What Is Shigella Infection?
Shigella infection (shigellosis) is a bacterial illness of the intestines. It causes diarrhea, which is often bloody, plus fever and stomach cramps. The germs spread through tiny traces of stool on hands, food, water, and during sex. Most people recover in 5 to 7 days with fluids and rest, but some need antibiotics.[1]
In this guide, you will learn:
- The symptoms that mean you should see a doctor
- What helps, what to avoid, and when antibiotics matter
- How to stop the germs from spreading to your family and partners
- What the new CDC data on drug-resistant Shigella means for you
What Is Shigella?
Shigella is a group of bacteria that infect the lining of the large intestine. The illness they cause is called shigellosis, and doctors sometimes call the severe, bloody form bacillary dysentery.[4] The CDC estimates that Shigella causes about 450,000 infections in the United States every year.[1]
These germs are tough, and they spread with very little effort. Swallowing as few as 10 organisms can make you sick.[5] For comparison, many other foodborne bacteria need a far larger dose. That tiny threshold explains why Shigella tears through daycares, camps, and households so quickly.
The Four Types (Species) of Shigella
| Species | What to know |
|---|---|
| Shigella sonnei | The most common type in the United States.[1] |
| Shigella flexneri | Common worldwide. Studies link it to more severe illness, including dysentery and hospital stays.[5] |
| Shigella boydii | Rare in the U.S. but still important in areas with limited resources.[1] |
| Shigella dysenteriae | Rare in the U.S. Type 1 can be deadly.[1] |
10 Key Facts About Shigella Infection
- A tiny dose is enough. Ten germs can start an infection.[5]
- It is common. About 450,000 Americans get shigellosis each year.[1]
- It strikes fast. Symptoms usually begin 1 to 2 days after exposure, though some people wait up to a week.[1][3]
- Most people heal on their own. Recovery typically takes 5 to 7 days.[2]
- You can spread it without feeling sick. Some infected people have no symptoms but still carry the germs.[4]
- You stay contagious after you feel better. The germs can pass in stool for up to a few weeks.[3]
- Anti-diarrhea pills can backfire. The CDC warns people with bloody diarrhea not to take loperamide or diphenoxylate-atropine.[2]
- Young children carry the biggest burden. Worldwide, shigellosis caused about 210,000 deaths in 2016, including roughly 63,700 in children under 5.[6]
- Drug resistance is rising. In U.S. surveillance, extensively drug-resistant strains went from 0% of isolates (2011–2015) to 8.5% in 2023.[5]
- Hand washing works. Soap, water, and 20 seconds of scrubbing remain your best defense.[3]
Symptoms of Shigella Infection
Shigella symptoms hit the gut hard. The classic pattern is diarrhea plus fever plus cramping, and the diarrhea may contain blood or mucus.[3] Common symptoms include:
- Diarrhea that can turn bloody or last longer than 3 days
- Fever
- Stomach pain and cramps
- Tenesmus: the feeling that you must pass stool even when your bowels are empty[1]
- Nausea or vomiting[3]
Shigella Incubation Period and Timeline
| Stage | What usually happens |
|---|---|
| Exposure | You swallow the bacteria from contaminated hands, food, water, or a sexual partner. |
| Days 1–2 | Symptoms start. A few people take up to a week to get sick.[3] |
| Days 3–7 | Diarrhea, fever, and cramps peak, then ease. Symptoms tend to last up to 7 days.[3] |
| Weeks 1–4 | You feel better, but germs may still pass in stool for up to a few weeks.[3] |
| Weeks to months | Bowel habits may take weeks or even months to return to normal.[3][4] |
Signs of Dehydration to Watch For
Dehydration is the most common danger of any diarrheal illness, and it can sneak up on young children quickly.
| Adults | Babies and children |
|---|---|
| Very little or no urine Very dry mouth and throat Dizziness when you stand[3] | No tears when crying Sunken eyes Dry diapers[3] |
When to See a Doctor
Call a doctor or seek urgent care if you or your child has:
- Bloody diarrhea
- Diarrhea lasting more than 3 days
- A fever of 102°F (39°C) or higher with diarrhea
- Severe stomach cramps or belly tenderness
- Repeated vomiting that keeps you from holding down liquids
- Signs of dehydration, such as little or no urine or dizziness[3]
Call right away if a child has a seizure. Also call at the first symptom if you have a weakened immune system, for example from HIV or chemotherapy, because the illness can last longer and hit harder.[3][2]
Causes: How Shigella Spreads
Shigella lives in stool. Anything that touches stool from an infected person can carry the germs, and you get sick when you swallow them. The main routes are:[1][3]
- Hand-to-mouth contact. This happens after changing a diaper, caring for a sick person, or touching a contaminated toy, doorknob, or changing table.
- Contaminated food. An infected person who prepares food without washing up can pass the germs to everyone who eats. Produce grown in or washed with sewage-tainted water can also carry them.
- Contaminated water. Swallowing water from lakes, rivers, ponds, or poorly maintained pools can cause infection.[4]
- Sexual contact. Any sexual activity that involves stool exposure, including oral-anal contact, can spread Shigella.[1]
Outbreaks cluster in child care centers, schools, public pools, water parks, and nursing homes, where people share space and surfaces.[3]
Who Is at Higher Risk?
- Children under 5. They are the group most likely to get shigellosis, although people of every age can catch it.[1]
- Travelers to places with unsafe water, limited sanitation, or poor food handling. Travelers also face a higher chance of strains that are harder to treat.[1]
- Gay, bisexual, and other men who have sex with men. Rates run higher in this group, but the risk exists for anyone with sexual activity that involves stool exposure.[1]
- People experiencing homelessness, who often have limited access to clean water and toilets.[3]
- People with weakened immune systems, who face a higher chance of severe illness.[3]
Complications of Shigellosis
Most cases clear up without lasting problems. Still, doctors watch for these complications, especially in babies, older adults, and people with weak immune systems:[3]
| Complication | What it means |
|---|---|
| Dehydration | Constant diarrhea drains fluids. Severe cases can lead to shock and death. |
| Seizures | Some children have seizures, most often with high fevers. |
| Rectal prolapse | Part of the lower large intestine slips outside the anus. It is more common in undernourished children. |
| Hemolytic uremic syndrome | A rare blood-vessel problem that can cause kidney failure. |
| Toxic megacolon | A rare, dangerous swelling of the colon that needs emergency care. |
| Reactive arthritis | Joint pain and swelling that can appear weeks later, sometimes with painful urination and eye irritation. |
| Bloodstream infection | Rarely, the bacteria enter the blood. This is more likely in young children and in adults with weak immune systems. |
“Serious dehydration can lead to shock and death.”
Mayo Clinic Staff, Shigella infection: Symptoms and causes
How Doctors Diagnose Shigellosis
A doctor may suspect Shigella from your symptoms alone, but a stool test confirms it.[4] The lab can also check which antibiotics the bacteria resist. That step matters more every year, because some strains no longer respond to common drugs.[2] Tell your doctor about recent travel, daycare exposure, sexual contacts, and any weakened immune system. Those details guide testing and treatment.
Shigella Treatment: What Actually Helps
1. Replace Fluids First
Fluids are the foundation of care. People with mild shigellosis may need nothing more than fluids and rest.[2] Oral rehydration solution (ORS), a precise mix of clean water, sugar, and salt available in pharmacies, replaces what diarrhea drains away. WHO and UNICEF back ORS as a core treatment for diarrhea, and they also recommend zinc for children for 10 to 14 days. Ask your child’s doctor for the right zinc dose.[7] Keep feeding children, and keep breastfeeding infants, while they recover.
2. Know What to Avoid
| Do | Don’t |
|---|---|
| Sip ORS or other fluids often | Take loperamide (Imodium) or diphenoxylate-atropine (Lomotil) if your diarrhea is bloody[2] |
| Rest and eat bland foods as you feel able | Buy or borrow antibiotics without a prescription |
| Wash your hands after every bathroom trip | Prepare food for others while you are sick[3] |
| Ask a doctor before using bismuth subsalicylate (such as Pepto-Bismol), which the CDC says may help adults[2] | Give bismuth subsalicylate to a child or teen without a doctor’s approval, since it contains a salicylate |
3. Antibiotics: When Doctors Prescribe Them
Most people recover without antibiotics in 5 to 7 days.[2] Doctors usually reserve antibiotics for severe illness, for people with weak immune systems, and for high-risk settings where the infection spreads easily.[5] Ciprofloxacin and azithromycin are two recommended oral options, but the right choice depends on lab results.[2] If you start an antibiotic and do not improve within a couple of days, tell your doctor. Your bacteria may resist that drug.[2] When you do get a prescription, finish every pill.
“Antibiotics can shorten the time you have fever and diarrhea by about 2 days.”
CDC, Treatment of Shigella Infection
Living in India or another region where antibiotics are sold over the counter? Please do not self-medicate for bloody diarrhea. Taking the wrong or incomplete course helps resistant bacteria survive and spread. Use ORS right away and see a doctor.
Drug-Resistant Shigella: What the Latest CDC Data Shows
In April 2026, CDC scientists reported a worrying trend. They studied 16,788 U.S. Shigella samples collected from 2011 to October 2023. Of those, 510 (3.0%) were extensively drug-resistant (XDR), meaning the bacteria resisted ampicillin, azithromycin, ceftriaxone, ciprofloxacin, and trimethoprim-sulfamethoxazole. No FDA-approved oral antibiotic exists for these infections.[5] News outlets picked up the findings in October 2026.[11]
XDR Shigella in the United States (CDC data)
| CDC data measure | Percentage |
|---|---|
| XDR share of isolates, 2011–2015 | 0% |
| XDR share of isolates, 2023 | 8.5% |
| XDR patients who were men* | 86.2% |
| XDR patients hospitalized** | 37.6% |
*Among 492 patients with age and sex data. **Among 258 patients with hospitalization data. No deaths were reported. Source: CDC MMWR, April 9, 2026.
Here is what the report means in plain English:
- Adults are now central to the story. Shigella once hit mainly young children in the U.S. Among XDR patients, the median age was 41, and most were men.[5]
- Sexual transmission plays a role. The CDC notes that sex between men is an important transmission route. The report also found HIV co-infection in 46.6% of XDR patients who had a known HIV status.[5] Researchers in England have documented similar XDR outbreaks linked to sexual transmission.[9]
- The true number is likely higher. Not every sample gets cultured or sequenced, so the CDC says it probably undercounts XDR cases.[5]
- Lab testing matters. Doctors should use susceptibility results to pick a drug whenever possible.[5]
“Treatment of XDR shigellosis remains challenging because no optimal therapy has been established.”
Logan N, et al., CDC, MMWR, April 9, 2026
For most healthy people, the practical message stays the same: hydrate, rest, see a doctor for severe or bloody illness, and prevent spread. The resistance trend simply raises the stakes for prevention.
How to Prevent Shigella Infection
Hand Washing That Works
Wash with soap and water, and scrub for at least 20 seconds. Make it a habit before you cook or eat, after using the bathroom or changing a diaper, and before sexual activity.[3]
At Home and in Child Care
- Throw soiled diapers into a covered, lined trash can.
- Disinfect changing areas right after each use, especially after leaks or spills.
- Watch young children as they wash their hands.
- Keep children with diarrhea home from child care, school, and play groups.[3]
Food and Water Safety (Including When You Travel)
- Wash fruits and vegetables thoroughly.[4]
- Use bottled or properly treated water for drinking and cooking where tap water may be unsafe.[4]
- Follow the CDC’s safe food and water habits for travelers during international trips.[1]
- Try not to swallow water in lakes, ponds, rivers, or untreated pools. Skip swimming until you fully recover from any diarrhea.[3]
Protecting Others When You Are Sick
- Do not prepare food for other people if you can avoid it.
- Stay home from health care, food service, and child care jobs while you are sick.[3]
- Wait at least 2 weeks after diarrhea ends before having sex. Bacteria can linger in stool after symptoms fade. The same rule applies if your partner has been sick.[1][3] The CDC offers guidance for sexually active people that covers this in more detail.[10]
Shigella is a hygiene and exposure issue, not a character issue. Anyone can catch it, and getting tested and treated promptly protects your partners, your family, and your community.
Frequently Asked Questions About Shigella
How long does a Shigella infection last?
Most people feel better in 5 to 7 days. Some cases last longer, and normal bowel habits can take weeks or months to return.
How do you catch Shigella?
You catch it by swallowing the bacteria. That usually happens through contaminated hands, food, or water, or through sexual contact that involves stool exposure.
Can Shigella go away without antibiotics?
Yes. Most healthy people recover without antibiotics, as long as they drink plenty of fluids. Doctors prescribe antibiotics mainly for severe cases and for people at higher risk.
Which antibiotics treat Shigella?
The CDC lists ciprofloxacin and azithromycin as two recommended oral antibiotics. Your doctor will choose based on lab results, because some strains resist these drugs.
Can I take Imodium for Shigella?
Not if your diarrhea is bloody. The CDC says anti-diarrheal medicines such as loperamide (Imodium) and diphenoxylate with atropine (Lomotil) may make symptoms worse. Ask a doctor before you use them for any suspected Shigella infection.
How long is Shigella contagious?
You are contagious while you have symptoms, and the germs can pass in your stool for up to a few weeks afterward. Some people spread the bacteria without ever feeling sick.
Is Shigella a sexually transmitted infection?
Shigella can spread during sexual contact that involves stool exposure, but it also spreads through food, water, and everyday contact. Anyone can get it. The CDC advises waiting at least 2 weeks after diarrhea ends before having sex.
Is Shigella dangerous for children?
Children under 5 get Shigella most often. Most recover well, but young children can become dehydrated quickly, and some have seizures. Call a doctor right away if your child has bloody diarrhea, a high fever, a seizure, or signs of dehydration.
Shigella infection is common, highly contagious, and usually short-lived. Fluids, rest, and careful hygiene get most people through it. The real danger comes from dehydration, complications in young children and people with weak immune systems, and a growing share of drug-resistant strains. Wash your hands, protect others while you recover, and call a doctor if you see blood in the stool, a high fever, or signs of dehydration.
Medical disclaimer: This content is for education only and is not medical advice, diagnosis, or treatment. Always talk with a qualified healthcare professional about your symptoms, especially before starting or stopping any medicine. In an emergency, call your local emergency number.
References
- Centers for Disease Control and Prevention. About Shigella Infection. Reviewed January 10, 2024.
- Centers for Disease Control and Prevention. Treatment of Shigella Infection. March 15, 2024.
- Mayo Clinic Staff. Shigella infection: Symptoms and causes. September 17, 2024.
- Cleveland Clinic. Shigellosis (Shigella Infection). Medically reviewed August 11, 2025.
- Logan N, et al. Emergence of Extensively Drug-Resistant Shigellosis — United States, 2011–2023. MMWR Morb Mortal Wkly Rep. 2026;75(13):174–178.
- Global Burden of Disease Study 1990–2016. Morbidity and mortality due to shigella and enterotoxigenic Escherichia coli diarrhoea. Lancet Infect Dis. 2018;18(11):1229–1240.
- World Health Organization and UNICEF. Clinical management of acute diarrhoea: WHO/UNICEF joint statement.
- Kotloff KL, Riddle MS, Platts-Mills JA, Pavlinac P, Zaidi AKM. Shigellosis. Lancet. 2018;391:801–812. (Further reading)
- Thorley K, et al. Emergence of extensively drug-resistant and multidrug-resistant Shigella flexneri serotype 2a associated with sexual transmission among gay, bisexual, and other men who have sex with men, in England. Lancet Infect Dis. 2023;23:732–739.
- Centers for Disease Control and Prevention. Preventing Shigella Infection Among Sexually Active People.
- USA TODAY. Sexually transmitted diarrhea and Shigella: what to know. October 9, 2026.
