Direct molecular characterization and placental tropism of trypanosoma cruzi populations involved in chagasic infection of pregnant women

BISIO MMC; MOREAU M; RISSO M; BURGOS JM; LEGUIZAMON S; LEVIN M; SEIDENSTEIN ME; SCHIJMAN AG

Rosario, Argentina

Congreso; VIII Congreso Argentino de Protozoología y Enfermedades Parasitarias; 2008

We analyzed the presence of T. cruzi by kDNA PCR in 303 serial peripheral blood and 49 placental samples from 120 pregnant women with indeterminate Chagas´ disease. To characterize the parasitic population, molecular typing of lineages was performed by PCR (LgPCR) and minicircle signatures by RFLP-PCR of the 330bp kDNA amplicons.The sensitivity of kDNA PCR was 64.5%, reaching 75.5% in serial analyses (3 samples per patient). We classified parasitemias in high (positive findings in all samples) and low (at least one negative finding).Out of 31 women analyzed, 14 (45,2%) had high parasitemias and 17 (54,8%) low ones. In 14/49 (48.6%) placental specimens we detected T cruzi. Four of them (28,6%) belonged to women with high parasitemia and 8 (47,1%) to low ones. Parasite lineages were identified in 9 bloodstream (8 Tc II and 1 Tc I) and 1 placenta (Tc IId) samples. Serum samples with negative LgPCR findings were typified by TSSA serodiagnosis (Trypomastigote small surface antigen). All of them showed a Tc II infection. RFLP-PCR performed in different samples of the same placenta gave similar profiles suggesting the presence of the same parasite population. Although all infecting parasites were Tc II, the bloodstream populations of each patient presented a patient s specific profile during pregnancy.Conclusions: the clinical sensitivity of PCR increases when serial samples are tested. Placental parasitism is not necessarily related to high bloodstream parasitemia. Moreover, women with PCR negative blood but PCR positive placental specimens could be infected by parasitic strains with placental tropism.