A nationwide genomic epidemiology study involving a researcher from Kingston University has revealed that sexually transmitted Shigella sonnei is spreading faster, over greater geographic distances and with higher transmission intensity than non-sexually transmitted strains in England.<\/p>\n
Published in The Lancet Infectious Diseases and led by the University of Cambridge and UK Health Security Agency (UKHSA), the study provides the most detailed mapping to date of how\u00a0Shigella – traditionally known as a food and water-borne intestinal infection – has evolved into a rapidly circulating, drug-resistant sexually transmitted infection (STI) primarily affecting sexual networks of gay, bisexual, and other men who have sex with men.<\/p>\n
Shigella, most commonly found in feces and contracted through contaminated food, can cause severe diarrhea, fever and stomach cramps.<\/p>\n
UKHSA figures show that there were more than 2,500 cases of sexually transmitted Shigella in England in 2025, up from just over 2,000 in 2023.<\/p>\n
The study analyzed 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.<\/p>\n
The study also found that 70 per cent of sexually transmitted Shigella strains were resistant to at least one clinically relevant antibiotic, compared with 40 per cent of non-sexually transmitted cases and 49 per cent of cases contracted while travelling.<\/p>\n
Historically, public health agencies relied on basic hygiene messages, such as washing hands and avoiding contaminated food or water, to curb outbreaks.<\/p>\n
However, researchers, including Lecturer in Biological Sciences at Kingston University, Dr Lewis Mason, stress these standard infection-prevention measures are largely ineffective against the sexual transmission of Shigella via direct or indirect oral-anal contact during sex.<\/p>\n
To control the spread of drug-resistant shigellosis, the researchers surmised it’s imperative that alternative interventions, such as effective vaccines, microbiological clearance pathways, and tailored treatment guidelines, are urgently developed in partnership with patient communities.<\/p>\n
Discussing the study’s findings, Dr Mason said it highlighted the need to better manage antimicrobial stewardship across pathogens at a public health level. “We have found a worrying increase in cases of antibiotic-resistant Shigella being transmitted sexually, and there isn’t enough public awareness or effective interventions out there currently to stop the spread of this infection – particularly with Shigella becoming resistant to more antibiotics.”<\/p>\n
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