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BACKGROUND Diphtheria is a rare vaccine-preventable disease in Germany, but since 2022 Corynebacterium diphtheriae cases have increased following an outbreak among newly arriving migrants. AIM We described epidemiological trends and differences between C. diphtheriae and C. ulcerans cases. METHODS We included laboratory-confirmed (toxigenic or tox gene positive) diphtheria cases and cases epidemiologically linked to laboratory-confirmed cases in Germany in 2017–2025. Enhanced surveillance data were available for a subset of cases in 2017–2022. We analysed cases by species assessing clinical, demographic and epidemiological characteristics descriptively, with chi-square and Fisher’s exact tests. RESULTS Overall, 512 diphtheria cases were reported (346 C. diphtheriae ; 166 C. ulcerans ; incidence: 0.07/100,000 population) including five deaths (three C. diphtheriae , two C. ulcerans , all reported since 2022). Of these, 460 (90%) cases had cutaneous, 30 (6%) respiratory and 22 (4%) double manifestation. Four epidemiological phases were identified. Acquisition of C. diphtheriae shifted from predominantly migration-associated (232/261) in 2022–2023 to autochthonous transmission (35/54) in 2024–2025. Autochthonous C. diphtheriae cases were older and more often hospitalised than imported cases (≥ 45 years: 23/45 vs 19/283; p < 0.001; hospitalisation: 36/45 vs 83/283; p < 0.001). All C. ulcerans cases were autochthonous and 70 of 89 (79%) reported contact with companion animals. CONCLUSION Diphtheria is re-emerging in Germany. Double manifestations warrant attention, being almost as common as respiratory manifestations. Clinicians should be aware of the disease to facilitate prompt diagnosis and treatment. Preventing severe cases and further transmission requires strengthening routine and catch-up vaccination services, particularly for older individuals and people experiencing homelessness.
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Schneider et al. (2026) studied this question.
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