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The University of Southampton
Interdisciplinary Research Excellence

Applied spatial modelling for population, health and the environment Event

Origin: 
University of Southampton Global Health Research Institute
Time:
12:00 - 13:00
Date:
6 April 2016
Venue:
Building 44, Room 3033 Highfield Campus University of Southampton SO17 1BJ

For more information regarding this event, please email Nicola Wardrop at nicola.wardrop@soton.ac.uk .

Event details

The malaria vector density in a community with high Long-Lasting Insecticide treated mosquito Net (LLIN) use: estimating the effect of indoor residual spraying (IRS) controlling for environmental factors

We are starting a new seminar/meeting group (which is a slightly updated version of the previous Disease Ecology meetings): “applied spatial modelling for population, health and the environment”. The applied spatial modelling seminar group will be meeting once a month, with an alternating focus on population/health and the environment, although the topics discussed should be of wider interest and will give the opportunity for those using spatial modelling methods to interact and hear about approaches in other application area.

These meetings are intended for everyone with an interest in the application of spatial analysis and modelling methods. All are welcome to join us – it’s a great opportunity to get together and discuss on-going research, methods, conferences, publications and more in a relaxed and informal atmosphere. Feel free to bring your lunch. If you would like to give a talk or chair a discussion or journal club at a future meeting, please get in touch with Nicola Wardrop (population and health topics: Nicola.Wardrop@soton.ac.uk)  or Felix Eigenbrod (environment topics: F.Eigenbrod@soton.ac.uk).

Dr Victor Alegana will be talking to us about his recent work looking at the impacts of indoor residual spraying on mosquito abundance. This work has used a Bayesian spatio-temporal modelling framework to control for environmental factors and the influence of other interventions (insecticide treated bed net use).

The malaria vector density in a community with high Long-Lasting Insecticide treated mosquito Net (LLIN) use: estimating the effect of indoor residual spraying (IRS) controlling for environmental factors

With increasing documentation of pyrethroid resistance on malaria control, few studies directly assess the direct impact of indoor residual spraying to malaria anopheles mosquito vectors. Here we assess the impact of household residual spraying on vector abundance in a cohort study with high use of long- lasting insecticides treated bed-nets. Anopheles mosquitoes were collected on a monthly basis via CDC light traps approach in 110 households selected randomly as part of a cohort study from September 2011 to December 2015. Information on use of malaria interventions in the household was also recorded via questionnaire. A Bayesian spatio-temporal model was used to model mosquito densities controlling for environment and interventions. Modelling results suggest that IRS had most impact on Anopheles Gambiae sensus stricto reducing density by approximately 27% compared to 14% on Anopheles funestus (odd ratios 97.5% credible intervals 0.7284 [0.5527 – 0.9563] and 0.8558 [0.5881 – 1.2360]) in area where average LLIN use was 99%. An Gambiae was the most abundant malaria vector collected (89.1%; n=119,008) compared to Anopheles funestus (10.1%, n=13,529). Results suggest that even with documented high levels of pyrethroid resistance and high coverage of long lasting insecticide treated nets, the use IRS was associated with a marked decline malaria vector species in high malaria transmission intensity site.

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