Sources of Infection & Risk Factors

Dad changing diaper

People who are sick with shigellosis have Shigella germs in their stool (poop) while they have diarrhea and for up to a week or two after the diarrhea has gone away. Shigella is very contagious; just a small amount of germs can make someone sick. People could get sick by:

  • Getting Shigella germs on their hands and then touching their food or mouth. This may happen after:
    • Touching surfaces contaminated with germs from stool from a sick person, such as toys, bathroom fixtures, changing tables or diaper pails.
    • Changing the diaper of a sick child or caring for a sick person.
  • Eating food that was prepared by someone who is sick with shigellosis.
    • Foods that are consumed raw are more likely to be contaminated with Shigella germs.
    • Shigella germs can contaminate fruits and vegetables if the fields where they grow contain human waste.
  • Swallowing recreational water (for example, lake or river water) while swimming or drinking water that is contaminated with stool (poop) containing the germ.
  • Having exposure to stool during sexual contact with someone who is sick or recently (several weeks) recovered from shigellosis.

Groups of People Who Are Most Likely to Get Shigellosis

  • Young children are the most likely to get shigellosis, but people of all ages can get this disease 1. Many outbreaks are related to childcare settings and schools. Illness commonly spreads from young children to their family members and others in their communities because it is so contagious.
  • Travelers to developing countries may be more likely to get shigellosis, and to become infected with strains of Shigella bacteria that can’t be treated effectively by important antibiotics 2,3. Travelers may get sick from food, drinking water, recreational water, and surfaces containing Shigella germs. Travelers can protect themselves by sticking to safe eating and drinking habits, and washing hands often with soap and water. For more information, see Travelers’ Health – Food and Water Safety.
  • Gay or bisexual men and other men who have sex with men are more likely to get shigellosis than other adults 4. Shigella germs pass from stools (poop) or soiled fingers of one person to the mouth of another person, which can happen during sexual activity. Many shigellosis outbreaks among gay and bisexual men have been reported in the United States, Canada, Tokyo, and Europe since 1999 5-11. For more information, see Shigella Infections among Gay & Bisexual Men.
  • People whose immune systems are weakened due to illness (such as HIV) or medical treatment (such as chemotherapy for cancer) can get a more serious illness. A severe shigellosis illness may involve the infection spreading into the blood, which can be life-threatening 12.
  • Large outbreaks of shigellosis often start in childcare settings and spread among small social groups such as in traditionally observant Jewish communities 13-15. Similar outbreaks could occur among any race, ethnicity or community social circle because Shigella germs can spread easily from one person to another.

The term “men who have sex with men” is used in CDC surveillance systems because it indicates men who engage in behaviors that may transmit Shigella infection, rather than how someone identifies their sexuality.

  1. 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.
  2. Kantele A. As far as travelers’ risk of acquiring resistant intestinal microbes is considered, no antibiotics (absorbable or nonabsorbable) are safe. ExternalClin Infect Dis. 2015.
  3. O’Donnell AT, Vieira AR, Huang JY, Whichard J, Cole D, Karp BE. Quinolone-resistant Salmonella enterica serotype Enteritidis infections associated with international travel.External Clin Infect Dis. 2014;59(9):e139-41
  4. 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.External Clin Infect Dis. 2007;44(3):327-34.
  5. 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.
  6. Gaudreau C, Barkati S, Leduc JM, Pilon PA, Favreau J, Bekal S. Shigella spp. with reduced azithromycin susceptibility, Quebec, Canada, 2012-2013. Emerg Infect Dis. 2014;20(5):854-6.
  7. Gaudreau C, Ratnayake R, Pilon PA, Gagnon S, Roger M, Levesque S. Ciprofloxacin-resistant Shigella sonnei among men who have sex with men, Canada, 2010. Emerg Infect Dis. 2011;17(9):1747-50.
  8. 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.
  9. 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.External Jpn J Infect Dis. 2012;65(3):277-8.
  10. 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. Cdc-pdf[PDF – 24 pages] MMWR Morb Mortal Wkly Rep. 2005;54(33):820-2.
  11. Bowen A, Eikmeier D, Talley P, Siston A, Smith S, Hurd J, Smith K, Leano F, Bicknese A, Norton C, Campbell D. Notes from the Field: Outbreaks of Shigella sonnei infection with decreased susceptibility to azithromycin among men who have sex with men — Chicago and Metropolitan Minneapolis-St. Paul, 2014. MMWR Morb Mortal Wkly Rep. 2015;64(21):597-8.
  12. HHS. 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. Cdc-pdf[PDF – 425 pages]External Panel on Opportunistic Infections in HIV-Infected Adults and Adolescents. 2015.
  13. 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.External Euro Surveill. 2011;16(14).
  14. 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.External Epidemiol Infect. 2006;134(6):1231-6.
  15. 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.External J Infect Dis. 1998;177(5):1405-9.