Background <p>Spatial–temporal variation exists in the density and species composition of malaria-carrying mosquitoes, which will in turn influence the transmission of the disease. While there has been extensive research on seasonality and other main drivers of the vector populations, the heterogeneity partitioned as random effects at various spatial–temporal scales is just as important but has not attracted the same attention.</p> Methods <p>To investigate the relative contributions of the between-house, between-village and between-year variations, as well as other house-level covariates such as inhabitant number and bed net usage on vector density and species composition, intensive pyrethroid spray catches (PSC) sampling was conducted across a 60-month period between 2012 and 2019 from four villages in the Sudano-Sahelian region of Burkina Faso.</p> Results <p>For density, measured by female <i>Anopheles gambiae</i><i> s.l.</i> counts, our modelling showed that the between-house variation was the largest variance component, followed by the between-year then between-village variation, after accounting for seasonality and other covariates. Density increased with the number of inhabitants within a household but was uncorrelated with bed net presence. A subset of female mosquitoes was genotyped for species identification, and the composition of <i>An. coluzzii</i> and <i>An. gambiae</i>, the two dominant vectors in the region, varied markedly across villages without an overall trend. The between-village variance contributed up to 76% of the total random variation in species composition, followed by the between-year variance. The between-house variation was statistically insignificant. Neither household size nor bed net usage had any impact on species composition.</p> Conclusions <p>Interestingly, the between-house component of variation was the largest contributor when measuring mosquito density, but it was the least important for species composition. For between-village variation, the converse was found. Together with the baseline entomological data, the variance components help parameterise potential field trials for novel vector control programmes and monitoring.</p> Graphical Abstract <p></p>

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Variance partitioning reveals contrasting random effect contributions to the density and species composition of malaria-transmitting mosquitoes in western Burkina Faso

  • Tin-Yu J. Hui,
  • Patric Stephane Epopa,
  • Abdoul Azize Millogo,
  • Franck A. Yao,
  • Dao Koulmaga,
  • Florian Noulin,
  • Abdoulaye Diabate,
  • Austin Burt

摘要

Background

Spatial–temporal variation exists in the density and species composition of malaria-carrying mosquitoes, which will in turn influence the transmission of the disease. While there has been extensive research on seasonality and other main drivers of the vector populations, the heterogeneity partitioned as random effects at various spatial–temporal scales is just as important but has not attracted the same attention.

Methods

To investigate the relative contributions of the between-house, between-village and between-year variations, as well as other house-level covariates such as inhabitant number and bed net usage on vector density and species composition, intensive pyrethroid spray catches (PSC) sampling was conducted across a 60-month period between 2012 and 2019 from four villages in the Sudano-Sahelian region of Burkina Faso.

Results

For density, measured by female Anopheles gambiae s.l. counts, our modelling showed that the between-house variation was the largest variance component, followed by the between-year then between-village variation, after accounting for seasonality and other covariates. Density increased with the number of inhabitants within a household but was uncorrelated with bed net presence. A subset of female mosquitoes was genotyped for species identification, and the composition of An. coluzzii and An. gambiae, the two dominant vectors in the region, varied markedly across villages without an overall trend. The between-village variance contributed up to 76% of the total random variation in species composition, followed by the between-year variance. The between-house variation was statistically insignificant. Neither household size nor bed net usage had any impact on species composition.

Conclusions

Interestingly, the between-house component of variation was the largest contributor when measuring mosquito density, but it was the least important for species composition. For between-village variation, the converse was found. Together with the baseline entomological data, the variance components help parameterise potential field trials for novel vector control programmes and monitoring.

Graphical Abstract