View source for Shigellosis

{{Short description|Infection of the intestines by Shigella bacteria}}
{{Use dmy dates|date=July 2020}}
{{Infobox medical condition (new)
| name          = Shigellosis
| synonyms      = Bacillary dysentery, Marlow syndrome
| image         = Shigella stool.jpg
| caption       = ''Shigella'' seen in a stool sample
| field         = [[Infectious disease (medical specialty)|Infectious disease]]
| symptoms      = Diarrhea, fever, abdominal pain<ref name=CDC2016Fact/>
| complications = [[Reactive arthritis]], [[sepsis]], [[seizures]], [[hemolytic uremic syndrome]]<ref name=CDC2016Fact/>
| onset         = 1–2 days post exposure<ref name=CDC2016Fact/>
| duration      = Usually 5–7 days<ref name=CDC2016Fact/>
| causes        = ''[[Shigella]]''<ref name=CDC2016Fact/>
| risks         =
| diagnosis     = [[Stool culture]]<ref name=CDC2016Fact/>
| differential  =
| prevention    = [[Handwashing]]<ref name=CDC2016Fact/>
| treatment     = Drinking fluids and rest<ref name=CDC2016Fact/>
| medication    = [[Antibiotics]] (severe cases)<ref name=CDC2016Fact/>
| prognosis     =
| frequency     = >80 million<ref name=WHO2015/>
| deaths        = 700,000<ref name=WHO2015/>
}}
<!-- Definition and symptoms -->

'''Shigellosis''', known historically as '''dysentery''', is an infection of the [[gastrointestinal tract|intestines]] caused by ''[[Shigella]]'' bacteria.<ref name="CDC2016Fact" /><ref name="ECDC">{{cite web |title=Factsheet about shigellosis |url=https://ecdc.europa.eu/en/shigellosis/facts |website=European Centre for Disease Prevention and Control |date=8 July 2010 |language=en}}</ref> Symptoms generally start one to two days after exposure and include [[diarrhea]], [[fever]], [[abdominal pain]], and [[rectal tenesmus|feeling the need to pass stools]] even when the bowels are empty.<ref name="CDC2016Fact" /> The diarrhea may be bloody.<ref name="CDC2016Fact" /> Symptoms typically last five to seven days and it may take several months before bowel habits return entirely to normal.<ref name="CDC2016Fact" /> Complications can include [[reactive arthritis]], [[sepsis]], [[seizures]], and [[hemolytic uremic syndrome]].<ref name="CDC2016Fact">{{cite web |title=General Information{{!}} ''Shigella'' – Shigellosis {{!}} CDC |url=https://www.cdc.gov/shigella/general-information.html |website=www.cdc.gov |access-date=20 April 2017 |language=en-us|date=3 August 2016 |url-status=live |archive-url=https://web.archive.org/web/20170416130145/https://www.cdc.gov/shigella/general-information.html |archive-date=16 April 2017}}</ref>

<!-- Cause and diagnosis -->
Shigellosis is caused by four specific types of ''Shigella''.<ref name=WHO2015>{{cite book |title=Guidelines for the control of shigellosis, including epidemics due to ''Shigella dysenteriae'' type 1 |date=2005 |publisher=WHO |isbn=978-92-4-159330-4 |page=2 |url=http://apps.who.int/iris/bitstream/10665/43252/1/924159330X.pdf |access-date=20 April 2017 |url-status=live |archive-url=https://web.archive.org/web/20170821075521/http://apps.who.int/iris/bitstream/10665/43252/1/924159330X.pdf |archive-date=21 August 2017}}</ref> These are typically spread by exposure to infected [[feces]].<ref name=CDC2016Fact/> This can occur via contaminated food, water, or hands or [[sexual contact]].<ref name=CDC2016Fact/><ref>{{cite book |title=Antibiotic Resistance Threats in the United States, 2019 |date=2019 |publisher=CDC |page=9 |url=https://www.cdc.gov/drugresistance/pdf/threats-report/2019-ar-threats-report-508.pdf |archive-url=https://ghostarchive.org/archive/20221010/https://www.cdc.gov/drugresistance/pdf/threats-report/2019-ar-threats-report-508.pdf |archive-date=2022-10-10 |url-status=live}}</ref> Contamination may be spread by [[flies]] or when changing [[diapers]] (nappies).<ref name=CDC2016Fact/> Diagnosis is by [[stool culture]].<ref name=CDC2016Fact/>

<!-- Prevention and treatment -->
The risk of infection can be reduced by properly washing the hands.<ref name=CDC2016Fact/> There is no [[vaccine]].<ref name=CDC2016Fact/> Shigellosis usually resolves without specific treatment.<ref name=CDC2016Fact/> Rest, and sufficient fluids by mouth, are recommended.<ref name=CDC2016Fact/> [[Bismuth subsalicylate]] may help with the symptoms; however, medications that slow the bowels such as [[loperamide]] are not recommended.<ref name=CDC2016Fact/> In severe cases [[antibiotics]] may be used but [[antibiotic resistance|resistance]] is common.<ref name=CDC2016Fact/><ref>{{cite web |title=Update – CDC Recommendations for Managing and Reporting ''Shigella'' Infections with Possible Reduced Susceptibility to Ciprofloxacin |url=https://emergency.cdc.gov/han/han00411.asp |website=emergency.cdc.gov |access-date=16 June 2018 |language=en-us |date=7 June 2018}}</ref> Commonly used antibiotics include [[ciprofloxacin]] and [[azithromycin]].<ref name=CDC2016Fact/>

<!-- Epidemiology -->
A 2005 report by the [[World Health Organization]] estimated that shigellosis occurs in at least 80 million people and results in about 700,000 deaths a year globally.<ref name=WHO2015/> Most cases occur in the [[developing world]].<ref name=WHO2015/> Young children are most commonly affected.<ref name=CDC2016Fact/> [[Outbreaks]] of disease may occur in childcare settings and schools.<ref name=CDC2016Fact/> It is also relatively common among travelers.<ref name=CDC2016Fact/> In the United States about half a million cases occur a year.<ref name=CDC2016Fact/>

==Signs and symptoms==
Signs and symptoms may range from mild [[abdomen|abdominal]] discomfort to severe [[dysentery]] characterized by [[cramps]], [[diarrhea]], with slimy-consistent stools, fever, blood, [[pus]], or [[mucus]] in stools or [[Rectal tenesmus|tenesmus]].<ref>{{cite web |title=Shigellosis |url=http://www.merckmanuals.com/home/infections/bacterial_infections/shigellosis.html |publisher=The Merck Manual Home Health Handbook |access-date=10 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20120104063319/http://www.merckmanuals.com/home/infections/bacterial_infections/shigellosis.html |archive-date=4 January 2012}}</ref><ref name="Niyogi">{{cite journal |last1=Niyogi |first1=SK |title=Shigellosis |journal=Journal of Microbiology (Seoul, Korea) |date=April 2005 |volume=43 |issue=2 |pages=133–43 |pmid=15880088}}</ref> Onset time is 12 to 96 hours, and recovery takes 5 to 7 days.<ref>{{cite web |title=Symptoms of ''Shigella'' Infection |url=http://www.about-shigella.com/shigella_symptoms_risks |website=About Shigella |access-date=10 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20120108012552/http://www.about-shigella.com/shigella_symptoms_risks |archive-date=8 January 2012}}</ref>
Infections are associated with [[ulcer (dermatology)|mucosal ulceration]], [[rectal bleeding]], and drastic [[dehydration]]. [[Reactive arthritis]] and [[hemolytic uremic syndrome]] are possible sequelae that have been reported in the aftermath of shigellosis.{{citation needed|date=January 2021}}

The most common neurological symptom includes [[seizure]]s.<ref name="WHO">{{cite web |url=https://www.who.int/vaccine_research/diseases/diarrhoeal/en/index6.html |title=Diarrhoeal Diseases: Shigellosis |publisher=World Health Organization |work=Initiative for Vaccine Research |access-date=11 May 2012 |archive-url=https://web.archive.org/web/20081215123745/http://www.who.int/vaccine_research/diseases/diarrhoeal/en/index6.html |archive-date=15 December 2008}}</ref>

==Cause==
===Bacteria===
Shigellosis is caused by a bacterial infection with ''[[Shigella]]'',<ref name=CDC2016Fact/> a bacterium that is genetically similar to and was once classified as ''[[E. coli]]''.<ref name="Ragupathi 2017">{{cite journal |last1=Devanga Ragupathi |first1=NK |last2=Muthuirulandi Sethuvel |first2=DP |last3=Inbanathan |first3=FY |last4=Veeraraghavan |first4=B |title=Accurate differentiation of ''Escherichia coli'' and ''Shigella'' serogroups: challenges and strategies |journal=New Microbes New Infect. |volume=21 |date=21 January 2018 |pages=58–62 |doi=10.1016/j.nmni.2017.09.003 |pmid=29204286 |pmc=5711669}}</ref> There are three [[serogroup]]s and one [[serotype]] of ''Shigella'':
* ''[[Shigella flexneri]]''
* ''[[Shigella boydii]]''
* ''[[Shigella dysenteriae]]'' and
* ''[[Shigella sonnei]]'' (serotype)<ref name=CDC2016Fact/>

The probability of being infected by any given strain of ''Shigella'' varies around the world. For instance, ''S. sonnei'' is the most common in the United States, while ''S. dysenteriae'' and ''S. boydii'' are rare there.<ref name=CDC2016Fact/>

=== Transmission ===
''Shigella'' is transmitted through the [[fecal-oral route]] of individuals infected with the disease, whether or not they are exhibiting symptoms.<ref name=CDC2016Fact/><ref name="Merck Shigellosis Prof">{{cite web |title=Shigellosis (Bacillary Dysentery) |url=https://www.merckmanuals.com/professional/infectious-diseases/gram-negative-bacilli/shigellosis |website=Merck Manual Professional Version | access-date=16 March 2018}}</ref> Long-term [[Asymptomatic carrier|carriers]] of the bacteria are rare.<ref name="Merck Shigellosis Prof" /> The bacteria can infect not just humans but other [[primates]] as well.<ref name=CDC2017TravelersHealth>{{cite web |last=Bowen |first=Anna |title=Travelers' Health, Chapter 3, Shigellosis (CDC) |url=https://wwwnc.cdc.gov/travel/yellowbook/2018/infectious-diseases-related-to-travel/shigellosis |access-date=17 March 2018 |language=en-us |date=31 May 2017}}</ref>

==Mechanism==
Upon ingestion, the bacteria pass through the [[gastrointestinal tract]] until they reach the [[small intestine]]. There they begin to multiply until they reach the [[large intestine]].<ref name="Aslam 2018">{{cite book |last1=Aslam |first1=A |last2=Gossman |first2=WG |title=''Shigella'' (Shigellosis) |date=14 February 2018 |location=Treasure Island, FL |publisher=StatPearls |pmid=29493962}}</ref> In the large intestine, the bacteria cause cell injury and the beginning stages of Shigellosis via two main mechanisms: direct invasion of epithelial cells in the large intestine and production of enterotoxin 1 and enterotoxin 2.<ref name="Aslam 2018" />

Unlike other bacteria, ''Shigella'' is not destroyed by the [[gastric acid]] in the stomach. As a result, it takes only 10 to 200 cells to cause an infection.<ref name="Aslam 2018" /> This [[infectious dose]] is several orders of magnitude smaller than that of other species of bacteria (e.g., [[cholera]], caused by the bacterium ''[[Vibrio cholerae]]'', has an infectious dose between 10<sup>8</sup> and 10<sup>11</sup> cells).<ref name="Nelson 2009">{{cite journal |last1=Nelson |first1=EJ |last2=Harris |first2=JB |last3=Glenn Morris Jr. |first3=J |last4=Calderwood |first4=SB |last5=Camilli |first5=A |title=Cholera transmission: the host, pathogen and bacteriophage dynamic |journal=Nat Rev Microbiol |date=October 2009 |volume=7 |issue=10 |pages=693–702 |doi=10.1038/nrmicro2204 |pmid=19756008 |pmc=3842031}}</ref>

==Diagnosis==
The diagnosis of shigellosis is made by isolating the organism from diarrheal fecal sample cultures. ''Shigella'' species are negative for motility and are generally not lactose fermenters, but ''S. sonnei'' can ferment lactose.<ref name="pmid1746953">{{cite journal |last1=Ito |first1=Hideo |last2=Kido |first2=Nobuo |last3=Arakawa |first3=Yoshichika |last4=Ohta |first4=Michio |last5=Sugiyama |first5=Tsuyoshi |last6=Kato |first6=Nobuo |title=Possible mechanisms underlying the slow lactose fermentation phenotype in ''Shigella'' spp |journal=Applied and Environmental Microbiology |volume=57 |issue=10 |pages=2912–7 |year=1991 |doi=10.1128/AEM.57.10.2912-2917.1991 |pmid=1746953 |pmc=183896 |bibcode=1991ApEnM..57.2912I}}</ref> They typically do not produce gas from carbohydrates (with the exception of certain strains of ''S. flexneri'') and tend to be overall biochemically inert. ''Shigella'' should also be urea hydrolysis negative. When inoculated to a [[TSI slant|triple sugar iron slant]], they react as follows: K/A, gas -, and H<sub>2</sub>S -. Indole reactions are mixed, positive and negative, with the exception of ''S. sonnei'', which is always indole negative. Growth on [[Hektoen enteric agar]] produces bluish-green colonies for ''Shigella'' and bluish-green colonies with black centers for ''Salmonella''.{{citation needed|date=July 2020}}

==Prevention==
Simple precautions can be taken to prevent getting shigellosis: wash hands before handling food and thoroughly cook all food before eating. The primary prevention methods are improved sanitation and personal and food hygiene, but a low-cost and efficacious vaccine would complement these methods.<ref name=":0">{{Cite journal |last1=Mani |first1=Sachin |last2=Wierzba |first2=Thomas |last3=Walker |first3=Richard I. |date=2016 |title=Status of vaccine research and development for ''Shigella'' |journal=Vaccine |volume=34 |issue=26 |pages=2887–2894 |doi=10.1016/j.vaccine.2016.02.075 |pmid=26979135 |doi-access=free}}</ref>

Since shigellosis is spread very quickly among children, keeping infected children out of daycare for 24 hours after their symptoms have disappeared, will decrease the occurrence of shigellosis in daycares.<ref>mayo clinic {{cite web |url=http://www.mayoclinic.org/diseases-conditions/shigella/basics/prevention/con-20028418 |title=''Shigella'' infection - Symptoms and causes |website=[[Mayo Clinic]] |access-date=2015-09-14 |url-status=live |archive-url=https://web.archive.org/web/20150906072705/http://www.mayoclinic.org/diseases-conditions/shigella/basics/prevention/con-20028418 |archive-date=6 September 2015}}</ref>

===Vaccine===
Currently, no licensed vaccine targeting ''Shigella'' exists. Several vaccine candidates for ''Shigella'' are in various stages of development including live attenuated, conjugate, ribosomal, and proteosome vaccines.<ref name=":0" /><ref>{{Cite web |url=https://www.who.int/immunization/research/vaccine_pipeline_tracker_spreadsheet/en/ |title=WHO vaccine pipeline tracker |website=World Health Organization |language=en-GB |access-date=2016-07-29 |archive-url=https://web.archive.org/web/20160725174627/http://who.int/immunization/research/vaccine_pipeline_tracker_spreadsheet/en/ |archive-date=25 July 2016}}</ref><ref>{{cite journal |date=14 March 1997 |title=Vaccine Research And Development: New strategies for accelerating ''Shigella'' vaccine development |url=https://www.who.int/docstore/wer/pdf/1997/wer7211.pdf |journal=Weekly Epidemiological Record |volume=72 |issue=11 |pages=73–80 |pmid=9115858 |access-date=10 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20090519182955/http://www.who.int/docstore/wer/pdf/1997/wer7211.pdf |archive-date=19 May 2009}}</ref> ''Shigella'' has been a longstanding [[World Health Organization]] target for vaccine development, and sharp declines in age-specific diarrhea/dysentery attack rates for this pathogen indicate that natural immunity does develop following exposure; thus, vaccination to prevent the disease should be feasible. ''Shigella'' species are resistant to many antibiotics,<ref name=CDC2016Fact /> so vaccination is an important part of the strategy to reduce morbidity and mortality.<ref name=":0" />

==Treatment==
Treatment consists mainly of replacing fluids and salts lost because of diarrhea. Replacement by mouth is satisfactory for most people, but some may need to receive fluids intravenously. Antidiarrheal drugs (such as [[diphenoxylate]] or [[loperamide]]) may prolong the infection and should not be used.<ref>{{cite web |url=https://www.cdc.gov/shigella/ |title=How can ''Shigella'' infections be treated? |date=17 January 2019 |publisher=Centers for Disease Control and Prevention |work=Shigellosis: General Information |url-status=live |archive-url=https://web.archive.org/web/20160208061009/http://www.cdc.gov/shigella/ |archive-date=8 February 2016}}</ref>

===Antibiotics===
Antibiotics should only be used in severe cases or for certain populations with mild symptoms (elderly, immunocompromised, food service industry workers, child care workers). For ''Shigella''-associated diarrhea, [[antibiotics]] shorten the length of infection,<ref>{{cite journal |last2=David |first2=Kirubah V |last3=John |first3=Sushil M |last4=Sankarapandian |first4=Venkatesan |last5=Christopher |first5=Prince RH |year=2010 |title=Antibiotic therapy for ''Shigella'' dysentery |journal=The Cochrane Database of Systematic Reviews |issue=8 |article-number=CD006784 |doi=10.1002/14651858.CD006784.pub4 |pmid=20687081 |pmc=6532574 |last1=Christopher |first1=Prince RH|volume=2010 }}</ref> but they are usually avoided in mild cases because many ''Shigella'' strains are becoming resistant to common antibiotics.<ref name="Kahsay">{{cite journal |last1=Kahsay |first1=AG |last2=Muthupandian |first2=S |title=A review on Sero diversity and antimicrobial resistance patterns of ''Shigella'' species in Africa, Asia and South America, 2001-2014 |journal=BMC Research Notes |date=30 August 2016 |volume=9 |issue=1 |page=422 |doi=10.1186/s13104-016-2236-7 |pmid=27576729 |pmc=5004314 |doi-access=free }}</ref> Furthermore, effective medications are often in short supply in developing countries, which carry the majority of the disease burden from ''Shigella''. Antidiarrheal agents may worsen the sickness, and should be avoided.<ref>{{cite web |title=How can ''Shigella'' infections be treated? |url=https://www.cdc.gov/nczved/divisions/dfbmd/diseases/shigellosis/#treat |work=Shigellosis: General Information |publisher=Centers for Disease Control and Prevention |access-date=11 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20120211044845/http://www.cdc.gov/nczved/divisions/dfbmd/diseases/shigellosis/#treat |archive-date=11 February 2012}}</ref>

In most cases, the disease resolves within four to eight days without antibiotics. Severe infections may last three to six weeks. Antibiotics, such as [[trimethoprim-sulfamethoxazole]], [[ciprofloxacin]] may be given when the person is very young or very old, when the disease is severe, or when the risk of the infection spreading to other people is high. Additionally, [[ampicillin]] (but not [[amoxicillin]]) was effective in treating this disease previously, but now the first choice of drug is [[pivmecillinam]].<ref>{{cite book |last=Katzung |first=Bertram G. |title=Basic and Clinical Pharmacology |year=2007 |publisher=McGraw Hill Medical |location=New York, NY |isbn=978-0-07-145153-6 |page=733}}</ref>

==Epidemiology==
Insufficient data exist,<ref>{{cite journal |last=Ram |first=PK |author2=Crump JA |author3=Gupta SK |author4=Miller MA |author5=Mintz ED |title=Analysis of Data Gaps Pertaining to ''Shigella'' Infections in Low and Medium Human Development Index Countries, 1984–2005 |journal=Epidemiology and Infection |year=2008 |volume=136 |issue=5 |pages=577–603 |pmc=2870860 |pmid=17686195 |doi=10.1017/S0950268807009351}}</ref> but it is estimated to have caused the death of 34,000 children under the age of five in 2013, and 40,000 deaths in people over five years of age.<ref name=":0" /> ''Shigella'' also causes about 580,000 cases annually among travelers and military personnel from industrialized countries.<ref>{{Cite book |url=http://apps.who.int/iris/bitstream/10665/69348/1/WHO_IVB_06.01_eng.pdf |title=State of the art of new vaccine research and development |last=World Health Organization |year=2006 |url-status=live |archive-url=https://web.archive.org/web/20160304130219/http://apps.who.int/iris/bitstream/10665/69348/1/WHO_IVB_06.01_eng.pdf |archive-date=4 March 2016}}</ref>

An estimated 500,000 cases of shigellosis occur annually in the United States.<ref name=":1">{{Cite web|url=https://www.cdc.gov/shigella/general-information.html#resistance|title=Shigella – Shigellosis|last=US Centers for Disease Control and Prevention|access-date=2016-07-29|url-status=live|archive-url=https://web.archive.org/web/20160724114503/http://www.cdc.gov/shigella/general-information.html#resistance|archive-date=24 July 2016}}</ref> Infants, the elderly, and the critically ill are susceptible to the most severe symptoms of disease, but all humans are susceptible to some degree. Individuals with acquired immune deficiency syndrome (AIDS) are more frequently infected with ''Shigella''.<ref>{{cite journal |last1=Angulo |first1=Frederick J. |last2=Swerdlow |first2=David L. |year=1995 |title=Bacterial Enteric Infections in Persons Infected with Human Immunodeficiency Virus |journal=Clinical Infectious Diseases |volume=21 |issue=Supplement 1 |pages=S84–S93 |doi=10.1093/clinids/21.supplement_1.s84 |pmid=8547518}}</ref> Shigellosis is a more common and serious condition in the developing world; fatality rates of shigellosis epidemics in developing countries can be 5–15%.<ref>{{cite web |last=Todar |first=Kenneth |title=''Shigella'' and Shigellosis |url=http://textbookofbacteriology.net/Shigella.html |work=Todar's Online Textbook of Bacteriology |access-date=10 February 2012 |url-status=live |archive-url=https://web.archive.org/web/20120209040938/http://textbookofbacteriology.net/Shigella.html |archive-date=9 February 2012}}</ref>

[[Orthodox Jewish]] communities (OJCs) are a known risk group for shigellosis; ''[[Shigella sonnei]]'' is cyclically epidemic in these communities in Israel, with sporadic outbreaks occurring elsewhere among these communities. "Through phylogenetic and genomic analysis, we showed that strains from outbreaks in OJCs outside of Israel are distinct from strains in the general population and relate to a single multidrug-resistant sublineage of ''S. sonnei'' that prevails in Israel. Further [[Bayesian inference in phylogeny|Bayesian phylogenetic analysis]] showed that this strain emerged approximately 30 years ago, demonstrating the speed at which antimicrobial drug–resistant pathogens can spread widely through geographically dispersed, but internationally connected, communities."<ref>{{cite journal |last=Baker |first=K |display-authors=etal |title=Travel- and Community-Based Transmission of Multidrug-Resistant ''Shigella sonnei'' Lineage among International Orthodox Jewish Communities |journal=Emerg Infect Dis |date=September 2016 |volume=22 |issue=9 |doi=10.3201/eid2209.151953 |pmid=27532625 |pmc=4994374 |pages=1545–1553}}</ref>

==See also==
* [[Gastroenteritis]]
* [[Shiga-like toxin]]
* [[Shiga toxin]]
* [[Traveler's diarrhea]]

== References ==
{{Reflist|colwidth=30em}}

==External links==
* [https://www.cdc.gov/shigella/ CDC's Shigellosis Page]
* [http://www.path.org/vaccineresources/shigella-etec.php Vaccine Resource Library: Shigellosis and enterotoxigenic ''Escherichia coli'' (ETEC)]
{{Medical condition classification and resources
| diseasesDB = 12005
| ICD10 = {{ICD10|A|03||a|00}}
| ICD9 = {{ICD9|004}}
| ICDO =
| OMIM =
| MedlinePlus = 000295
| eMedicineSubj = med
| eMedicineTopic = 2112
| MeshID = D004405
}}
{{Bacterial diseases}}
{{Bacterial cutaneous infections}}
{{Authority control}}

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[[Category:Foodborne illnesses]]
[[Category:Intestinal infectious diseases]]
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[[Category:Wikipedia infectious disease articles ready to translate]]