Editing Chagas disease (section)

==Cause==
[[File:Trypanosoma cruzi LifeCycle.gif|thumb|upright=1.4|alt=See "Cause" section.|Life cycle and transmission of ''T. cruzi'']]
Chagas disease is caused by infection with the [[protozoa]]n parasite {{nowrap|''T. cruzi''}}, which is typically introduced into humans through the bite of triatomine bugs, also called "kissing bugs".<ref name="Bern2015"/> When the insect defecates at the bite site, motile {{nowrap|''T. cruzi''}} forms called trypomastigotes enter the bloodstream and invade various host cells.<ref name=CDC/> Inside a host cell, the parasite transforms into a replicative form called an amastigote, which undergoes several rounds of replication.<ref name=CDC/> The replicated amastigotes transform back into trypomastigotes, which burst the host cell and are released into the bloodstream.<ref name="Molina2018"/> Trypomastigotes then disseminate throughout the body to various tissues, where they invade cells and replicate.<ref name="Molina2018"/> Over many years, cycles of parasite replication and immune response can severely damage these tissues, particularly the heart and digestive tract.<ref name="Molina2018"/>

===Transmission===
[[File:Triatoma infestans - ZSM.jpg|thumb|left|upright=0.35|alt=A brown winged insect|''[[Triatoma infestans]]'', a common vector of ''T. cruzi''<ref name="AlbaSoto2019"/>]]
''T. cruzi'' can be transmitted by various triatomine bugs in the genera ''[[Triatoma]]'', ''[[Panstrongylus]]'', and ''[[Rhodnius]]''.<ref name="Molina2018"/> The primary [[vector (epidemiology)|vectors]] for human infection are the species of triatomine bugs that inhabit human dwellings, namely ''[[Triatoma infestans]]'', ''[[Rhodnius prolixus]]'', ''[[Triatoma dimidiata]]'' and ''[[Panstrongylus megistus]]''.<ref name="AlbaSoto2019"/> These insects are known by a number of local names, including ''vinchuca'' in Argentina, Bolivia, Chile and Paraguay, ''barbeiro'' (the [[barber surgeon|barber]]) in Brazil, ''pito'' in Colombia, ''chinche'' in Central America, and ''chipo'' in Venezuela.<ref>{{cite book|veditors=Maudlin I, Holmes PH, Miles MA|title=The Trypanosomiases|date=2004|publisher=CAB International|location=Wallingford|isbn=9780851990347|page= [https://books.google.com/books?id=6Z1zUWY9LroC&pg=PA184 184]}}</ref> The bugs tend to [[Nocturnality|feed at night]], preferring moist surfaces near the eyes or mouth.<ref name=PD7/><ref name="AlbaSoto2019">{{cite book|vauthors=Alba Soto CD, González Cappa SM|title=Chagas Disease |chapter=Trypanosoma cruzi Journey from the Insect Vector to the Host Cell |veditors=Marcelo Altcheh J, Freilij H|url=https://books.google.com/books?id=WpyuDwAAQBAJ|series=Birkhäuser Advances in Infectious Diseases|date=9 September 2019|publisher=Springer Nature|location=Switzerland|isbn=978-3-030-00054-7|pages=25–59|issn=2504-3811|doi=10.1007/978-3-030-00054-7_2|s2cid=203357705}}</ref> A triatomine bug can become infected with {{nowrap|''T. cruzi''}} when it feeds on an infected host.<ref name=PD7/> {{nowrap|''T. cruzi''}} replicates in the insect's intestinal tract and is shed in the bug's feces.<ref name=PD7/> When an infected triatomine feeds, it pierces the skin and takes in a [[Hematophagy|blood meal]], defecating at the same time to make room for the new meal.<ref name=PD7>{{cite book|chapter=American Trypanosomiasis |pages=71–84 |title=Parasitic Diseases |edition=7 |vauthors=Despommier DD, Griffin DO, Gwadz RW, Hotez PJ, Knirsch CA |publisher=Parasites Without Borders |location=New York |date=2019 |url=https://parasiteswithoutborders.com/books/ |access-date=26 March 2020}}</ref> The bite is typically painless, but causes itching.<ref name=PD7/> Scratching at the bite introduces the {{nowrap|''T. cruzi''}}-laden feces into the bite wound, initiating infection.<ref name=PD7/>

In addition to classical vector spread, Chagas disease can be transmitted through the consumption of food or drink contaminated with triatomine insects or their feces.<ref name=Robertson2016>{{cite journal|title=Trypanosoma cruzi: Time for International Recognition as Foodborne Parasite |vauthors=Robertson LJ, Deveesschauwer B, de Noya BA, Gozalez ON, Togerson PR |date=June 2016 |journal=PLOS Neglected Tropical Diseases |volume=10 |issue=6 |doi=10.1371/journal.pntd.0004656 |page=e0004656|pmid=27253136 |pmc=4890754 |doi-access=free }}</ref> Since heating or drying kills the parasites, drinks and especially fruit juices are the most frequent source of infection.<ref name=Robertson2016/> This oral route of transmission has been implicated in several outbreaks, where it led to unusually severe symptoms, likely due to infection with a higher parasite load than from the bite of a triatomine bug—<ref name=Gua2019/><ref name=Robertson2016/>a single crushed triatomine in a food or beverage harboring ''T cruzi'' can contain about 600,000 metacyclic trypomastigotes, while triatomine fecal matter contains 3,000-4,000 per μL.<ref>{{cite web | title=Oral Transmission of Chagas Disease Has Severe Effects (with section 'Seven Things to Know About Orally Transmitted Chagas Disease')| website=Medscape | date=1 March 2024 | url=https://www.medscape.com/viewarticle/oral-transmission-chagas-disease-has-severe-effects-2024a100042f?ecd=wnl_tp10_daily_240304_MSCPEDIT_etid6352192&uac=88149SY&impID=6352192}}</ref>

''T. cruzi'' can be transmitted independent of the triatomine bug during blood transfusion, following organ transplantation, or across the [[placenta]] during pregnancy.<ref name="Molina2018"/> Transfusion with the blood of an infected donor infects the recipient 10–25% of the time.<ref name="Molina2018"/> To prevent this, blood donations are screened for {{nowrap|''T. cruzi''}} in many countries with endemic Chagas disease, as well as the United States.<ref name=Gua2019/> Similarly, transplantation of solid organs from an infected donor can transmit {{nowrap|''T. cruzi''}} to the recipient.<ref name="Molina2018"/> This is especially true for [[Heart transplantation|heart transplant]], which transmits ''T. cruzi'' 75–100% of the time, and less so for transplantation of the [[Liver transplantation|liver]] (0–29%) or a [[Kidney transplantation|kidney]] (0–19%).<ref name="Molina2018"/> An infected mother can pass {{nowrap|''T. cruzi''}} to her child through the placenta; this occurs in up to 15% of births by infected mothers.<ref name=Messenger2018>{{cite journal|title=Congenital Chagas disease: current diagnostics, limitations, and future perspectives |journal=Current Opinion in Infectious Diseases |volume=31 |issue=5 |pages=415–21 |doi=10.1097/QCO.0000000000000478 |vauthors=Messenger LA, Bern C |date=2018|pmid=30095485 |s2cid=51955023 |url=https://researchonline.lshtm.ac.uk/id/eprint/4650860/1/Messenger-Bern-Congenital-Chagas-Disease.pdf |archive-url=https://web.archive.org/web/20200305151311/https://researchonline.lshtm.ac.uk/id/eprint/4650860/1/Messenger-Bern-Congenital-Chagas-Disease.pdf |archive-date=2020-03-05 |url-status=live }}</ref> As of 2019, 22.5% of new infections occurred through congenital transmission.<ref name="Bern2019">{{cite journal|vauthors=Bern C, Messenger LA, Whitman JD, Maguire JH|title=Chagas Disease in the United States: a Public Health Approach|journal=Clinical Microbiology Reviews|volume=33|issue=1|year=2019|issn=0893-8512|doi=10.1128/CMR.00023-19|pmid=31776135|pmc=6927308|type=Review}}</ref>