What is Shigellosis and how can a gut infection be passed through sexual contact?

Introduction

Concerns about unfamiliar infections can understandably cause worry, particularly when symptoms involve the digestive system and questions arise about possible sexual transmission. Shigellosis is a bacterial gut infection that, while most commonly spread through contaminated food or water, can in some cases be passed through sexual contact. Understanding how this happens — and when testing may be appropriate — can provide important clarity.

Our clinic provides confidential STI testing services. We do not provide GP services or dermatology consultations, but we can advise on appropriate next steps if further medical care is needed.

What is Shigellosis? A Direct Answer

Shigellosis is a bacterial infection of the gut caused by the Shigella bacterium. It is primarily associated with gastrointestinal symptoms such as diarrhoea, stomach cramps, and fever. Whilst it is not classified as a traditional sexually transmitted infection, it can be passed between individuals through faecal-oral transmission during certain sexual activities.

Common features of shigellosis may include:

• Diarrhoea, sometimes containing blood or mucus
• Stomach cramps and abdominal pain
• Nausea or vomiting
• Fever or chills
• An urgent need to pass stools

Symptoms alone cannot confirm the cause. Testing may help provide clarity when there is potential exposure or persistent symptoms.

When Could Gut Symptoms Be Linked to Sexual Contact?

Gastrointestinal symptoms such as diarrhoea, cramping, and nausea have many possible causes. In some cases, however, these symptoms may be linked to sexual activity if there has been exposure to faecal bacteria during anal sex, rimming (oral-anal contact), or other close physical contact where faecal-oral transmission is possible. This does not mean that all gut symptoms following sexual activity are infection-related, as digestive upset can occur for many unrelated reasons.

Section 1: Understanding Shigellosis

Shigellosis is caused by a group of bacteria known as Shigella, which includes several species such as Shigella sonnei and Shigella flexneri. The infection targets the lining of the intestine and can cause significant inflammation. It is relatively common globally and does not exclusively affect any particular group of people. In the United Kingdom, cases have been reported across various communities, with some clusters observed among individuals who have had sexual contact involving anal or oral-anal activity.

The infection is notable for the fact that very few bacteria are needed to cause illness — meaning transmission can occur even with minimal exposure.

Section 2: Common Non-Sexual Causes of Shigellosis

Shigellosis is most frequently acquired through routes that have nothing to do with sexual contact. These may include:

• Contaminated food or water — particularly in regions with lower sanitation standards
• Person-to-person spread — within households or care settings through poor hand hygiene
• Contact with contaminated surfaces — the bacteria can survive briefly on hands and objects
• Travel-related exposure — sometimes referred to as traveller's diarrhoea
• Swimming in contaminated water

It is important to note that experiencing shigellosis does not automatically indicate sexual transmission. Many people acquire the infection through everyday routes.

Section 3: Situations Where Shigellosis May Arise

Shigellosis can present in a variety of contexts, and symptoms may appear one to four days after exposure. Some situations where individuals may encounter a higher risk include:

• After travelling abroad to regions with differing water and sanitation standards
• Following close physical or sexual contact involving anal or oral-anal activity
• In communal living environments such as care homes or shared accommodation
• After consuming food prepared in settings with poor hygiene

Digestive symptoms following sexual activity may be concerning, but they can also reflect unrelated causes such as dietary changes, stress, or mild viral illness.

Section 4: STIs That May Cause Similar Symptoms

Certain sexually transmitted infections can produce symptoms that overlap with those of shigellosis, which may cause confusion. These may include:

• Gonorrhoea — rectal gonorrhoea can cause discharge, discomfort, and changes in bowel habits
• Chlamydia — rectal chlamydia may produce few or no symptoms but can occasionally cause irritation or discharge
• Syphilis — rectal sores or ulcers may develop in some cases
• LGV (Lymphogranuloma venereum) — a form of chlamydia that can cause significant rectal inflammation

Because several of these infections may present with digestive or rectal symptoms, it can be difficult to distinguish between them based on symptoms alone. A full STI screen may help to identify or rule out multiple possible causes.

Section 5: How Symptoms Can Overlap With Other Conditions

The symptoms of shigellosis — cramping, loose stools, and discomfort — are not unique to this infection. Irritable bowel syndrome, viral gastroenteritis, food intolerance, and other gastrointestinal conditions can all produce similar presentations. Equally, rectal STIs such as chlamydia or gonorrhoea may cause minimal symptoms that are easily attributed to other causes.

Because many conditions share overlapping features, appearance or symptoms alone cannot confirm the cause of gut or rectal discomfort. Laboratory testing is the reliable method for identification.

Section 6: When STI Testing May Be Sensible

Testing may be worth considering in certain circumstances, including:

• Persistent or worsening gastrointestinal symptoms following sexual contact
• Unprotected anal sex or oral-anal contact with a new or casual partner
• A sexual partner who has been diagnosed with shigellosis or a rectal STI
• Symptoms that return or recur after initial improvement
• Uncertainty about potential exposure routes

Testing decisions depend on individual circumstances, symptoms, and exposure history.

Section 7: How STI Testing Works

STI testing is straightforward and typically involves one or more of the following:

• Swab tests — rectal swabs may be used to detect bacterial infections including gonorrhoea, chlamydia, and related conditions
• Urine tests — commonly used for gonorrhoea and chlamydia
• Blood tests — used to detect infections such as syphilis, HIV, and hepatitis
• Stool samples — used to identify bacterial gut infections including Shigella (typically arranged through a GP or specialist)

Results from laboratory testing are processed confidentially. Our clinic provides private STI testing services with discreet results delivery.

Section 8: When Symptoms Are Less Likely to Be Related to an STI

In many cases, gut symptoms following sexual activity are not related to infection at all. Possible benign explanations include:

• Temporary digestive upset following dietary changes
• Mild viral illness unrelated to sexual contact
• Stress-related gastrointestinal changes
• Minor reactions to lubricants or products used during sex
• Ordinary variability in bowel habits

These possibilities are worth considering before assuming a more serious cause.

Frequently Asked Questions

Can shigellosis be passed through sexual contact?

Yes, in some cases. Shigella bacteria can be transmitted through faecal-oral contact during sexual activities such as anal sex or rimming. However, it can also be acquired through many non-sexual routes.

Does having shigellosis mean I have an STI?

Not necessarily. Shigellosis is a bacterial gut infection with multiple possible transmission routes. Sexual transmission is one possibility, but it is not the only one. Symptoms alone cannot confirm how the infection was acquired.

Should I get tested even if symptoms have gone away?

If there has been potential exposure to shigellosis or an STI, testing may still be relevant even after symptoms resolve. Some infections can persist without symptoms.

How soon after possible exposure should I test?

Testing timelines vary depending on the infection being considered. If you are unsure, contacting a clinic for guidance based on your specific circumstances is advisable.

Are gut symptoms after sex common?

Mild digestive discomfort following sexual activity can occur for various reasons and does not automatically indicate infection. If symptoms are persistent, worsening, or accompanied by fever or blood in stools, further assessment is advisable.

Is shigellosis treatable?

Shigellosis is typically managed medically. For treatment options and clinical assessment, consultation with a GP or appropriate healthcare provider is recommended.

Section 9: When to Seek Medical Advice

Certain symptoms warrant prompt medical attention. These may include:

• Blood in stools or severe diarrhoea
• High fever or chills
• Significant abdominal pain or cramping
• Symptoms that persist for more than a few days
• Rectal sores, ulcers, or discharge
• Dehydration signs such as dizziness or reduced urination

If symptoms persist or worsen, consultation with an appropriate healthcare service may be advised. Our clinic can advise on appropriate next steps based on your circumstances.

Confidential STI Testing in the UK

If you are concerned about possible STI symptoms or potential exposure following sexual contact, confidential STI testing appointments are available at our UK clinic. Testing decisions depend on symptoms, exposure history, and individual risk factors.

For further context on related rectal conditions, read our article on proctitis and which rectal swabs help identify its cause.

Medical Disclaimer: This article is for general informational purposes only and does not constitute medical advice, diagnosis, or treatment. Sexual health concerns should be assessed based on individual circumstances. If you are experiencing persistent, severe, or worsening symptoms, consultation with an appropriate healthcare service is advised. Our clinic provides private STI testing services only.