Transcript Chagas Testing

Chagas Testing
Icky things that can drop on you
from your thatched roof!
ABC 7-04
Chagas Disease
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Trypanosoma cruzi Endemic: Central & So.
America (related to, but distinct from, sleeping
sickness trypanosome in Africa)
Infected reduviid (kissing) bug falls from thatched
roof, defecates and inoculates skin
Clearly under-recognized cause of heart failure
Only 7 cases Tx transmission documented in
US/Canada
Screened for in Brazil and other LA countries
Chagas Symptoms
 Acute:
Uncommon- Chagoma(primary
inflammatory skin swelling),
lymphadenopathy, facial, eye swelling,
encephalitis
 Chronic- (often asymptomatic for >20
years)
 Cardiac:
Rhythm defects (RBBB), CHF
 GI: Esophageal and Colonic dysmotilitymegaesophagus and megacolon
Chagas Heart disease In US
 Hager:
NEJM (1991) 325:763
 Prentation:
Symptomatic AV block, CHF,
anginal chest pain, sudden death,
sustained ventricular tachycardia
 EKG frequently suggested coronary artery
disease. Majority had some EKG
abnormality.
 LV aneurysm 14/25, segmental akinesia
5/25 and diffuse hypkinesia 3/25.
 Angiography required to rule out coronary
disease
Chagas screening strategies
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Limited geographic or ethnic origin screening
proposed….but
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2/7 transfusion transmissions occurred in Western
Canada..donors were Mennonite Missionaries
who had spent time in S. America
Most recent transfusion transmission occurred in
Rhode Island, following implementation of a
diversity effort to increase donations among
Hispanics.
Donor Demographics
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Fastest growing minorities in Minnesota, US
are Hispanics (Note: in much of Florida and
California, they aren’t the minority!)
 Many blood centers implementing collection
programs targeting Hispanic donations
(translating/preparing Spanish language
materials & donor history)
Chagas Screening in Central
and South America
 In
many endemic areas dual EIA
strategy used to screen for Chagas
 Chagas is the leading cause of cardiac
failure in many endemic areas
 May be spread by direct innoculation,
transfusion or even congenitally.
Challenges to new testing
 Sensitivity
 Issues
and specificity of new testing
of cross-reactivity with Malaria and
Leishmaniasis
 Abbott test had 0.1% false positive repeat
reactive tests.
 No licensed confirmatory, hence no way to
reinstate donors deferred due to false
positive tests, either in clinical trials or
if/when instituted
Chagas confirmatory testing
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Various unlicensed assays available for
confirmation including line immunoassay
(LIA), Immunofluorescence, and radioactive
immunoprecipitation assay (RIPA).
 RIPA currently considered “gold standard” but
only available @ ARC-Holland lab- D. Leiby
and Dr. Kirchoff- University of Iowa
Chagas and the press
 ARC
very active in promoting need for
Chagas testing.
 Many recent lay press articles on
potential for Chagas testing.
 Several US Manufacturer’s currently
working on EIA assay development and
clinical trials planned. (Keep tuned….)