BACKGROUND Trypanosoma cruzi shows an exuberant genetic diversity. Currently, seven phylogenetic lineages, called discrete typing units (DTUs), are recognised: TcI-TcVI and Tcbat. Despite advances in studies on T. cruzi and its populations, there is no consensus regarding its heterogeneity. OBJECTIVES This study aimed to perform molecular characterisation of T. cruzi strains, isolated in the state of São Paulo, to identify the DTUs involved and evaluate their genetic diversity. METHODS T. cruzi strains were isolated from biological samples of chronic chagasic patients, marsupials and triatomines through culture techniques and subjected to molecular characterisation using the fluorescent fragment length barcoding (FFLB) technique. Subsequently, the results were correlated with complementary information to enable better discrimination between the identified DTUs. FINDINGS It was possible to identify TcI in two humans and two triatomines; TcII/VI in 19 humans, two marsupials and one triatomine; and TcIII in one human host, an individual that also presented a result for TcI, which indicated the possibility of a mixed infection. Regarding the strains characterised by the TcII/VI profile, the correlation with complementary information allowed to suggest that, in general, these parasite populations indeed correspond to the TcII genotype. MAIN CONCLUSIONS The TcII/VI profile, associated with domestic cycles and patients with chronic Chagas disease, was the most prevalent among the identified DTUs. Furthermore, the correlation of the study results with complementary information made it possible to suggest that TcII is the predominant lineage of this work.

Foi realizada reavaliação sobre o estado de preservação de ovos de helmintos e cistos de protozoários mantidos por cerca de 40 anos em solução de iodo-mercurato de potássio a 0,2%. Foi observado que ovos de Schistosoma mansoni, Ancylostomidae e Trichuris trichiura e oocistos de Isospora belli mantiveram-se em condições adequadas para a sua identificação ao microscópio ótico comum. No material examinado, foi possível verificar a presença de miracídio em ovo de Schistosoma mansoni, forma larvada em ovo de T. trichiura e esporozoitos em oocistos de I. belli.