RESUMO
Chagas disease ranks among the world's most neglected tropical diseases and congenital transmission is increasingly responsible for urbanization of Chagas disease in non-endemic areas. Molecular assays for amplification and profiling of parasite minicircle DNA (kDNA) and identification of discrete typing units (DTUs) were prospectively conducted in bloodstream and placental samples from pregnant women cursing chronic Chagas disease residing in Buenos Aires city. Sensitivity of kDNA-PCR increased from 75.6% to 95.6% when one to three sequential blood samples were analysed. Congenital infection (CI) was diagnosed in 3 neonates born to kDNA-PCR positive mothers, one who had transmitted CI in a previous gestation, pointing to family clustering of congenital transmission. Fourteen of 44 placental samples were kDNA-PCR positive, all from non-CI transmitting women, indicating that placental PCR is not useful for CI diagnosis. Placental PCR positivity was not related to maternal bloodstream PCR positivity and placental parasitic subpopulations not observed in bloodstream were detected by minicircle signatures. PCR targeted to intergenic regions of spliced-leader genes and serological tests using trypomastigote small surface recombinant antigens showed predominance of DTU group TcII/V/VI and only one patient infected with TcI. To our knowledge, this is the first PCR-based follow-up study of bloodstream and placental T. cruzi infections during pregnancy, including identification of DTUs. kDNA-PCR assays in serial blood samples provided high sensitivity for detection of T. cruzi DNA in pregnant women with chronic Chagas disease.
Assuntos
Doença de Chagas/epidemiologia , Doença de Chagas/transmissão , DNA de Cinetoplasto/genética , Doenças Placentárias/parasitologia , Trypanosoma cruzi/patogenicidade , Urbanização , Adulto , Argentina/epidemiologia , Western Blotting , Doença de Chagas/genética , Doença Crônica , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Recém-Nascido , Doenças Placentárias/epidemiologia , Reação em Cadeia da Polimerase , Gravidez , Complicações Parasitárias na Gravidez/epidemiologia , Complicações Parasitárias na Gravidez/genética , Estudos Prospectivos , Trypanosoma cruzi/genéticaRESUMO
Congenital transmission of Trypanosoma cruzi may occur in some or all the gestations from a T. cruzi-infected mother. Variable rates of congenital transmission have been reported in different geographical areas where different parasitic strains predominate, suggesting that parasitic genotypes might play a role in the risk of congenital transmission. Moreover, in cases of transmission it is unknown if the whole maternal T. cruzi population or certain clones are preferentially transmitted by the transplacental route. In this study, bloodstream T. cruzi lineages were identified in blood samples from congenitally infected children, transmitting and non-transmitting mothers and unrelated Chagas disease patients, using improved PCR strategies targeted to nuclear genomic markers. T. cruzi IId was the prevalent genotype among 36/38 PCR-positive congenitally infected infants, 5/5 mothers who transmitted congenital Chagas disease, 12/13 mothers who delivered non-infected children and 28/34 unrelated Chagas disease patients, all coming from endemic localities of Argentina and Bolivia. These figures indicate no association between a particular genotype and vertical transmission. Furthermore, minicircle signatures from the maternal and infants' bloodstream trypanosomes were profiled by restriction fragment length polymorphism of the 330-bp PCR-amplified variable regions in seven cases of mothers and congenitally infected infants. Minicircle signatures were nearly identical between each mother and her infant/s and unique to each mother-infant/s case, a feature that was also observed in twin deliveries. Moreover, allelic size polymorphism analysis of microsatellite loci from populations transmitted to twins showed that all clones from the maternal polyclonal population were equally infective to both siblings.