Shigella is the bacterium that causes the disease shigellosis, also known as bacillary dysentery. Shigella is one of the most easily transmitted bacterial diarrheas, since it can occur after fewer than 100 bacteria are ingested. While reported cases of Shigella range between 14,000 and 20,000 annually, with the majority of these cases occurring between July and October. Shigella Sonnei is the most common type of Shigella. It accounts for over two-thirds of cases of shigellosis in the United States.
Shigella bacteria are generally transmitted through a fecal-oral route. Foods that come into contact with human or animal waste can transmit Shigella. Thus, handling toddlers’ diapers, eating vegetables from a field contaminated with sewage, or drinking pool water are all activities that can lead to shigellosis.
Symptoms of Shigella Food Poisoning
Symptoms of Shigella poisoning most commonly develop one to three days after exposure to Shigella bacteria, and usually go away within five to seven days. It is also possible to get Shigella but experience no symptoms, and still be contagious to others, a condition known as being asymptomatic.
Common Shigella Food Poisoning Symptoms
- Diarrhea: Diarrhea ranges from mild to severe. It is bloody in 25 to 50 percent of cases and usually contains mucus
- Stomach cramps
- Rectal spasms
Complications from Shigella
Complications from shigellosis can include severe dehydration, seizures in small children, rectal bleeding, and invasion of the blood stream by the bacteria. Young children and the elderly are at the highest risk of death. The following is a list of specific complications caused by Shigella.
Proctitis and Rectal Prolapse: The bacteria that causes shingellosis can also cause inflammation of the lining of the rectum or rectal prolapse.
Reactive Arthritis: Approximately 3 percent of patients with Shigella infection, most often those with Shigella flexneri, develop Reactive Arthritis. It occurs when the immune system attempts to combat Shigella but instead attacks the body. Symptoms of Reactive Arthritis include inflammation of the joints, eyes, or reproductive or urinary organs. On average, symptoms appear 18 days after infection.
Toxic Megacolon: In this rare complication, the colon is paralyzed and unable to pass bowel movements or gas. Symptoms of Toxic Megacolon include abdominal pain and swelling, fever, weakness, and disorientation. If this complication goes untreated and the colon ruptures, the patient’s condition can be life-threatening.
Hemolytic Uremic Syndrome, or HUS: Shigella rarely results in HUS, which is more commonly a complication of Shiga toxin-producing E. coli infections. HUS can lead to kidney failure.
Diagnosis of Shigella
A Shigella infection is diagnosed through laboratory testing of a stool sample.
Shigella Food Poisoning Treatment
A Shigella infection usually goes away on its own in five to seven days, although bowel movements may continue to be abnormal for up to a month following infection. Antibiotics, however, can shorten the course of the illness. A doctor can prescribe antibiotics after testing a stool sample for the presence of Shigella bacteria.
Some strains of shigellosis are resistant to antibiotics, meaning that antibiotics might not always be an effective treatment. Antidiarrheal medication should be avoided, as it can actually make the illness worse.
Preventing a Shigella Infection
Frequent hand washing is key to preventing Shigella, since individuals can carry Shigella without noticing symptoms, and Shigella bacteria can remain active for weeks after illness.
Steps for Preventing the Spread of Shigella Infection
- If a child in diapers has shigellosis, wash your hands after changing their diaper and wipe down the changing area with disinfectant
- People with Shigella should not prepare food for others for at least two days after diarrhea has stopped
- Drink only treated or boiled water while traveling and only eat fruits you peel yourself
- Only swim in pools maintaining a chlorine level of 0.5 parts per million and stay clear of pools where children not yet toilet trained are swimming
Additional Resources for Shigella
About-Shigella.com is a comprehensive site with in-depth information about Shigella bacteria and Shigella infection.
Shigella Blog provides up-to-date news related to Shigella outbreaks, research, and more.