Questions & Answers
Shigella (shih-GEHL-uh) bacteria cause an infection called shigellosis. Shigella cause an estimated 450,000 infections in the United States each year.
The four species of Shigella are:
- Shigella sonnei (the most common species in the United States)
- Shigella flexneri
- Shigella boydii
- Shigella dysenteriae
S. dysenteriae and S. boydii are rare in the United States, though they continue to be important causes of disease in low-resource areas. Shigella dysenteriae type 1 can be deadly.
How do Shigella bacteria spread?
Shigella spread easily; it takes just a small number of bacteria to make someone ill. People with a Shigella infection can spread the infection to others for several weeks after their diarrhea ends.
You can get infected by swallowing Shigella. Some ways Shigella can get into your mouth are:
- Getting Shigella on your hands and touching your mouth. Shigella can get on your hands by:
- Touching surfaces, such as toys, bathroom fixtures, changing tables, and diaper pails contaminated with Shigella bacteria from someone with an infection.
- Changing the diaper of a child with a Shigella infection.
- Taking care of a person with an infection, including cleaning up after the person uses the toilet.
- Eating food prepared by someone with a Shigella infection.
- Swallowing recreational water, such as lake water or improperly treated swimming pool water.
- Swallowing contaminated drinking water, such as water from a well that’s been contaminated with sewage or flood water.
- Exposure to stool (poop) during sexual contact with someone with a Shigella infection or who has recently recovered from a Shigella infection.
What are the symptoms of Shigella infection and how long do they last?
Most people with Shigella infection experience:
- Diarrhea that can be bloody
- Stomach pain
- Feeling the need to pass stool (poop) even when the bowels are empty
Symptoms usually start 1–2 days after infection and last 7 days. In some cases, bowel habits (frequency and consistency of stool) do not return to normal for several months.
Who is most likely to get Shigella infection?
- Young children are the most likely to get a Shigella infection, but people of all ages can be affected.
- Many outbreaks occur in childcare settings and schools. Infection commonly spreads from young children to their family members and other people in their communities because these bacteria spread easily.
- Travelers to areas with poor sanitation and hygiene systems are more likely to get a Shigella infection and to become infected with strains of the bacteria that are resistant to antibiotics used for treatment. Travelers may be exposed to the bacteria through contaminated food, water (both drinking and recreational water), or surfaces. Travelers can protect themselves by strictly following food and water precautions and washing hands with soap often. For more information, see Travelers’ Health – Food and Water Safety.
- Gay, bisexual, and other men who have sex with men (MSM)* are more likely to get a Shigella infection than the general adult population. Shigella can pass from stool or soiled fingers of one person to the mouth of another person, including during sexual activity. Many Shigella outbreaks among this population have been reported in the United States, Canada, Japan, and Europe since 1999.
- People who have weakened immune systems due to illness (such as HIV) or medical treatment (such as chemotherapy) can get a more serious illness. A severe Shigella infection can spread into the blood, which can be life-threatening.
*The term “men who have sex with men” is used in CDC surveillance systems to indicate men who engage in sexual behavior that may spread Shigella; it does not indicate how people identify their sexuality.
What should I know about antibiotic resistance and resistant Shigella?
Some antibiotics may not be effective for treating some Shigella infections because of antibiotic resistance. Healthcare providers can order laboratory tests to determine which antibiotics are likely to work.
If Shigella bacteria are resistant, first-choice antibiotics recommended to treat these infections may not work. Healthcare providers might need to prescribe second- or third-choice drugs for treatment. However, these drugs might be less effective, may need to be taken through a vein (IV) instead of by mouth, may be more toxic, and may be more expensive. Recommended antibiotics for severe infections include fluoroquinolones, azithromycin, and ceftriaxone.
What can be done to prevent antibiotic resistance and resistant bacteria?
Any use of antibiotics can cause resistance. Resistance and resistant bacteria, including some Shigella bacteria, can spread between people and the environment. Appropriate use of antibiotics (using them only when needed and exactly as prescribed) can help prevent antibiotic resistance and the spread of resistant bacteria.
How does CDC track antibiotic-resistant Shigella infections?
CDC tracks these infections through the National Antimicrobial Resistance Monitoring System (NARMS). The NARMS program at CDC helps protect public health by providing information about emerging bacterial resistance, the ways in which resistance is spread, and how resistant infections differ from susceptible infections.
Learn more about antibiotic-resistant Shigella with these resources from NARMS:
How can Shigella infection be diagnosed?
Many kinds of germs can cause diarrhea. Knowing which germ is causing an illness is important to help guide appropriate treatment. Healthcare providers can order laboratory tests to identify Shigella germs in the stool of an infected person.
How can Shigella infection be treated?
People who have shigellosis usually get better without antibiotic treatment in 5 to 7 days. People with mild shigellosis may need only fluids and rest. Bismuth subsalicylate (for example, Pepto-Bismol) may be helpful 1,2, but people sick with shigellosis should not use medications that cause the gut to slow down and interfere with the way the body digests food, such as loperamide (for example, Imodium) or diphenoxylate with atropine (for example, Lomotil) 3.
Healthcare providers may prescribe antibiotics for people with severe cases of shigellosis to help them get better faster. However, some antibiotics are not effective against certain types of Shigella. Healthcare providers can order laboratory tests to determine which antibiotics are likely to work. Tell your healthcare provider if you do not get better within a couple of days after starting antibiotics. They can do more tests to learn whether your type of Shigella bacteria can be treated effectively with the antibiotic you are taking. If not, your doctor may prescribe another type of antibiotic.
How can I reduce my chance of getting a Shigella infection?
You can reduce your chance of getting sick from Shigella by taking these steps:
- Carefully washing your hands with soap and water during key times:
- Before preparing food and eating.
- After changing a diaper or helping to clean another person who has defecated (pooped).
- If you care for a child in diapers who has shigellosis, promptly throw away the soiled diapers in a covered, lined garbage can. Wash your hands and the child’s hands carefully with soap and water right after changing the diapers. Clean up any leaks or spills of diaper contents immediately.
- Avoid swallowing water from ponds, lakes, or untreated swimming pools.
- When traveling internationally, stick to safe eating and drinking habits, and wash hands often with soap and water. For more information, see Travelers’ Health – Food and Water Safety.
- Avoid having sex (vaginal, anal, and oral) for one week after your partner recovers from diarrhea. Because Shigella germs may be in stool for several weeks, follow safe sexual practices, or ideally avoid having sex, for several weeks after your partner has recovered.
I was diagnosed with a Shigella infection. What can I do to avoid giving it to other people?
- Wash your hands carefully and frequently with soap and water, especially after using the bathroom.
- Do not prepare food for others while you are sick. After you get better, wash your hands carefully with soap and water before preparing food for others.
- Stay home from childcare, school and food service facilities while sick. Your local health department may have a policy on when to return to childcare or school. Refer to your local health department website for more information.
- Avoid swimming until you have fully recovered.
- Wait to have sex (vaginal, anal, and oral) for one week after you no longer have diarrhea. Because Shigella germs may be in stool for several weeks, follow safe sexual practices, or ideally avoid having sex, for several weeks after you have recovered.
My child was diagnosed with a Shigella infection. How can I keep others from catching it?
- Supervise handwashing of toddlers and small children after they use the bathroom. Wash your hands and your infant’s hands with soap and water after diaper changes.
- Throw away soiled diapers in a covered, lined garbage can. Clean diaper changing areas after using them. (Safe & Healthy Diapering in the Home)
- Keep your child out of childcare and group play settings while sick with diarrhea, and follow the guidance of your local health department about returning your child to their childcare facility.
- Avoid taking your child swimming or to group water play venues until after they no longer have diarrhea.
- Have children and staff shower with soap before swimming.
- If a child is too young to shower independently, have staff wash the child, particularly the rear end, with soap and water.
- Take frequent bathroom breaks or check their diapers often.
- Change diapers in a diaper-changing area or bathroom and not by the water.
- Discourage children from getting the water in their mouths and swallowing it.
- Have children and staff shower with soap before swimming.