Diphtheria Outbreak in Western Europe Linked to Migration Travel, Not Origin Countries

A comprehensive study published in the New England Journal of Medicine has shed light on the recent diphtheria epidemic affecting Western Europe. The largest outbreak in seven decades began in 2022, primarily among migrant populations, and continued into 2023, with cases identified across several countries including Austria, France, Germany, Switzerland, the Netherlands, and the UK. Notably, this outbreak was traced back to contaminations occurring during migratory journeys or within European reception centers, rather than in the migrants' countries of origin.

Despite the initial surge among migrants from Afghanistan and Syria, genetic analyses of the bacterial strains involved in the epidemic revealed a high genetic similarity across cases in different countries, indicative of a recent common source outside the country of origin. This suggests that the bacterium, responsible for diphtheria (Corynebacterium diphtheriae), has been silently circulating within Western Europe.

While vaccination programs have proven effective, the study emphasizes the importance of maintaining high immunity levels, especially among vulnerable groups such as migrants, homeless individuals, injecting drug users, and the elderly. Since the outbreak's start, 362 cases were reported in 2022, with 536 cases overall leading to at least three deaths, despite rapid intervention measures like contact tracing and screening.

The research analyzed 363 bacterial isolates from 362 patients across ten countries, predominantly affecting young males with a median age of 18. Most infections were cutaneous, with some severe respiratory cases. The findings underscore that the current epidemic is linked to exposure during migration or in reception environments, rather than in the countries of origin.

Epidemiologists highlight that the point of contact or crossing during migratory routes likely facilitated transmission. The high genetic proximity among strains suggests recent dissemination, emphasizing the significance of cross-border epidemiological surveillance and international cooperation. Public health recommendations include increasing vaccination coverage, improving access to healthcare for vulnerable populations, raising awareness among clinicians, and ongoing monitoring for antibiotic resistance.

As the epidemic continues to evolve, health authorities stress the importance of vigilance, especially among clinicians aware of diphtheria symptoms and at-risk groups. Enhanced collaboration and timely data sharing are vital to controlling the spread and preventing future outbreaks.

This investigation reflects the need for comprehensive public health strategies to protect vulnerable populations and prevent similar epidemics in the future.

Source: https://medicalxpress.com/news/2025-06-diphtheria-epidemic-western-europe-migration.html