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Shigellosis

Definition

Shigellosis is an acute bacterial infection of the lining of the intestines.

Alternative Names

Shigella gastroenteritis; Shigella enteritis; Enteritis - shigella; Gastroenteritis - shigella

Causes, incidence, and risk factors

Shigellosis is caused by a group of bacteria called Shigella.

There are several types of Shigella.

• Shigella sonnei, also called "group D" Shigella, is responsible for most cases of shigellosis in the United States.
• Shigella flexneri, or "group B" Shigella, cause almost all other cases.
• Shigella dysenteriae type 1 is rare in the U.S. but can lead to deadly outbreaks in developing countries.

People infected with the bacteria release it into their stool. The bacteria can spread from an infected person to contaminate water or food, or directly to another person. Getting just a little bit of the Shigella bacteria into your mouth is enough to cause symptoms.

Outbreaks of shigellosis are associated with poor sanitation, contaminated food and water, and crowded living conditions.

Shigellosis is common among travelers in developing countries and workers or residents of refugee camps.

There are about 18,000 cases of shigellosis per year in the United States. The condition is most commonly seen in day care centers and similar places.

Symptoms

Symptoms usually develop about 1 to 7 days (average 3 days) after you come in contact with the bacteria.

Symptoms include:

• Acute (sudden) abdominal pain or cramping
• Acute (sudden) fever
• Blood, mucus, or pus in stool
• Crampy rectal pain (tenesmus)
• Nausea and vomiting
• Watery diarrhea

Signs and tests

• Dehydration with fast heart rate and low blood pressure
• Abdominal tenderness
• Elevated white blood cell count
• Stool culture
• White blood cells in stool

Treatment

The symptoms usually last 2 to 7 days. The goal of treatment is to replace fluids and electrolytes (salt and minerals) lost in diarrhea.

Medications that stop diarrhea are generally not given because they may prolong the course of the disease.

Self-care measures to avoid dehydration include drinking electrolyte solutions to replace the fluids lost by diarrhea. Several varieties of electrolyte solutions are now available over the counter.

Antibiotics can help shorten the length of the illness and help prevent it from spreading to others in group living or day care situations. They may also be prescribed for patients with severe symptoms. Frequently used antibiotics include sulfamethoxazole and trimethoprim (Bactrim), ampicillin, ciprofloxacin (Cipro), or azithromycin.

Persons with diarrhea who cannot drink fluids by mouth because of nausea may need medical attention and fluids through a vein ( intravenously).This is especially common in small children.

Persons who take diuretics ("water pills") may need to stop taking such medicines if they have acute shigella enteritis. Never stop taking any medicine without first talking to your health care provider.

Support Groups

Expectations (prognosis)

Often the infection is mild and goes away on its own. Most patients, except malnourished children and those with weakened immune systems, have an excellent outlook.

Complications

Complications may include:

• Dehydration - severe
• Hemolytic-uremic syndrome (HUS), a form of kidney failure with anemia and clotting problems
• Reactive arthritis

Up to 40% of children with severe shigella enteritis develop neurological problems including febrile seizures or brain disease (encephalopathy) with headache, lethargy, confusion, and stiff neck.

Calling your health care provider

Call your provider if diarrhea does not improve, if there is blood in the stool, or if there are signs of dehydration.

Go to the emergency room if the following occur in a person with shigellosis:

• Confusion
• Headache with stiff neck
• Lethargy
• Seizures

Such symptoms are most common in children.

Prevention

Prevention involves the proper handling, storage, and preparation of food, in addition to good cleanliness. Hand washing is the most effective preventive measure. Avoid contaminated food and water.

References

DuPont HL. Shigella species (bacillary dysentery). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 224.

Ochoa TJ, Cleary TG. Shigella. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 196.