Schistosomiasis as an urban disease: 13 years of studies in the neighborhoods of Salvador, BA, Brazil
6 affiliations
- 1Laboratory for Pathology and Molecular Biology, Gonçalo Moniz Institute, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil
- 2Laboratory of Clinical Parasitology, Bahiana School of Medicine and Public Health, Salvador, Bahia, Brazil
- 3Health Surveillance Directorate, Municipal Health Secretariat of Salvador, Salvador, Bahia, Brazil
- 4Health Sciences Institute, Federal University of Bahia, Salvador, Bahia, Brazil
- 5Epidemiology of Microbial Diseases, Yale University, New Haven, Connecticut, United States of America
- 6Department of Tropical Medicine and Infectious Disease, Tulane Celia Scott Weatherhead School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States of America
Abstract
Background: Rapid urbanization in Brazil has shifted the epidemiological landscape of parasitic diseases, such as schistosomiasis and malaria. Although typically considered a rural infection, Schistosoma mansoni transmission persists in urban settings where sanitation and water access remain uneven. This study investigates the persistence and dynamics of urban schistosomiasis across neighborhoods of Salvador, Bahia, Brazil. Methods: Between 2011 and 2024 cross-sectional surveys were conducted to identify neighborhoods with the highest prevalence in the major metropolitan area of Salvador, Bahia. A total of 6,863 residents provided demographic information and Kato-Katz examination of at least one stool sample. We conducted demographic surveys and stool examination on 3,964 individuals who were re-examined on up to three occasions at intervals ranging from 1-5 years. Findings: The overall prevalence of initial examination was 7%. Regardless of treatment intervals, the community-wide prevalence declined by more than half and did not rebound. Apparent Incidence decreased to <0.5%/year following a second period of treatment. In nearly all communities, most infections occurred among individuals born in Salvador with no travel history outside the city. Interpretation: Overall, the study provides one of the first individual-level longitudinal assessments of schistosomiasis persistence in an urban Brazilian setting, combining repeated parasitological surveys with demographic and environmental data across multiple neighborhoods. These findings indicate that schistosomiasis transmission in Salvador is largely local rather than imported. The decline in prevalence coincides with observed community-level improvements in sanitation and reduced contact with surface water. f prevalence rates were applied across the population of Salvador, this city could be considered one of the state’s most important endemic areas. Author summary: Rapid urbanization and the lack of accompanying sanitation is urbanizing diseases previously considered rural. While sanitation in Salvador is generally good, Schistosoma mansoni infection was identified in all poor neighborhoods examined, and most evidence indicates this is a result of active transmission. Studies in urban environments pose difficulties not experienced or experienced to a lesser degree in most rural areas. Participation in research is lower, and violence is generally higher. Urban areas also offer opportunities for effective intervention due to the greater impact of infrastructure modifications and population density. Interventions tend to more easily affect a greater number of people. The prevalence of infection and the size of the city make urban infection an important focus for management. The Brazilian setting may provide a preview of schistosomiasis transmission as endemic areas become increasingly urbanized.
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BibTeX
@article{santosmuccillo2026schistosomiasis,
title = {{Schistosomiasis as an urban disease: 13 years of studies in the neighborhoods of Salvador, BA, Brazil}},
author = {Pedro Santos-Muccillo and Fernanda Mac-Allister Cedraz and Luciano K. Silva and Lúcio M. Barbosa and Vanessa T. Moretto and Vanessa S. Zanardi and Camila F. Chaves and João R. P. Cruz-Filho and Lee S. A. Andrade and Cláudio R. A. Santos and Eliana A. G. Reis and Cristiane W. Cardoso and Rogerio S. Teixeira and Fabiano M. Simões and Roberto J. M. Nascimento and Jackson M. L. Costa and Mitermayer G. Reis and Ronald E. Blanton},
journal = {PLOS Neglected Tropical Diseases},
year = {2026},
month = oct,
doi = {10.1371/journal.pntd.0013418},
url = {https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0013418},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Schistosomiasis as an urban disease: 13 years of studies in the neighborhoods of Salvador, BA, Brazil
AU - Pedro Santos-Muccillo
AU - Fernanda Mac-Allister Cedraz
AU - Luciano K. Silva
AU - Lúcio M. Barbosa
AU - Vanessa T. Moretto
AU - Vanessa S. Zanardi
AU - Camila F. Chaves
AU - João R. P. Cruz-Filho
AU - Lee S. A. Andrade
AU - Cláudio R. A. Santos
AU - Eliana A. G. Reis
AU - Cristiane W. Cardoso
AU - Rogerio S. Teixeira
AU - Fabiano M. Simões
AU - Roberto J. M. Nascimento
AU - Jackson M. L. Costa
AU - Mitermayer G. Reis
AU - Ronald E. Blanton
PY - 2026
DA - 2026/10/23
JO - PLOS Neglected Tropical Diseases
DO - 10.1371/journal.pntd.0013418
UR - https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0013418
AB - Background: Rapid urbanization in Brazil has shifted the epidemiological landscape of parasitic diseases, such as schistosomiasis and malaria. Although typically considered a rural infection, Schistosoma mansoni transmission persists in urban settings where sanitation and water access remain uneven. This study investigates the persistence and dynamics of urban schistosomiasis across neighborhoods of Salvador, Bahia, Brazil. Methods: Between 2011 and 2024 cross-sectional surveys were conducted to identify neighborhoods with the highest prevalence in the major metropolitan area of Salvador, Bahia. A total of 6,863 residents provided demographic information and Kato-Katz examination of at least one stool sample. We conducted demographic surveys and stool examination on 3,964 individuals who were re-examined on up to three occasions at intervals ranging from 1-5 years. Findings: The overall prevalence of initial examination was 7%. Regardless of treatment intervals, the community-wide prevalence declined by more than half and did not rebound. Apparent Incidence decreased to <0.5%/year following a second period of treatment. In nearly all communities, most infections occurred among individuals born in Salvador with no travel history outside the city. Interpretation: Overall, the study provides one of the first individual-level longitudinal assessments of schistosomiasis persistence in an urban Brazilian setting, combining repeated parasitological surveys with demographic and environmental data across multiple neighborhoods. These findings indicate that schistosomiasis transmission in Salvador is largely local rather than imported. The decline in prevalence coincides with observed community-level improvements in sanitation and reduced contact with surface water. f prevalence rates were applied across the population of Salvador, this city could be considered one of the state’s most important endemic areas. Author summary: Rapid urbanization and the lack of accompanying sanitation is urbanizing diseases previously considered rural. While sanitation in Salvador is generally good, Schistosoma mansoni infection was identified in all poor neighborhoods examined, and most evidence indicates this is a result of active transmission. Studies in urban environments pose difficulties not experienced or experienced to a lesser degree in most rural areas. Participation in research is lower, and violence is generally higher. Urban areas also offer opportunities for effective intervention due to the greater impact of infrastructure modifications and population density. Interventions tend to more easily affect a greater number of people. The prevalence of infection and the size of the city make urban infection an important focus for management. The Brazilian setting may provide a preview of schistosomiasis transmission as endemic areas become increasingly urbanized.
SN - 1935-2735
SN - 1935-2727
ER -