“…Consequently, genetic strain differences may influence parasitaemia in man and partially explain the discrepancies of PCR sensitivity between studies carried out in different endemic areas. For instance, in Bolivia and most part of Brazil, in areas where T. cruzi II stocks circulate, PCR shows high sensitivity, contrasting with areas from the Brazilian Amazon and Mexico, where only T. cruzi I stocks occur (Avila et al 1993, Wincker et al 1994a, b, 1997, Zingales et al 1998, Fernandes et al 2001.…”