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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. [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.

People at Risk

  • 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.(
  • 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.

Antibiotic Resistance

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

Foodborne Diseases Active Surveillance Network (FoodNet)

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

Foodborne Diseases Active Surveillance Network, referred to as FoodNet, is the principal foodborne disease component of CDC's Emerging Infections Program. FoodNet is a sentinel surveillance system* that collects information from sites in 10 states—covering 15% of the US population, or 46 million Americans—about diseases that are caused by any of seven bacteria and two parasites§ commonly transmitted through food. The system has been in operation since 1995. Investigators actively seek out laboratory confirmed cases of illness in an attempt to detect every person in the 10 sites who went to a doctor's office, had a sample tested, and was diagnosed with one of these infections. With the information on epidemiology, incidence, and trends of foodborne diseases in the US, public health officials can conduct analyses and epidemiological studies.

FoodNet is a collaborative program among CDC, the U.S. Department of Agriculture's Food Safety and Inspection Service (USDA-FSIS), the Food and Drug Administration (FDA), and state health departments in Connecticut, Georgia, Maryland, Minnesota, New Mexico, Oregon, Tennessee, and selected counties in California, Colorado, and New York.

For more information, see FoodNet.

*Sentinel surveillance involves the collection of case data from only part of the total population (from a sample of providers) to learn something about the larger population, such as trends in disease. For more information, visit Foodborne Illness Surveillance, Response, and Data Systems.

§Campylobacter, Cryptosporidium, Cyclospora, Listeria, Salmonella, Escherichia coli O157 and non-O157, Shigella, Vibrio, and Yersinia

Laboratory-based Enteric Disease Surveillance (LEDS)

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.

National Antimicrobial Resistance Monitoring System (NARMS)

Tracking trends in resistance

The National Antimicrobial Resistance Monitoring System (NARMS) is a collaboration among state and local health departments, CDC, FDA, and USDA. NARMS monitors antimicrobial resistance in enteric (intestinal) bacteria isolated from humans, retail meats, and food animals.  CDC’s primary role is to track and report antibiotic resistance in enteric bacteria isolated from people who have infections caused by Shigella, Campylobacter, Escherichia coli O157, Salmonella, or Vibrio species other than V. cholerae.


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

National Notifiable Diseases Surveillance System (NNDSS)

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. The general system has been in existence since 1878. Notifiable disease surveillance is "passive" (i.e., the investigator at CDC waits for disease reports from those required to report) and is susceptible to underreporting. Foodborne diseases that are reportable include botulism, hemolytic uremic syndrome (HUS), listeriosis (Listeria), shigellosis (Shigella), salmonellosis (Salmonella), Shiga Toxin-producing Escherichia coli (STEC) infections, and vibriosis (cholera and its relatives).

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

The National Outbreak Reporting System (NORS)

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. Analysis is done through subtyping and categorization of foodborne bacterial pathogens though a standardized process of pulsed-field gel electrophoresis (PFGE) *. PulseNet is a national network of local, state, territorial, agricultural, and federal laboratories—in all 50 states and 82 countries—coordinated by CDC and the Association of Public Health Laboratories (APHL) since 1996. PulseNet allows investigators from participating sites to upload PFGE patterns to an electronic database and compare them with patterns of other pathogens isolated from humans, animals, and foods to identify matches and possible linkages between pathogens (e.g., outbreaks).

*PFGE is a technique used to distinguish between strains of organisms, such as different types of E. coli and Shigella. By applying an electric field that constantly changes direction to a gel matrix, large DNA molecules are separated, which allows scientists to see the unique DNA pattern—or "fingerprint"—of the organism and compare it to others


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Educational Resources

General Public

  • 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.

Childcare Settings


Swimming Hygiene

Traditionally Observant Jews

Food Service

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

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  1. Scallan E, Hoekstra RM, Angulo FJ, Tauxe RV, Widdowson MA, Roy SL, Jones JL, Griffin PM. Foodborne illness acquired in the United States--major pathogens. Emerg Infect Dis. 2011;17(1):7-15.
  2. Crim SM, Iwamoto M, Huang JY, Griffin PM, Gilliss D, Cronquist AB, Cartter M, Tobin-D'Angelo M, Blythe D, Smith K, Lathrop S, Zansky S, Cieslak PR, Dunn J, Holt KG, Lance S, Tauxe R, Henao OL. Incidence and trends of infection with pathogens transmitted commonly through food--Foodborne Diseases Active Surveillance Network, 10 U.S. sites, 2006-2013. MMWR Morb Mortal Wkly Rep. 2014;63(15):328-32.
  3. Simon DG, Kaslow RA, Rosenbaum J, Kaye RL, Calin A. Reiter's syndrome following epidemic shigellosis J Rheumatol. 1981;8(6):969-73.
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  6. Van Bohemen CG, Lionarons RJ, van Bodegom P, Dinant HJ, Landheer JE, Nabbe AJ, Grumet FC,and Zanen HC. Susceptibility and HLA-B27 in post-dysenteric arthropathies. Immunology. 1985;56(2):377-9.
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  10. American Academy of Pediatrics. Red Book: Report of the Committee on Infectious Diseases. 2012. 645-647.
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  12. Hannu T, Mattila L, Siitonen A, Leirisalo-Repo M. Reactive arthritis attributable to Shigella infection: a clinical and epidemiological nationwide study. Ann Rheum Dis. 2005;64(4):594-8.
  13. Morduchowicz G, Huminer D, Siegman-Igra Y, Drucker M, Block CS, Pitlik SD. Shigella bacteremia in adults. A report of five cases and review of the literature. Arch Intern Med. 1987;147(11):2034-7.
  14. Appannanavar SB, Goyal K, Garg R, Ray P, Rathi M, Taneja N. Shigellemia in a post renal transplant patient: a case report and literature review. J Infect Dev Ctries. 2014;8(2):237-9.
  15. Goldberg EM, Balamuth F, Desrochers CR, Mittal MK. Seizure and altered mental status in a 12-year-old child with Shigella sonnei gastroenteritis. Pediatr Emerg Care. 2011;27(2):135-7.
  16. Lahat E, Katz Y, Bistritzer T, Eshel G, Aladjem M. Recurrent seizures in children with Shigella-associated convulsions. Ann Neurol. 1990;28(3):393-5.
  17. Khan WA, Dhar U, Salam MA, Griffiths JK, Rand W, Bennish ML. Central nervous system manifestations of childhood shigellosis: prevalence, risk factors, and outcome. Pediatrics. 1999;103(2):E18.
  18. Galanakis E, Tzoufi M, Charisi M, Levidiotou S, Papadopoulou ZL. Rate of seizures in children with shigellosis. Acta Paediatr. 2002;91(1):101-2.
  19. Shamsizadeh A, Nikfar R, Bavarsadian E. Neurological manifestations of shigellosis in children in southwestern Iran. Pediatr Int. 2012;54(1):127-30.
  20. Butler T. Haemolytic uraemic syndrome during shigellosis. Trans R Soc Trop Med Hyg. 2012;106(7):395-9.
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  22. Bloom PD, MacPhail AP, Klugman K, Louw M, Raubenheimer C,and Fischer C. Haemolytic-uraemic syndrome in adults with resistant Shigella dysenteriae type I. Lancet. 1994;344(8916):206.
  23. DuPont HL, Levine MM, Hornick RB, Formal SB. Inoculum size in shigellosis and implications for expected mode of transmission. J Infect Dis. 1989;159(6):1126-8.
  24. DuPont HL, Hornick RB, Dawkins AT, Snyder MJ, Formal SB. The response of man to virulent Shigella flexneri 2a. J Infect Dis. 1969;119(3):296-9.
  25. Beuchat LR, Ryu JH. Produce handling and processing practices. Emerg Infect Dis. 1997;3(4):459-65.
  26. Adams DA, Jajosky RA, Ajani U, Kriseman J, Sharp P, Onwen DH, Schley AW, Anderson WJ, Grigoryan A, Aranas AE, Wodajo MS, Abellera JP. Summary of notifiable diseases--United States, 2012. MMWR Morb Mortal Wkly Rep. 2014;61(53):1-121.
  27. Aragon TJ, Vugia DJ, Shallow S, Samuel MC, Reingold A, Angulo FJ, Bradford WZ. Case-control study of shigellosis in San Francisco: the role of sexual transmission and HIV infection. Clin Infect Dis. 2007;44(3):327-34.
  28. Gaudreau C, Barkati S, Leduc JM, Pilon PA, Favreau J, Bekal S. Shigellaspp. with reduced azithromycin susceptibility, Quebec, Canada, 2012-2013. Emerg Infect Dis. 2014;20(5):854-6.
  29. Gaudreau C, Ratnayake R, Pilon PA, Gagnon S, Roger M, Levesque S. Ciprofloxacin-resistant Shigellasonnei among men who have sex with men, Canada, 2010. Emerg Infect Dis. 2011;17(9):1747-50.
  30. Panel on Opportunistic Infections in HIV-Infected Adults and Adolescents. Guidelines for the prevention and treatment of opportunistic infections in HIV-infected adults and adolescents: recommendations from the Centers for Disease Control and Prevention, the National Institutes of Health, and the HIV Medicine Association of the Infectious Diseases Society of America. [PDF - 408 pages]. US Department of Health and Human Services, 2015.
  31. Okame M, Adachi E, Sato H, Shimizu S, Kikuchi T, Miyazaki N, Koga M, Nakamura H, Suzuki M, Oyaizu N, Fujii T, Iwamoto A, Koibuchi T. Shigella sonnei outbreak among men who have sex with men in Tokyo. Jpn J Infect Dis. 2012;65(3):277-8.
  32. Heiman KE, Karlsson M, Grass J, Howie B, Kirkcaldy RD, Mahon B, Brooks JT, Bowen A. Notes from the field: Shigella with decreased susceptibility to azithromycin among men who have sex with men - United States, 2002-2013. MMWR Morb Mortal Wkly Rep. 2014;63(6):132-3.
  33. Watson JT, Jones RC, Fernandez J, Cortes C, Gerber SI, Kuo KJ, Price JS, Brooks JT, Jennings D, Fair M, Mintz E, Bowen A. Shigella flexneri serotype 3 infections among men who have sex with men--Chicago, Illinois, 2003-2004. [PDF - 24 pages] MMWR Morb Mortal Wkly Rep. 2005;54(33):820-2.
  34. Baker KS, Dallman TJ, Ashton PM, Day M, Hughes G, Crook PD, Gilbart VL, Zittermann S, Allen VG, Howden BP, Tomita T, Valcanis M, Harris SR, Connor TR, Sintchenko V, Howard P, Brown JD, Petty NK, Gouali M, Thanh DP, Keddy KH, Smith AM, Talukder KA, Faruque SM, Parkhill J, Baker S, Weill FX, Jenkins C,Thomson NR. Intercontinental dissemination of azithromycin-resistant shigellosis through sexual transmission: a cross-sectional study. Lancet Infect Dis. 2015.
  35. Bowen A, Hurd J, Hoover C, Khachadourian Y, Traphagen E, Harvey E, Libby T, Ehlers S, Ongpin M, Norton JC, Bicknese A, Kimura A. Importation and domestic transmission of Shigella sonnei resistant to ciprofloxacin - United States, May 2014-February 2015. MMWR Morb Mortal Wkly Rep. 2015;64(12):318-20.
  36. Hoffmann C, Sahly H, Jessen A, Ingiliz P, Stellbrink HJ, Neifer S, Schewe K, Dupke S, Baumgarten A, Kuschel A, Krznaric I. High rates of quinolone-resistant strains of Shigella sonnei in HIV-infected MSM. Infection. 2013;41(5):999-1003.
  37. Morgan O, Crook P, Cheasty T, Jiggle B, Giraudon I, Hughes H, Jones SM. Shigella sonnei outbreak among homosexual men, London. Emerg Infect Dis. 2006;12(9):1458-60.
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  39. De Schrijver K, Bertrand S, Gutierrez Garitano I, Van den Branden D, Van Schaeren J. Outbreak of Shigella sonnei infections in the Orthodox Jewish community of Antwerp, Belgium, April to August 2008. Euro Surveill. 2011;16(14).
  40. Garrett V, Bornschlegel K, Lange D, Reddy V, Kornstein L, Kornblum J, Agasan A, Hoekstra M, Layton M, Sobel J. A recurring outbreak of Shigella sonnei among traditionally observant Jewish children in New York City: the risks of daycare and household transmission. Epidemiol Infect. 2006;134(6):1231-6.
  41. Sobel J, Cameron DN, Ismail J, Strockbine N, Williams M, Diaz PS, Westley B, Rittmann M, DiCristina J, Ragazzoni H, Tauxe RV, Mintz ED. A prolonged outbreak of Shigella sonnei infections in traditionally observant Jewish communities in North America caused by a molecularly distinct bacterial subtype. J Infect Dis. 1998;177(5):1405-9.
  42. Kantele A. As far as travelers' risk of acquiring resistant intestinal microbes is considered, no antibiotics (absorbable or nonabsorbable) are safe. Clin Infect Dis. 2015.
  43. O'Donnell AT, Vieira AR, Huang JY, Whichard J, Cole D, Karp BE. Quinolone-resistant Salmonella enterica serotype Enteritidis infections associated with international travel. Clin Infect Dis. 2014;59(9):e139-41.
  44. Pons MJ, Gomes C, Martinez-Puchol S, Ruiz L, Mensa L, Vila J, Gascon J, Ruiz J. Antimicrobial resistance in Shigella spp. causing traveller's diarrhoea (1995-2010): a retrospective analysis. Travel Med Infect Dis. 2013;11(5):315-9.
  45. De Lappe N, O'Connor J, Garvey P, McKeown P, Cormican M. Ciprofloxacin-Resistant Shigella sonnei Associated with Travel to India. Emerg Infect Dis. 2015;21(5):894-6.
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