Shigella Infection

Reviewed on 10/13/2021

Shigellosis facts*

Shigella
Shigella is a germ that causes a highly contagious disease called shigellosis (bacillary dysentery).

*Shigellosis facts by John P. Cunha, DO, FACOEP

  • Shigellosis is an infectious disease caused by a group of bacteria called Shigella. There are four species of Shigella:
    • Shigella sonnei (the most common species in the U.S.)
    • Shigella flexneri
    • Shigella boydii
    • Shigella dysenteriae
  • The transmission of most Shigella infections is caused by the bacterium passing from stools or soiled fingers of one person to the mouth of another person. This happens when basic hygiene and hand-washing habits are inadequate and can happen during certain types of sexual activity. It may also be acquired from eating contaminated food.
  • Shigella is highly contagious and being exposed to even a miniscule amount of contaminated fecal matter can cause infection.
  • Risk factors for getting Shigella infection include living or traveling in areas where sanitation is lacking such as developing countries, being a toddler or changing toddler diapers, living or spending time in large institutional facilities (nursing homes, community pools, military barracks, jails), and being a sexually active gay man.
  • Outbreaks of Shigella can occur in child-care facilities and schools or when food is not properly handled. An outbreak of Shigella was reported in Flint, Mich., in October 2016. The lead-contaminated water in the town is causing residents to avoid exposure to it, which has lead to reduced hand washing and the spread of the bacteria.
  • Signs and symptoms of Shigella infection include diarrhea (often bloody), fever, stomach cramps, abdominal pain, and feeling as if you need to have a bowel movement even when bowels are empty (tenesmus), starting a day or two after exposure to the bacteria. This is the incubation period.
  • Women infected with Shigella during pregnancy need to ensure they do not become dehydrated or experience electrolyte imbalances due to diarrhea from the illness.
  • The diagnosis of shigellosis is made using laboratory tests to identify Shigella in the stools of an infected person. Tests can also be performed to determine which antibiotics may be used to best treat the infection.
  • Treatment for mild Shigella infection usually involves just rest and fluids, and the illness resolves on its own without antibiotics.
  • Over-the-counter treatment may include bismuth subsalicylate (Pepto-Bismol). Antidiarrheal drugs such as loperamide (Imodium) or diphenoxylate with atropine (Lomotil) can make the illness worse and should be avoided.
  • Antibiotics can shorten the duration of the illness and kill the Shigella bacteria. Shigella can be resistant to some antibiotics, so a doctor will perform a stool test to see which antibiotics may help. Antibiotics commonly used to treat Shigella are ampicillin, trimethoprim/sulfamethoxazole (Bactrim, Septra), ceftriaxone (Rocephin), or ciprofloxacin.
  • Precautions can prevent the spread of Shigella. Prevention includes hand washing with soap, basic food-safety preparations, proper disposal of soiled diapers, and avoiding swallowing water from ponds, lakes, or untreated pools.
  • The prognosis for shigellosis is generally good and most people recover even without medications within five to seven days.

What is shigellosis?

Shigellosis is a diarrheal disease caused by a group of bacteria called Shigella. Shigella causes about 500,000 cases of diarrhea in the United States annually. There are four different species of Shigella:

  • 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 the developing world. Shigella dysenteriae type 1 can cause deadly epidemics.

What are the symptoms of Shigella?

Symptoms of shigellosis typically start 1-2 days after exposure and include:

How long after infection do symptoms appear?

  • 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.

How long will symptoms last?

  • In persons with healthy immune systems, symptoms usually last about 5 to 7 days.
  • Persons with diarrhea usually recover completely, although it may be several months before their bowel habits are entirely normal.
  • Once someone has had shigellosis, they are not likely to get infected with that specific type again for at least several years.
  • However, they can still get infected with other types of Shigella.

How can Shigella infections be diagnosed?

Many different kinds of germs can cause diarrhea, so establishing the cause will help guide treatment. Healthcare providers can order laboratory tests to identify Shigella in the stools of an infected person. The laboratory can also do special tests to determine which antibiotics, if any, would be best to treat the infection.

QUESTION

Bowel regularity means a bowel movement every day. See Answer

Can there be any complications from Shigella infections?

Possible complications from Shigella infections include:

  • Post-infectious arthritis. About 2% of persons who are infected with Shigella flexneri later develop pains in their joints, irritation of the eyes, and painful urination. This is called post-infectious arthritis. It can last for months or years and can lead to chronic arthritis. Post-infectious arthritis is caused by a reaction to Shigella infection that happens only in people who are genetically predisposed to it.
  • Bloodstream infections. Although rare, bloodstream infections are caused either by Shigella organisms or by other germs in the gut that get into the bloodstream when the lining of the intestines is damaged during shigellosis. Bloodstream infections are most common among patients with weakened immune systems, such as those with HIV, cancer, or severe malnutrition.
  • Seizures. Generalized seizures have been reported occasionally among young children with shigellosis, and usually, resolve without treatment. Children who experience seizures while infected with Shigella typically have a high fever or abnormal blood electrolytes (salts), but it is not well understood why the seizures occur.
  • Hemolytic-uremic syndrome or HUS. HUS occurs when bacteria enter the digestive system and produce a toxin that destroys red blood cells. Patients with HUS often have bloody diarrhea. HUS is only associated with Shiga-toxin-producing Shigella, which is found most commonly in Shigella dysenteriae.

How can Shigella infections be treated?

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.
    • Safe & Healthy Diapering in the Home
    • Diaper-Changing Steps for Childcare Settings
  • 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 TravelersHealth – 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.

Is antibiotic resistance a problem with 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, maybe more toxic, and maybe more expensive. Recommended antibiotics for severe infections include fluoroquinolones, azithromycin, and ceftriaxone.

What should I know about antibiotic resistance and resistant Shigella infection?

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 treating 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, maybe more toxic, and maybe more expensive. Recommended antibiotics for severe infections include fluoroquinolones, azithromycin, and ceftriaxone.

What should I do if I have an antibiotic-resistant Shigella infection?

Please follow the advice of your healthcare provider. If you do not feel better within a couple of days after beginning treatments, tell your healthcare provider. Protect others by washing your hands carefully with soap after using the toilet, and wait until your diarrhea has stopped before preparing food for others, swimming, or having sex.

How can we reduce the spread of antibiotic-resistant Shigella?

Reducing the spread of antibiotic-resistant Shigella requires a multi-pronged approach:

  • preventing infections,
  • tracking resistance,
  • improving antibiotic use, and
  • developing new treatments.

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How is Shigella spread?

Shigella germs are present in the stools of infected persons while they have diarrhea and for up to a week or two after diarrhea has gone away. Shigella is very contagious; exposure to even a tiny amount of contaminated fecal matter -- too small to see-- can cause infection. Transmission of Shigella occurs when people put something in their mouths or swallow something that has come into contact with the stool of a person infected with Shigella. This can happen when:

  • Contaminated hands touch your food or mouth. Hands can become contaminated through a variety of activities, such as touching surfaces (e.g., toys, bathroom fixtures, changing tables, diaper pails) that have been contaminated by stool from an infected person. Hands can also become contaminated with Shigella while changing the diaper of an infected child or caring for an infected person.
  • Eating food contaminated with Shigella. Food may become contaminated if food handlers have shigellosis. Produce can become contaminated if growing fields contain human sewage. Flies can breed in infected feces and then contaminate food when they land on it.
  • Swallowing recreational (for example, lake or river water while swimming) or drinking water that was contaminated by infected fecal matter.
  • Exposure to feces through sexual contact.

How can I reduce my risk of getting shigellosis?

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.
    • Safe & Healthy Diapering in the Home
    • Diaper-Changing Steps for Childcare Settings
  • 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 shigellosis. What can I do to avoid giving it to other people?

  • Wash your hands with soap carefully and frequently, especially after using the toilet.
  • Do not prepare food for others while you are sick. After you get better, wash your hands carefully with soap before preparing food for others.
  • For those who work in healthcare, food service, or childcare facilities should not prepare or handle food for others until their local health department has authorized them to return to work. Improvements in worker sick leave policies and providing adequate hygiene facilities and education for food service workers may prevent shigellosis caused by contaminated foods.
  • Avoid swimming until you have fully recovered.
  • Don't have sex until several days after you no longer have diarrhea.

My child was diagnosed with shigellosis. 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.

What can be done if an outbreak of Shigella occurs in the childcare setting?

  • Exclude any child with diarrhea from the childcare setting until diarrhea has stopped.
  • Children who have recently recovered from shigellosis can be grouped in one classroom (cohort) to minimize exposing uninfected children and staff to Shigella.
  • Assign separate staff to change diapers and prepare or serve food.
  • Reassign adults with diarrhea to jobs that minimize opportunities for spreading infection (for example, administrative work instead of food preparation).
  • Establish, implement, and enforce policies on water-play and swimming that:
    • Exclude children ill with diarrhea from water-play and swimming activities.
    • Exclude children diagnosed with Shigella from water-play and swimming activities for an additional week after their diarrhea has resolved.
    • Have children and staff wash their hands before using water tables.
    • Have children and staff shower with soap before swimming in the water.
      • 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 children's 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.
    • Prohibit the use of temporary inflatable or rigid fill-and-drain swimming pools and slides because they can spread germs in childcare facilities.

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 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. 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.

QUESTION

Bowel regularity means a bowel movement every day. See Answer

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References
United States. Centers for Disease Control and Prevention. "Shigella -- Shigellosis." <http://www.cdc.gov/shigella/general-information.html>. Last updated: 10/8/2020

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