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{{short description|Species of parasitic euglenoids (protozoans)}}
{{Short description|Species of parasitic euglenoids (protozoans)}}
{{Speciesbox
{{Speciesbox
| image = Trypanosoma cruzi crithidia.jpeg
| image = Trypanosoma cruzi in a blood smear.jpg
| image_alt = "Trypanosoma cruzi", crithidia
| image_alt =
| image_caption = ''Trypanosoma cruzi'', [[crithidia]]
| image_caption = ''Trypanosoma cruzi'' in human blood Giemsa stain. They are typically seen as a C-shape and have a more pronounced [[kinetoplast]] compared to other species.
| genus = Trypanosoma
| genus = Trypanosoma
| species = cruzi
| species = cruzi
| authority = [[Carlos Chagas|Chagas]], 1909<ref>{{cite journal |last1=Chagas |first1=C. |year=1909 |title=Neue Trypanosomen: Vorläufige mitteilung |trans-title=New trypanosome. Preliminary communication |language=de |journal=Archiv für Schiffs-und Tropenhygiene |volume=13 |pages=120–122 }}</ref><ref>{{cite journal |last1=Chagas |first1=Carlos |year=1909 |title=Nouvelle espèce de trypanosomiase humaine |trans-title=New species of human trypanosomiasis |language=fr |journal=Bulletin de la Société de Pathologie Exotique |volume=2 |issue=6 |pages=304–307 |url=http://www.pathexo.fr/documents/articles-bull/T102-5-352-355.pdf }}</ref><ref>{{cite journal |last1=Chagas |first1=C. |year=1909 |title=Nova especie morbida do homem, produzida por um ''Trypanozoma'' (''Trypanozoma cruzi''): nota prévia |trans-title=New morbid species of man, produced by a ''Trypanozoma'' (''Trypanozoma cruzi''): previous note |language=fr |journal=Brazil-Medico |volume=23 |issue=16 |pages=161 }}</ref>
| authority = [[Carlos Chagas|Chagas]], 1909<ref>{{cite journal |last1=Chagas |first1=C. |year=1909 |title=Neue Trypanosomen: Vorläufige mitteilung |trans-title=New trypanosome. Preliminary communication |language=de |journal=Archiv für Schiffs-und Tropenhygiene |volume=13 |pages=120–122 }}</ref><ref>{{cite journal |last1=Chagas |first1=Carlos |year=1909 |title=Nouvelle espèce de trypanosomiase humaine |trans-title=New species of human trypanosomiasis |language=fr |journal=Bulletin de la Société de Pathologie Exotique |volume=2 |issue=6 |pages=304–307 |url=http://www.pathexo.fr/documents/articles-bull/T102-5-352-355.pdf }}</ref><ref>{{cite journal |last1=Chagas |first1=C. |year=1909 |title=Nova especie morbida do homem, produzida por um ''Trypanozoma'' (''Trypanozoma cruzi''): nota prévia |trans-title=New morbid species of man, produced by a ''Trypanozoma'' (''Trypanozoma cruzi''): previous note |language=fr |journal=Brazil-Medico |volume=23 |issue=16 |pages=161 }}</ref>
| synonyms =
| synonyms =
| synonyms_ref =
| synonyms_ref =
}}
}}


'''''Trypanosoma cruzi''''' is a species of [[parasite|parasitic]] [[euglenoid]]s. Amongst the protozoa, the [[Trypanosoma|trypanosomes]] characteristically bore tissue in another organism and feed on blood (primarily) and also lymph. This behaviour causes disease or the likelihood of disease that varies with the organism: [[Chagas disease]] in humans, [[covering sickness|dourine]] and [[surra]] in horses, and a [[brucellosis]]-like disease in cattle. Parasites need a host body and the haematophagous insect [[Triatominae|triatomine]] (descriptions "assassin bug", "cone-nose bug", and "kissing bug") is the major [[Vector (epidemiology)|vector]] in accord with a mechanism of infection. The triatomine likes the nests of vertebrate animals for shelter, where it bites and sucks blood for food. Individual triatomines infected with protozoa from other contact with animals transmit trypanosomes when the triatomine deposits its faeces on the host's skin surface and then bites. Penetration of the infected [[faeces]] is further facilitated by the scratching of the bite area by the human or animal host.
'''''Trypanosoma cruzi''''' is a species of [[parasite|parasitic]] [[euglenoid]]s. Among the protozoa, the [[Trypanosoma|trypanosomes]] characteristically bore tissue in another organism and feed on blood (primarily) and also lymph. This behaviour causes disease or the likelihood of disease that varies with the organism: [[Chagas disease]] in humans, [[covering sickness|dourine]] and [[surra]] in horses, and a [[brucellosis]]-like disease in cattle. Parasites need a host body and the haematophagous insect [[Triatominae|triatomine]] (descriptions "assassin bug", "cone-nose bug", and "kissing bug") is the major [[Vector (epidemiology)|vector]] in accord with a mechanism of infection. The triatomine likes the nests of vertebrate animals for shelter, where it bites and sucks blood for food. Individual triatomines infected with protozoa from other contact with animals transmit trypanosomes when the triatomine deposits its faeces on the host's skin surface and then bites. Penetration of the infected [[faeces]] is further facilitated by the scratching of the bite area by the human or animal host.


==Life cycle==
==Etymology==
The [[Specific name (zoology)|specific name]] ''"cruzi"'' is an honor to Brazilian scientist [[Oswaldo Cruz]], who taught discoverer Carlos Chagas.<ref>{{Cite journal |last1=Kropf |first1=Simone Petraglia |last2=Sá |first2=Magali Romero |date=July 2009 |title=The discovery of Trypanosoma cruzi and Chagas disease (1908-1909): tropical medicine in Brazil |journal=História, Ciências, Saúde-Manguinhos |language=en |volume=16 |pages=13–34 |doi=10.1590/S0104-59702009000500002 |pmid=20027916 |issn=0104-5970|doi-access=free }}</ref>
[[File:Trypanosoma cruzi in a blood smear.jpg|thumb|Trypanosoma cruzi in human blood Giemsa stain]]


==Life cycle==
The ''Trypanosoma cruzi'' life cycle starts in an animal reservoir, usually mammals, wild or domestic, including humans. A triatomine bug serves as the vector. While taking a blood meal, it ingests ''T. cruzi''. In the triatomine bug (''[[Triatoma infestans]]'') the parasite goes into the [[epimastigote]] stage, making it possible to reproduce. After reproducing through binary fission, the epimastigotes move onto the rectal cell wall, where they become infectious. Infectious ''T. cruzi'' are called metacyclic trypomastigotes. When the triatomine bug subsequently takes a blood meal from a human, it defecates. The trypomastigotes are in the feces and are capable of swimming into the host's cells using flagella, a characteristic swimming tail dominant in the Euglenoid class of protists.<ref>{{cite book |doi=10.1016/S0074-7696(05)44006-1 |chapter=The Flagellum of Trypanosomes |chapter-url=https://books.google.com/books?id=Xn5lqO8yup8C&pg=PA227 |title=A Survey of Cell Biology |series=International Review of Cytology |year=2005 |last1=Kohl |first1=Linda |last2=Bastin |first2=Philippe |isbn=978-0-08-045779-6 |volume=244 |pages=227–85 |editor1-first=Kwang W. |editor1-last=Jeon |pmid=16157182|url=https://hal.archives-ouvertes.fr/hal-00109408/file/KohlBastin02.pdf }}</ref>
The ''Trypanosoma cruzi'' life cycle starts in an animal reservoir, usually mammals, wild or domestic, including humans. A triatomine bug serves as the vector. While taking a blood meal, it ingests ''T. cruzi''. In the triatomine bug (the principal species of which in terms of parasite transmission to humans being ''[[Triatoma infestans]]'') the parasite goes into the [[epimastigote]] stage, making it possible to reproduce. After reproducing through binary fission, the epimastigotes move onto the rectal cell wall, where they become infectious. Infectious ''T. cruzi'' are called metacyclic trypomastigotes. When the triatomine bug subsequently takes a blood meal from a host, it defecates&mdash;its waste containing ''T. cruzi'' propagation stages. As a result, Trumper and Gorla 1991 find transmission success centers around the triatomine's defecation behaviors.<ref name="Krinsky-2002">{{cite book | editor1-last=Mullen | editor1-first=Gary | editor2-last=Durden | editor2-first=Lance | title=Medical and veterinary entomology | publisher=[[Academic Press]] | publication-place=[[Amsterdam]] [[Boston]] | year=2002 | isbn=978-0-12-510451-7 | oclc=50752006 | s2cid=82769743 | pages=67–86/xv–597 | last=Krinsky | first=William L.| doi=10.1016/B978-012510451-7/50007-4 }} {{ISBN|0125104510}}. {{ISBN|9780080536071}}.</ref><ref name="Telleria-Tibayrenc-2017">{{cite book | editor1-last=Telleria | editor1-first=Jenny | editor2-last=Tibayrenc | editor2-first=Michel | title=American trypanosomiasis Chagas disease : one hundred years of research | publisher=[[Elsevier]] | publication-place=[[Amsterdam, Netherlands]] | year=2017 | doi=10.1016/B978-0-12-801029-7.00007-1 | isbn=978-0-12-801029-7 | oclc=971022099 | s2cid=82080107}} {{ISBN|0128010290}}.</ref><ref name="SantAnna-et-al-2017">{{cite journal | last1=Sant’Anna | first1=Maurício Roberto Viana | last2=Soares | first2=Adriana Coelho | last3=Araujo | first3=Ricardo Nascimento | last4=Gontijo | first4=Nelder Figueiredo | last5=Pereira | first5=Marcos Horácio | title=Triatomines (Hemiptera, Reduviidae) blood intake: Physical constraints and biological adaptations | journal=[[Journal of Insect Physiology]] | publisher=[[Elsevier]] | volume=97 | year=2017 | issn=0022-1910 | doi=10.1016/j.jinsphys.2016.08.004 | pages=20–26| pmid=27521585 | doi-access=free }}</ref> Alternatively, in nature and in most recent cases of epidemiological outbreaks, infection occurs through the oral ingestion of parasites (mainly through a lack of infected food disinfection in the case of human infection). <ref>{{cite journal |last1=Pereira |first1=Karen Signori |last2=Schmidt |first2=Flávio Luis |last3=Guaraldo |first3=Ana M.A. |last4=Franco |first4=Regina M.B. |last5=Dias |first5=Viviane L. |last6=Passos |first6=Luiz A.C. |title=Chagas' Disease as a Foodborne Illness |journal=Journal of Food Protection |date=February 2009 |volume=72 |issue=2 |pages=441–446 |doi=10.4315/0362-028X-72.2.441 |url=https://linkinghub.elsevier.com/retrieve/pii/S0362028X22002812}}</ref><ref>{{cite journal |last1=Kribs-Zaleta |first1=Christopher |title=Vector Consumption and Contact Process Saturation in Sylvatic Transmission of T. cruzi |journal=Mathematical Population Studies |date=September 2006 |volume=13 |issue=3 |pages=135–152 |doi=10.1080/08898480600788576 |url=https://www.tandfonline.com/doi/full/10.1080/08898480600788576}}</ref>

The trypomastigotes enter the human host through the bite wound or by crossing mucous membranes. The host cells contain macromolecules such as [[laminin]], [[thrombospondin]], heparin sulphate, and [[fibronectin]] that cover their surface.<ref name="ley">{{cite journal |doi=10.1084/jem.168.2.649 |title=Amastigotes of ''Trypanosoma cruzi'' sustain an infective cycle in mammalian cells |year=1988 |last1=Ley |first1=Victoria |journal=Journal of Experimental Medicine |volume=168 |issue=2 |pages=649–59 |pmid=3045248 |last2=Andrews |first2=Norma W. |last3=Robbins |first3=Edith S. |last4=Nussenzweig |first4=Victor |pmc=2189010}}</ref> These macromolecules are essential for adhesion between parasite and host and for the process of host invasion by the parasite. The trypomastigotes must cross a network of proteins that line the exterior of the host cells in order to make contact and invade the host cells. The molecules and proteins on the [[cytoskeleton]] of the cell also bind to the surface of the parasite and initiate host invasion.<ref name="ley" />
The trypomastigotes are in the feces and are capable of swimming into the host's cells using flagella, a characteristic swimming tail dominant in the Euglenoid class of protists.<ref>{{cite book |doi=10.1016/S0074-7696(05)44006-1 |chapter=The Flagellum of Trypanosomes |chapter-url=https://books.google.com/books?id=Xn5lqO8yup8C&pg=PA227 |title=A Survey of Cell Biology |series=International Review of Cytology |year=2005 |last1=Kohl |first1=Linda |last2=Bastin |first2=Philippe |isbn=978-0-08-045779-6 |volume=244 |pages=227–85 |editor1-first=Kwang W. |editor1-last=Jeon |pmid=16157182|url=https://hal.archives-ouvertes.fr/hal-00109408/file/KohlBastin02.pdf }}</ref> The trypomastigotes enter the host through the bite wound or by crossing mucous membranes. The host cells contain macromolecules such as [[laminin]], [[thrombospondin]], heparin sulphate, and [[fibronectin]] that cover their surface.<ref name="ley">{{cite journal |doi=10.1084/jem.168.2.649 |title=Amastigotes of ''Trypanosoma cruzi'' sustain an infective cycle in mammalian cells |year=1988 |last1=Ley |first1=Victoria |journal=Journal of Experimental Medicine |volume=168 |issue=2 |pages=649–59 |pmid=3045248 |last2=Andrews |first2=Norma W. |last3=Robbins |first3=Edith S. |last4=Nussenzweig |first4=Victor |pmc=2189010}}</ref> These macromolecules are essential for adhesion between parasite and host and for the process of host invasion by the parasite. The trypomastigotes must cross a network of proteins that line the exterior of the host cells in order to make contact and invade the host cells. The molecules and proteins on the [[cytoskeleton]] of the cell also bind to the surface of the parasite and initiate host invasion.<ref name="ley" />


==Pathophysiology==
==Pathophysiology==
Trypanosomiasis in humans progresses with the development of the trypanosome into a [[trypomastigote]] in the blood and into an [[amastigote]] in tissues. The acute form of trypanosomiasis is usually unnoticed, although it may manifest itself as a localized swelling at the site of entry. The chronic form may develop 30 to 40 years after infection and affect internal organs (e.g., the [[heart]], the [[oesophagus]], the [[colon (anatomy)|colon]], and the [[peripheral nervous system]]). Affected people may die from heart failure.{{cn|date=May 2021}}
Trypanosomiasis in humans progresses with the development of the trypanosome into a [[trypomastigote]] in the blood and into an [[amastigote]] in tissues. As the infection progresses, the number of infected cells increases, as well as the number of amastigotes per infected cell (APC). If the average of APC is one or close to one, the infection has just begun. A higher APC means that amastigotes have started to replicate.<ref name=":0">{{Cite journal |last1=Arias-del-Angel |first1=Jorge A. |last2=Santana-Solano |first2=Jesús |last3=Santillán |first3=Moisés |last4=Manning-Cela |first4=Rebeca G. |date=2020-09-28 |title=Motility patterns of Trypanosoma cruzi trypomastigotes correlate with the efficiency of parasite invasion in vitro |journal=Scientific Reports |language=en |volume=10 |issue=1 |pages=15894 |doi=10.1038/s41598-020-72604-4 |issn=2045-2322 |pmc=7522242 |pmid=32985548|bibcode=2020NatSR..1015894A }}</ref>


The acute form of trypanosomiasis is usually unnoticed, although it may manifest itself as a localized swelling at the site of entry. In this form appears elevated parasitism, myocarditis, and changes in the myocardial gene expression. The chronic form may develop 30 to 40 years after infection and affect internal organs (e.g., the [[heart]], the [[oesophagus]], the [[colon (anatomy)|colon]], and the [[peripheral nervous system]]). Affected people may die from heart failure and severe heart lesions.<ref>{{Cite journal |last1=Ferreira |first1=Ludmila Rodrigues Pinto |last2=Ferreira |first2=Frederico Moraes |last3=Laugier |first3=Laurie |last4=Cabantous |first4=Sandrine |last5=Navarro |first5=Isabela Cunha |last6=da Silva Cândido |first6=Darlan |last7=Rigaud |first7=Vagner Carvalho |last8=Real |first8=Juliana Monte |last9=Pereira |first9=Glaucia Vilar |last10=Pereira |first10=Isabela Resende |last11=Ruivo |first11=Leonardo |last12=Pandey |first12=Ramendra Pati |last13=Savoia |first13=Marilda |last14=Kalil |first14=Jorge |last15=Lannes-Vieira |first15=Joseli |date=2017-12-21 |title=Integration of miRNA and gene expression profiles suggest a role for miRNAs in the pathobiological processes of acute Trypanosoma cruzi infection |journal=Scientific Reports |language=en |volume=7 |issue=1 |pages=17990 |doi=10.1038/s41598-017-18080-9 |issn=2045-2322 |pmc=5740174 |pmid=29269773|bibcode=2017NatSR...717990F }}</ref>
⚫
Acute cases are treated with [[nifurtimox]] and [[benznidazole]], but no effective therapy for chronic cases is currently known.{{cn|date=May 2021}}

⚫
Acute cases are treated with [[nifurtimox]] and [[benznidazole]], but no effective therapy for chronic cases is currently known.{{citation needed|date=May 2021}}


=== Cardiac manifestations ===
=== Cardiac manifestations ===
Researchers of Chagas’ disease have demonstrated several processes that occur with all cardiomyopathies. The first event is an inflammatory response. Following inflammation, cellular damage occurs. Finally, in the body's attempt to recover from the cellular damage, fibrosis begins in the cardiac tissue.<ref>{{cite journal |doi=10.1046/j.1537-2995.2002.00077.x |title=''Trypanosoma cruzi'' in Los Angeles and Miami blood donors: Impact of evolving donor demographics on seroprevalence and implications for transfusion transmission |year=2002 |last1=Leiby |first1=David A. |last2=Herron Jr |first2=Ross M. |last3=Read |first3=Elizabeth J. |last4=Lenes |first4=Bruce A. |last5=Stumpf |first5=Robert J. |journal=Transfusion |volume=42 |issue=5 |pages=549–55 |pmid=12084162}}</ref>
Researchers of Chagas’ disease have demonstrated several processes that occur with all cardiomyopathies. The first event is an inflammatory response. Following inflammation, cellular damage occurs. Finally, in the body's attempt to recover from the cellular damage, fibrosis begins in the cardiac tissue.<ref>{{cite journal |doi=10.1046/j.1537-2995.2002.00077.x |title=''Trypanosoma cruzi'' in Los Angeles and Miami blood donors: Impact of evolving donor demographics on seroprevalence and implications for transfusion transmission |year=2002 |last1=Leiby |first1=David A. |last2=Herron Jr |first2=Ross M. |last3=Read |first3=Elizabeth J. |last4=Lenes |first4=Bruce A. |last5=Stumpf |first5=Robert J. |journal=Transfusion |volume=42 |issue=5 |pages=549–55 |pmid=12084162|s2cid=11997057 }}</ref>


Another cardiomyopathy found in nearly all cases of chronic Chagas’ disease is thromboembolic syndrome. Thromboembolism describes thrombosis, the formation of a clot, and its main complication is embolism, the carrying of a clot to a distal section of a vessel and causing blockage there. This occurrence contributes to the death of a patient by four means: arrhythmias, stasis secondary to cardiac dilation, mural endocarditis, and cardiac fibrosis. These thrombi also affect other organs such as the brain, spleen and kidney.<ref>{{cite journal |doi=10.1161/CIRCULATIONAHA.106.624296 |title=Pathogenesis of Chronic Chagas Heart Disease |year=2007 |last1=Marin-Neto |first1=Jose Antonio |last2=Cunha-Neto |first2=Edécio |last3=MacIel |first3=Benedito C. |last4=Simões |first4=Marcus V. |journal=Circulation |volume=115 |issue=9 |pages=1109–23 |pmid=17339569|doi-access=free }}</ref>
Another cardiomyopathy found in nearly all cases of chronic Chagas’ disease is thromboembolic syndrome. Thromboembolism describes thrombosis, the formation of a clot, and its main complication is embolism, the carrying of a clot to a distal section of a vessel and causing blockage there. This occurrence contributes to the death of a patient by four means: arrhythmias, stasis secondary to cardiac dilation, mural endocarditis, and cardiac fibrosis. These thrombi also affect other organs such as the brain, spleen and kidney.<ref>{{cite journal |doi=10.1161/CIRCULATIONAHA.106.624296 |title=Pathogenesis of Chronic Chagas Heart Disease |year=2007 |last1=Marin-Neto |first1=Jose Antonio |last2=Cunha-Neto |first2=Edécio |last3=MacIel |first3=Benedito C. |last4=Simões |first4=Marcus V. |journal=Circulation |volume=115 |issue=9 |pages=1109–23 |pmid=17339569|doi-access=free }}</ref>
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Subcellular findings in murine studies with induced ''T. cruzi'' infection revealed that the chronic state is associated with the persistent elevation of phosphorylated (activated) extracellular-signal-regulated kinase ([[Extracellular signal-regulated kinases|ERK]]), [[AP-1 (transcription factor)|AP-1]], and [[NF-κB]]. Also, the mitotic regulator for G1 progression, [[cyclin D1]] was found to be activated. Although there was no increase in any isoform of ERK, there was an increased concentration of phosphorylated ERK in mice infected with ''T. cruzi''. It was found that within seven days the concentration of AP-1 was significantly higher in ''T. cruzi''–infected mice when compared to the control. Elevated levels of NF-κB have also been found in myocardial tissue, with the highest concentrations being found in the vasculature. It was indicated through [[Western blot]] that cyclin D1 was upregulated from day 1 to day 60 post-infection. It was also indicated through immunohistochemical analysis that the areas that produced the most cyclin D1 were the vasculature and interstitial regions of the heart.<ref>{{cite journal |doi=10.1128/IAI.71.5.2859-2867.2003 |title=Activation of Transcription Factors AP-1 and NF- B in Murine Chagasic Myocarditis |year=2003 |last1=Huang |first1=Huan |last2=Petkova |first2=Stefka B. |last3=Cohen |first3=Alex W. |last4=Bouzahzah |first4=Boumediene |last5=Chan |first5=John |last6=Zhou |first6=Jian-nian |last7=Factor |first7=Stephen M. |last8=Weiss |first8=Louis M. |last9=Krishnamachary |first9=Mohan |last10=Mukherjee |first10=Shankar |last11=Wittner |first11=Murray |last12=Kitsis |first12=Richard N. |last13=Pestell |first13=Richard G. |last14=Lisanti |first14=Michael P. |last15=Albanese |first15=Chris |last16=Tanowitz |first16=Herbert B. |journal=Infection and Immunity |volume=71 |issue=5 |pages=2859–67 |pmid=12704159 |pmc=153290}}</ref>
Subcellular findings in murine studies with induced ''T. cruzi'' infection revealed that the chronic state is associated with the persistent elevation of phosphorylated (activated) extracellular-signal-regulated kinase ([[Extracellular signal-regulated kinases|ERK]]), [[AP-1 (transcription factor)|AP-1]], and [[NF-κB]]. Also, the mitotic regulator for G1 progression, [[cyclin D1]] was found to be activated. Although there was no increase in any isoform of ERK, there was an increased concentration of phosphorylated ERK in mice infected with ''T. cruzi''. It was found that within seven days the concentration of AP-1 was significantly higher in ''T. cruzi''–infected mice when compared to the control. Elevated levels of NF-κB have also been found in myocardial tissue, with the highest concentrations being found in the vasculature. It was indicated through [[Western blot]] that cyclin D1 was upregulated from day 1 to day 60 post-infection. It was also indicated through immunohistochemical analysis that the areas that produced the most cyclin D1 were the vasculature and interstitial regions of the heart.<ref>{{cite journal |doi=10.1128/IAI.71.5.2859-2867.2003 |title=Activation of Transcription Factors AP-1 and NF- B in Murine Chagasic Myocarditis |year=2003 |last1=Huang |first1=Huan |last2=Petkova |first2=Stefka B. |last3=Cohen |first3=Alex W. |last4=Bouzahzah |first4=Boumediene |last5=Chan |first5=John |last6=Zhou |first6=Jian-nian |last7=Factor |first7=Stephen M. |last8=Weiss |first8=Louis M. |last9=Krishnamachary |first9=Mohan |last10=Mukherjee |first10=Shankar |last11=Wittner |first11=Murray |last12=Kitsis |first12=Richard N. |last13=Pestell |first13=Richard G. |last14=Lisanti |first14=Michael P. |last15=Albanese |first15=Chris |last16=Tanowitz |first16=Herbert B. |journal=Infection and Immunity |volume=71 |issue=5 |pages=2859–67 |pmid=12704159 |pmc=153290}}</ref>


====Rhythm abnormalities ====
====Rhythm abnormalities====
Conduction abnormalities are also associated with ''T. cruzi''. At the base of these conduction abnormalities is a depopulation of parasympathetic neuronal endings on the heart. Without proper parasympathetic innervations, one could expect to find not only [[chronotropic]] but also [[Inotrope|inotropic]] abnormalities. It is true that all inflammatory and non-inflammatory heart disease may display forms of parasympathetic denervation; this denervation presents in a descriptive fashion in Chagas’ disease. It has also been indicated that the loss of parasympathetic innervations can lead to sudden death due to a severe cardiac failure that occurs during the acute stage of infection.<ref>{{cite journal |doi=10.1016/S0167-5273(96)02878-1 |title=Sudden and unexpected death in clinically 'silent' Chagas' disease. A hypothesis |year=1997 |last1=Baroldi |first1=Giorgio |last2=Oliveira |first2=Samuel J.M |last3=Silver |first3=Malcolm D |journal=International Journal of Cardiology |volume=58 |issue=3 |pages=263–8 |pmid=9076552}}</ref>
Conduction abnormalities are also associated with ''T. cruzi''. At the base of these conduction abnormalities is a depopulation of parasympathetic neuronal endings on the heart. Without proper parasympathetic innervations, one could expect to find not only [[chronotropic]] but also [[Inotrope|inotropic]] abnormalities. It is true that all inflammatory and non-inflammatory heart disease may display forms of parasympathetic denervation; this denervation presents in a descriptive fashion in Chagas’ disease. It has also been indicated that the loss of parasympathetic innervations can lead to sudden death due to a severe cardiac failure that occurs during the acute stage of infection.<ref>{{cite journal |doi=10.1016/S0167-5273(96)02878-1 |title=Sudden and unexpected death in clinically 'silent' Chagas' disease. A hypothesis |year=1997 |last1=Baroldi |first1=Giorgio |last2=Oliveira |first2=Samuel J.M |last3=Silver |first3=Malcolm D |journal=International Journal of Cardiology |volume=58 |issue=3 |pages=263–8 |pmid=9076552}}</ref>


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Villous plaque is characterized by exophytic [[epicardial]] thickening, meaning that the growth occurs at the border of the epicardium and not the center of mass. Unlike milk spots and chagasic rosary, inflammatory cells and vasculature are present in villous plaque. Since villous plaque contains inflammatory cells it is reasonable to suspect that these lesions are more recently formed than milk spots or chagasic rosary.<ref>{{cite journal |doi=10.1590/S0066-782X2007000400022 |title=Lesões epicárdicas na cardiopatia chagásica são reflexo de processo inflamatório |trans-title=Epicardial lesions in Chagas' heart disease reflect an inflammatory process |language=pt |year=2007 |last1=Benvenuti |first1=Luiz Alberto |last2=Gutierrez |first2=Paulo Sampaio |journal=Arquivos Brasileiros de Cardiologia |volume=88 |issue=4 |pages=496–8 |pmid=17546284|doi-access=free }}</ref>
Villous plaque is characterized by exophytic [[epicardial]] thickening, meaning that the growth occurs at the border of the epicardium and not the center of mass. Unlike milk spots and chagasic rosary, inflammatory cells and vasculature are present in villous plaque. Since villous plaque contains inflammatory cells it is reasonable to suspect that these lesions are more recently formed than milk spots or chagasic rosary.<ref>{{cite journal |doi=10.1590/S0066-782X2007000400022 |title=Lesões epicárdicas na cardiopatia chagásica são reflexo de processo inflamatório |trans-title=Epicardial lesions in Chagas' heart disease reflect an inflammatory process |language=pt |year=2007 |last1=Benvenuti |first1=Luiz Alberto |last2=Gutierrez |first2=Paulo Sampaio |journal=Arquivos Brasileiros de Cardiologia |volume=88 |issue=4 |pages=496–8 |pmid=17546284|doi-access=free }}</ref>


==Epidemiology==
== Motility ==
When mammalian cells are present, trypomastigotes move in a sub diffusive fashion in short periods of time, but under control conditions their motion is diffusive.


Parasites increase their mean speed; they explore smaller areas at short time scales and show a preference to be located nearby cells’ periphery. The extent of these changes depends on the cell type. Therefore, ''T. cruzi'' trypomastigotes can sense mammalian cells and modify their motility patterns to prepare themselves for infection.<ref name=":0" />

=== Parasite reorientation ===
Epimastigotes, which are the culture forms of ''T. cruzi'', swim in the direction of their flagellum, due to tip-to-base symmetrical flagellar beats, that are interrupted by base-to-tip highly asymmetric beats. Switching between both beating modes facilitates parasite reorientation, allowing many movements and trajectories. Epimastigote motility is characterized by alternation of quasi-rectilinear and restricted and complex paths.<ref name=":0" />

== Invasion efficiency ==
The invasion efficiency is positively correlated with the average parasite mean speed, and negatively correlated with the mean square displacement (MSD). Therefore, the motility modifications undergone by the parasites in the presence of mammalian cells may be functionally related to the cell invasion process.

Moreover, different parasite strains infect different tissues with a variable invasion efficiency, due to the high genetic and phenotypic variability found among ''T. cruzi'' strains. ''T. cruzi'' trypomastigotes are capable of sensing mammalian cells to a different degree, depending on the cell type, and can modify their motility patterns to increase their invasion efficiency.<ref name=":0" />

== Virulence chemistry ==
''T. cruzi'' does not produce prostaglandins itself. Instead Pinge-Filho et al. 1999 finds that the parasite induces [[mouse|mice]] to overproduce [[2-series prostaglandin]]s themselves.<ref name="Lieb-2004">{{cite journal | last=Lieb | first=Julian | title=The immunostimulating and antimicrobial properties of lithium and antidepressants | journal=[[Journal of Infection]] | publisher=[[British Infection Association]] ([[Elsevier]]) | volume=49 | issue=2 | year=2004 | issn=0163-4453 | doi=10.1016/j.jinf.2004.03.006 | pages=88–93| pmid=15236914 }}</ref> These PG{{sub|2}}s are [[immunosuppressant|immunosuppressive]] and so aid in [[immune evasion]].<ref name="Lieb-2004" />

[[Imipramine]]s are [[trypanocidal]].<ref name="Lieb-2004" /> Doyle & Weinbach 1989 find imipramine and various of its derivatives {{endash}} [[3-Chlorimipramine]], [[2-Nitroimipramine]], and [[2-Nitrodesmethylimipramine]] {{endash}} are trypanocidal ''in vitro''.<ref name="Lieb-2004" /> They find 2-Nitrodesmethylimipramine is the most effective among them.<ref name="Lieb-2004" />

==Epidemiology==
{{Main|Chagas disease#Epidemiology}}
''T. cruzi'' transmission has been documented in the Southwestern U.S., and warming trends may allow vector species to move north. U.S. domestic and wild animals are reservoirs for ''T. cruzi''. Triatomine species in the southern U.S. have taken human blood meals, but because triatomines do not favor typical U.S. housing, risk to the U.S. population is very low.<ref>{{cite journal |last1=Stevens |first1=Lori |last2=Dorn |first2=Patricia L. |last3=Hobson |first3=Julia |last4=de la Rua |first4=Nicholas M. |last5=Lucero |first5=David E. |last6=Klotz |first6=John H. |last7=Schmidt |first7=Justin O. |last8=Klotz |first8=Stephen A. |title=Vector Blood Meals and Chagas Disease Transmission Potential, United States |journal=Emerging Infectious Diseases |date=2012 |volume=18 |issue=4 |pages=646–649 |doi=10.3201/eid1804.111396 |pmid=22469536 |pmc=3309679 }}</ref>
''T. cruzi'' transmission has been documented in the Southwestern U.S., and warming trends may allow vector species to move north. U.S. domestic and wild animals are reservoirs for ''T. cruzi''. Triatomine species in the southern U.S. have taken human blood meals, but because triatomines do not favor typical U.S. housing, risk to the U.S. population is very low.<ref>{{cite journal |last1=Stevens |first1=Lori |last2=Dorn |first2=Patricia L. |last3=Hobson |first3=Julia |last4=de la Rua |first4=Nicholas M. |last5=Lucero |first5=David E. |last6=Klotz |first6=John H. |last7=Schmidt |first7=Justin O. |last8=Klotz |first8=Stephen A. |title=Vector Blood Meals and Chagas Disease Transmission Potential, United States |journal=Emerging Infectious Diseases |date=2012 |volume=18 |issue=4 |pages=646–649 |doi=10.3201/eid1804.111396 |pmid=22469536 |pmc=3309679 }}</ref>


Chagas' disease's geographical occurrence happens worldwide but high-risk individuals include those who don't have access to proper housing. Its reservoir is in wild animals but its vector is a [[kissing bug]]. This is a contagious disease and can be transmitted through a number of ways: congenital transmission, blood transfusion, organ transplantation, consumption of uncooked food that has been contaminated with feces from infected bugs, and accidental laboratory exposure. {{cn|date=May 2021}}
Chagas' disease's geographical occurrence happens worldwide but high-risk individuals include those who don't have access to proper housing. Its reservoir is in wild animals but its vector is a [[kissing bug]]. This is a contagious disease and can be transmitted through a number of ways: congenital transmission, blood transfusion, organ transplantation, consumption of uncooked food that has been contaminated with feces from infected bugs, and accidental laboratory exposure. {{citation needed|date=May 2021}}


Over 130 species can transmit this parasite<ref name=Monteiro2018>{{cite book |doi=10.1016/bs.apar.2017.12.002 |chapter=Evolution, Systematics, and Biogeography of the Triatominae, Vectors of Chagas Disease |title=Advances in Parasitology |year=2018 |last1=Monteiro |first1=Fernando Araujo |last2=Weirauch |first2=Christiane |last3=Felix |first3=Márcio |last4=Lazoski |first4=Cristiano |last5=Abad-Franch |first5=Fernando |volume=99 |pages=265–344 |pmid=29530308 |isbn=978-0-12-815192-1 }}</ref>
Over 130 species can transmit this parasite<ref name=Monteiro2018>{{cite book |doi=10.1016/bs.apar.2017.12.002 |chapter=Evolution, Systematics, and Biogeography of the Triatominae, Vectors of Chagas Disease |title=Advances in Parasitology |year=2018 |last1=Monteiro |first1=Fernando Araujo |last2=Weirauch |first2=Christiane |last3=Felix |first3=Márcio |last4=Lazoski |first4=Cristiano |last5=Abad-Franch |first5=Fernando |volume=99 |pages=265–344 |pmid=29530308 |isbn=978-0-12-815192-1 }}</ref>


Six taxonomic subunits are recognised.<ref>{{cite journal |last1=Reis-Cunha |first1=João Luís |last2=Baptista |first2=Rodrigo P. |last3=Rodrigues-Luiz |first3=Gabriela F. |last4=Coqueiro-dos-Santos |first4=Anderson |last5=Valdivia |first5=Hugo O. |last6=de Almeida |first6=Laila Viana |last7=Cardoso |first7=Mariana Santos |last8=D’Ávila |first8=Daniella Alchaar |last9=Dias |first9=Fernando Hugo Cunha |last10=Fujiwara |first10=Ricardo Toshio |last11=Galvão |first11=Lúcia M. C. |last12=Chiari |first12=Egler |last13=Cerqueira |first13=Gustavo Coutinho |last14=Bartholomeu |first14=Daniella C. |title=Whole genome sequencing of Trypanosoma cruzi field isolates reveals extensive genomic variability and complex aneuploidy patterns within TcII DTU |journal=BMC Genomics |date=13 November 2018 |volume=19 |issue=1 |pages=816 |doi=10.1186/s12864-018-5198-4 |pmid=30424726 |pmc=6234542 }}</ref>
Six taxonomic subunits are recognised.<ref>{{cite journal |last1=Reis-Cunha |first1=João Luís |last2=Baptista |first2=Rodrigo P. |last3=Rodrigues-Luiz |first3=Gabriela F. |last4=Coqueiro-dos-Santos |first4=Anderson |last5=Valdivia |first5=Hugo O. |last6=de Almeida |first6=Laila Viana |last7=Cardoso |first7=Mariana Santos |last8=D’Ávila |first8=Daniella Alchaar |last9=Dias |first9=Fernando Hugo Cunha |last10=Fujiwara |first10=Ricardo Toshio |last11=Galvão |first11=Lúcia M. C. |last12=Chiari |first12=Egler |last13=Cerqueira |first13=Gustavo Coutinho |last14=Bartholomeu |first14=Daniella C. |title=Whole genome sequencing of Trypanosoma cruzi field isolates reveals extensive genomic variability and complex aneuploidy patterns within TcII DTU |journal=BMC Genomics |date=13 November 2018 |volume=19 |issue=1 |pages=816 |doi=10.1186/s12864-018-5198-4 |pmid=30424726 |pmc=6234542 |doi-access=free }}</ref>


==Clinical==
==Clinical==
The incubation period is five to fourteen days after a host comes in contact with feces. Chagas disease undergoes two phases, which are the acute and the chronic phase. The acute phase can last from two weeks to two months but can go unnoticed because symptoms are minor and short-lived. Symptoms of the acute phase include swelling, fever, fatigue, and diarrhea. The chronic phase causes digestive problems, constipation, heart failure, and pain in the abdomen. {{cn|date=May 2021}}
The incubation period is five to fourteen days after a host comes in contact with feces. Chagas disease undergoes two phases, which are the acute and the chronic phase. The acute phase can last from two weeks to two months but can go unnoticed because symptoms are minor and short-lived. Symptoms of the acute phase include swelling, fever, fatigue, and diarrhea. The chronic phase causes digestive problems, constipation, heart failure, and pain in the abdomen. {{citation needed|date=May 2021}}


Diagnostic methods include microscopic examination, serology, or the isolation of the parasite by inoculating blood into a guinea pig, mouse, or rat.
Diagnostic methods include microscopic examination, serology, or the isolation of the parasite by inoculating blood into a guinea pig, mouse, or rat.{{citation needed|date=August 2022}}


No vaccines are available. The most used method for epidemiological management and disease prevention resides within vector control,<ref>{{Cite journal |doi = 10.1111/tmi.12620|pmid = 26458237|title = Ten years (2004–2014) of Chagas disease surveillance and vector control in Ecuador: Successes and challenges|journal = Tropical Medicine & International Health|volume = 21|issue = 1|pages = 84–92|year = 2016|last1 = Quinde-Calderón|first1 = Leonardo|last2 = Rios-Quituizaca|first2 = Paulina|last3 = Solorzano|first3 = Luis|last4 = Dumonteil|first4 = Eric|url = http://www.dspace.uce.edu.ec/bitstream/25000/5241/1/Ten%20years%20of%20Chagas%20disease%20surveillance%20and%20vector%20control%20in%20Ecuador%20successes%20and%20challenges.pdf}}</ref> mainly by the use of insecticides and taking preventative measures such as applying bug repellent on the skin, wearing protective clothing, and staying in higher quality hotels when traveling. Investing in quality housing would be ideal to decrease risk of contracting this disease. Consider installing plaster walls or new flooring to decrease the crevices that bugs can hide in.<ref>{{Cite web|url=https://www.cdc.gov/ |title=CDC Works 24/7 |publisher=Centers for Disease Control and Prevention|access-date=2016-04-16}}</ref>{{failed verification|date=September 2019}}
No vaccines are available. The most used method for epidemiological management and disease prevention resides within vector control,<ref>{{Cite journal |doi = 10.1111/tmi.12620|pmid = 26458237|title = Ten years (2004–2014) of Chagas disease surveillance and vector control in Ecuador: Successes and challenges|journal = Tropical Medicine & International Health|volume = 21|issue = 1|pages = 84–92|year = 2016|last1 = Quinde-Calderón|first1 = Leonardo|last2 = Rios-Quituizaca|first2 = Paulina|last3 = Solorzano|first3 = Luis|last4 = Dumonteil|first4 = Eric|s2cid = 25754153|url = http://www.dspace.uce.edu.ec/bitstream/25000/5241/1/Ten%20years%20of%20Chagas%20disease%20surveillance%20and%20vector%20control%20in%20Ecuador%20successes%20and%20challenges.pdf}}</ref> mainly by the use of insecticides and taking preventative measures such as applying bug repellent on the skin, wearing protective clothing, and staying in higher quality hotels when traveling. Investing in quality housing would be ideal to decrease risk of contracting this disease.<ref>{{Cite web|url=https://www.cdc.gov/ |title=CDC Works 24/7 |publisher=Centers for Disease Control and Prevention|access-date=2016-04-16}}</ref>


==Genetic exchange==
==Genetic exchange==


Genetic exchange has been identified among field populations of ''T. cruzi''.<ref name="pmid26188331">{{cite journal |vauthors=Messenger LA, Miles MA |title=Evidence and importance of genetic exchange among field populations of Trypanosoma cruzi |journal=Acta Trop. |volume=151 |pages=150–5 |year=2015 |pmid=26188331 |pmc=4644990 |doi=10.1016/j.actatropica.2015.05.007 }}</ref> This process appears to involve [[genetic recombination]] as well as a [[meiosis|meiotic mechanism]]. Despite the capability for [[sexual reproduction]], natural populations of ''T. cruzi'' exhibit clonal population structures. It appears that frequent sexual reproduction events occur primarily between close relatives resulting in an apparent clonal population structure.<ref>{{cite journal |last1=Berry |first1=Alexander S. F. |last2=Salazar-Sánchez |first2=Renzo |last3=Castillo-Neyra |first3=Ricardo |last4=Borrini-Mayorí |first4=Katty |last5=Chipana-Ramos |first5=Claudia |last6=Vargas-Maquera |first6=Melina |last7=Ancca-Juarez |first7=Jenny |last8=Náquira-Velarde |first8=César |last9=Levy |first9=Michael Z. |last10=Brisson |first10=Dustin |last11=Bartholomeu |first11=Daniella Castanheira |title=Sexual reproduction in a natural Trypanosoma cruzi population |journal=PLOS Neglected Tropical Diseases |date=20 May 2019 |volume=13 |issue=5 |pages=e0007392 |doi=10.1371/journal.pntd.0007392 |pmid=31107905 |pmc=6544315 }}</ref>
Genetic exchange has been identified among field populations of ''T. cruzi''.<ref name="pmid26188331">{{cite journal |vauthors=Messenger LA, Miles MA |title=Evidence and importance of genetic exchange among field populations of Trypanosoma cruzi |journal=Acta Trop. |volume=151 |pages=150–5 |year=2015 |pmid=26188331 |pmc=4644990 |doi=10.1016/j.actatropica.2015.05.007 }}</ref> This process appears to involve [[genetic recombination]] as well as a [[meiosis|meiotic mechanism]]. Despite the capability for [[sexual reproduction]], natural populations of ''T. cruzi'' exhibit clonal population structures. It appears that frequent sexual reproduction events occur primarily between close relatives resulting in an apparent clonal population structure.<ref>{{cite journal |last1=Berry |first1=Alexander S. F. |last2=Salazar-Sánchez |first2=Renzo |last3=Castillo-Neyra |first3=Ricardo |last4=Borrini-Mayorí |first4=Katty |last5=Chipana-Ramos |first5=Claudia |last6=Vargas-Maquera |first6=Melina |last7=Ancca-Juarez |first7=Jenny |last8=Náquira-Velarde |first8=César |last9=Levy |first9=Michael Z. |last10=Brisson |first10=Dustin |last11=Bartholomeu |first11=Daniella Castanheira |title=Sexual reproduction in a natural Trypanosoma cruzi population |journal=PLOS Neglected Tropical Diseases |date=20 May 2019 |volume=13 |issue=5 |pages=e0007392 |doi=10.1371/journal.pntd.0007392 |pmid=31107905 |pmc=6544315 |doi-access=free }}</ref>


== See also ==
== See also ==
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{{Excavata diseases}}
{{Excavata diseases}}
{{Taxonbar|from=Q150162}}
{{Taxonbar|from=Q150162}}
{{Authority control}}


[[Category:Parasitic excavates]]
[[Category:Parasitic excavates]]
[[Category:Parasites of mammals]]
[[Category:Parasites of mammals]]
[[Category:Trypanosomatida]]
[[Category:Trypanosomatida]]
[[Category:Species described in 1909]]
[[Category:Protists described in 1909]]
[[Category:Chagas disease]]
[[Category:Chagas disease]]
[[Category:Euglenozoa species]]

Latest revision as of 18:01, 12 April 2024

Trypanosoma cruzi
Trypanosoma cruzi in human blood Giemsa stain. They are typically seen as a C-shape and have a more pronounced kinetoplast compared to other species.
Scientific classification Edit this classification
Domain: Eukaryota
Phylum: Euglenozoa
Class: Kinetoplastea
Order: Trypanosomatida
Family: Trypanosomatidae
Genus: Trypanosoma
Species:
T. cruzi
Binomial name
Trypanosoma cruzi

Trypanosoma cruzi is a species of parasitic euglenoids. Among the protozoa, the trypanosomes characteristically bore tissue in another organism and feed on blood (primarily) and also lymph. This behaviour causes disease or the likelihood of disease that varies with the organism: Chagas disease in humans, dourine and surra in horses, and a brucellosis-like disease in cattle. Parasites need a host body and the haematophagous insect triatomine (descriptions "assassin bug", "cone-nose bug", and "kissing bug") is the major vector in accord with a mechanism of infection. The triatomine likes the nests of vertebrate animals for shelter, where it bites and sucks blood for food. Individual triatomines infected with protozoa from other contact with animals transmit trypanosomes when the triatomine deposits its faeces on the host's skin surface and then bites. Penetration of the infected faeces is further facilitated by the scratching of the bite area by the human or animal host.

Etymology

[edit]

The specific name "cruzi" is an honor to Brazilian scientist Oswaldo Cruz, who taught discoverer Carlos Chagas.[4]

Life cycle

[edit]

The Trypanosoma cruzi life cycle starts in an animal reservoir, usually mammals, wild or domestic, including humans. A triatomine bug serves as the vector. While taking a blood meal, it ingests T. cruzi. In the triatomine bug (the principal species of which in terms of parasite transmission to humans being Triatoma infestans) the parasite goes into the epimastigote stage, making it possible to reproduce. After reproducing through binary fission, the epimastigotes move onto the rectal cell wall, where they become infectious. Infectious T. cruzi are called metacyclic trypomastigotes. When the triatomine bug subsequently takes a blood meal from a host, it defecates—its waste containing T. cruzi propagation stages. As a result, Trumper and Gorla 1991 find transmission success centers around the triatomine's defecation behaviors.[5][6][7] Alternatively, in nature and in most recent cases of epidemiological outbreaks, infection occurs through the oral ingestion of parasites (mainly through a lack of infected food disinfection in the case of human infection). [8][9] The trypomastigotes are in the feces and are capable of swimming into the host's cells using flagella, a characteristic swimming tail dominant in the Euglenoid class of protists.[10] The trypomastigotes enter the host through the bite wound or by crossing mucous membranes. The host cells contain macromolecules such as laminin, thrombospondin, heparin sulphate, and fibronectin that cover their surface.[11] These macromolecules are essential for adhesion between parasite and host and for the process of host invasion by the parasite. The trypomastigotes must cross a network of proteins that line the exterior of the host cells in order to make contact and invade the host cells. The molecules and proteins on the cytoskeleton of the cell also bind to the surface of the parasite and initiate host invasion.[11]

Pathophysiology

[edit]

Trypanosomiasis in humans progresses with the development of the trypanosome into a trypomastigote in the blood and into an amastigote in tissues. As the infection progresses, the number of infected cells increases, as well as the number of amastigotes per infected cell (APC). If the average of APC is one or close to one, the infection has just begun. A higher APC means that amastigotes have started to replicate.[12]

The acute form of trypanosomiasis is usually unnoticed, although it may manifest itself as a localized swelling at the site of entry. In this form appears elevated parasitism, myocarditis, and changes in the myocardial gene expression. The chronic form may develop 30 to 40 years after infection and affect internal organs (e.g., the heart, the oesophagus, the colon, and the peripheral nervous system). Affected people may die from heart failure and severe heart lesions.[13]

Acute cases are treated with nifurtimox and benznidazole, but no effective therapy for chronic cases is currently known.[citation needed]

Cardiac manifestations

[edit]

Researchers of Chagas’ disease have demonstrated several processes that occur with all cardiomyopathies. The first event is an inflammatory response. Following inflammation, cellular damage occurs. Finally, in the body's attempt to recover from the cellular damage, fibrosis begins in the cardiac tissue.[14]

Another cardiomyopathy found in nearly all cases of chronic Chagas’ disease is thromboembolic syndrome. Thromboembolism describes thrombosis, the formation of a clot, and its main complication is embolism, the carrying of a clot to a distal section of a vessel and causing blockage there. This occurrence contributes to the death of a patient by four means: arrhythmias, stasis secondary to cardiac dilation, mural endocarditis, and cardiac fibrosis. These thrombi also affect other organs such as the brain, spleen and kidney.[15]

Myocardial biochemical response

[edit]

Subcellular findings in murine studies with induced T. cruzi infection revealed that the chronic state is associated with the persistent elevation of phosphorylated (activated) extracellular-signal-regulated kinase (ERK), AP-1, and NF-κB. Also, the mitotic regulator for G1 progression, cyclin D1 was found to be activated. Although there was no increase in any isoform of ERK, there was an increased concentration of phosphorylated ERK in mice infected with T. cruzi. It was found that within seven days the concentration of AP-1 was significantly higher in T. cruzi–infected mice when compared to the control. Elevated levels of NF-κB have also been found in myocardial tissue, with the highest concentrations being found in the vasculature. It was indicated through Western blot that cyclin D1 was upregulated from day 1 to day 60 post-infection. It was also indicated through immunohistochemical analysis that the areas that produced the most cyclin D1 were the vasculature and interstitial regions of the heart.[16]

Rhythm abnormalities

[edit]

Conduction abnormalities are also associated with T. cruzi. At the base of these conduction abnormalities is a depopulation of parasympathetic neuronal endings on the heart. Without proper parasympathetic innervations, one could expect to find not only chronotropic but also inotropic abnormalities. It is true that all inflammatory and non-inflammatory heart disease may display forms of parasympathetic denervation; this denervation presents in a descriptive fashion in Chagas’ disease. It has also been indicated that the loss of parasympathetic innervations can lead to sudden death due to a severe cardiac failure that occurs during the acute stage of infection.[17]

Another conduction abnormality presented with chronic Chagas’ disease is a change in ventricular repolarization, which is represented on an electrocardiogram as the T-wave. This change in repolarization inhibits the heart from relaxing and properly entering diastole. Changes in the ventricular repolarization in Chagas’ disease are likely due to myocardial ischemia. This ischemia can also lead to fibrillation. This sign is usually observed in chronic Chagas’ disease and is considered a minor electromyocardiopathy.[18]

Epicardial lesions

[edit]

Villous plaque is characterized by exophytic epicardial thickening, meaning that the growth occurs at the border of the epicardium and not the center of mass. Unlike milk spots and chagasic rosary, inflammatory cells and vasculature are present in villous plaque. Since villous plaque contains inflammatory cells it is reasonable to suspect that these lesions are more recently formed than milk spots or chagasic rosary.[19]

Motility

[edit]

When mammalian cells are present, trypomastigotes move in a sub diffusive fashion in short periods of time, but under control conditions their motion is diffusive.

Parasites increase their mean speed; they explore smaller areas at short time scales and show a preference to be located nearby cells’ periphery. The extent of these changes depends on the cell type. Therefore, T. cruzi trypomastigotes can sense mammalian cells and modify their motility patterns to prepare themselves for infection.[12]

Parasite reorientation

[edit]

Epimastigotes, which are the culture forms of T. cruzi, swim in the direction of their flagellum, due to tip-to-base symmetrical flagellar beats, that are interrupted by base-to-tip highly asymmetric beats. Switching between both beating modes facilitates parasite reorientation, allowing many movements and trajectories. Epimastigote motility is characterized by alternation of quasi-rectilinear and restricted and complex paths.[12]

Invasion efficiency

[edit]

The invasion efficiency is positively correlated with the average parasite mean speed, and negatively correlated with the mean square displacement (MSD). Therefore, the motility modifications undergone by the parasites in the presence of mammalian cells may be functionally related to the cell invasion process.

Moreover, different parasite strains infect different tissues with a variable invasion efficiency, due to the high genetic and phenotypic variability found among T. cruzi strains. T. cruzi trypomastigotes are capable of sensing mammalian cells to a different degree, depending on the cell type, and can modify their motility patterns to increase their invasion efficiency.[12]

Virulence chemistry

[edit]

T. cruzi does not produce prostaglandins itself. Instead Pinge-Filho et al. 1999 finds that the parasite induces mice to overproduce 2-series prostaglandins themselves.[20] These PG2s are immunosuppressive and so aid in immune evasion.[20]

Imipramines are trypanocidal.[20] Doyle & Weinbach 1989 find imipramine and various of its derivatives – 3-Chlorimipramine, 2-Nitroimipramine, and 2-Nitrodesmethylimipramine – are trypanocidal in vitro.[20] They find 2-Nitrodesmethylimipramine is the most effective among them.[20]

Epidemiology

[edit]
Main article: Chagas disease § Epidemiology

T. cruzi transmission has been documented in the Southwestern U.S., and warming trends may allow vector species to move north. U.S. domestic and wild animals are reservoirs for T. cruzi. Triatomine species in the southern U.S. have taken human blood meals, but because triatomines do not favor typical U.S. housing, risk to the U.S. population is very low.[21]

Chagas' disease's geographical occurrence happens worldwide but high-risk individuals include those who don't have access to proper housing. Its reservoir is in wild animals but its vector is a kissing bug. This is a contagious disease and can be transmitted through a number of ways: congenital transmission, blood transfusion, organ transplantation, consumption of uncooked food that has been contaminated with feces from infected bugs, and accidental laboratory exposure. [citation needed]

Over 130 species can transmit this parasite[22]

Six taxonomic subunits are recognised.[23]

Clinical

[edit]

The incubation period is five to fourteen days after a host comes in contact with feces. Chagas disease undergoes two phases, which are the acute and the chronic phase. The acute phase can last from two weeks to two months but can go unnoticed because symptoms are minor and short-lived. Symptoms of the acute phase include swelling, fever, fatigue, and diarrhea. The chronic phase causes digestive problems, constipation, heart failure, and pain in the abdomen. [citation needed]

Diagnostic methods include microscopic examination, serology, or the isolation of the parasite by inoculating blood into a guinea pig, mouse, or rat.[citation needed]

No vaccines are available. The most used method for epidemiological management and disease prevention resides within vector control,[24] mainly by the use of insecticides and taking preventative measures such as applying bug repellent on the skin, wearing protective clothing, and staying in higher quality hotels when traveling. Investing in quality housing would be ideal to decrease risk of contracting this disease.[25]

Genetic exchange

[edit]

Genetic exchange has been identified among field populations of T. cruzi.[26] This process appears to involve genetic recombination as well as a meiotic mechanism. Despite the capability for sexual reproduction, natural populations of T. cruzi exhibit clonal population structures. It appears that frequent sexual reproduction events occur primarily between close relatives resulting in an apparent clonal population structure.[27]

See also

[edit]

References

[edit]
  1. ^ Chagas, C. (1909). "Neue Trypanosomen: Vorläufige mitteilung" [New trypanosome. Preliminary communication]. Archiv für Schiffs-und Tropenhygiene (in German). 13: 120–122.
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