Treatment of congenital Chagas' disease diagnosed and followed up by the polymerase chain reaction.

Abstract

Abstract. In 1991 and 1992, a prenatal screening of Trypanosoma cruzi infection was carried out using ELISA and indirect immunofluorescence techniques. A total of 840 blood samples from pregnant women, obtained at the Maternity Ward of the Hospital de Clínicas, National University of Asunción (Asunción, Paraguay), and 1,022 samples from the Regional Hospital of the San Pedro Department of Paraguay were examined. It was observed that 7.7% and 10.5%, respectively, of the pregnant women were serologically positive for infection with T. cruzi. When blood samples obtained from newborns on the day of birth or, at the most, on the first few days afterwards were examined by direct microscopic observation, an incidence of congenital transmission of 3% was found. These results are consistent with those of neighboring countries. When a serologic follow-up was conducted on the newborns until six months of age, the incidence of congenital transmission reached 10%. The same incidence rate was obtained when the samples collected during the first days after birth were examined by the polymerase chain reaction (PCR). Fiftyeight infants born to seropositive mothers were followed-up, two of which were positive by direct microscopic observation at birth, and four who were PCR-positive, but microscopy-negative at birth. None of the infants were positive for IgM at birth. The infected babies were treated with benznidazole and were followed-up by serology and PCR for four years. We conclude that the PCR has a clear advantage over conventional techniques for the early detection of congenital transmission of T. cruzi infection, and for monitoring infants undergoing chemotherapy.

Usefulness of PCR-based assays to assess drug efficacy in Chagas disease chemotherapy: value and limitations

“…Several therapeutic studies confirm the usefulness of usual PCR strategies to evaluate treatment outcome in either acute or chronic cases of Chagas disease (Russomando et al 1998, Lauria-Pires et al 2000, Britto et al 2001, Solari et al 2001, Galvão et al 2003, Schijman et al 2003, Zulantay et al 2004. PCR is a helpful tool for the early detection of treatment failure when comparing drug efficacy, tolerance, therapeutic schemes, periods of follow-up and cure criteria.…”

“…Several months were required to obtain a prolonged negative result by PCR, even though positive XD rapidly dropped 3-6 months after treatment from 79.1-1.6%, probably due to the lower sensitivity of the method. In this study, the slow rate of PCR conversion could be explained by the late administration of the drug after infection as compared to the early efficacy of treatment in congenital cases, from a few days to three months (Russomando et al 1998). According to Solari et al (2001), PCR was the most effective test to monitor children three years post-chemotherapy, when all treated children converted from positive to negative, and no significance was found between patient age and PCR conversion.…”

“…In general, the true potential of real-time PCR will be recognized in situations for which PCR-based techniques have been promoted, such as congenital infections (Schijman et al 2003, Virreira et al 2003, Mora et al 2005, monitoring parasitaemia during and after treatment (Russomando et al 1998, Britto et al 2001, Schijman et al 2003, early detection of relapses after heart transplantation (Maldonado et al 2004) and other immunosuppressive circumstances. To deal with more precise results and make them comparable between laboratories, the main constraint until now has been the lack of a universal reagent presenting accurately quantified T. cruzi DNA samples to be used as standards in all quantification assays (Piron et al 2007).…”

“…Anti-parasitic treatment has greater success in newborns close to birth and is strongly indicated (Freilij & Altcheh 1995, Luquetti 1997. In search of more sensitive laboratory tests to detect infection and evaluate treatment outcome in congenital infections, PCR appears to be a promising laboratory tool (Russomando et al 1998, Schijman et al 2003, Virreira et al 2005, Duffy et al 2009). Russomando et al (1998) examined 58 infants born to seropositive mothers for congenital transmission of Chagas disease in Paraguay using direct microscopy, immunofluorescence for anti-T. cruzi IgM antibodies and PCR targeted to nuclear genomic markers (Moser et al 1989).…”

Chagas disease prevention through improved housing using an ecosystem approach to health

“…Serology is currently positive in some 13% of pregnant women, and congenital transmission is around 10% (Russomando et al, 1998). Congenital transmission is associated with socioeconomic variables like level of schooling (UCA/ UNA, 1994), the mother's perception of the disease (González-Terlaz, 1989), family income, and access to health services in a given population.…”