Small boat crossings have led to a “sharp increase” in diphtheria cases in the UK and across Europe, according to scientists.

Researchers at the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) said outbreaks seen across the continent over the past year have been “mostly linked to incoming migrants”.

Diphtheria, a highly contagious bacterial infection which can be fatal, is rare in the UK because babies and children have been routinely vaccinated against it since the 1940s.

The ESCMID report for England uses figures from the UK Health Security Agency (UKHSA), and is based on genomic testing of hundreds of cases across 10 countries in Europe, including 59 in England.

It highlights how 73 cases of the disease were recorded in England in 2022 overall – up from 12 cases the previous year – and one further case was recorded in 2023.

Most of the patients (97%) were “young Afghan males” aged under 18 with “unknown vaccination history” – although the UKHSA notes that this group may be “over-represented” due to “greater clinical awareness and case ascertainment” among the demographic.

Around half of those infected (51%) presented with skin problems caused by the disease, which can include blisters on the legs, feet and hands, and large ulcers.

Some 12% had no symptoms, and the disease in these cases was picked up through screening or contact tracing.

The authors said: “Linked to an increase in migrant arrivals via small boat in the summer of 2022, the UK experienced a sharp increase in diphtheria cases caused by toxigenic Corynebacterium diphtheriae last year.”

Speaking about data for Europe as a whole, they said there had been “evident transmission among migrant people” which they believed had occurred “during travel within migrant facilities”.

Migrant Channel crossing incidents
A report has linked a ‘sharp rise’ in diphtheria cases in the UK to small boat crossings (Gareth Fuller/PA) 

They added that “a lack of proper vaccination among the migrant people” was the reason for the outbreaks.

To avoid future diphtheria outbreaks, the researchers recommended “increased awareness among physicians who provide care to migrants”, “thorough vaccination protocols” and “timely screening of at-risk individuals”.

They added: “Further monitoring of this situation using molecular typing and genomic approaches will be key to define the source and routes of this resurgence.”

The research was led by Dr Helena Seth-Smith, from the University of Zurich, and Dr Sylvain Brisse, of the Institut Pasteur in Paris, who worked with scientists from across Europe including at the European Centres for Disease Control and Prevention.

The ESCMID said the report has been peer-reviewed, but it has not yet been submitted to a medical journal for publication.

The data was published at the European Congress of Clinical Microbiology and Infectious Diseases.