Immunological diagnostic
methods for
Trypanosoma cruzi depend specifically on the presence of
antibodies and parasitological
methods lack
sensitivity during the chronic and “indeterminate” stages of the
disease. This study performed a serological
survey of 1,033 subjects from 52
rural communities in 12 of the 18 municipalities in the
state of Querétaro,
Mexico. We detected anti-T. cruzi
antibodies using the following tests indirect haemagglutination assay (IHA),
indirect immunofluorescence assay (IFA),
ELISA and recombinant
ELISA (rELISA). We also performed
Western blot (WB)
analysis using
iron superoxide dismutase (FeSOD), a detoxifying
enzyme excreted by the
parasite, as the
antigen. Positive test results were distributed as follows
ELISA 8%, rELISA 6.2%, IFA and IHA 5.4% in both cases and FeSOD 8%. A
comparative study of the five tests was undertaken.
Sensitivity levels,
specificity, positive and
negative predictive values, concordance percentage and kappa index were considered. Living with
animals, trips to other
communities,
gender, age, type of
housing and
symptomatology at the
time of the
survey were statistically analysed using SPSS
software v.11.5.
Detection of the FeSOD
enzyme that was secreted by the
parasite and used as an antigenic fraction in WBs showed a 100% correlation with traditional
ELISA tests.