10 minutes read10 minutes readSummary:
- Some gut infections, such as Shigella, Giardia and Hepatitis A, can be passed on during sex. In the UK, the cases passed on this way are mostly in gay, bisexual and other men who have sex with men.
- England had 2,560 diagnoses of sexually transmitted Shigella in 2025, up from 2,318 in 2024. More than half of the Shigella sonnei samples tested were resistant to all 3 of the usual antibiotics.
- Gut infections are found by testing a sample of your poo, which our STI tests don’t do. UK guidelines also recommend a full STI screen: the Better2Know Confidence Screen can be taken from 28 days after sex, with results in 5 days.
When most people think of STIs, they think of infections that affect the genitals. But some infections of the gut can be passed on during sex too. Doctors call them sexually transmitted enteric infections.
In September 2025, a review in the journal Clinical Microbiology Reviews looked at these infections in men who have sex with men. In this blog, we explain what the review says, what the latest UK figures show, how these infections are passed on, and what to do if you think you have one.
What does the review say?
The review says gut infections passed on through sex have been reported in men who have sex with men since the 1960s, and are being recognised more often as laboratory tests improve. It was written by Kira Newman, Gretchen Snoeyenbos Newman, Chase Cannon and Ferric Fang, and published online on 17 September 2025.
Its summary makes 3 points:
- hard to count: the true number of cases is difficult to measure, because these infections fall between the usual groupings of STIs and foodborne diseases
- drug resistance: extensively drug-resistant Shigella and Campylobacter infections have emerged around the world among men who have sex with men, and could cross over into other groups
- open questions: it isn’t yet clear how the medicines taken to prevent HIV and other STIs (PrEP and PEP) affect these infections
The authors say the spread of drug-resistant infections makes timely diagnosis and the right treatment important, and that education and testing in the community need to be considered.
Only the summary of the review is free to read, so the rest of this blog draws mainly on UK sources.
What do the UK figures show?
Sexually transmitted Shigella is rising in England, and most of the samples tested are resistant to antibiotics. The UK Health Security Agency (UKHSA) reports:
- diagnoses: 2,052 in 2023, 2,318 in 2024 and 2,560 in 2025
- where: 54% of the 2025 diagnoses were in London
- resistance: in 2025, 86% of Shigella sonnei samples and 94% of Shigella flexneri samples tested showed resistance to antibiotics
- extensive resistance: more than half of the Shigella sonnei samples tested were resistant to all 3 of the antibiotics usually used
UKHSA says sexually transmitted Shigella mostly affects gay, bisexual and other men who have sex with men. Nobody’s sexuality is recorded when a sample is tested, so it counts Shigella in adult men who haven’t reported travelling abroad as a stand-in for infections caught through sex.
Most cases of Shigella get better without treatment. Resistance matters for the people who become seriously ill, because UKHSA says the treatment options for them are becoming limited.
Shigella isn’t the only one. The British Association for Sexual Health and HIV (BASHH) says rates of sexually transmitted gut infections are increasing, particularly among men who have sex with men. England also had outbreaks of Hepatitis A among gay and bisexual men in 2016 and 2017.
Which gut infections can be passed on through sex?
UK guidelines name Shigella, Hepatitis A, Giardia, Campylobacter, some types of E. coli and amoebic dysentery. BASHH’s guideline covers the infections with the strongest evidence that they’re passed on through sex:
| Infection | Symptoms | What to know |
| Shigella | Diarrhoea, which can be bloody, stomach cramps, fever, nausea and vomiting | Symptoms usually start within 1 to 4 days. Most people recover within 4 to 5 days, but the illness can last up to 2 weeks |
| Hepatitis A | A high temperature, flu-like symptoms, feeling or being sick, pain in your upper tummy, dark pee, pale poo and yellowing of the skin and eyes | A liver infection that is spread in the poo of someone who has it. It usually clears up by itself within 3 to 6 months, and there’s a vaccine |
| Giardia | Smelly diarrhoea, tummy pain or cramps, farting, bloating and weight loss | Confirmed infections are treated with medicine. Symptoms should then stop in about a week, but can last longer |
| Campylobacter | Diarrhoea, tummy pain, feeling or being sick and a high temperature | Best known as the most common cause of food poisoning in the UK |
| E. coli that makes Shiga toxin (STEC) | Diarrhoea, which is bloody in about half of cases | Antibiotics aren’t recommended, because they’re likely to raise the risk of complications |
| Amoebic dysentery (Entamoeba histolytica) | Often none. It can cause diarrhoea, stomach pain and cramps, and in severe cases bloody poo and a fever | BASHH says confirmed infections should always be treated |
BASHH’s patient leaflet adds LGV, an invasive type of Chlamydia that infects the rectum. It causes pain in the bottom, mucus or blood when you poo, and a feeling that you haven’t emptied your bowels. In England in 2024, 98% of LGV diagnoses were in men.
Other germs can occasionally spread this way too. UKHSA lists sexual contact as one way people are exposed to Cryptosporidium. Read more in “Can STIs cause diarrhoea?”
How are gut infections passed on during sex?
These infections spread when a tiny amount of infected poo gets into your mouth. UKHSA says Shigella can be passed on during sex, directly or through unwashed hands, and that only a tiny amount of bacteria is needed. UK sources list these ways:
- rimming (oral sex on the anus)
- giving oral sex after anal sex
- fingering and fisting
- sharing sex toys
- licking skin, condoms or toys that have poo on them
They’re also caught in the usual ways: from contaminated food or drink, or from unwashed hands after using the toilet.
Chemsex and meeting partners through apps can play a part. When researchers interviewed 34 men who have sex with men who were diagnosed in a Shigella outbreak in England and Wales in 2012 and 2013, 21 had used chemsex drugs, and 30 had never heard of the infection.
Anyone can catch these infections. BASHH says they’re most commonly seen in gay, bisexual and other men who have sex with men, including trans and non-binary people, and that they can also affect heterosexual people. Read more in “Can you get an STI from rimming?”
When should you get medical help?
Get urgent medical help if you have bloody diarrhoea or bleeding from your bottom. The NHS says to do the same if:
- you’ve had diarrhoea for more than 7 days, or been sick for more than 2 days
- you keep being sick and can’t keep fluid down
- you still have signs of dehydration, such as dark, smelly pee or peeing less than usual, after using rehydration sachets
Call 999 if you have a sudden, severe tummy ache, your skin, lips or tongue look blue, grey, pale or blotchy, or you’re confused.
If your symptoms are milder and you think you caught a gut infection through sex, see a doctor. Tell them it may have been caught through sex, and mention Shigella, so that you get the right tests. UKHSA says Shigella is often mistaken for food poisoning.
How are gut infections tested for and treated?
Gut infections are found by testing a sample of your poo. BASHH recommends a PCR test, which looks for the genetic material of bacteria and parasites. If you have pain, discharge or bleeding from your bottom, you’ll need a rectal swab as well, to check for infections such as LGV, Gonorrhoea and Herpes.
Treatment
- rest and fluids: BASHH says most infections that cause diarrhoea get better on their own, without antibiotics
- antibiotics: these are for more severe illness, such as a fever, diarrhoea that has lasted 7 days or more, or a stay in hospital. Giardia and amoebic dysentery are always treated
- anti-diarrhoea medicine: the NHS says not to use it if you have dysentery, which is diarrhoea with blood in it
Other tests and partners
BASHH recommends a full STI screen for everyone diagnosed with one of these infections, with blood tests and samples from the genitals, rectum and throat. If you’re HIV negative, it also recommends a conversation about PrEP. BASHH’s leaflet says some studies suggest people living with HIV are more likely to become unwell and need hospital care.
Anyone you’ve had sex with since your symptoms started, or in the 4 weeks before, should be told. BASHH says partners without symptoms usually only need a routine STI screen.
What should you do if you have Shigella?
Avoid sex until 7 days after your last symptom. That’s UKHSA’s advice, and BASHH says it includes oral sex and rimming. UKHSA and BASHH also advise:
- hands: wash them with soap and warm water after using the toilet, and before eating or preparing food
- food: don’t prepare food for other people
- water and towels: avoid spas, swimming pools, jacuzzis and hot tubs, and don’t share towels
- work: stay off work until at least 48 hours after your symptoms stop. If you handle food, or work in healthcare or with young children, you may need the all clear first
- rest: give yourself time to recover, keep hydrated and get lots of rest
A person with Shigella can stay infectious for up to a month, even after they start to feel better, so keep washing your hands well.
How can you lower the risk?
Good hygiene during and after sex, and condoms, lower the risk. UKHSA lists these steps:
- wash your hands after sex, and 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
A dental dam, a thin sheet of latex, works as a barrier for rimming. It also helps to wait if you or a partner have diarrhoea.
There’s a vaccine for Hepatitis A. The UK’s immunisation guidance recommends it for gay, bisexual and other men who have sex with men, and BASHH recommends that sexual health clinics offer it. Read more in “Is unprotected anal sex dangerous?”
Which test do you need?
Better2Know’s STI tests don’t check for gut infections such as Shigella. For those, you need a doctor to test a sample of your poo.
What we can test for are the STIs that UK guidelines say to check at the same time, including Chlamydia and Gonorrhoea in the rectum. Better2Know offers:
- Confidence Screen: for gay and bisexual men. It tests for 7 infections, including HIV, Syphilis and Hepatitis B, and Chlamydia and Gonorrhoea in urine, throat and rectal samples, from 28 days after sex, with results in 5 days. You can book it at one of our clinics or order a home test kit.
- Chlamydia and Gonorrhoea (Rectal Swab): checks your rectum for Chlamydia and Gonorrhoea, from 14 days after sex, or straight away if you have symptoms, with results in 2 days.
If you test before 45 days, a negative HIV result needs a repeat test. A Syphilis test in the first 3 months after sex can miss the infection, so you may need a repeat test. Not sure which test you need? Our Patient Care Team is available 24/7 on 020 7099 0955.
FAQs
Is Shigella an STI?
It can be. Shigella is a gut infection that is often caught from contaminated food or water, or from unwashed hands. UKHSA says it can also be a sexually transmitted infection, particularly among gay, bisexual and other men who have sex with men.
Can straight people catch gut infections through sex?
Yes. Anyone can catch one if infected poo gets into their mouth during sex. BASHH says these infections can affect heterosexual people too, although they’re most commonly seen in men who have sex with men.
How long after Shigella can you have sex?
UKHSA says to avoid sex until 7 days after your last symptom. You can stay infectious for up to a month, so keep washing your hands well after that.
Final thoughts
Gut infections passed on through sex aren’t new, but they’re being found more often, and some are getting harder to treat. In England, sexually transmitted Shigella rose again in 2025. Most people get better with rest and fluids. What helps most is knowing how these infections spread, washing your hands, and telling a doctor that your symptoms may be linked to sex.
A gut infection caught through sex is also a reason to check for other STIs. Book a Confidence Screen at a clinic near you or order a home test kit. Our Patient Care Team is available 24/7 on 020 7099 0955.
About this article
Not in the UK? Choose your country from the selector at the top of the page for local tests and prices.
This article originally appeared on 3 October 2025 and was last updated on 3 October 2026.
Medical review. This article was medically reviewed by Dr Steve Chapman, Doctor with a wealth of clinical experience in the field of STIs, on 27 November 2025. It is general information and not a substitute for personal medical advice.
Sources
- Newman KL, Snoeyenbos Newman G, Cannon CA and Fang FC, Sexually transmitted enteric infections in men who have sex with men, Clinical Microbiology Reviews, 2025. https://journals.asm.org/doi/10.1128/cmr.00075-23
- UK Health Security Agency, Sexually transmitted Shigella spp. in England: 2016 to 2025, 26 March 2026. https://www.gov.uk/government/publications/non-travel-associated-shigella-infections/sexually-transmitted-shigella-spp-in-england-2016-to-2025
- UK Health Security Agency, Increase in drug-resistant Shigella cases among gay and bisexual men, 26 March 2026. https://www.gov.uk/government/news/increase-in-drug-resistant-shigella-cases-among-gay-and-bisexual-men
- UK Health Security Agency, What is Shigella? How do you catch it and how can it be avoided?, 26 March 2026. https://ukhsa.blog.gov.uk/2026/03/26/what-is-shigella-how-do-you-catch-it-and-how-can-it-be-avoided/
- British Association for Sexual Health and HIV, UK national guideline for the management of sexually transmitted enteric infections, 2023. https://www.bashh.org/_userfiles/pages/files/resources/bashhentericguidelines2023.pdf
- British Association for Sexual Health and HIV, Sexually transmitted enteric ‘gut’ infections, patient information leaflet, October 2023. https://www.bashh.org/_userfiles/pages/files/resources/enteric_pil_mobilepdf_01.pdf
- UK Health Security Agency, Hepatitis A: the green book, chapter 17, January 2024. https://www.gov.uk/government/publications/hepatitis-a-the-green-book-chapter-17
- British Association for Sexual Health and HIV, Guidelines on the management of viral hepatitis, 2026. https://www.bashh.org/_userfiles/pages/files/guidelines_on_the_management_of_viral_hepatitis_2026.pdf
- NHS, Hepatitis A, reviewed 24 April 2026. https://www.nhs.uk/conditions/hepatitis-a/
- NHS, Giardiasis, reviewed 28 August 2026. https://www.nhs.uk/conditions/giardiasis/
- NHS, Food poisoning, reviewed 19 December 2024. https://www.nhs.uk/conditions/food-poisoning/
- UK Health Security Agency, Shiga toxin-producing Escherichia coli (STEC): symptoms, how to avoid, how to treat, updated 29 June 2026. https://www.gov.uk/government/publications/vero-cytotoxin-producing-escherichia-coli-symptoms-how-to-avoid-how-to-treat/vero-cytotoxin-producing-escherichia-coli-symptoms-how-to-avoid-how-to-treat
- Centers for Disease Control and Prevention, Amebiasis, updated 20 June 2025. https://www.cdc.gov/amebiasis/about/index.html
- British Association for Sexual Health and HIV, Lymphogranuloma venereum (LGV), patient information leaflet. https://www.bashh.org/_userfiles/pages/files/resources/lgv_pil_digital_2_2015.pdf
- UK Health Security Agency, Trends of lymphogranuloma venereum (LGV) in England: 2014 to 2024, 10 December 2025. https://www.gov.uk/government/publications/lgv-infections-in-the-uk-trends-and-epidemiology/trends-of-lymphogranuloma-venereum-lgv-in-england-2014-to-2024
- UK Health Security Agency, Cryptosporidium: public advice, 1 November 2023. https://www.gov.uk/guidance/cryptosporidium-public-advice
- Public Health England, Shigella: leaflet and poster for men who have sex with men, updated 17 March 2016. https://www.gov.uk/government/publications/shigella-leaflet-and-poster
- Gilbart VL and others, Sex, drugs and smart phone applications: findings from semistructured interviews with men who have sex with men diagnosed with Shigella flexneri 3a in England and Wales, Sexually Transmitted Infections, 2015. https://sti.bmj.com/content/91/8/598
- NHS, Dysentery, reviewed 17 July 2024. https://www.nhs.uk/conditions/dysentery/
- NHS, Diarrhoea and vomiting, reviewed 21 December 2023. https://www.nhs.uk/conditions/diarrhoea-and-vomiting/
