Chagas disease is a parasitic infection with high socioeconomic impact throughout Latin America. Although this severe, incurable disease can be transmitted by several routes, oral transmission is currently the most important route in the Amazon Basin. Acai pulp has nutritional properties and is popular throughout Brazil and abroad. However, this pulp has been associated with microepidemics of acute Chagas disease (ACD) in northern Brazil, where agar fruit is the main food supplement. In this study, we examined the in vitro survival and in vivo virulence of Trypanosoma cruzi Y strain in acai pulp. Aliquots of in natura acai pulp produced in Belem city in the northern Brazilian state of Para were mixed with 10(5) trypomastigotes. The samples were incubated at room temperature or at 4 or 20 C for various periods, and the parasites were isolated by forced sieving. The resulting eluates were examined by microscopy, and the trypomastigotes were administered intraperitoneally, orally, or by gavage to immunodeficient mice (C.B-17-Prkdc(scid)/PasUnib) that had been pretreated with antibiotics. Parasitemia was quantified by the Brener method, and mortality was recorded daily. All routes of administration resulted in ACD. A 5-day delay in the onset of parasitemia occurred with oral administration. The survival and virulence of the parasites were unaffected by prior incubation at room temperature for 24 h, at 4 degrees C for 144 h, and at -20 degrees C for 26 h. These results indicate that T. cruzi can survive and retain its virulence in acai pulp under various conditions and that cooling and freezing are not suitable methods for preventing foodborne ACD Ver menos