Food Recall Resource

Shigella Infection: Things You Should Not Miss about the Symptoms, Causes, and Treatment

Did you know nearly one-third of Shigella infections in the US are foodborne? Learn more facts as well as the symptoms, causes, treatment, complications, and prevention methods.

What is Shigella?

Shigella is a group of bacteria that can cause an infection in the intestines, which is called shigellosis. Four types of Shigella bacteria are known to cause illness in humans. These include:

  • Shigella sonnei
  • flexneri
  • boydii
  • dysenteriae

S. sonnei and S. flexneri are the most common causes of shigellosis while infections by S. boydii and S. dysenteriae are rare in the US.

Shigellosis food poisoning occurs when a person consumes food or water contaminated with Shigella bacteria. In addition, some people may contract the illness through direct contact with an infected person. The most common signs of Shigella infection are bloody diarrhea and severe stomach cramps.

The bacteria cause bloody diarrhea in two ways: first, it damages the linings of the intestines; second, it releases toxins that further enhance its negative effects.

Mild symptoms of shigellosis usually resolve within a week without any specific treatment. However, antibiotics may be necessary for treating severe symptoms. Antibiotic therapy helps reduce the severity of the symptoms and duration of the illness.

Though shigellosis can affect anyone, kids younger than five years are at a greater risk.

What are the Symptoms?

The symptoms usually develop within two to three days of exposure to the bacteria. In some people, it may take up to seven days.

The symptoms may include:

  • Bloody diarrhea
  • Stomach cramps that are often severe
  • A feeling of incomplete bowel evacuation
  • An urgency to pass stools
  • Fever
  • Vomiting
  • Dehydration

In healthy adults, the symptoms usually last about a week. However, if you have continuous diarrhea for more than three days, you should talk to your doctor.

What are the Causes of Shigella Infection?

Any of the species of Shigella bacteria can cause shigellosis. The bacteria can enter into your body in many ways. The methods of transmission are:

Touching infected objects

A person who has touched an object that is contaminated with the fecal matter of another person who is infected can unknowingly spread the germs.

For example, if you do not thoroughly wash your hands after changing the diaper of an infected child, you will likely become infected. In addition, you may also spread the germs to other objects you touch afterward.

Eating contaminated foods

Eating foods that contain Shigella bacteria is almost sure to cause an infection. Shigella transmission through contaminated foods is most likely when an infected person prepares or handles foods without washing their hands.

Moreover, you may also get an infection if you consume fresh fruits and vegetables that contain the bacteria.

Drinking tainted water

You may accidentally drink contaminated water that contains the Shigella bacteria. This is likely to happen if you go swimming in a pool or pond that has been contaminated with sewage or fecal matter of an infected person.

Who are at Risk?

People who are at a higher risk for Shigella are:

  • Prison inmates
  • Children in daycare
  • International travelers
  • Men who have sex with men
  • HIV patients
  • Those who live in poor sanitation conditions

Treatment: What are Your Options?

Treatment should begin as early as possible, preferably within the first day of the appearance of symptoms. Doing so will shorten the duration of illness and significantly reduce the risk of complications.

Shigella diagnosis can be confirmed only after examining ones stool in the laboratory. However, supportive treatment including proper hydration can be started before the report becomes available.

In addition to taking plenty of fluids, you may take over-the-counter medications to reduce fever. If your kid has contracted the illness, do not give them Aspirin to control fever. Instead, use acetaminophen (Tylenol). This is critically important because the use of Aspirin in kids and teens can cause a rare but potentially serious condition called Reye’s syndrome.

Once the laboratory report shows Shigella bacteria in your stool, your doctor may prescribe antibiotics. In fact, most patients with shigellosis get antibiotic therapy. Make sure to follow your doctor’s instructions while taking an antibiotic.

Most notably, you should not take over-the-counter medications to treat diarrhea before talking to your doctor. These medications called OTC antidiarrheals can slow down the downward movement of the intestines and lead to the accumulation of bacteria in the gut.

Complications of Shigella Infection

Complications due to Shigella infection are not common. However, when they occur, they can be life threatening.


It is a serious infection of the bloodstream. Bacteremia or septicemia can result when the bacteria in the gut move to the circulating blood. It can lead to sepsis, in which the major organs of the body fail to function.


Continuous diarrhea can cause a severe loss of fluids and electrolytes from the body. The symptoms of dehydration include dizziness, few tears when crying, and sunken eyes. If not promptly treated, it can lead to shock and even death.


Seizures can occur in some infected kids who have very high fevers. Seek an immediate medical help if your child has a seizure.

Hemolytic uremic syndrome (HUS)

HUS is a leading cause of kidney failure in young children. In addition, it can also cause anemia and reduced platelet count.

Toxic megacolon

Also called megarectum, this rare complication occurs when your large intestine becomes abnormally large. If you fail to get an immediate treatment, the large intestine can rupture and lead to a fatal condition called peritonitis.

Reactive Arthritis

Arthritis associated with Shigella infection is rare. Symptoms include swelling and pain in the joints, red, itchy eyes, and pain during urination.

Methods of Prevention

We do not have a vaccine to prevent shigellosis. Luckily, you can significantly reduce the risk of an infection by practicing the following easy tips.

  • Wash hands more often using soap and water.
  • Ask your kids to wash their hands thoroughly after using the bathroom, before eating, and after touching anything that might contain the germs.
  • Drink only filtered water. Do not swallow water while swimming in lakes or ponds.
  • Do not prepare or handle food until you have fully recovered.
  • Dispose of dirty diapers properly.
  • Kids with the infection should not continue going to school.
  • Avoid intimate contact with someone with shigellosis or someone who has just recovered.

Top 10 Interesting Shigella Facts

  1. Each year, Shigella affects 500,000 persons in the US. Among them, most cases are due to S. sonnei. In fact, S. sonnei and S. flexneri account for up to 90 percent of the cases.
  2. 27,000 drug-resistant Shigella infections occur in the United States each year, according to the CDC.
  3. Globally, shigellosis causes bloody diarrhea in 80 million people and 700,000 deaths each year.
  4. The first of its kind in the medical literature, S. sonnei was associated with inflamed gallbladder in a traveler who had returned from Vietnam, reported a 2018 case study published in the Journal of Travel Medicine.
  5. Shigella is one of the top three causes of bacterial diarrhea among travelers.
  6. An outbreak of antibiotic-resistant Shigella in the US occurs usually among men who have sex with men.
  7. Lactose-free diet may help relieve the symptoms of Shigella.
  8. No vaccine is currently available for shigellosis.
  9. Shigella is highly contagious and highly lethal; as few as 10-100 organisms can cause diarrhea.
  10. Reactive arthritis, a complication of Shigella infection, is more common in men aged 20-40 years compared to women and men in other age groups.


How can we help you?