The largest diphtheria outbreak in Western Europe in 70 years has been affecting vulnerable people such as migrants and homeless people since 2022.

Diphtheria is a highly contagious bacterial infection that can attack the respiratory tract and spread throughout the body, causing sore throat, fever, and other symptoms.

For unvaccinated people, it can be fatal in about 30% of cases, and it is more deadly for children, according to the World Health Organization.

In 2022, there was an unusual spike in the bacteria that causes diphtheria — Corynebacterium diphtheriae — in several European countries, especially among recently arrived migrants, according to a study in the New England Journal of Medicine.

This year, the European Centre for Disease Prevention and Control has recorded 362 cases.

Contact tracing and screening have helped to contain the outbreak, but rare infections continue to be reported, researchers warn.

Since the beginning of 2022, a total of 536 cases have been reported in Europe, including three deaths.

Samples from patients in 10 countries show that 98% of cases are in men with an average age of 18. Almost all were recent migrants.

"The epidemic, which has mainly affected migrants from Afghanistan and Syria, is not the result of people becoming infected in their countries of origin, but during their migration journeys or in their places of accommodation in European countries," said a joint statement by the French public health agency and the Pasteur Institute.

The genetic similarity between the strains observed in people from different countries suggests that there was a “recent point of contact outside the country of origin” at the source of the epidemic, the statement added.

The exact areas affected by the epidemic remain unclear.

The genetic link between the 2022 strain and the one detected in Germany this year indicates that the bacterium continues to circulate quietly in Western Europe.

Vaccination is highly effective in preventing diphtheria, and researchers have emphasized the importance of immunization programs for the general public. They also called on European countries to do more to ensure that their most vulnerable people avoid infection with the disease. This includes raising awareness of the symptoms among doctors and people who are in contact with migrants and homeless people, as well as increasing access to vaccines and antibiotics. | BGNES