Congenital Chagas Disease in Bolivia Is Not Associated With Dna Polymorphism of Trypanosoma Cruzi

Abstract

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.

Genotyping of Trypanosoma cruzi Sublineage in Human Samples from a North-East Argentina Area by Hybridization with DNA Probes and Specific Polymerase Chain Reaction (PCR)

“…40 These results would indicate that congenital transmission is not caused by a specific genotype as was yet suggested by Virreira and others. 40 In conclusion, our data about T. cruzi genotypes present in the Reconquista region of Santa Fe province, in coincidence with reports of other regions of our country cited previously, support the assumption that human infection by T. cruzi in Argentina is due principally to T. cruzi II. In that context, a correlation between clinical manifestation and the genotypes could be hypothesized as the cardiac sign that Chagas disease is predominant in Santa Fe province and in all of the country of Argentina.…”

“…Similar results were obtained in northwestern Argentina 36 and in a previous study performed in Bolivia. 40 These results would indicate that congenital transmission is not caused by a specific genotype as was yet suggested by Virreira and others. 40 In conclusion, our data about T. cruzi genotypes present in the Reconquista region of Santa Fe province, in coincidence with reports of other regions of our country cited previously, support the assumption that human infection by T. cruzi in Argentina is due principally to T. cruzi II.…”

“…Indeed, when reference strains were amplified using 0.3 pg of template, SC43 cl1 and MN cl2 were highly amplified with both sets of primers, whereas JGG, XHCH56, and NR cl3, were highly amplified with P primers but not with O primers. As MN cl2 belongs to MNcl2-like and SC43 cl1 belongs to TPK-like (previously classified by Virreira and others 40 ), but rendered similar results by MLS-PCR, these results could indicate that the PCR discriminates two variants within TcIId sublineage instead of three.…”

“…The difference between the hybridization test performed by Virreira and others 40 and MLS-PCR assay may be a result of a different ratio of O and P sequences in the purified DNA from samples as O sequence obtained from S121-122 generic PCR is less amplified than P sequence according to Table 1 . Therefore, probably the amount of O sequences present in DNA template is insufficient to be amplified by means of this amount of template.…”

Diagnosis of Chagas disease: what has been achieved? What remains to be done with regard to diagnosis and follow up studies?

“…The third period, from 1975 until the present day, has been characterised by the use of high technology in parasitological and serological approaches. Parasitological diagnosis was further improved with the introduction of polymerase chain reaction (PCR) (Moser et al 1989, Sturn et al 1989, Britto et al 1995 and quantitative real time PCR (Cummings & Tarleton 2003, Virreira et al 2006, Piron et al 2007, Duffy et al 2009). Serological diagnosis stopped using the crude antigens that were previously used and began to include a number of purified antigens, such as GP90 kDa, GP72 kDa, GP25 kDa, GP55 kDa and shortly thereafter, recombinant antigens and synthetic peptides, which were evaluated by way of multicentre trials (Moncayo & Luquetti 1990, Levin et al 1991, Umezawa et al 1999.…”