Predictive role of polymerase chain reaction in the early diagnosis of congenital Trypanosoma cruzi infection.

The efficacy of specific chemotherapy in congenital Chagas disease before the first year of life ranges between 90 and 100%. Between this age and 15 years of age, the efficacy decreases to around 60%. Therefore, early infection detection is a priority in vertical transmission. The aim of this work was to assess whether polymerase chain reaction (PCR) plays a predictive role in the diagnosis of congenital Chagas disease as compared to conventional parasitological and serological methods. To this end, we studied a total of 468 children born to Trypanosoma cruzi seroreactive mothers came from Argentina, Bolivia and Paraguay, who lived in the city of Buenos Aires and suburban areas (Argentina), a non-endemic area of this country. These children were assessed by PCR from 2004 to 2009 with the specific primers Tcz1 and Tcz2, and 121 and 122. PCR allowed detecting 49 T. cruzi-positive children. Eight of these 49 children were excluded from the analysis: six because they did not complete follow-up and two because the first control was performed after 12 months of age. Parasitological methods allowed detecting 25 positive children, 7 of whom had been earlier diagnosed by PCR (1.53±2.00 vs. 6.71±1.46 months; p=0.0002). Serological methods allowed detecting 16 positive children, 12 of whom had been earlier diagnosed by PCR (1.46±1.48 vs. 11.77±4.40 months; p<0.0001). None of the children negative by PCR was positive by serological or parasitological methods. This study shows that PCR allows early diagnosis in congenital Chagas disease. At present, an early positive PCR is not indicative for treatment. However, a positive PCR would alert the health system to search only those infected infants diagnosed by early PCR and thus generate greater efficiency in the diagnosis and treatment of congenital T. cruzi infection.

Evaluación de ELISA F29 como marcador de eficacia del tratamiento etiológico en la enfermedad de Chagas / Assessment of ELISA F29 as a marker of etiological treatment efficacy for Chagas disease

A transversal study was performed on sera from chronic chagas ic patients treated with nifurtimox (Nx) or benznidazole (Bz), in order to evaluate the Trypanosoma cruzi flagellar calcium-binding protein (F29) as a marker for therapeutic effectiveness. An ELISA was used with these F29 recombinant antigen, and its relation to conventional serology (CS) and parasitological and clinical evolution was analysed. Sera from 118 patients with retrospective, serological, parasitological and clinical information was available, were analyzed. Patients were grouped into: A) 30 treated patients whose CS became negative after treatment; B) 34 treated patients whose CS remained positive; C) 54 untreated patients. A double-blind trial was conducted simultaneously in all serum samples, by means ofCS (indirect hemagglutination, direct agglutination and indirect immunofluorescence) and ELISA F29. The ELISA F29 test was non reactive in: 100 percent of group A, 82.4 percent of group B and 13 percent> of group C. The infected patients who presented electrocardiographic alterations compatible with chronic chagasic myocardiopathy (n = 11) were reactive for ELISA F29. All patients whose parasitological studies (xenodiagnosis and/or strout method) were positive presented a high reactivity to the ELISA F29 test. The correlation between ELISA F29 and CS was statistically significant (p < 005) in the treated group whose CS was non reactive (group A) and the untreated group (group C). As opposed to this, in the group of treated patients whose CS remained positive (group B), the ELISA F29 test was reactive only in a 17.6 percent>. These results suggest that the fast and user-friendly ELISA F29 test could be useful to monitor changes after trypanocidal treatment.

La proteína flagelar F29 es una proteína ligadora de calcio del Trypanosoma cruzi. En el presente trabajo se realizó un estudio transversal en sueros de pacientes con infección crónica por T. cruzi tratados con nifurtimox (Nx) o benznidazol (Bz) y no tratados, para evaluar el antígeno F29 como marcador de eficacia terapéutica. Se utilizó un ensayo inmuno-enzimático con la proteína recombinante F29 (ELISA F29) y se analizó su relación con la serología convencional (SC) y la evolución parasitológica y clínica en esos pacientes. Se estudiaron 118 sueros de pacientes que formaban parte de una cohorte, de los cuales se disponía de información retrospectiva, serológica, parasitológica y clínica. Los pacientes se dividieron en 3 grupos: A) 30 tratados negativizaron SC post-tratamiento; B) 34 tratados permanecieron con SC reactiva; C) 54 no tratados. Las muestras de suero se procesaron a doble ciego en forma simultánea mediante serología convencional (hemoaglutinación indirecta, aglutinación directa e inmunofluorescencia indirecta) y ELISA F29. El test ELISA F29 resultó no reactivo en: 100 por ciento del grupo A, 82,4 por ciento del grupo B y 13 por ciento del grupo C. Los infectados con alteraciones electrocardiográficas compatibles con miocardiopatía chagásica crónica (n = 11) fueron reactivos al ELISA F29. Los pacientes en quienes los estudios parasitológicos (xenodiagnóstico y/o strout) fueron (+) presentaron elevada reactividad al ELISA F29. La correlación entre ELISA F29 y SC en los pacientes tratados con SC no reactiva (grupo A) y no tratados (grupo C), fue significativa (p < 0,05). En cambio, en pacientes tratados que mantuvieron la SC reactiva (grupo B) el test de ELISA F29 fue reactivo sólo en 17,6 por ciento. Estos resultados sugieren que el test ELISA F29, rápido y sencillo, podría ser útil para monitorear cambios post-tratamiento tripanocida.