Editing Gastroenteritis (section)

==Cause==
[[Viruses]] (particularly [[rotavirus]] (in children) and [[norovirus]] (in adults)) and the bacteria ''[[Escherichia coli]]'' and ''[[Campylobacter]]'' species are the primary causes of gastroenteritis.<ref name=Web09/><ref name=Sz2010/> There are, however, many other infectious agents that can cause this syndrome including [[parasites]] and [[fungus|fungi]].<ref name=M93/><ref name=Helm2006/> Non-infectious causes are seen on occasion, but they are less likely than a viral or bacterial cause.<ref name=EBMED2010/> Risk of infection is higher in children due to their lack of [[immunity (medical)|immunity]].<ref name=EBMED2010/> Children are also at higher risk because they are less likely to practice good [[hygiene]] habits.<ref name=EBMED2010/> Children living in areas without easy [[WASH|access to water and soap]] are especially vulnerable.<ref name=EBMED2010/>

===Viral===
[[Rotavirus]]es, [[norovirus]]es, [[adenovirus]]es, and [[astrovirus]]es are known to cause viral gastroenteritis.<ref name=Kumar2020>{{cite book |last1=Barlow |first1=Gavin |last2=Irving |first2=William L. |last3=Moss |first3=Peter J. |editor1-last=Feather |editor1-first=Adam |editor2-last=Randall |editor2-first=David |editor3-last=Waterhouse |editor3-first=Mona |title=Kumar and Clark's Clinical Medicine |date=2020 |publisher=Elsevier |isbn=978-0-7020-7870-5 |pages=529–530 |edition=10th |chapter-url=https://books.google.com/books?id=sl3sDwAAQBAJ&pg=PA529 |language=en |chapter=20. Infectious disease }}</ref> Rotavirus is the most common cause of gastroenteritis in children,<ref name=Sz2010/> and produces similar rates in both the [[developed world|developed]] and [[developing world]].<ref name=Rota2011/> Viruses cause about 70% of episodes of infectious diarrhea in the pediatric age group.<ref name=Webb2005/> Rotavirus is a less common cause in adults due to acquired immunity.<ref name="ID2011">{{cite journal |vauthors=Desselberger U, Huppertz HI |title=Immune responses to rotavirus infection and vaccination and associated correlates of protection |journal=The Journal of Infectious Diseases |volume=203 |issue=2 |pages=188–95 |date=January 2011 |pmid=21288818 |pmc=3071058 |doi=10.1093/infdis/jiq031 }}</ref> Norovirus is the cause in about 18% of all cases.<ref>{{cite journal|last1=Ahmed|first1=Sharia M|last2=Hall|first2=Aron J|last3=Robinson|first3=Anne E|last4=Verhoef|first4=Linda|last5=Premkumar|first5=Prasanna|last6=Parashar|first6=Umesh D|last7=Koopmans|first7=Marion|last8=Lopman|first8=Benjamin A|title=Global prevalence of norovirus in cases of gastroenteritis: a systematic review and meta-analysis|journal=The Lancet Infectious Diseases|doi=10.1016/S1473-3099(14)70767-4|pmid=24981041|volume=14|issue=8|date=Aug 2014|pages=725–30|pmc=8006533|url=https://zenodo.org/record/1260252}}</ref> Generally speaking, viral gastroenteritis accounts for 21–40% of the cases of infectious diarrhea in developed countries.<ref>{{Cite journal|last=Baumgart|first=Alexander J. Eckardt and Daniel C.|date=2010-12-31|title=Viral Gastroenteritis in Adults|url=https://www.eurekaselect.com/76857/article|access-date=2020-12-22|journal=Recent Patents on Anti-Infective Drug Discovery|volume=6|issue=1|pages=54–63|doi=10.2174/157489111794407877|pmid=21210762|language=en|url-access=subscription}}</ref>

Norovirus is the leading cause of gastroenteritis among adults in America accounting for about 90% of viral gastroenteritis outbreaks.<ref name=Eck2011/> These localized [[epidemic]]s typically occur when groups of people spend time proximate to each other, such as on [[cruise ships]],<ref name=Eck2011/> in hospitals, or in restaurants.<ref name=EBMED2010/> People may remain infectious even after their diarrhea has ended.<ref name=Eck2011/> Norovirus is the cause of about 10% of cases in children.<ref name=EBMED2010/>

===Bacterial===
[[File:Salmonella Typhimurium Gram.jpg|thumb|''Salmonella enterica'' serovar Typhimurium (ATCC 14028) as seen with a microscope at 1000 fold magnification and following Gram staining]]
In some countries, ''[[Campylobacter jejuni]]'' is the primary cause of bacterial gastroenteritis, with half of these cases associated with exposure to [[poultry]].<ref name="Bact2007">{{cite journal|last=Galanis|first=E|title=Campylobacter and bacterial gastroenteritis.|journal=Canadian Medical Association Journal |date=11 September 2007 |volume=177|issue=6|pages=570–1|pmid=17846438|doi=10.1503/cmaj.070660|pmc=1963361}}</ref> In children, bacteria are the cause in about 15% of cases, with the most common types being ''[[Escherichia coli]]'', ''[[Salmonella]]'', ''[[Shigella]]'', and ''Campylobacter'' species.<ref name=Webb2005/> If food becomes contaminated with bacteria and remains at room temperature for several hours, the bacteria multiply and increase the risk of infection in those who consume the food.<ref name=M93/> Some foods commonly associated with illness include raw or undercooked meat, poultry, seafood, and eggs; raw sprouts; unpasteurized milk and soft cheeses; and fruit and vegetable juices.<ref>{{cite journal|last=Nyachuba|first=DG|title=Foodborne illness: is it on the rise?|journal=Nutrition Reviews|date=May 2010 |volume=68|issue=5|pages=257–69|pmid=20500787|doi=10.1111/j.1753-4887.2010.00286.x}}</ref> In the developing world, especially sub-Saharan Africa and Asia, [[cholera]] is a common cause of gastroenteritis.<!-- <ref name=Cholera11/> --> This infection is usually transmitted by contaminated water or food.<ref name="Cholera11">{{cite journal|last=Charles|first=RC|author2=Ryan, ET|title=Cholera in the 21st century.|journal=Current Opinion in Infectious Diseases|date=October 2011 |volume=24|issue=5|pages=472–7|pmid=21799407|doi=10.1097/QCO.0b013e32834a88af|s2cid=6907842}}</ref>

Toxigenic ''[[Clostridioides difficile infection|Clostridioides difficile]]'' is an important cause of diarrhea that occurs more often in the elderly.<ref name=M93/> Infants can carry these bacteria without developing symptoms.<ref name=M93/> It is a common cause of diarrhea in those who are hospitalized and is frequently associated with antibiotic use.<ref>{{cite journal|last=Moudgal|first=V|author2=Sobel, JD|title=''Clostridium difficile'' colitis: a review.|journal=Hospital Practice |date=February 2012 |volume=40|issue=1|pages=139–48|pmid=22406889|doi=10.3810/hp.2012.02.954|s2cid=23015631}}</ref> ''[[Staphylococcus aureus]]'' infectious diarrhea may also occur in those who have used antibiotics.<ref>{{cite journal|last=Lin|first=Z|author2=Kotler, DP |author3=Schlievert, PM |author4= Sordillo, EM |title=Staphylococcal enterocolitis: forgotten but not gone?|journal=Digestive Diseases and Sciences|date=May 2010 |volume=55|issue=5|pages=1200–7|pmid=19609675|doi=10.1007/s10620-009-0886-1|s2cid=2023416}}</ref> Acute "[[traveler's diarrhea]]" is usually a type of bacterial gastroenteritis, while the persistent form is usually parasitic.<ref name="CDC Travelers'">{{cite web|title=Persistent Travelers' Diarrhea|url=http://wwwnc.cdc.gov/travel/yellowbook/2016/post-travel-evaluation/persistent-travelers-diarrhea|publisher=United States Centers for Disease Control and Prevention|access-date=9 January 2016|date=10 July 2015|quote=Although most cases of travelers' diarrhea are acute and self-limited, a certain percentage of travelers will develop persistent (>14 days) gastrointestinal symptoms&nbsp;... Parasites as a group are the pathogens most likely to be isolated from patients with persistent diarrhea|url-status=live|archive-url=https://web.archive.org/web/20160103203635/http://wwwnc.cdc.gov/travel/yellowbook/2016/post-travel-evaluation/persistent-travelers-diarrhea|archive-date=3 January 2016}}</ref> Acid-suppressing medication appears to increase the risk of significant infection after exposure to several organisms, including ''Clostridioides difficile'', ''Salmonella'', and ''Campylobacter'' species.<ref name="PPI2007">{{cite journal|last=Leonard|first=J |author2=Marshall, JK |author3=Moayyedi, P|title=Systematic review of the risk of enteric infection in patients taking acid suppression.|journal=The American Journal of Gastroenterology|date=September 2007 |volume=102|issue=9|pages=2047–56; quiz 2057|doi=10.1111/j.1572-0241.2007.01275.x |pmid=17509031|s2cid=12326803 }}</ref> The risk is greater in those taking [[proton pump inhibitors]] than with [[H2 antagonist|H<sub>2</sub> antagonist]]s.<ref name=PPI2007/>

===Parasitic===
A number of [[parasites]] can cause gastroenteritis.<ref name=Webb2005/> ''[[Giardia lamblia]]'' is most common, but ''[[Entamoeba histolytica]]'', ''[[Cryptosporidium]]'' spp., and other species have also been implicated.<ref name=Webb2005/><ref name="CDC Travelers'" /> As a group, these agents comprise about 10% of cases in children.<ref name=BMJ2007 /><ref name="CDC Travelers'" /> ''Giardia'' occurs more commonly in the developing world, but this type of illness can occur nearly everywhere.<ref name="Giar2010">{{cite journal|last=Escobedo|first=AA|author2=Almirall, P |author3=Robertson, LJ |author4=Franco, RM |author5=Hanevik, K |author6=Mørch, K |author7=Cimerman, S |title=Giardiasis: the ever-present threat of a neglected disease|journal=Infectious Disorders Drug Targets|date=October 2010 |volume=10|issue=5|pages=329–48|pmid=20701575|doi=10.2174/187152610793180821}}</ref> It occurs more commonly in persons who have traveled to areas with high prevalence, children who attend [[day care]], [[men who have sex with men]], and following [[disasters]].<ref name=Giar2010/>

===Transmission===
Transmission may occur from drinking contaminated water or when people share personal objects.<ref name=Web09/> Water quality typically worsens during the rainy season and outbreaks are more common at this time.<ref name=Web09/> In [[Temperateness|areas with four seasons]], infections are more common in the winter.<ref name=M93/> Worldwide, [[bottle-feeding]] of babies with improperly sanitized bottles is a significant cause.<ref name=Web09/> Transmission rates are also related to poor hygiene, (especially among children),<ref name=Eck2011/> in crowded households,<ref>{{cite journal|last=Grimwood|first=K|author2=Forbes, DA|title=Acute and persistent diarrhea|journal=Pediatric Clinics of North America|date=December 2009 |volume=56|issue=6|pages=1343–61|pmid=19962025|doi=10.1016/j.pcl.2009.09.004}}</ref> and in those with poor nutritional status.<ref name=M93/> Adults who have developed immunities might still carry certain organisms without exhibiting symptoms.<ref name=M93/> Thus, adults can become [[natural reservoirs]] of certain diseases.<ref name=M93/> While some agents (such as ''Shigella'') only occur in [[primates]], others (such as ''Giardia'') may occur in a wide variety of animals.<ref name=M93/>

===Non-infectious===
There are a number of non-infectious causes of inflammation of the gastrointestinal tract.<ref name=EBMED2010/> Some of the more common include medications (like [[NSAIDs]]), certain foods such as [[lactose]] (in those who are intolerant), and [[gluten]] (in those with [[Coeliac disease|celiac disease]]). [[Crohn's disease]] is also a non-infectious cause of (often severe) gastroenteritis.<ref name=EBMED2010/> Disease secondary to [[toxin]]s may also occur. Some food-related conditions associated with nausea, vomiting, and diarrhea include: [[Ciguatera|ciguatera poisoning]] due to consumption of contaminated predatory fish, [[scombroid food poisoning|scombroid]] associated with the consumption of certain types of spoiled fish, [[Tetrodotoxin#Poisoning|tetrodotoxin poisoning]] from the consumption of [[puffer fish]] among others, and [[botulism]] typically due to improperly preserved food.<ref>{{cite journal|last=Lawrence|first=DT|author2=Dobmeier, SG |author3=Bechtel, LK |author4= Holstege, CP |title=Food poisoning|journal=Emergency Medicine Clinics of North America|date=May 2007 |volume=25|issue=2|pages=357–73; abstract ix|pmid=17482025|doi=10.1016/j.emc.2007.02.014}}</ref>

In the United States, rates of emergency department use for noninfectious gastroenteritis dropped 30% from 2006 until 2011. Of the twenty most common conditions seen in the emergency department, rates of noninfectious gastroenteritis had the largest decrease in visits in that time period.<ref>{{cite journal | vauthors = Skiner HG, Blanchard J, Elixhauser A | title = Trends in Emergency Department Visits, 2006–2011 | journal =HCUP Statistical Brief |issue=179 | publisher = Agency for Healthcare Research and Quality | location = Rockville, MD | date = September 2014 | url = https://www.hcup-us.ahrq.gov/reports/statbriefs/sb179-Emergency-Department-Trends.jsp | url-status=live | archive-url = https://web.archive.org/web/20141224224220/http://www.hcup-us.ahrq.gov/reports/statbriefs/sb179-Emergency-Department-Trends.jsp | archive-date = 2014-12-24 }}</ref>