INTRODUCTION: Schistosomiasis is a public health problem that affects neglected populations living in poor areas of the globe. The dissemination and maintenance of the disease is closely related to socioeconomic factors, such as sanitation and family income. Mass drug administration (MDA) of praziquantel has been historically used and worldwide recommended by the World Health Organization (WHO) as a preventive strategy for the control and elimination of schistosomiasis as a public health problem. However, in Brazil, preventive chemotherapy does not seem to be effective for the long-term control of schistosomiasis. Here we share results from different studies conducted at the same rural area of the state of Bahia, Brazil over the past 20 years. METHODOLOGY: This cohort included all habitants of villages in the rural area of Conde-Bahia-Brazil. All participants provided stool samples for Kato-Katz (KK). Studies in this region started in 2001 and follow-up continues to date. Considering the high prevalence of schistosomiasis observed in the region since the beginning of the works, mass drug administration (MDA) of praziquantel (PZQ) were carried out in the years 2001, 2005-2006 (3x), 2010 and 2018. RESULTS: At the begging to the study in 2001 the overall prevalence of schistosomiasis was 83.3% with mean parasite load 243.2  357.3 epg (range: 12-2,112 epg). At that moment 18.2% of them were classified as high parasite burden (≥400 epg). This population was submitted to MDA and reassessed in 2004, when the prevalence of schistosomiasis was 77.7%, of which 8.5% had a high parasite load. During the years of 2005 and 2006 the population underwent up to three rounds of MDA with PZQ. In 2010 the population were reevaluated and a socioeconomic questionnaire was administered. At that time point the prevalence of schistosomiasis was 57.8% with 4.2% of high parasite load, and about half of the households did not have running water or bathroom. Another MDA was performed in 2010 and the population reevaluated in 2018. After eight years without evaluation, the prevalence of schistosomiasis remained at 55.6%, with 4.8% of them with a high parasitic load. At that moment all houses were supplied with running water and 24.8% were not equipped with a toilet. Exactly one year after the last MDA, the prevalence of schistosomiasis was already at 16.5%. CONCLUSION: After 20 years, with at least five MDA carried out, schistosomiasis is still not controlled in the region and is far from being eliminated as a public health problem, defined as less than 1% of heavy-intensity infection. This observation evidences that MDA alone is not capable of controlling or eliminating schistosomiasis in the long term. Although there has been a small improvement in socioeconomic conditions over time, these conditions are currently still below expectations, probably justifying the maintenance of schistosomiasis in the region. Thus, it is necessary to carry out structural interventions that allow the control of schistosomiasis in a more consistent and permanent way, such as basic sanitation, health education activities and environmental control.