What To Know About the Shigella Infection

Mark Gurarie
·8 min read
5

Medically reviewed by Dale Garber, MD

Shigella is a strain of bacteria that causes an infection of the lining of the intestines. This infection is known as shigellosis. These bacteria are highly contagious—typically spreading through contaminated water or food or through direct contact with someone with the infection.

Outbreaks of shigellosis tend to occur in areas that have crowded living conditions or poor sanitation. The Shigella infection is also more common in children under the age of five and those who are immunocompromised. It’s estimated that 450,000 Americans contract the infection each year.

The hallmark symptom of shigellosis is diarrhea. The infection can also cause abdominal pain, fever, and cramping, among other symptoms. Most people who contract this disease recover fully—sometimes even without treatment. The average duration of untreated shigellosis is about a week. But, getting treatment can be important as it can shorten the length of the illness, reduce the chances of the infection spreading, and help you reduce symptoms faster.

Symptoms

Symptoms usually develop one to three days after you've been exposed to the Shigella bacteria. In most cases, symptoms tend to resolve within a week. But some people may have lingering symptoms for up to one month. The most common symptoms of shigellosis include:

In addition, diarrhea due to shigellosis reduces the amount of water you have in your body. As a result, you might be at an increased risk of experiencing dehydration. The symptoms of dehydration include:

Dehydration in children can also produce its own subset of symptoms, such as not having tears when they cry, not wetting their diapers for three or more hours, having a high fever, and feeling excessively sleepy or irritable.

Causes

Shigellosis occurs when you have exposure to the Shigella bacteria. There are several strains of the Shigella bacteria, all of which are highly contagious. In the U.S., shigellosis most often occurs due to types of strains called Shigella sonnei and Shigella flexneri. A third type, Shigella dysenteria, is more common in other countries.

People contract shigellosis by getting Shigella in their mouths. The infection often spreads by getting the bacteria on your hands. This can happen by:

  • Changing a diaper

  • Touching contaminated surfaces

  • Consuming food that’s been prepared by someone who has the infection

  • Drinking infected water

  • Swallowing spoiled water while swimming or bathing

  • Having sexual contact with someone who has or recently had the infection

Risk Factors

Certain groups of people are at an increased risk of contracting shigellosis. These include:

  • Young children, as many infections can occur in daycare or school settings

  • Travelers to or residents of countries with reduced access to clean water

  • Gay or bisexual assigned males at birth or other men that have sex with men

  • People with HIV/AIDS, diabetes, or other conditions that affect immunity

  • Those with cancer who are undergoing chemotherapy

Diagnosis

If you suspect you may have been exposed to the Shigella infection or are experiencing symptoms of shigellosis, it's good practice to see your healthcare provider. Your provider will likely ask you about your medical history, the symptoms you're experiencing, and whether you have been traveling. They may also perform a physical exam to better understand your symptoms.

Additionally, it's common for your provider to order diagnostic exams to accurately test for the Shigella infection. These tests may include:

  • Dehydration screening: Uses blood tests that measure the level of electrolytes in your system to check if you’re dehydrated (don’t have enough water in your body).

  • White blood tests: Your provider may order a blood test that takes a sample of your white blood cells (WBC) to check their levels. Having high levels of WBCs can indicate that you have an infection in your body.

  • Stool culture: Healthcare providers take a stool (poop) sample and send the sample to a lab to detect the Shigella bacteria. The presence of the bacteria in your poop signals can identify that you have shigellosis.

Treatment

The Shigella infection can sometimes resolve on its own without the need for treatment. That said, antibiotics can help reduce the duration of infection, self-care methods may help with dehydration, and other procedures may prove necessary in more severe cases.

Antibiotics

Antibiotics are medications that specifically target Shigella bacteria—killing them and preventing them from multiplying. These shorten how long the illness lasts in your body and can help you from spreading the infection to others. The most common antibiotics for shigellosis include:

  • Cipro XR (ciprofloxacin)

  • Ceftrisol Plus (ceftriaxone)

  • Zithromax (azithromycin)

Self-Care

Because shigellosis can cause diarrhea and lead to dehydration, healthcare providers recommend drinking plenty of fluids—especially those that contain electrolytes—to reduce symptoms of dehydration.

It's important to note that you should not use the medication Imodium (loperamide) or other over-the-counter diarrhea treatments for diarrhea. These medications can prolong the illness and worsen the infection. In addition, if you take diuretics (or, water pills), your provider may recommend to stop taking them until you fully heal from the infection.

Medical Treatment

In severe cases of diarrhea, you or your child may experience nausea and excessive vomiting. This may warrant a trip to the hospital for medical treatment. You or your child may need additional treatment under the supervision of a healthcare provider because of difficulty drinking fluids or trouble holding fluids down. As a result, your healthcare provider may deliver fluids via an intravenous (IV) drip.

How to Prevent Shigellosis

Shigellosis prevention primarily involves ensuring that you don’t swallow the Shigella bacteria. There are several steps you can take to protect yourself and others:

  • Washing your hands: Make sure to wash your hands thoroughly by using soap and water, especially before any sexual activity, before cooking, preparing food, or eating, and after going to the bathroom, cleaning, or changing a diaper.

  • Safely changing diapers: When changing diapers, throw away the used diaper in a safe, lined trashcan, clean any leaking fluids or solids as soon as possible, and wash both your own and your child’s hands immediately after.

  • Avoid swallowing water: If you’re swimming in a pool, lake, river, or pond, do your best not to swallow any water as it may be contaminated.

  • Traveling safely: Since shigellosis can occur worldwide, make sure to keep up with handwashing and follow other safe practices when you travel. It's also important to avoid eating raw foods, ensure the drinking water is safe, and opt for safely packaged drinks or foods.

  • Reducing sex with an infected partner: If your partner has shigellosis, avoid having sex with them for at least two weeks after their diarrhea and other symptoms have subsided.

Complications

Depending on the type of Shigella bacteria that are causing your infection and your overall health status, you might be at risk of experiencing rare, but serious symptoms. These complications include:

  • Reactive arthritis: About 2% of the time, shigellosis causes joint pain and inflammation, eye irritation, and painful urination. This reactive arthritis typically lasts three to five months. But in some people, this condition can become chronic (long-term).

  • Bloodstream infection: This infection is a potentially fatal complication that can happen in 0.4% to 7.3% of cases. A bloodstream infection is more likely to affect people with weakened immunity due to underlying conditions such as human immunodeficiency virus (HIV/AIDS), cancer, diabetes, or malnutrition.

  • Seizures: Seizures are sudden bursts of electrical activity in the brain that cause changes in movements, behavior, or level of consciousness. Young children are most likely to experience this complication and may also have a high fever, low blood sugar, or abnormal salt levels in the blood as accompanying symptoms. It's worth noting that seizures tend to resolve on their own without treatment.

  • Hemolytic-uremic syndrome: Another rare complication that’s usually only seen in children, hemolytic-uremic syndrome (HUS) can occur when bacteria enter the digestive system and damage red blood cells. In turn, this can affect kidney function and sometimes cause kidney failure. HUS, which can occur if the Shigella bacteria are resistant to antibiotics, is the leading cause of death due to shigellosis.

A Quick Review

Shigella is a type of bacteria that causes shigellosis—a highly contagious infection of the intestines that causes diarrhea, nausea, vomiting, and dehydration, among other symptoms. Young children, those with compromised immune systems, and people living or working in crowded areas are most at risk.

Healthcare providers diagnose this condition by evaluating symptoms and performing laboratory analyses of stool samples. Treatments focus on preventing dehydration, with providers sometimes prescribing antibiotics to reduce the length of the infection and decrease symptoms. Keys to the prevention of shigellosis include regular handwashing, avoiding swallowing infected water, and avoiding sex with someone with the infection for up to two weeks after symptoms have passed.

Frequently Asked Questions

What's the difference between Shigella and E. coli?


Both Shigella and E. coli are strains of bacteria that can cause shigellosis. Though they may cause similar effects, these bacteria are structurally different. E. coli is known to be less “virulent” than Shigella, meaning that E. coli infections are generally less severe.

Is Shigella contagious?


Shigella is a highly contagious bacteria that causes shigellosis. When you have shigellosis, your body expels Shigella bacteria by defecating (pooping). Shigellosis spreads when another person comes in contact with that bacteria. Even a small amount of exposure to th bacteria can cause the infection.

Can Shigella bacteria cause death?


Most Shigella infections aren’t fatal, but, in rare cases, they can become very serious. Every year in the U.S., researchers estimate that of the 450,000 people who develop shigellosis, 6,000 end up in the hospital, and about 40 die of this illness.

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