Impact of seven years of mass drug administration and recrudescence of Schistosoma haematobium infections after one year of treatment gap in Zanzibar: Repeated cross-sectional studies
PLOS Neglected Tropical Diseases·
- DOI
- 10.1371/journal.pntd.0009127
- PMID
- 33577601
- PMCID
- PMC7880478
- OpenAlex
- W3128576432
- Study type
- Cross-sectional study
- Publisher
- Public Library of Science (PLoS)
- Article type
- journal-article
- Integrity
- current
Why this research matters now
The study demonstrates that interruption of mass drug administration can lead to rapid recrudescence of urogenital schistosomiasis in hotspot areas. The authors recommend re-intensifying MDA plus additional interventions in hotspots and adapting strategies from mass administration to targeted surveillance-response in low-prevalence areas.
Structured evidence summary
Research question
The study monitored Schistosoma haematobium prevalence in Zanzibar from 2012 to 2020 and assessed recrudescence patterns following a 16-month treatment gap in 2019, after seven years of mass drug administration.
Study design
Repeated cross-sectional surveys were conducted annually from 2011/12 to 2020 in 90 communities and 90 schools in Zanzibar, enrolling approximately 4,500 adults and up to 20,000 schoolchildren each year. Infection was detected by urine filtration and reagent strips, and risk factors in 2020 were analyzed using generalized estimated equation models.
Population and setting
The study enrolled adults and schoolchildren in 90 communities and 90 schools across Zanzibar, Tanzania.
Main findings
Apparent prevalence in adults declined from 3.9% in 2011 to 0.4% in 2020, and in schoolchildren from 6.6% in 2012 to 1.2% in 2019. However, after the 16-month treatment gap, prevalence rebounded sharply from 2.8% in 2019 to 9.1% in 2020 in 29 schools with historically moderate prevalences, representing a 225% increase. Male sex was a significant risk factor for infection in both adults and schoolchildren in 2020, and living near natural freshwater increased infection odds in adults.
Public-health relevance
The study demonstrates that interruption of mass drug administration can lead to rapid recrudescence of urogenital schistosomiasis in hotspot areas. The authors recommend re-intensifying MDA plus additional interventions in hotspots and adapting strategies from mass administration to targeted surveillance-response in low-prevalence areas.
Important limitations
This summary relies on the supplied single-article abstract and metadata. Full interpretation of study limitations, including diagnostic sensitivity, representativeness of sampling, potential confounders, and generalizability, requires review of the complete published paper.
GIDS interpretation
The article was identified through disease classifier links for Schistosomiasis and country links for Tanzania, supporting discoverability for surveillance of neglected tropical diseases and intervention impact monitoring. The study provides evidence on recrudescence dynamics following treatment interruption, relevant for designing sustainable elimination strategies.
Related GIDS surveillance
Literature context does not validate, explain, or change a surveillance signal. Exact and contextual relationships are shown separately.
Evidence relationships
This article has 10 auditable classifier relationships to diseases, places, topics, and study design.