Trypanosoma cruzi: Difference between revisions
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Trypanosoma cruzi
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+ | == Background == |
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− | = ''Trypanosoma cruzi'' (Chagas disease) = |
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+ | *Causes '''Chagas disease''' (South American trypanosomiasis) |
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− | == Microbiology == |
||
+ | ===Microbiology=== |
||
− | * Protozoan parasite that causes Chagas disease (South American trypanosomiasis) |
||
+ | *Protozoan parasite |
||
− | == Life Cycle == |
||
+ | ===Epidemiology=== |
||
− | [[File:Chagas_LifeCycle_19.jpg|T. cruzi Lifecycle]] |
||
+ | *Endemic '''throughout the Americas''' from the southern half of the United States to Argentina |
||
− | == Epidemiology == |
||
+ | **Particularly in rural, impoverished areas |
||
+ | **A small number of autochthonous cases of Chagas disease in the US |
||
+ | *Reservoirs include '''armadillos''', opossums, raccoons, woodrats, some other rodents, and domestic dogs |
||
+ | *'''Triatomine''' vector species for trypanosomiasis belong to the genera ''Triatoma'', ''Rhodnius'', and ''Panstrongylus'' |
||
+ | **Bugs live in substandard dwellings (especially wood, mud, or stone houses) |
||
+ | **Vector is present from southern US to southern Argentina |
||
+ | **Transmission is via feces, either in direct contact with mucous membranes (especially conjunctivae), breaks in the skin, or contaminating the bite of the insect |
||
+ | *Can also be transmitted via '''blood transfusion''' or '''vertically''' from mother to child or via '''ingestion''' of contaminated food and drink |
||
+ | ===Pathophysiology=== |
||
− | * Endemic '''throughout the Americas''' from the southern half of the United States to Argentina |
||
− | ** Particularly in rural, impoverished areas |
||
− | ** A small number of autochthonous cases of Chagas disease in the US |
||
− | * Reservoirs include '''armadillos''', opossums, raccoons, woodrats, some other rodents, and domestic dogs |
||
− | * '''Triatomine''' vector species for trypanosomiasis belong to the genera ''Triatoma'', ''Rhodnius'', and ''Panstrongylus'' |
||
− | ** Bugs live in substandard dwellings (especially wood, mud, or stone houses) |
||
− | ** Vector is present from southern US to southern Argentina |
||
− | ** Transmission is via feces, either in direct contact with mucous membranes (especially conjunctivae), breaks in the skin, or contaminating the bite of the insect |
||
− | * Can also be transmitted via '''blood transfusion''' or '''vertically''' from mother to child or via '''ingestion''' of contaminated food and drink |
||
+ | *Infective metacyclic trypomastigotes from feces enter the skin or mucosa |
||
− | == Pathophysiology == |
||
+ | *Multiply in host cells as amastigotes, developing into trypomastigotes intracellularly and rupturing the cell, releasing more trypomastigotes |
||
+ | **Chagoma develops at site of inoculation |
||
+ | **Intracellular amastigotes visible as characteristic pseudocysts on histopathology |
||
+ | *Hematogenous spread to distant sites, especially muscles, with the cycle repeating |
||
+ | **Especially tropic for myocardium, where it causes biventricular enlargement, thinning of ventricular walls, apical aneurysms, and mural thrombi |
||
+ | *Parasitemia maintained for years |
||
+ | ==Clinical Manifestations== |
||
− | * Infective metacyclic trypomastigotes from feces enter the skin or mucosa |
||
− | * Multiply in host cells as amastigotes, developing into trypomastigotes intracellularly and rupturing the cell, releasing more trypomastigotes |
||
− | ** Chagoma develops at site of inoculation |
||
− | ** Intracellular amastigotes visible as characteristic pseudocysts on histopathology |
||
− | * Hematogenous spread to distant sites, especially muscles, with the cycle repeating |
||
− | ** Especially tropic for myocardium, where it causes biventricular enlargement, thinning of ventricular walls, apical aneurysms, and mural thrombi |
||
− | * Parasitemia maintained for years |
||
+ | ===Acute Disease=== |
||
− | == Clinical Presentation == |
||
+ | *Often asymptomatic |
||
− | === Acute disease === |
||
+ | *Incubation period of about [[Usual incubation period::1 week]] |
||
+ | *Usually mild febrile illness, sometimes with hepatosplenomegaly, rash, edema, local inflammation |
||
+ | **Incurs in 20% of infections |
||
+ | **More common in children |
||
+ | *Nodular lesions ("chagomas") may develop at site of inoculation |
||
+ | **Romaña sign if periorbital, often with ipsilateral lymphadenopathy |
||
+ | **Often 1-2 weeks after exposure |
||
+ | *Acute myocarditis, pericardial effusion, and meningoencephalitis in 1-5% |
||
+ | ===Indeterminate Phase=== |
||
− | * Often asymptomatic |
||
− | * Incubation period of about 1 week |
||
− | * Usually mild febrile illness, sometimes with hepatosplenomegaly, rash, edema, local inflammation |
||
− | ** Incurs in 20% of infections |
||
− | ** More common in children |
||
− | * Nodular lesions ("chagomas") may develop at site of inoculation |
||
− | ** Romaña sign if periorbital, often with ipsilateral lymphadenopathy |
||
− | ** Often 1-2 weeks after exposure |
||
− | * Acute myocarditis, pericardial effusion, and meningoencephalitis in 1-5% |
||
+ | *Following acute infection, may enter a latent phase |
||
− | === Indeterminate phase === |
||
+ | ===Chronic Disease=== |
||
− | * Following acute infection, may enter a latent phase |
||
+ | *Following acute infection can remain asymptomatic (indeterminate form) |
||
− | === Chronic disease === |
||
+ | *Cardiac complications in 25-30% (1.5-5% per year) |
||
+ | **Non-ischemic dilated biventricular (right more than left) cardiomyopathy with heart failure |
||
+ | **Apical aneurysms and mural thrombi |
||
+ | **Conduction defects, with heart blocks, bundle branch blocks, sinus node dysfunction, bradycardia, and ventricular arrhythmias |
||
+ | **Can cause sudden cardiac death |
||
+ | *GI involvement in 10-15% |
||
+ | **Megaesophagus, with dysphagia, odynophagia, chest pain, cough, and regurgitation |
||
+ | ***May result in aspiration and recurrent pneumonias |
||
+ | **Megacolon, with constipation and abdominal pain |
||
+ | *Meningoencephalitis |
||
+ | *Other: polyneuropathy, stroke syndrome |
||
+ | ===Immunocompromised Patients=== |
||
− | * Following acute infection can remain asymptomatic (indeterminate form) |
||
− | * Cardiac complications in 25-30% (1.5-5% per year) |
||
− | ** Non-ischemic dilated biventricular (right more than left) cardiomyopathy with heart failure |
||
− | ** Apical aneurysms and mural thrombi |
||
− | ** Conduction defects, with heart blocks, bundle branch blocks, sinus node dysfunction, bradycardia, and ventricular arrhythmias |
||
− | ** Can cause sudden cardiac death |
||
− | * GI involvement in 10-15% |
||
− | ** Megaesophagus, with dysphagia, odynophagia, chest pain, cough, and regurgitation |
||
− | *** May result in aspiration and recurrent pneumonias |
||
− | ** Megacolon, with constipation and abdominal pain |
||
− | * Meningoencephalitis |
||
− | * Other: polyneuropathy, stroke syndrome |
||
+ | *May have reactivation following immune suppression or HIV |
||
− | === Immunocompromised patients === |
||
+ | *Severe acute infection; may have skin lesions and cerebral masses/abscesses |
||
+ | *Meningoencephalitis |
||
+ | ==Diagnosis== |
||
− | * May have reactivation following immune suppression or HIV |
||
− | * Severe acute infection; may have skin lesions and cerebral masses/abscesses |
||
− | * Meningoencephalitis |
||
− | == |
+ | ===Acute Disease=== |
+ | *'''Direct microscopy''' blood film or tissue biopsy (e.g. lymph node, bone marrow, pericardial fluid, CSF) |
||
− | === Acute disease === |
||
+ | **In immunocompromised, these other samples are even more important |
||
+ | *Hemoculture is only 50% sensitive and takes several weeks |
||
+ | *Serology for IgM is useless |
||
+ | *'''PCR''' is sensitive and specific |
||
+ | *Xenodiagnosis |
||
+ | ===Indeterminate and Chronic Disease=== |
||
− | * '''Direct microscopy''' blood film or tissue biopsy (e.g. lymph node, bone marrow, pericardial fluid, CSF) |
||
− | ** In immunocompromised, these other samples are even more important |
||
− | * Hemoculture is only 50% sensitive and takes several weeks |
||
− | * Serology for IgM is useless |
||
− | * '''PCR''' is sensitive and specific |
||
− | * Xenodiagnosis |
||
+ | *No gold standard |
||
− | === Indeterminate and chronic disease === |
||
+ | *Serology for IgG is most useful |
||
+ | **Detectable after 6 to 9 months following infection |
||
+ | **Many assays (ELISA, indirect hemagglutination, chemiluminescence, and IFA) |
||
+ | *PCR (of blood) less sensitive |
||
+ | ==Management== |
||
− | * No gold standard |
||
− | * Serology for IgG is most useful |
||
− | ** Detectable after 6 to 9 months following infection |
||
− | ** Many assays (ELISA, indirect hemagglutination, chemiluminescence, and IFA) |
||
− | * PCR (of blood) less sensitive |
||
− | == |
+ | ===Acute=== |
+ | *Treatment is most useful in acute disease, congenital Chagas, and children with chronic infection up to 18 years |
||
− | === Acute === |
||
+ | **It can decrease illness severity and mortality |
||
+ | **Start ASAP before infection can become established |
||
+ | **However, treatment may not result in parasitologic cure |
||
+ | *Treatment options |
||
+ | **Nifurtimox: 90-120 day treatment course; AEs include anorexia, weight loss, neurologic symptoms |
||
+ | **Benznidazole: 60 day treatment course; AEs include hypersensitivity, GI upset, rare polyneuropathy and agranulocytosis |
||
+ | *Adverse events are common during treatment |
||
+ | ===Chronic=== |
||
− | * Treatment is most useful in acute disease, congenital Chagas, and children with chronic infection up to 18 years |
||
− | ** It can decrease illness severity and mortality |
||
− | ** Start ASAP before infection can become established |
||
− | ** However, treatment may not result in parasitologic cure |
||
− | * Treatment options |
||
− | ** Nifurtimox: 90-120 day treatment course; AEs include anorexia, weightloss, neurologic symptoms |
||
− | ** Benznidazole: 60 day treatment course; AEs include hypersensitivity, GI upset, rare polyneuropathy and agranulocytosis |
||
− | * Adverse events are common during treatment |
||
+ | *Less clear benefit to antiparasitic treatment |
||
− | === Chronic === |
||
+ | *Cardiac disease |
||
+ | **May benefit from pacemaker in patients with conduction disease |
||
+ | ***Monitor with ECG q6mo |
||
+ | **May need heart transplantation, though this can become complicated by ongoing chronic infection or recrudescence |
||
+ | *Megaesophagus: balloon dilatation or surgical management |
||
+ | *Megacolon may need surgical management |
||
+ | ==Prevention== |
||
− | * Less clear benefit to antiparasitic treatment |
||
− | * Cardiac disease |
||
− | ** May benefit from pacemaker in patients with conduction disease |
||
− | *** Monitor with ECG q6mo |
||
− | ** May need heart transplantation, though this can become complicated by ongoing chronic infection or recrudescence |
||
− | * Megaesophagus: balloon dilatation or surgical management |
||
− | * Megacolon may need surgical management |
||
+ | *Screening immigrants and then following up with regular cardiac screening, if positive |
||
− | == Prevention == |
||
+ | *Avoid sleeping in dilapidated dwellings in endemic countries, use insect repellent and bed nets |
||
+ | *Improve housing in endemic areas |
||
+ | ===Canadian Blood Services=== |
||
− | * Screening immigrants and then following up with regular cardiac screening, if positive |
||
− | * Avoid sleeping in dilapidated dwellings in endemic countries, use insect repellent and bed nets |
||
− | * Improve housing in endemic areas |
||
+ | *Samples are only tested for antibodies when increased risk is present, determined by the donor screening questions |
||
− | === Canadian Blood Services === |
||
+ | *No reported cases since screening began in 2010 |
||
+ | {{DISPLAYTITLE:''Trypanosoma cruzi''}} |
||
− | * Samples are only tested for antibodies when increased risk is present, determined by the donor screening questions |
||
+ | [[Category:Protozoa]] |
||
− | * No reported cases since screening began in 2010 |
Latest revision as of 11:43, 6 March 2023
Background
- Causes Chagas disease (South American trypanosomiasis)
Microbiology
- Protozoan parasite
Epidemiology
- Endemic throughout the Americas from the southern half of the United States to Argentina
- Particularly in rural, impoverished areas
- A small number of autochthonous cases of Chagas disease in the US
- Reservoirs include armadillos, opossums, raccoons, woodrats, some other rodents, and domestic dogs
- Triatomine vector species for trypanosomiasis belong to the genera Triatoma, Rhodnius, and Panstrongylus
- Bugs live in substandard dwellings (especially wood, mud, or stone houses)
- Vector is present from southern US to southern Argentina
- Transmission is via feces, either in direct contact with mucous membranes (especially conjunctivae), breaks in the skin, or contaminating the bite of the insect
- Can also be transmitted via blood transfusion or vertically from mother to child or via ingestion of contaminated food and drink
Pathophysiology
- Infective metacyclic trypomastigotes from feces enter the skin or mucosa
- Multiply in host cells as amastigotes, developing into trypomastigotes intracellularly and rupturing the cell, releasing more trypomastigotes
- Chagoma develops at site of inoculation
- Intracellular amastigotes visible as characteristic pseudocysts on histopathology
- Hematogenous spread to distant sites, especially muscles, with the cycle repeating
- Especially tropic for myocardium, where it causes biventricular enlargement, thinning of ventricular walls, apical aneurysms, and mural thrombi
- Parasitemia maintained for years
Clinical Manifestations
Acute Disease
- Often asymptomatic
- Incubation period of about 1 week
- Usually mild febrile illness, sometimes with hepatosplenomegaly, rash, edema, local inflammation
- Incurs in 20% of infections
- More common in children
- Nodular lesions ("chagomas") may develop at site of inoculation
- Romaña sign if periorbital, often with ipsilateral lymphadenopathy
- Often 1-2 weeks after exposure
- Acute myocarditis, pericardial effusion, and meningoencephalitis in 1-5%
Indeterminate Phase
- Following acute infection, may enter a latent phase
Chronic Disease
- Following acute infection can remain asymptomatic (indeterminate form)
- Cardiac complications in 25-30% (1.5-5% per year)
- Non-ischemic dilated biventricular (right more than left) cardiomyopathy with heart failure
- Apical aneurysms and mural thrombi
- Conduction defects, with heart blocks, bundle branch blocks, sinus node dysfunction, bradycardia, and ventricular arrhythmias
- Can cause sudden cardiac death
- GI involvement in 10-15%
- Megaesophagus, with dysphagia, odynophagia, chest pain, cough, and regurgitation
- May result in aspiration and recurrent pneumonias
- Megacolon, with constipation and abdominal pain
- Megaesophagus, with dysphagia, odynophagia, chest pain, cough, and regurgitation
- Meningoencephalitis
- Other: polyneuropathy, stroke syndrome
Immunocompromised Patients
- May have reactivation following immune suppression or HIV
- Severe acute infection; may have skin lesions and cerebral masses/abscesses
- Meningoencephalitis
Diagnosis
Acute Disease
- Direct microscopy blood film or tissue biopsy (e.g. lymph node, bone marrow, pericardial fluid, CSF)
- In immunocompromised, these other samples are even more important
- Hemoculture is only 50% sensitive and takes several weeks
- Serology for IgM is useless
- PCR is sensitive and specific
- Xenodiagnosis
Indeterminate and Chronic Disease
- No gold standard
- Serology for IgG is most useful
- Detectable after 6 to 9 months following infection
- Many assays (ELISA, indirect hemagglutination, chemiluminescence, and IFA)
- PCR (of blood) less sensitive
Management
Acute
- Treatment is most useful in acute disease, congenital Chagas, and children with chronic infection up to 18 years
- It can decrease illness severity and mortality
- Start ASAP before infection can become established
- However, treatment may not result in parasitologic cure
- Treatment options
- Nifurtimox: 90-120 day treatment course; AEs include anorexia, weight loss, neurologic symptoms
- Benznidazole: 60 day treatment course; AEs include hypersensitivity, GI upset, rare polyneuropathy and agranulocytosis
- Adverse events are common during treatment
Chronic
- Less clear benefit to antiparasitic treatment
- Cardiac disease
- May benefit from pacemaker in patients with conduction disease
- Monitor with ECG q6mo
- May need heart transplantation, though this can become complicated by ongoing chronic infection or recrudescence
- May benefit from pacemaker in patients with conduction disease
- Megaesophagus: balloon dilatation or surgical management
- Megacolon may need surgical management
Prevention
- Screening immigrants and then following up with regular cardiac screening, if positive
- Avoid sleeping in dilapidated dwellings in endemic countries, use insect repellent and bed nets
- Improve housing in endemic areas
Canadian Blood Services
- Samples are only tested for antibodies when increased risk is present, determined by the donor screening questions
- No reported cases since screening began in 2010