A sexually transmitted bacterial infection causing severe diarrhea is emerging as a significant public health concern in the United Kingdom, with experts warning that it is becoming increasingly difficult to treat due to antibiotic resistance.
Researchers have identified a surge in sexually transmitted shigellosis, a gut infection caused by shigella bacteria, which has seen a 24.8% increase in diagnoses in England between 2023 and 2025. The UK Health Security Agency reported a rise from 2,052 to 2,560 suspected cases in that period, with over half occurring in London. The infection can lead to severe diarrhea, often with blood, stomach cramps, fever, and vomiting. Globally, shigellosis causes over 200,000 deaths annually, primarily due to dehydration, intestinal perforation, and malnutrition.
While shigellosis is typically spread through contaminated food or surfaces, scientists have found it is increasingly transmitted through sexual contact, particularly among gay and bisexual men. This transmission route is attributed to the bacteria's ability to spread through contact with feces during anal sex.
Rising Antibiotic Resistance
A study published in The Lancet Infectious Diseases analyzed Shigella sonnei samples collected across the UK between 2004 and early 2020. The research found that sexually transmitted strains of the bacteria are spreading more rapidly and over greater distances than other forms of the infection. Approximately one-third of the analyzed cases were classified as likely sexually transmitted among men who have sex with men.
Crucially, sexually transmitted cases are showing significantly higher rates of antibiotic resistance compared to infections acquired through other routes. Around 70% of sexually transmitted infections were resistant to at least one key antibiotic, such as ciprofloxacin, azithromycin, and ceftriaxone, compared to 40% of other acquired infections and 50% of travel-related cases. This growing resistance has led researchers to describe the infection as "virtually untreatable with drugs."
Distinct Public Health Threat
Researchers noted that sexually transmitted shigellosis presents a "distinct and intensifying" transmission pattern that requires specific public health strategies. Traditional prevention methods like handwashing and food hygiene may not be sufficient to curb its spread through sexual contact. Experts are calling for the development of alternative interventions.
Dr. Hamish Mohammed, a consultant epidemiologist at the UKHSA, confirmed that sexually transmitted Shigella predominantly affects gay and bisexual men and is a growing concern. He emphasized the importance of good hygiene during and after sex to reduce the risk of transmission and urged individuals experiencing symptoms such as fever, stomach cramps, and severe diarrhea not to dismiss them. Testing is recommended, as individuals diagnosed with Shigella may have also been exposed to other sexually transmitted infections, including HIV, making a comprehensive sexual health screen advisable.
Symptoms of shigellosis, which can appear one to three days after exposure, include frequent diarrhea, stomach cramps, feverishness, and sometimes vomiting. Health officials advise individuals experiencing these symptoms to seek medical attention from a doctor or sexual health clinic. To lower the risk, men who have sex with men are advised to practice meticulous hygiene, including washing hands and sex toys after sex, changing condoms between different types of sexual contact, and using barriers during certain sexual practices.