What is Shigella? How do you catch it? And how can it be avoided?

Shigella is a bacterial infection that can cause severe diarrhoea and stomach cramps. It's more common than many people realise and understanding how it spreads is key to protecting yourself and others. Here, we answer some of the most frequently asked questions relating to it.

What is Shigella?

Shigella is a group of bacteria that cause shigellosis (also known as bacillary dysentery) which is an infection of the intestines. There are 4 species of Shigella bacteria:

S. sonnei S. flexneri S. boydii S. dysenteriae

The ones most commonly found in the UK are S. sonnei and S. flexneri.

What are the symptoms?

The most common symptoms are diarrhoea (which can be bloody), stomach cramps, fever, nausea and vomiting. Some people also experience headaches and loss of appetite. Symptoms typically begin 1 to 3 days after exposure, though it can take up to a week to feel unwell.

Most people recover within 4 to 5 days, but illness can last up to 2 weeks. In some cases, particularly with certain species of Shigella, symptoms can be more severe and may require hospital treatment.

Some people can carry and pass on the bacteria without feeling ill themselves.

Is Shigella a sexually transmitted infection?

Shigella is spread from person to person, often by eating food that has been prepared by an infected person or by touching surfaces contaminated by infected faeces (poo).

Shigella can also be a sexually transmitted infection (STI), particularly among gay, bisexual, and other men who have sex with men (MSM). One of the most important things to understand about Shigella is that the infectious dose is very low, meaning that ingesting just a tiny amount of contaminated material can be enough to cause illness. This makes it relatively easy to transmit from person to person.

Transmission can happen in the following ways:

through poor hand hygiene, particularly after using the toilet by eating or drinking something that has been contaminated by touching a contaminated surface and then touching your mouth through sexual contact, including anal-oral sex (‘rimming’) and giving oral sex after anal sex Who is most at risk?

Anyone can get Shigella. Globally, the majority of cases occur in children under 5. Travellers to countries with limited access to clean water and sanitation are also at higher risk. In the UK, however, rates among adults who have not travelled have been rising over the past decade.

There is also a well-established risk of transmission through sexual contact, particularly among men who have sex with men. Outbreaks linked to sexual transmission have been reported in England.

How long is someone infectious?

A person with Shigella can remain infectious – and capable of passing the infection on to others – for up to a month, even after they start to feel better. This is why it is important to follow hygiene precautions throughout recovery – including before and after intimate contact with other people. Do not return to work while you are unwell.

How is Shigella treated?

Mild cases are often self-limiting, meaning healthy people will recover on their own without medication. Staying well hydrated is important. However, antibiotics are recommended where symptoms are more severe, particularly if there is bloody diarrhoea, or if there are complications. Antibiotic treatment can shorten the duration of illness, reduce the risk of complications and speed up the clearance of bacteria from the body.

If you think you may have Shigella, contact your GP or, if sexual transmission is a possibility, visit a sexual health clinic. Ask for an urgent GP appointment or get help from NHS 111 if you or your child have bloody diarrhoea.

You should stay away from work – and children should be kept off nursery or school – until you’ve been symptom-free for at least 48 hours. The timeframe applies for preparing food for others and sexual contact.

How can I protect myself?

The most effective way to reduce your risk and the risk to others is thorough and regular handwashing – especially after using the toilet, before preparing food and before eating. When travelling to areas with poor sanitation, take care with food and drinking water.

If you are sexually active, there are steps you can take to reduce the risk of transmission during sex:

wash your hands after sex shower if possible change condoms between anal and oral sex use latex or non-latex gloves for fingering or fisting avoid sharing sex toys or douching equipment Is Shigella a serious public health concern?

Yes. Shigella remains a significant public health issue both in the UK and globally. It is one of the leading causes of bloody diarrhoea worldwide, and drug-resistant strains are an increasing concern. UKHSA monitors cases and outbreaks closely to identify trends and support the public health response.

What is UKHSA’s role in this area?

The UK Health Security Agency (UKHSA) is responsible for protecting the nation from both STIs and gastrointestinal infections, by conducting surveillance, monitoring outbreaks, and analysing data from clinics to inform prevention strategies. We work with partners to reduce infection rates, and support local authorities with guidance. You will find our latest guidance, data and analysis of Shigella on GOV.UK.

https://ukhsa.blog.gov.uk/2026/03/26/what-is-shigella-how-do-you-catch-it-and-how-can-it-be-avoided/

seen at 14:41, 26 March in UK Health Security Agency.