Sexually transmitted gut infection shigella a 'distinct public health threat' to UK, experts warn

Sexually transmitted cases of bacterial gut infection shigella are spreading rapidly, a study has found - with experts warning of a "distinct public health threat".

Shigella cases transmitted through sexual contact spread more than twice as fast in terms of distance as other strains of the infection and are becoming increasingly resistant to treatment, according to a study led by the University of Cambridge and the UK Health Security Agency (UKHSA).

Shigella, the bacteria behind dysentery, is most commonly found in faeces and contracted through contaminated food and causes diarrhoea, stomach cramps and fever.

Certain strains - specifically shigella sonnei and shigella flexneri - can be spread through sexual contact, primarily among gay and bisexual men.

UKHSA figures show that there were 2,560 cases of sexually transmitted shigella in England in 2025, up from 2,052 in 2023.

The study, published in the Lancet Infectious Diseases journal, analysed 3,514 samples of shigella from people over the age of 16 in the UK between 2004 and 2020.

Over a two-and-a-half-year period, the sexually transmitted shigella strains were found to spread an average distance of 117km, compared with 46km for non-sexually transmitted strains.

The study also found that 70% of sexually transmitted shigella strains were resistant to at least one clinically relevant antibiotic, compared with 40% of non-sexually transmitted cases and 49% of cases contracted while travelling.

Researchers said the findings show "the distinct and intensifying sexual transmission of shigellosis, highlighting the urgent need to address sexually transmissible shigellosis as a distinct health threat".

Professor Kate Baker, from the University of Cambridge's Department of Genetics, said: "Many men who have sex with men are unaware of the serious and increasing risk posed by sexually transmitted shigella.

"Sexual infection is now a sustained part of shigella transmission in the UK.

"It is vital that this message reaches the communities most affected, so we can help to prevent the spread."

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Prof Baker added: "If you start to feel unwell, or are recently recovering from a scary bout of diarrhoea, do not engage in sexual activity until two weeks after you're fully recovered, mention your sexual history to your doctor if you seek medical care, and ask about having a full sexual health screen."

Marc Tweed, from the Terrence Higgins Trust, said the "growing problem" of shigella among some sexual networks is "a real cause for concern" and urged anyone who thinks they might have shigella to contact their local sexual health clinic.

(c) Sky News 2026: Sexually transmitted gut infection shigella a 'distinct public health threat' to UK, experts wa