Direct molecular characterization and follow-up of Trypanosoma cruzi lineages and populations involved in Congenital Chagas disease

J. BURGOS; BISIO M; SEIDENSTEIN MJ .; DUFFY T; ALTCHEH, J; LEVIN MJ; FREILIJ H; SCHIJMAN AG

Londres, Reino Unido

Congreso; Centennary of the Royal Society of Tropical Medicine and Hygiene; 2007

Royal Society of Tropical Medicine and Hygiene

Trypanosoma cruzi populations are conformed by multiple clones, classified into different phylogenetic lineages. This variability may play a role in the risk of congenital  transmission of Chagas disease (CCD), whose rates differ among geographical regions. A small proportion of infected mothers transmit the parasite in some or all their gestations. Moreover, in cases of transmission, only a subset of the maternal parasite populations might reach the on-growing foetuses and establish CCD. In this context, parasite lineages were identified in blood samples of 34 CCD children, 7 transmitting- and 13 non-transmitting-women, who acquired T.cruzi in Argentina, Bolivia and Paraguay, using PCRs for nuclear T.cruzi genes. Profiling of parasite minicircle signatures was performed in 7 mother-CCD infants cases and 7 non-transmitting mothers using RFLP- and/or LSSP-PCR. Allelic analysis of microsatellite loci allowed characterize the clonal complexity of the strains. All CCD patients were treated with benznidazole; parasitological response was followed-up by PCR and serological tests. All CCD children were infected by Tcruzi IId, except one with perinatal AIDS, coinfected by T.cruzi I. After treatment, PCR became negative before serological conversion to negative in all patients. Lineage IId was detected in all CCD-transmitting- and 12/13 non-transmitting-women. Minicircle signatures were unique for each family and nearly identical within each mother-infant case and between  twins .  No association of CCD with a particular signature or lineage was found. CCD involved transmission of the whole maternal bloodstream trypanosome population, without differential passage of clones.  In a twins’ mother infected by a multiclonal strain, all clones were equally transmitted. The high degree of intra-family homogeneity opens new possibilities for epidemiological surveys of re-emergent Chagas disease, in which the sources of transmission need to be determined. The high degree of intra-family homogeneity opens new possibilities for epidemiological surveys of re-emergent Chagas disease, in which the sources of transmission need to be determined.