Editing Salmonellosis (section)

== Causes ==
[[File:Prevention of Salmonella from the farm to table infographic.png|thumb|upright=1.3|An infographic illustrating how ''Salmonella'' bacteria  spread from the farm]]
* Contaminated food, often having no unusual look or smell<ref>{{cite web |url=http://now.tufts.edu/articles/food-bacteria-smell-taste-bad-illness |title=Are the bacteria that make food smell and taste bad the same ones that make you sick? |website=Tufts.edu |date=24 February 2012  |author=Jeanne Goldberg |access-date= 28 May 2018}}</ref>
* Poor kitchen hygiene, especially problematic in institutional kitchens and restaurants because this can lead to a significant outbreak
* Excretions from either sick or infected but apparently clinically healthy people and animals (especially dangerous are caregivers and animals)
* Polluted surface water and standing water (such as in shower hoses or unused water dispensers)
* Unhygienically thawed poultry (the meltwater contains many bacteria)
* An association with reptiles (pet tortoises, snakes, iguanas,<ref>{{cite journal|title=Reptile-Associated Salmonellosis—Selected States, 1998–2002|journal=Centers for Disease Control and Prevention|date=12 December 2003|access-date=9 October 2011|url=https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5249a3.htm|url-status=live|archive-url=https://web.archive.org/web/20111006191405/http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5249a3.htm|archive-date=6 October 2011}}</ref><ref>{{cite journal|title=Iguanas and Salmonella marina infection in children: a reflection of the increasing incidence of reptile-associated salmonellosis in the United States|journal=Pediatrics|date=March 1997|pmid=9041295|volume=99|issue=3|pages=399–402|vauthors=Mermin J, Hoar B, Angulo FJ |doi=10.1542/peds.99.3.399}}</ref> and aquatic turtles) is well described.<ref>{{cite journal|title=Ongoing investigation into reptile associated salmonella infections|journal=Health Protection Report|volume=3|issue=14|date=9 April 2009|access-date=12 April 2009|url=http://www.hpa.org.uk/hpr/archives/2009/news1409.htm#reptiles|url-status=live|archive-url=https://web.archive.org/web/20090429110621/http://www.hpa.org.uk/hpr/archives/2009/news1409.htm#reptiles|archive-date=29 April 2009}}</ref>
* Amphibians such as frogs

''Salmonella'' bacteria can survive for some time without a host; they are frequently found in polluted water, with contamination from the excrement of carrier animals being particularly important.{{citation needed|date=January 2021}}

The [[European Food Safety Authority]] <!-- (EFSA) --> highly recommends that when handling raw turkey meat, consumers and people involved in the food supply chain should pay attention to personal and food hygiene.<ref>{{Cite journal|title = Multi-country outbreak of Salmonella Stanley infections Update|date = 21 September 2012|journal = EFSA Journal|doi = 10.2903/j.efsa.2012.2893|volume=10|issue = 9|pages=2893|doi-access = free}}</ref>

An estimated 142,000 Americans are infected each year with ''Salmonella'' Enteritidis from [[chicken eggs]],<ref>{{cite news | title = Playing It Safe With Eggs | url = https://www.fda.gov/Food/ResourcesForYou/Consumers/ucm077342.htm | quote = The U.S. Food and Drug Administration (FDA) estimates that 142,000 illnesses each year are caused by consuming eggs contaminated with Salmonella. | work = FDA Food Facts | access-date = 2013-03-02 | date = 2013-02-28 | url-status = live | archive-url = https://web.archive.org/web/20130301230156/https://www.fda.gov/Food/ResourcesForYou/Consumers/ucm077342.htm | archive-date = 2013-03-01 }}</ref> and about 30 die.<ref name="Was2009">{{cite news|url=https://www.washingtonpost.com/wp-dyn/content/article/2009/07/07/AR2009070702343.html?hpid=topnews|title=Administration Urged to Boost Food Safety Efforts|date=2009-07-08|work=[[Washington Post]]|last2=O'Keefe|first2=Ed|quote=Among them is a final rule, issued by the FDA, to reduce the contamination in eggs. About 142,000 Americans are infected each year with ''Salmonella'' enteritidis from eggs, the result of an infected hen passing along the bacterium. About 30 die.|access-date=2009-07-07|first1=Jane|last1=Black|url-status=live|archive-url=https://web.archive.org/web/20110604113540/http://www.washingtonpost.com/wp-dyn/content/article/2009/07/07/AR2009070702343.html?hpid=topnews|archive-date=2011-06-04}}</ref> The shell of the egg may be contaminated with ''Salmonella'' by feces or environment, or its interior (yolk) may be contaminated by penetration of the bacteria through the porous shell or from a hen whose infected ovaries contaminate the egg during egg formation.<ref>{{cite journal | title = Mechanisms of egg contamination by Salmonella Enteritidis | journal = FEMS Microbiology Reviews | date = July 2009 | first = Inne | last = Gantois |author2=Richard Ducatelle |author3=Frank Pasmans |author4=Freddy Haesebrouck |author5=Richard Gast |author6=Tom J. Humphrey |author7=Filip Van Immerseel  | pmid = 19207743 | volume = 33 | issue = 4 | pages = 718–738| doi = 10.1111/j.1574-6976.2008.00161.x| quote = Eggs can be contaminated on the outer shell surface and internally. Internal contamination can be the result of penetration through the eggshell or by direct contamination of egg contents before oviposition, originating from infection of the reproductive organs. Once inside the egg, the bacteria need to cope with antimicrobial factors in the albumen and vitelline membrane before migration to the yolk can occur| doi-access = free }}</ref><ref>{{cite journal | title = Contamination of egg shell and contents with Salmonella enteritidis: a review | journal = International Journal of Food Microbiology | date = January 1994 | first = T. J. | last = Humphrey | pmid = 8155476 | volume = 21 | issue = 1–2 | pages = 31–40| doi = 10.1016/0168-1605(94)90197-X | quote = Salmonella enteritidis can contaminate the contents of clean, intact shell eggs as a result of infections of the reproductive tissue of laying hens. The principal site of infection appears to be the upper oviduct. In egg contents, the most important contamination sites are the outside of the vitelline membrane or the albumen surrounding it. In fresh eggs, only a few salmonellae are present. As albumen is an iron-restricted environment, growth only occurs with storage-related changes to vitelline membrane permeability, which allows salmonellae to invade yolk contents.}}</ref>

Nevertheless, such interior egg yolk contamination is theoretically unlikely.<ref>{{cite journal | title = Penetration and Growth of Salmonella in Shell Eggs | journal = Journal of Food Science | date = September 1956 | first = J.L. | last = Stokes |author2=W.W. Osborne |author3=H.G. Bayne | volume = 21 | issue = 5 | pages = 510–518| doi = 10.1111/j.1365-2621.1956.tb16950.x| quote = Normally, the oviduct of the hen is sterile and therefore the shell and internal contents of the egg are also free of microorganisms (10,16). In some instances, however, the ovaries and oviduct may be infected with ''Salmonella'' and these may be deposited inside the egg (12). More frequently, however, the egg becomes contaminated after it is laid.}}</ref><ref>{{cite journal | doi = 10.2307/1593012 | title = Differences Among Six Salmonella Serovars in Abilities to Colonize Reproductive Organs and to Contaminate Egges in Laying Hens | journal = Avian Diseases | year = 2001 | first = Masashi | last = Okamura |author2=Yuka Kamijima |author3=Tadashi Miyamoto |author4=Hiroyuki Tani |author5=Kazumi Sasai |author6=Eiichiroh Baba  | volume = 45 | issue = 1 | pages = 61–69| pmid = 11332500  | jstor = 1593012| quote = when hens were artificially infected to test for transmission rate to yolks: "Mature laying hens were inoculated intravenously with 106 colony-forming units of ''Salmonella'' enteritidis, ''Salmonella'' typhimurium, ''Salmonella'' infantis, ''Salmonella'' hadar, ''Salmonella'' heidelberg, or ''Salmonella'' montevideo to cause the systemic infection. ''Salmonella'' Enteritidis was recovered from three yolks of the laid eggs (7.0%), suggesting egg contamination from the transovarian transmission of S. enteritidis."}}</ref><ref>{{cite journal | doi = 10.3382/ps.2009-00440 | title = In vitro penetration of ''Salmonella'' enteritidis through yolk membranes of eggs from 6 genetically distinct commercial lines of laying hens | journal = Poultry Science | date = August 2010 | first = RK | last = Gast | author2 = D.R. Jones | author3 = K.E. Anderson | author4 = R. Guraya | author5 = J. Guard | author6 = P.S. Holt | volume = 89 | issue = 8 | pages = 1732–1736 | pmid = 20634530 | url = http://ps.fass.org/cgi/content/abstract/89/8/1732 | access-date = 2010-08-20 | quote = In this study, egg yolks were infected at the surface of the yolk (vitelline membrane) to determine the percentage of yolk contamination (a measure used to determine egg contamination resistance, with numbers lower than 95% indicating increasing resistance): Overall, the frequency of penetration of Salmonella Enteritidis into the yolk contents of eggs from individual lines of hens ranged from 30 to 58% and the mean concentration of Salmonella Enteritidis in yolk contents after incubation ranged from 0.8 to 2.0 log10 cfu/mL. | url-status = live | archive-url = https://web.archive.org/web/20110724195805/http://ps.fass.org/cgi/content/abstract/89/8/1732 | archive-date = 2011-07-24 | doi-access = free }}</ref><ref>{{cite journal | title = Contamination of eggs of laying hens with S. Enteritidis | journal = Veterinary Survey (Tierärztliche Umschau) | date = Jul–Aug 2009 | first = Gerald | last = Jaeger | volume = 64 | issue = 7–8 | pages = 344–348 | url = https://www.scopus.com/record/display.url?eid=2-s2.0-70249089685&origin=AuthorNamesList&txGid=zUlZlrGCjw9FgQXhSMPv1sc%3a3 | access-date = 2010-08-20 | quote = The migration of the bacterium into the nutritionally rich yolk is constrained by the lysozyme loaded vitelline membrane, and would need warm enough storage conditions within days and weeks. The high concentration on of antibodies of the yolk does not inhibit the ''Salmonella'' multiplication. Only seldom does transovarian contamination of the developing eggs with S. enteritidis make this bacterium occur in laid eggs, because of the bactericidal efficacy of the antimicrobial peptides}}</ref> Even under natural conditions, the rate of infection was very small (0.6% in a study of naturally contaminated eggs<ref>{{cite journal | title = Numbers of Salmonella enteritidis in the contents of naturally contaminated hens' eggs | journal = Epidemiology and Infection | year = 1991 | first = T.J. | last = Humphrey | author2 = A. Whitehead | author3 = A. H. L. Gawler | author4 = A. Henley | author5 = B. Rowe | pmid = 2050203 | volume = 106 | issue = 3 | pmc = 2271858 | pages = 489–496 | doi = 10.1017/S0950268800067546 | quote = Over 5700 hens eggs from 15 flocks naturally infected with Salmonella enteritidis were examined individually for the presence of the organism in either egg contents or on shells. Thirty-two eggs (0·6%) were positive in the contents. In the majority, levels of contamination were low. }}</ref> and 3.0% among artificially and heavily infected hens<ref>{{cite journal | title = Colonization of specific regions of the reproductive tract and deposition at different locations inside eggs laid by hens infected with Salmonella Enteritidis or Salmonella Heidelberg | journal =  Avian Diseases| date = March 2007 | first = Richard | last = Gast | author2 = Rupa Guraya | author3 = Jean Guard | author4 = Peter Holt | author5 = Randle Moore | volume = 51 | issue = 1 | pages = 40–44 | pmid = 17461265 | url = http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=196876 | access-date = 2010-08-20 | quote = when hens are artificially infected with unrealistically large doses (according to the author): In the present study, groups of laying hens were experimentally infected with large oral doses of Salmonella Heidelberg, Salmonella Enteritidis phage type 13a, or Salmonella Enteritidis phage type 14b. For all of these isolates, the overall frequency of ovarian colonization (34.0%) was significantly higher than the frequency of recovery from either the upper (22.9%) or lower (18.1%) regions of the oviduct. No significant differences were observed between the frequencies of Salmonella isolation from egg yolk and albumen (4.0% and 3.3%, respectively). | doi = 10.1637/0005-2086(2007)051[0040:cosrot]2.0.co;2 | url-status = live | archive-url = https://web.archive.org/web/20100310002101/http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=196876 | archive-date = 2010-03-10 }}</ref>).