Schistosomiasis is a parasitic disease estimated to infect more than 250 million people worldwide (World Health Organization (WHO, 2021). The disease is caused by trematode parasites of the genus Schistosoma, with Schistosoma mansoni being the specie responsible for schistosomiasis in Brazil. It is estimated that 1.5 million people live in risk areas spread across 19 states, where transmission occurs through contact with freshwater bodies contaminated by the parasite's cercariae (Ministério da Saúde, 2014).

Currently, there is no vaccine available for schistosomiasis, and treatment relies on a single chemotherapeutic agent, praziquantel (PZQ). Praziquantel is considered effective against all Schistosoma species that infects humans (Doenhoff et al., 2008); however, its widespread use in mass drug administration (MDA) programs has raised concerns about the potential development of drug-tolerant or resistant parasite strains (Botros and Bennett, 2007; Pinto-Almeida et al., 2015, 2016). Reports of reduced efficacy and differential susceptibility among S. mansoni isolates emphasize the urgent need for alternative therapeutic strategies.

Despite decades of continuous research efforts by the scientific community, no commercially approved therapeutic alternatives to PZQ have been developed. Previous studies have demonstrated that different strains of S. mansoni exhibit varying responses not only to PZQ but also to other pharmacological compounds (Frezza et al., 2013; Corrêa et al., 2019; Badoco et al., 2022). This variability may contribute to difficulty in identifying universally effective treatments and highlights the importance of investigating strain-specific differences.

In this study, we aimed to compare three Brazilian strains of S. mansoni originating from Belo Horizonte/MG (SmBH), Ilha das Flores/SE (SmSE) and São José dos Campo/SP (SmSJ). Our objective was to assess differences in pathogenesis, morphometric characteristics of adult worms and eggs, and susceptibility to PZQ in murine schistosomiasis. Understanding these strain-specific variations may provide valuable insights into the mechanisms of drug susceptibility and resistance, ultimately contributing to the development of more effective treatments for schistosomiasis.