Using routine health data to evaluate the impact of indoor residual spraying on malaria transmission in Madagascar
BMJ Global Health·
- DOI
- 10.1136/bmjgh-2022-010818
- PMID
- 37463785
- PMCID
- PMC10357738
- OpenAlex
- W4384655747
- Study type
- Journal article
- Publisher
- BMJ
- Article type
- journal-article
- Integrity
- current
Why this research matters now
The findings suggest that sustained non-pyrethroid IRS can substantially reduce malaria burden in Madagascar when implemented alongside ITNs, with cumulative benefits from multi-year deployment supporting programmatic investment in long-term vector control strategies.
Structured evidence summary
Research question
The study evaluated whether indoor residual spraying with non-pyrethroid insecticides reduced malaria transmission in nine districts of Madagascar from 2017 to 2020, and whether sustained multi-year implementation and spray coverage levels influenced effectiveness.
Study design
This was a retrospective observational study using routine health facility data and propensity score matching to compare malaria incidence in IRS-exposed districts versus matched control facilities. Multilevel negative-binomial models controlled for ITN survivorship, mass drug administration, precipitation, vegetation, seasonality, and district.
Population and setting
The study analyzed all-ages confirmed malaria cases at health facilities in nine districts of Madagascar where non-pyrethroid IRS complemented standard pyrethroid ITNs between July 2016 and June 2021.
Main findings
IRS exposure reduced malaria case incidence by an estimated 30.3% in the 12 months following campaigns. A third consecutive year of IRS reduced cases by an additional 30.9% compared to the first year. Spray coverage of 86-90% was associated with a 19.7% incidence reduction versus coverage below 85%, though this finding was not robust in sensitivity analysis.
Public-health relevance
The findings suggest that sustained non-pyrethroid IRS can substantially reduce malaria burden in Madagascar when implemented alongside ITNs, with cumulative benefits from multi-year deployment supporting programmatic investment in long-term vector control strategies.
Important limitations
The study excluded facilities with missing data and non-geolocated communes. The coverage-level findings were not robust to sensitivity analysis. This summary is based solely on the supplied abstract and metadata; the original article is required for decision-grade interpretation of analytic choices, residual confounding, and generalizability.
GIDS interpretation
This article is discoverable through GIDS classifiers for malaria, Madagascar, and topics including transmission dynamics and climate-environment interactions. The supplied metadata enables editors to assess relevance to surveillance priorities but does not constitute confirmation of a live epidemiologic signal.
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 8 auditable classifier relationships to diseases, places, topics, and study design.