad etc.).

- Disruptions caused by the COVID-19 pandemic, causing significant drop of vaccination coverage between the first and the third dose across all affected countries. Although in response to declining immunization coverage, global partners launched The Big Catch-up, a coordinated effort to restore and strengthen immunization services and close immunity gaps, especially for vaccine-preventable diseases such as diphtheria.

- Weak health system capacity in most affected countries (shortage of health professionals, low clinical management capacity, etc.). 

- Shortage of laboratory supplies reported by most affected countries, leading to delays in case reporting and laboratory confirmation. 

- Global shortage of diphtheria anti-toxin (DAT) necessary for the treatment of affected persons. 

- High case fatality ratio observed in many of the affected countries.

- High internal and cross-border movements of susceptible individuals (unvaccinated or not fully vaccinated). 

- Insufficient resources to control the outbreaks across most affected countries.

The overall public health risk posed by the diphtheria event at the global level is classified as ‘’low’’ due to:

-- The global risk of diphtheria outbreaks from the ongoing multi-country diphtheria outbreak in the African Region is assessed as low, given the existence of routine immunization programs in most countries. 

- Nonetheless, the risk posed by international travel of susceptible populations from the African Region cannot be overlooked, highlighting the need to strengthen risk communication and surveillance globally. 

(...)

Source: 

Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---diphtheria--african-region-v.1

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#Corynebacterium diphtheriae #Outbreak in #Migrant Populations in #Europe

Abstract

Background

A surge of cases of Corynebacterium diphtheriae infection was observed in reception centers for migrants in Europe beginning in the summer of 2022. Most of the cases were cutaneous, although some respiratory cases as well as one death were reported. A pan-European consortium was created to assess the clinical, epidemiologic, and microbiologic features of this outbreak.

Methods

We assessed cases of toxigenic C. diphtheriae infection that were reported in 10 European countries from January through November 2022. Data regarding countries of origin and transit routes were obtained from interviews with the patients. Whole-genome sequencing and antimicrobial-susceptibility testing were performed on bacterial isolates that were obtained from the patients. The phylogenetic relationships of the isolates and their antimicrobial-resistance genes were evaluated.

Results

A total of 363 toxigenic C. diphtheriae isolates were identified among 362 patients during the study period. Clinical data were available for 346 patients (95.6%): 268 (77.5%) had cutaneous diphtheria, 53 (15.3%) had respiratory diphtheria (11 [3.2%] had a pseudomembrane), and 9 (2.6%) had both respiratory and cutaneous symptoms. Four major genetic clusters were identified, which indicated the multiclonal nature of the outbreak. The ermX gene (which codes for erythromycin resistance) and the pbp2m and blaOXA-2 genes (which code for beta-lactam resistance) were detected in a subgroup of isolates. Isolates that carried ermX were resistant to erythromycin, and isolates that carried pbp2m were resistant to penicillin but were susceptible to amoxicillin. On the basis of the genomic variation within the four genetic clusters, their most recent common ancestors were estimated to have existed between 2017 and 2020.

Conclusions

The distribution of each genetic cluster of C. diphtheriae isolates across multiple countries in Europe showed repeated cross-border spread. The large number of C. diphtheriae infections among migrants is a cause for concern, particularly given that antimicrobial-resistance phenotypes threaten the efficacy of first-line treatments. (Funded by the Bavarian State Ministry of Health, Care, and Prevention and others.)

Source: The New England Journal of Medicine, https://www.nejm.org/doi/full/10.1056/NEJMoa2311981?query=TOC

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