RESUMO
A survey of human Trypanosoma cruzi infection in four rural communities of two Venezuelan states with different epidemiological Chagas' disease situations was carried out using the Dot-ELISA and conventional serology. In the two hamlets of Zulia state, no seropositives were found in the under-15 age group whereas seropositivity in the over-15 group was 15.6%. In Cojedes state, the two hamlets studied exhibited a seropositivity of 8.9% in the under-15 group and 51.6% in the over-15 group. Upon comparison with conventional methods, Dot-ELISA evidenced high co-positivity, co-negativity and efficiency indexes. In the samples taken from Zulia, the predictive value of the test was 66% and 60% for cytoplasmatic and integral antigens, respectively; with the Cojedes samples, 100% and 95%. The results suggest that Dot-ELISA could be a practical alternative for seroepidemiological Chagas' disease studies in underdeveloped regions.
Assuntos
Doença de Chagas/diagnóstico , Immunoblotting , Adolescente , Adulto , Doença de Chagas/epidemiologia , Criança , Pré-Escolar , Imunofluorescência , Testes de Hemaglutinação , Humanos , Lactente , Valor Preditivo dos Testes , Saúde da População Rural , Venezuela/epidemiologiaRESUMO
Using the Dot-ELISA technique, two antigenic preparations of Trypanosoma cruzi epimastigote forms have been compared for the diagnosis of Chagas' disease: (1) The cytoplasmic fraction (cytoplasmic antigen) and (2) whole formalin fixed epimastigotes (integral antigen). There was been used sera from 95 chagasic patients with chronic cardiomyopathy, positive conventional serology and either positive or negative xenodiagnosis; 74 subjects with negative conventional serology, and either clinically normal or presenting cardiomyopathy; 74 patients with different diseases including syphilis, toxoplasmosis, leishmaniasis or autoantibodies such as rheumatoid factor and antinuclear antibodies. By defining the diagnostic titers (cut off): 1:512 for cytoplasmic antigen and 1:128 for the integral antigen, a sensitivity of 100% has been obtained with both antigenic preparations, being the specificity of 96% for the former and 100% for the latter when leishmaniasis sera were not included. A comparative study with conventional serology was carried out using 147 sera from a Laboratory of Chagas' diagnosis; Dot-ELISA with cytoplasmic antigen showed co-positivity index of 1.0, co-negativity 0.989 and efficiency of 0.993, and Dot-ELISA with integral antigen 1.0, 0.979 and 0.986 respectively. According to this evaluation, Dot-ELISA using whole formalin fixed epimastigotes might be a practical alternative for the serological diagnosis of Chagas' disease.
