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Risk statement
Diphtheria remains a public health threat in the WHO African Region. Since 1 March 2026, transmission has continued in Chad, Guinea, Mali, Mauritania, Niger, Nigeria and South Africa, and a new outbreak has been detected in Senegal.
The current situation in Algeria could not be assessed as no updated epidemiological information for 2026 was available when this RRA was performed.
Most recent incidence data came in week 32/2026 (ending 9 August 2026) from Senegal, reporting 12 laboratory-confirmed diphtheria cases, including two deaths, reported between 21 July and 10 August 2026.
Based on the most recent information available through epidemiological week 33 of 2026, Nigeria continues to report the largest number of cases (68% of all cases).
Guinea has reported a recent increase in morbidity and mortality, with over 100 recorded deaths and a persistently high case fatality ratio (CFR) of 15.8%.
Geographically extensive transmission is reported in Mauritania and Niger, as well as new cases identified in Senegal.
Mali has reported cases across several regions, although incidence has declined substantially.
In Niger, the number of cases and deaths reported, and the CFR remain lower than during the corresponding period of 2025.
South Africa continues to report clusters and sporadic respiratory cases, albeit with good contact tracing and case investigation.
Comparisons across countries should be interpreted cautiously because reporting periods, case definitions and classification practices differ.
National authorities, WHO and partners continue to implement coordination, surveillance, laboratory testing, vaccination, case and contact management, and risk communication and community engagement activities. However, persistent population-immunity gaps, very low laboratory confirmation rates in most countries, delayed and incomplete reporting, uneven access to timely treatment (antibiotics and diphtheria antitoxin (DAT)), insecurity, displacement and population movements continue to impede outbreak control.
Assuming that no additional interventions are implemented beyond those already in place, transmission is likely to persist, with the potential for further spread among susceptible populations and continued severe outcomes where case detection, referral and treatment are delayed.
The overall risk at the regional level is assessed as moderate, unchanged from RRA v2.
Factors sustaining the risk include:
• Ongoing transmission in eight countries (Chad, Guinea, Mali, Mauritania, Niger, Nigeria, Senegal, and South Africa), indicating persistent circulation across the Region.
• In Nigeria, the epidemic is highly geographically concentrated, with 90% of reported cases originating from Kano, Bauchi, Katsina, Borno and Sokoto States.
• In Guinea, recent increases in cases and deaths and a persistently high CFR potentially indicate continuing gaps in early detection, timely referral, and access to appropriate treatment.
• Geographically extensive transmission in Mauritania and Niger, as well as continued transmission across several regions of Mali, including in settings affected by insecurity, displacement, population movements, and limited access to health services.
• Persistent gaps in primary vaccination and limited booster-dose coverage, leaving susceptible cohorts among older children, adolescents, and adults, particularly within displaced, mobile, and hard-to-reach populations.
• Decline in the coverage of DTP1 (76% in 2024 to 67% in 2025) and DTP3 (74% in 2024 to 65% in 2025) in South Africa – according to WHO/UNICEF estimates released in July 2026.
• Low laboratory confirmation rates, due to limited laboratory supplies, lack of reagents, challenges with sample collection and shipment, and shortages of trained personnel.
• Delayed and incomplete reporting, retrospective reporting, and inconsistent use of standard case definitions and case classification across affected countries, which constrain timely detection and interpretation of epidemiological trends.
• Limited availability of diphtheria antitoxin (DAT) in national stocks, hindering appropriate clinical care for respiratory diphtheria.
• Limited availability of specialized trained clinical and laboratory personnel
• Cross-border population movements and gaps in information exchange, which sustain the risk of spreading between neighbouring countries.
These concerns are moderated by established national coordination and response mechanisms and continued technical and operational support from WHO and partners. Incidence has declined substantially in Mali, while the number of cases and CFR reported in Niger remain lower than during the corresponding period of 2025. However, cases in Guinea remain higher than in the comparable period in 2025. Declining or relatively stable trends have also been observed in some other affected countries.
Surveillance, case investigation, contact management, laboratory testing, reactive vaccination and catch-up activities continue, although their implementation and performance vary across countries. Case-management capacity has been strengthened and essential supplies distributed in selected settings, while risk communication and community engagement activities remain ongoing.
Although transmission persists and localized cross-border spread remains possible, despite Senegal reporting cases, available information does not indicate widespread regional acceleration or sustained transmission in additional countries.
The risk at the global level is assessed as low, unchanged from RRA v2. Reported transmission remains concentrated in affected countries in the WHO African Region, with no documented sustained transmission beyond the Region. Nevertheless, international spread through travel and population movements remains possible, particularly among susceptible populations.
Confidence in the assessment is moderate because of low laboratory confirmation in most settings, differences in reporting periods and case definitions, retrospective reporting and reclassification, and delayed or incomplete reporting from some countries.
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Source:
Link: https://www.who.int/publications/m/item/who-rapid-risk-assessment---diphtheria--african-region-v.3
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