Resources for Public Health & Medical Professionals

Technical Information

Water or bloody diarrhea, abdominal pain, tenesmus, fever, and malaise. Stools tend to be of small volume, and severe dehydration is uncommon.

Four species of Shigella: sonnei, flexneri, dysenteriae, and boydii.

In the United States, there are about 500,000 cases of shigellosis every year, making it the third most common bacterial enteric disease 1. Shigellosis does not have a marked seasonality, likely reflecting the importance of person-to-person transmission. For more information, see the FoodNet 2012 Surveillance Report. Cdc-pdf[PDF – 36 pages]

In 2013, the average annual incidence of shigellosis in the United States was 4.82 cases per 100,000 individuals 2.

Possible complications from Shigella infections include:

  • Post-infectious arthritis. A syndrome of joint pains, eye irritation, and painful urination after an infection is called post-infectious arthritis. This can happen in about 2% 3-6 of persons who are infected with Shigella flexneri. Few cases have been reported in association with S. sonnei 7, 8 or S. dysenteriae infection 9. 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 3, 10-12.
  • Blood stream infections. Although rare, blood stream 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. Blood stream infections are most common among patients with weakened immune systems, such as those with HIV, cancer, or severe malnutrition 10, 13, 14.
  • 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 10, 15-19.
  • 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 most commonly Shigella dysenteriae 10, 20-22.

Shigella is very contagious; a small inoculum (10 to 200 organisms) is sufficient to cause infection 23. Shigella germs are present in the stools of infected persons while they have diarrhea and for up to a few weeks after the diarrhea has gone away 24. Transmission of Shigella occurs when people put something in their mouths or swallow something that has come into contact with 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 25. 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.
  • Young children are the most likely to get shigellosis, but people from all age groups are affected 26. Many outbreaks are related to childcare settings and schools, and illness commonly spreads from young children to their family members and others in their communities because it is so contagious.
  • Gay, bisexual, and other men who have sex with men (MSM) are more likely to acquire shigellosis than the general adult population 27. Shigella passes from stools or soiled fingers of one person to the mouth of another person, which can happen during sexual activity. Many shigellosis outbreaks among MSM have been reported in the United States, Canada, Japan, and Europe since 1999 28-35. Resistance to clinically important antimicrobials may also be more prevalent among shigellae isolated from MSM 27-29, 31-34, 36, 37. For more information, see Shigella Infections among Gay & Bisexual Men.(https://www.cdc.gov/shigella/msm.html)
  • HIV-infected persons can have more severe and prolonged shigellosis, including having the infection spread into the blood, which can be life-threatening 30, 38.
  • Large outbreaks of Shigella have occurred in traditionally observant Jewish communities 39-41. Documented outbreaks in traditionally observant Jewish communities often begin in childcare settings and spread within and between households during social gatherings.
  • Travelers to developing countries may be more likely to get shigellosis, and to become infected with strains of Shigella that are resistant to important antibiotics 34, 35, 42-45. Travelers may be exposed 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 frequently. For more information, see Travelers’ Health – Food and Water Safety. 

The term men who have sex with men is used in CDC surveillance systems because it indicates the behaviors that transmit Shigella infection, rather than how individuals self-identify in terms of their sexuality.

Resistance to traditional first-line drugs such as ampicillin and trimethoprim-sulfamethoxazole is common. Healthcare providers now rely on alternative drugs like ciprofloxacin and azithromycin to treat infections. However, strains of Shigella resistant to these antibiotics are becoming more common in the United States 46. Infections caused by antibiotic-resistant Shigella strains can last longer than infections caused by antibiotic-susceptible bacteria 47. Because initial treatment can fail and effective treatments may require intravenous or intramuscular administration, costs are expected to be higher for resistant infections 47

For more information, see Antibiotic / Antimicrobial Resistance.

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Surveillance

Clinical laboratories report isolations of Shigella to state health departments, which then report tem to CDC. Shigellosis is a notifiable infectious disease.

Reports trends in foodborne infections and tracks the impact of food safety policies nationally.

Foodborne Diseases Active Surveillance Network (FoodNet), conducts surveillance for Campylobacter, Cryptosporidium, Cyclospora, Listeria, Salmonella, Shiga toxin-producing Escherichia coli (STEC) O157 and non-O157, Shigella, Vibrio, and Yersinia infections diagnosed by laboratory testing of samples from patients.

The network, established in July 1995, is a collaborative program among CDC, 10 state health departments, the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA-FSIS)External, and the Food and Drug Administration (FDA)External. FoodNet personnel in state health departments get timely reports of infections diagnosed in residents of ConnecticutExternal, GeorgiaExternal, MarylandExternal, MinnesotaExternal, New MexicoExternal, OregonExternalTennesseeExternal and selected counties in CaliforniaExternal, ColoradoExternal, and New YorkExternal and are in regular contact with the clinical laboratories serving these areas.  The surveillance area includes 15% of the United States population (about 49 million persons). FoodNet is the principal foodborne disease component of CDC’s Emerging Infections Program.

FoodNet accomplishes its work through active laboratory-based surveillance; surveys of laboratories and the general population; and population-based epidemiologic studies.

Collects laboratory data, such as serotype, on Shigella

National Shigella surveillance data are collected through passive surveillance of laboratory-confirmed human Shigella infections. Clinical diagnostic laboratories submit Shigella isolates to state and territorial public health laboratories, where they are confirmed, speciated, and subtyped. Unusual or untypable serotypes are forwarded to the Centers for Disease Control and Prevention’s (CDC) National Shigella Reference Laboratory at the Enteric Diseases Laboratory Branch (EDLB) for further characterization or confirmation; results are reported back to state and territorial public health laboratories.

State and territorial public health laboratories report Shigella infections electronically to CDC through a variety of mechanisms. Data are collected into the Laboratory-based Enteric Disease Surveillance (LEDS) system. The Division of Foodborne, Waterborne, and Environmental Diseases (DFWED) in the National Center for Emerging and Zoonotic Infectious Diseases maintains the national Shigella surveillance data in LEDS. The annual summaries of these data are the only regularly published national source of serotype information for Shigella.

For more information, see Foodborne Illness Surveillance, Response, and Data Systems.

Tracking trends in resistance

The National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS) is an interagency public health surveillance system that tracks antimicrobial resistance in foodborne and other enteric (intestinal) bacteria from humans, retail meats, and food animals in the United States. The NARMS program at CDC helps protect public health by providing information about resistance in bacteria isolated from ill people, the ways in which resistance is spread, and how resistant infections differ from susceptible infections.

Data

For more information, see National Antimicrobial Resistance Monitoring System (NARMS).

The National Notifiable Disease Surveillance System, or NNDSS, tracks contagious diseases that laboratory professionals and doctors are required to report to the state or territorial public health agency. These agencies voluntarily submit the information to NNDSS, which CDC oversees. Notifiable disease surveillance is “passive” (i.e., the investigator at CDC waits for disease reports from those requested to report) and is susceptible to underreporting. Foodborne diseases that are nationally notifiable include botulism, hemolytic uremic syndrome (HUS), listeriosis (Listeria), shigellosis (Shigella), salmonellosis (Salmonella), Shiga Toxin-producing Escherichia coli (STEC) infections, cryptosporidiosis and vibriosis (cholera and its relatives).

For more information, see National Notifiable Diseases Surveillance System (NNDSS).

The National Outbreak Reporting System, or NORS, is a web-based platform designed to support reporting to CDC by local, state, and territorial health departments in the United States of all waterborne disease outbreaks and enteric disease outbreaks transmitted by food, contact with environmental sources, infected persons or animals, or unknown modes of transmission.

For more information, see The National Outbreak Reporting System (NORS).

To find outbreaks, see the Foodborne Outbreak Online Database (FOOD).

Connects cases of illness nationwide to quickly identify outbreaks, including many that would otherwise go undetected

The National Molecular Subtyping Network for Foodborne Disease Surveillance, or PulseNet, connects cases to potential outbreaks, especially across states. PulseNet has revolutionized the detection and investigation of foodborne disease outbreaks, especially those occurring in multiple sites across the country which, before PulseNet, often went undetected or were detected only after they grew very large. The PulseNet USA network of 83 local, state, territorial, agricultural, and federal laboratories in all 50 states is coordinated by CDC along with the Association of Public Health Laboratories (APHL). PulseNet International has 7 regions in 88 countries. Each laboratory tests enteric bacteria that cause illness, like E. coli and Shigella, through a standardized subtyping process using multiple analytical tools, including pulsed-field gel electrophoresis (PFGE)*, multiple locus variable number tandem repeat analysis (MLVA), and whole genome sequencing (WGS). All of these techniques are used to determine the DNA fingerprint of the bacteria.

*Public health scientists upload these different fingerprints (such as PFGE patterns, MLVA profiles, and DNA sequences) to their respective electronic databases to compare them to fingerprints isolated from other people, animals, and foods to identify matches that may indicate an outbreak is happening.

Data

 

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Educational Resources

  • If you or your child have diarrhea, find more information to protect yourself, your family, and your community, as well as steps to get better.
  • Handwashing is the #1 way to protect yourself against Shigella infections. Please see the CDC handwashing website for more information.

Below you will find useful links related to hygiene and handwashing in the food service industry.

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References
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