Diphtheria: A "significant" epidemic spread in Western Europe among migrants in 2022-2023

Vigilance against diphtheria is essential in Western Europe. This is the conclusion of a study published this Tuesday, June 3, in the New England Journal of Medicine (NEJM). As researchers, including French researchers from the Pasteur Institute and Public Health France, explain, the epidemic of this disease, "the most significant in Western Europe in 70 years," was spread by vulnerable people.

It "was declared in 2022 among migrants and spread in 2023 to other vulnerable populations in several European countries, resulting from contaminations occurring during migratory journeys or in European destination countries, and not in the countries of origin," we can read in a press release.

Diphtheria is a disease that develops after contamination by bacteria. It manifests itself as a respiratory infection "which causes damage to the central nervous system, throat or other organs, leading to death by asphyxiation" according to the Pasteur Institute . More frequent and less serious forms of skin infections are also noted.

Data analyzed by the researchers based on 362 patients in ten European countries shows that 98% of those sampled were men, with a median age of 18 years, the vast majority of whom (96%) had recently migrated to Europe.

The epidemic mainly affected migrant populations from Syria and Afghanistan , but their contamination did not occur in their countries of origin, "but during migratory journeys or in places of accommodation in European countries," this study reveals.

"The most likely hypothesis is that this point of contact is one or more places frequented by migrants during their journey from their country of origin or in the destination countries," the epidemiologists further explain.

The exact extent of the epidemic among these vulnerable individuals could not be determined due to the low number of tests conducted in this population. However, the researchers believe that "the bacteria continues to circulate quietly in Western Europe."

What lessons can be learned from this study? Public health experts are calling for improved health care to support these vulnerable populations. The findings "highlight the need to strengthen infectious disease surveillance in vulnerable populations, improve access to care and vaccination for migrant populations," and monitor the emergence of antibiotic-resistant bacteria with increased vigilance.

Isabelle Parent du Châtelet, a representative of the French Public Health Agency, emphasizes the importance of vaccination in the general population and particularly among these groups, including the homeless, drug users, and people with comorbidities.

In France, protection against diphtheria is included in the so-called "DTP" vaccine, diphtheria, tetanus, and polio. This vaccine is mandatory (two doses) for all children born after January 1, 2018. In France, protection against diphtheria has been mandatory since 1938. It is particularly effective since barely 69 cases were observed in the country during the decade 2010-2020, all imported, with associated deaths.