Trypanosoma cruzi DTU parasite diversity and clinical outcomes in mesoregions of the Northeast Brazilian State of Pernambuco.

BACKGROUND

Chagas disease (CD), caused by infection with the protozoan parasite Trypanosoma cruzi, is a neglected tropical illness that affects 6-7 million individuals worldwide. CD may progress to chronic cardiac (CARD), digestive (DIG), or cardio-digestive (CARD/DIG) forms. Parasite genetic diversity, defined in discrete typing units (DTUs) TcI-TcVI and TcBat, may contribute to clinical forms. Here, we challenged this idea by studying a population born in the State of Pernambuco, Northeast of Brazil.

METHODOLOGY/PRINCIPAL FINDINGS: Patients born in eco-geographically distinct mesoregions (Sertão, Agreste, Zona da Mata, and Metropolitan Region) attending the referral PROCAPE hospital were serologically diagnosed for CD and characterized as non-CARD (16.5%), CARD (67%), DIG (12.1%), and CARD/DIG (4.3%). Out of 346 CD patients not subjected to etiological treatment, 128 (37%) were positive for conventional PCR targeting T. cruzi kDNA. DTU genotyping using pre-established primers and algorithms revealed 85/128 (66%) samples amplified for at least one target, and of these, 49 (58%) were classified into DTUs, showing a higher distribution of DTUs TcV (16) and TcIII (13) but also TcIV (7), TcI (3), TcVI (3), and TcII (1). Mixed infections by TcI + TcV (2), TcIII + TcIV (3), and TcIII + TcV (1) were also found. Out of the 49 classified samples, 36 were CARD patients (73.5%), infected mainly by TcV (13) and TcIII (10). Considering patients' birthplace, in the Agreste, all DTUs were detected, with prevailing TcV and TcIII; in Zona da Mata, DTU characterization reflected the input of samples (21/49, 43%), again mainly TcV and TcIII.

CONCLUSION/SIGNIFICANCE: DTUs TcI-TcVI were only detected in the blood of patients born in the Agreste, area of ecological transition. Although not frequently found in human infections in Brazil, the prevailing TcV, TcIII, and TcIV were detected in patients born in Pernambuco. These data could not disclose an identifiable association of T. cruzi DTU circulating in the blood of patients with clinical forms of CD.