Western Europe is facing its worst diphtheria outbreak in seven decades, with more than 500 confirmed cases since 2022, a new study suggests. The findings published in the New England Journal of Medicine have revealed that migrants and homeless populations are among the frequently infected.
Diphtheria is a bacterial infection caused by Corynebacterium diphtheriae that targets the respiratory system. Symptoms include fever, sore throat, and swollen lymph nodes. The disease can be fatal in up to 30% of cases, especially in unvaccinated individuals.
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According to the researchers, the 2022 outbreak saw an unusual spike, with 362 diphtheria cases reported across various European nations. Since then, the total has climbed to 536 cases, including three deaths. Nearly all affected individuals were young males, averaging 18 years old, with recent migration histories.
“The outbreak, which mainly affected migrants from Afghanistan and Syria, was not the result of people being infected in their countries of origin, but during their migration journeys or in their places of accommodation in European countries,” said a joint statement from France’s public health agency and the Pasteur Institute.
Additionally, the team also found a genetic link between the 2022 outbreak strain and cases reported in Germany in 2025, suggesting that the bacteria “continues to circulate quietly in Western Europe”. However, the exact geographic scope of the outbreak remains uncertain.
Amid the surge in diphtheria cases, the researchers emphasised the importance of immunisation programs among high-risk groups. The team also urged European nations to increase awareness about the infection and provide access to vaccines and antibiotic drugs.
