Shigella is a bacterial gut infection. It spreads easily during sex, it's rising sharply in this community, and it's becoming resistant to the antibiotics that used to clear it quickly.

It's not technically classified as an STI. That distinction doesn't matter much here. It moves through sexual networks, it disproportionately hits gay and bisexual men, and the guys who don't know about it are the ones who end up treating it wrong.

2,560 cases in England in 2025. Up from 2,052 in 2023. The trend line is going the wrong way.

🔩 How It Spreads

Shigella is fecal-oral. A tiny amount of stool, invisible to the naked eye, is enough to infect someone. The infectious dose is as low as 10-100 bacteria. That's what makes it unusually easy to pick up during sexual contact.

The routes:

  • Rimming: the most efficient sexual transmission route. Direct oral-anal contact without a barrier.
  • Fingers: hand-to-anus contact, then hand-to-mouth, directly or indirectly.
  • Toys: oral contact with toys that have had anal contact.
  • Hands: unwashed hands touching food or a partner's mouth after anal play.

It doesn't transmit via blood or semen. Standard anal sex isn't a direct route. The handwashing, or lack of it, around sex is.

⚠️ What It Does to You

Symptoms hit within 1-4 days of exposure.

The picture:

  • Diarrhoea (sometimes bloody)
  • Stomach cramps
  • Fever
  • Nausea

It looks exactly like food poisoning. Most guys assume that's what it is. If you've had unprotected rimming or oral-anal contact recently, that's not an assumption worth making.

Severity varies. Some people clear it in a week without treatment. Others, especially anyone who's immunocompromised, can get a prolonged or severe illness, particularly with a resistant strain.

🦠 The Resistance Problem

This is the part that changes what you should actually do.

In England in 2025: 86% of Shigella sonnei resistant to first-line antibiotics. 94% of Shigella flexneri. That's not a marginal increase. It's a near-complete collapse of ciprofloxacin as a reliable treatment.

What this means in practice:

  • Don't self-treat with antibiotics you have at home. Wrong antibiotic, resistant strain: you've delayed proper treatment and contributed to the resistance problem.
  • Get a stool culture with sensitivity testing before starting antibiotics. This tells you which drug will actually work on the specific strain you've got.
  • If you're prescribed something and don't improve within a couple of days, go back. This is not a situation for waiting it out.

A standard GP visit for a gut infection might not automatically include sensitivities. Be specific: "I want culture and sensitivity testing. I know there's high antibiotic resistance in sexually transmitted Shigella." That prompt will get you the right test.

🛡️ Prevention

No vaccine. Prevention is hygiene and barriers. Full stop.

During sex:

  • Dental dams or cut condoms for rimming: the direct fix for the highest-risk route. Available free from most sexual health clinics.
  • Wash hands before and after any anal contact, and before touching your face or mouth.
  • Cover anal toys with condoms. Remove and replace before any oral contact.

After sex:

  • Shower properly.
  • Don't prepare food for others without washing your hands thoroughly.
  • Don't share towels.

If you have symptoms:

  • No sex, particularly no rimming or anal-oral contact, until you're symptom-free for at least 48 hours. UKHSA guidance is 7 days after symptoms clear before resuming sexual activity.
  • No communal swimming pools.
  • No preparing food for others.

🔬 Getting Diagnosed

What to ask for: Stool sample, culture, and sensitivity testing. Tell the clinic you've been symptomatic after sexual contact and specifically want Shigella investigated with resistance testing included.

Most sexual health clinics that see MSM are now across the resistance issue. If yours isn't, be direct: "I understand there are high rates of antibiotic-resistant Shigella in this community. Can we get sensitivities before committing to a treatment?"

While you're there: Get a full STI screen. Sexual contact that transmits Shigella can also transmit gonorrhoea, chlamydia, syphilis, and Hepatitis A. A Shigella diagnosis is a reason to check everything, not just the gut infection.

Hydration: Whatever else is happening, your body needs fluids. Oral rehydration salts (available at any pharmacy) are more effective than water alone. Get them.

🔁 After Recovery

Getting Shigella once doesn't give you lasting immunity. You can pick it up again.

If you were diagnosed with a resistant strain, tell recent partners. Shigella is transmissible before symptoms appear. They may already be incubating it and not know yet.

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