Chagas disease was investigated in four periurban areas of Ceará state, northeastern Brazil, through serological, parasitological and molecular methods in humans, reservoirs and vectors. A cross-sectional survey revealed a seroprevalence rate of 1.2% (13/1076 residents, six also proving positive through PCR). Trypanosoma cruzi infection was not detected in children under 10 years old. Triatoma pseudomaculata prevailed in the peridomiciles: 63 specimens, 69% (34/49) infected with trypanosomatids. Rhodnius nasutus was captured in Copernicia prunifera palm trees (n=280; 25.0% infected with trypanosomatids) and inside dwellings (n=8, all uninfected). Trypanosoma cruzi seropositive reservoirs, represented by Didelphis albiventris (n=27), Rattus rattus (n=24), Thrichomys laurentius (n=2), Mus musculus (n=1) and Monodelphis domestica (n=1), were identified. Among domestic dogs (n=96) seroprevalence reached 21.9%. Miniexon multiplex PCR assays characterized TcI in triatomines. Both TcI and TcII were detected in wild mammal hosts. We conclude that Trypanosoma cruzi circulates within a domestic zoonotic cycle, requiring continuous surveillance. Insecticide application to domiciles does not appear to prevent continuous reintroduction of wild triatomine specimens, presenting a challenge to authorities involved in Chagas disease control.

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Chagas disease is one of the most significant systemic parasitosis in Latin America, caused by Trypanosoma cruzi, which is mainly transmitted by hematophagous insects, the triatomines. This research was carried out in both domestic and wild environments throughout a Northeastern rural locality. Triatomines were captured in both peridomicile and wild environments, obtaining 508 specimens of triatomines, of which 99.6% were Triatoma brasiliensis. Insects were captured in 10 (18.5%) peridomiciles with an average of 8.3 triatomines per residence. Triatoma brasiliensis nymphs and adults were found in six peridomiciles, generating a 11.1% colonization. No T. cruzi infection was detected in the 447 peridomestic insects analyzed. On the other hand, of the 55 sylvatic T. brasiliensis molecularly examined for T. cruzi, 12 (21%) were positive, all harboring T. cruzi I. The blood meal analysis by enzyme-linked immunosorbent assay from gut content revealed that both peridomestic and wild triatomine populations fed mainly on birds, refractory to the parasite, which may explain the null rate of natural infection prevalence in the domestic environment. However, infected triatomines for potential home infestation within the radius of insect dispersion capacity were registered in rock outcrops around the dwellings. Anthropogenic environmental influences are able to rapidly alter these scenarios. Therefore, to avoid disease transmission to humans, we recommend constant vector control combined with periodic serological surveillance. The associated methodology presented herein may serve as a model for early detections of risk factors for Chagas disease transmission in the Brazilian Northeast.