ABSTRACT
To better understand the factors involved in maternal-fetal transmission of Trypanosoma cruzi, we compared DNA levels-obtained by use of quantitative real-time PCR and parasitic genotypes determined by PCR amplification followed by hybridization-in Bolivian mothers and their congenitally infected newborns. Mothers and their neonates displayed markedly different parasitic DNA levels, as most maternal estimated parasitemias (> 90%) were < 10 parasites/mL, whereas those of 76% of their newborns were > 1,000 parasites/mL. Comparison of T. cruzi TcII sublineages infecting mothers and newborns showed identity, without evidence of mixed infection in mothers or neonates. Analysis of minor variants of TcIId-genotyped parasites using sequence class probes hybridizing with hypervariable domains of kDNA minicircles showed discrepancies in half of mother/newborn pairs.
Subject(s)
Chagas Disease/transmission , DNA, Protozoan/analysis , Infectious Disease Transmission, Vertical , Pregnancy Complications, Infectious/parasitology , Trypanosoma cruzi/genetics , Animals , Bolivia , Chagas Disease/blood , Chagas Disease/congenital , Chagas Disease/parasitology , Female , Humans , Infant, Newborn , Polymerase Chain Reaction , Pregnancy , Pregnancy Complications, Infectious/blood , Trypanosoma cruzi/classification , Trypanosoma cruzi/isolation & purificationABSTRACT
This study aims to typify the Trypanosoma cruzi (sub)lineage(s) in umbilical cord blood of congenitally infected Bolivian newborns, using PCR amplifications of "Region Markers", mini-exon or kDNA fragments followed by hybridization or sequencing. New probes were also designed to distinguish three variants within the TcIId sublineage. The IIb, IId, or IIe T. cruzi sublineages, as well as different variants of the IId sublineage, were detected in infected neonates, whereas mixed infections were not found. The frequencies of the IId sublineage were similar in neonates (95.1%) and adults of the same area (94.1%). The IId-infected newborns displayed either asymptomatic, or severe and fatal clinical forms of congenital Chagas disease, as well as low or high parasitemia. Altogether these data show that T. cruzi DNA polymorphism, based on the presently available markers, is not associated with the occurrence of congenital infection or the development of severe clinical forms of congenital Chagas disease.
