Sexually transmitted shigella infections are rising sharply in the UK and US, with new research showing a 15% faster year-on-year growth between 2015 and 2020 compared with other transmission routes. By the end of the study period, upwards of 70% of sexually transmissible strains were resistant to at least one antibiotic, versus 40% among non-sexually transmitted strains.
UK diagnoses and expert warning
UK Health Security Agency (UKHSA) data recorded 2,560 transmissions via sexual contact over the past year, described as a 'sharp rise in laboratory diagnoses during 2025'. Professor Kate Baker, senior author of the study from Cambridge's Department of Genetics, said: '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.'
Sexually transmitted shigella, first identified in the US in 1974, has been rising in many western countries since the 2000s and is now considered 'endemic' among certain groups of men who have sex with men. Molecular biologist Shangxin Yang told CIDRAP News that hospital workers at the University of California, Los Angeles are now seeing roughly one case every month, whereas in 2022 only one was recorded all year.
Symptoms and antibiotic resistance
Dr Bhavini Shah, GP with LloydsPharmacy Online Doctor, explained that shigella is caused by bacteria found in faeces and can be passed on through sex involving faecal contact, including anal sex, fisting, handling a condom or sex toy used for anal sex, oral sex after anal sex, touching someone's backside or rimming. The infection commonly causes diarrhoea and vomiting, as well as abdominal pain and fever, according to Dr Shah. UKHSA notes some people also experience headaches and loss of appetite, with symptoms typically starting one to three days after exposure. Most recover within four or five days, but the illness can last up to two weeks, and in some cases symptoms can be more severe and may require hospital treatment.
In July, the US Centers for Disease Control reported that drug-resistant strains had risen from 0% in 2011 to 8.5% in 2023. In the UK, a 53% increase in antibiotic-resistant shigella cases was recorded from January to November 2023, with between 86% and 94% of samples tested by UKHSA researchers earlier this year showing resistance. The 2026 Cambridge study suggests 'bystander resistance' — where antibiotics given for another infection kill off gut bacteria, leaving behind only the strongest — may be a driver.
Treatment and prevention advice
Dr Shah advises contacting a GP or local sexual health clinic if symptoms appear, and recommends abstaining from sex until seven days after symptoms end, avoiding sharing bedding, towels, or clothing, avoiding preparing food for others, and washing hands often with soap and warm water. She also suggests working from home or taking sick leave until at least 48 hours after symptoms cease, especially for those handling food or working in healthcare.
To avoid contracting shigella, Dr Shah recommends 'good sexual hygiene', including washing hands after sex, sanitising sex toys, using a dental dam for anal rimming, and avoiding oral sex after anal sex. NHS guidelines also warn against drinking tap water or consuming ice cubes and raw vegetables washed in local tap water when travelling in countries with poor sanitation systems.
