Sexually Transmitted Shigella Infection Becomes a Growing Public Health Threat in the UK, Experts Warn

Introduction

A sexually transmitted form of the bacterial gut infection shigella is spreading rapidly across the UK, with health experts warning that it is becoming a serious and distinct public health concern.

New research led by the University of Cambridge and the UK Health Security Agency (UKHSA) has revealed that sexually transmitted shigella strains are spreading faster geographically than other forms of the infection and are showing increasing levels of antibiotic resistance.

Although shigella is traditionally associated with contaminated food and poor sanitation, certain strains can also spread through sexual contact. Health professionals are now urging greater awareness, particularly among communities most affected, to help reduce transmission and prevent further spread.

What Is Shigella Infection?

Shigella is a type of bacteria that causes an intestinal infection known as shigellosis. It is the bacteria responsible for dysentery, a condition that can lead to severe diarrhoea and abdominal discomfort.

The bacteria are commonly found in human faeces and can spread when tiny amounts of contaminated material enter another person’s mouth. This can happen through contaminated food, unsafe water, poor hand hygiene, or direct contact during sexual activity.

The strains most commonly linked to sexual transmission are:

• Shigella sonnei
• Shigella flexneri

While anyone can contract shigella, sexually transmitted cases have been particularly reported among gay and bisexual men and other men who have sex with men.

Rise in Sexually Transmitted Shigella Cases in the UK

According to UK Health Security Agency figures, sexually transmitted shigella cases in England increased from 2,052 cases in 2023 to 2,560 cases in 2025.

Researchers say the increase highlights the need for improved awareness and prevention strategies.

The recent study, published in the medical journal The Lancet Infectious Diseases, analysed 3,514 shigella samples collected from people aged over 16 across the UK between 2004 and 2020.

Scientists compared sexually transmitted strains with those spread through other routes, including food contamination and travel-related infections.

The findings showed that sexually transmitted shigella strains travelled further and spread more quickly between populations.

Sexually Transmitted Strains Spread Further and Faster

Researchers found that sexually transmitted shigella strains spread an average distance of 117 kilometres over a two-and-a-half-year period.

In comparison, non-sexually transmitted strains spread an average distance of 46 kilometres.

This suggests that sexual networks may play an important role in how certain shigella strains move between communities.

Professor Kate Baker from the University of Cambridge’s Department of Genetics said that many people who may be at risk are unaware of the growing threat.

She explained that sexual transmission has now become a sustained part of shigella transmission in the UK and that reaching affected communities with accurate information is essential.

Growing Concern Over Antibiotic Resistance

One of the biggest concerns highlighted by researchers is the increasing resistance of sexually transmitted shigella strains to antibiotics.

The study found that:

• Around 70% of sexually transmitted shigella strains showed resistance to at least one clinically important antibiotic.
• Around 40% of non-sexually transmitted cases showed antibiotic resistance.
• Around 49% of travel-associated cases showed resistance.

Antibiotic resistance makes infections harder to treat and increases the risk of longer illness periods and further transmission.

Health experts say preventing infection through awareness, testing, and safer practices is becoming increasingly important as treatment options become more limited.

Symptoms of Shigella Infection

The symptoms of shigella infection can vary from mild to severe. According to the NHS, common symptoms include:

• Watery diarrhoea
• Diarrhoea containing blood, mucus, or pus in more serious cases
• Stomach cramps and abdominal pain
• Feeling sick or vomiting
• A high temperature or fever above 38°C
• Feeling tired, unwell, or experiencing low mood

Symptoms usually develop within a few days after exposure, although the timing can vary.

People experiencing severe diarrhoea, blood in their stool, signs of dehydration, or symptoms that do not improve should seek medical advice.

How Shigella Can Spread Through Sexual Contact

Sexually transmitted shigella does not require penetrative sex to spread. Transmission can occur through activities where microscopic amounts of faecal matter come into contact with the mouth.

Activities that may increase the risk include:

• Oral-anal contact
• Sexual activities involving contaminated hands or objects
• Close sexual contact without proper hygiene precautions

Because shigella can be passed easily, people may unknowingly transmit the infection even if symptoms are mild or have disappeared.

Health Experts Encourage Testing and Prevention

Experts are encouraging people who develop symptoms or believe they may have been exposed to seek medical advice and consider sexual health screening.

Marc Tweed from the Terrence Higgins Trust described the rise in sexually transmitted shigella cases as a growing concern and encouraged anyone who suspects they may have the infection to contact their local sexual health clinic.

Professor Baker also advised people recovering from shigella infection to avoid sexual activity until two weeks after they have fully recovered. She also recommended informing healthcare providers about recent sexual activity to ensure appropriate testing and treatment.

Protecting Yourself and Reducing Transmission

Several steps can help reduce the risk of shigella infection:

• Wash hands thoroughly with soap and water, especially after using the toilet and before preparing food.
• Avoid sexual contact while experiencing diarrhoea or recovering from infection.
• Wait until at least two weeks after full recovery before resuming sexual activity.
• Consider sexual health screening if symptoms appear or exposure is suspected.
• Discuss symptoms openly with healthcare professionals.

Public health specialists stress that stigma and embarrassment can prevent people from seeking help. Open conversations and accurate information are essential for controlling outbreaks.

Conclusion

The rise of sexually transmitted shigella infections in the UK highlights a changing pattern in how this bacterial illness spreads. Research shows that sexually transmitted strains are spreading faster, travelling further, and becoming increasingly resistant to antibiotics.

Health experts say greater awareness, early testing, and improved communication with affected communities are key to reducing transmission.

Anyone experiencing symptoms of shigella or concerned about possible exposure should seek medical advice from a healthcare professional or sexual health clinic.

Sources

• University of Cambridge and UK Health Security Agency research published in The Lancet Infectious Diseases.
• UK Health Security Agency data on sexually transmitted shigella cases in England.
• NHS guidance on shigella symptoms and infection management.
• Sky News report on sexually transmitted shigella infections and public health concerns.

Disclaimer

This article is intended for general informational purposes only and does not replace professional medical advice. If you have symptoms of shigella infection, concerns about sexual health, or possible exposure to the bacteria, consult a qualified healthcare professional or contact a local sexual health service for appropriate testing and guidance.