Cargando…

Forecasting the effectiveness of indoor residual spraying for reducing dengue burden

BACKGROUND: Historically, mosquito control programs successfully helped contain malaria and yellow fever, but recent efforts have been unable to halt the spread of dengue, chikungunya, or Zika, all transmitted by Aedes mosquitoes. Using a dengue transmission model and results from indoor residual sp...

Descripción completa

Detalles Bibliográficos
Autores principales: Hladish, Thomas J., Pearson, Carl A. B., Patricia Rojas, Diana, Gomez-Dantes, Hector, Halloran, M. Elizabeth, Vazquez-Prokopec, Gonzalo M., Longini, Ira M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6042783/
https://www.ncbi.nlm.nih.gov/pubmed/29939983
http://dx.doi.org/10.1371/journal.pntd.0006570
_version_ 1783339219385581568
author Hladish, Thomas J.
Pearson, Carl A. B.
Patricia Rojas, Diana
Gomez-Dantes, Hector
Halloran, M. Elizabeth
Vazquez-Prokopec, Gonzalo M.
Longini, Ira M.
author_facet Hladish, Thomas J.
Pearson, Carl A. B.
Patricia Rojas, Diana
Gomez-Dantes, Hector
Halloran, M. Elizabeth
Vazquez-Prokopec, Gonzalo M.
Longini, Ira M.
author_sort Hladish, Thomas J.
collection PubMed
description BACKGROUND: Historically, mosquito control programs successfully helped contain malaria and yellow fever, but recent efforts have been unable to halt the spread of dengue, chikungunya, or Zika, all transmitted by Aedes mosquitoes. Using a dengue transmission model and results from indoor residual spraying (IRS) field experiments, we investigated how IRS-like campaign scenarios could effectively control dengue in an endemic setting. METHODS AND FINDINGS: In our model, we found that high levels of household coverage (75% treated once per year), applied proactively before the typical dengue season could reduce symptomatic infections by 89.7% (median of 1000 simulations; interquartile range [IQR]:[83.0%, 94.8%]) in year one and 78.2% (IQR: [71.2%, 88.0%]) cumulatively over the first five years of an annual program. Lower coverage had correspondingly lower effectiveness, as did reactive campaigns. Though less effective than preventative campaigns, reactive and even post-epidemic interventions retain some effectiveness; these campaigns disrupt inter-seasonal transmission, highlighting an off-season control opportunity. Regardless, none of the campaign scenarios maintain their initial effectiveness beyond two seasons, instead stabilizing at much lower levels of benefit: in year 20, median effectiveness was only 27.3% (IQR: [-21.3%, 56.6%]). Furthermore, simply ceasing an initially successful program exposes a population with lowered herd immunity to the same historical threat, and we observed outbreaks more than four-fold larger than pre-intervention outbreaks. These results do not take into account evolving insecticide resistance, thus long-term effectiveness may be lower if new, efficacious insecticides are not developed. CONCLUSIONS: Using a detailed agent-based dengue transmission model for Yucatán State, Mexico, we predict that high coverage indoor residual spraying (IRS) interventions can largely eliminate transmission for a few years, when applied a few months before the typical seasonal epidemic peak. However, vector control succeeds by preventing infections, which precludes natural immunization. Thus, as a population benefits from mosquito control, it gradually loses naturally acquired herd immunity, and the control effectiveness declines; this occurs across all of our modeled scenarios, and is consistent with other empirical work. Long term control that maintains early effectiveness would require some combination of increasing investment, complementary interventions such as vaccination, and control programs across a broad region to diminish risk of importation.
format Online
Article
Text
id pubmed-6042783
institution National Center for Biotechnology Information
language English
publishDate 2018
publisher Public Library of Science
record_format MEDLINE/PubMed
spelling pubmed-60427832018-07-26 Forecasting the effectiveness of indoor residual spraying for reducing dengue burden Hladish, Thomas J. Pearson, Carl A. B. Patricia Rojas, Diana Gomez-Dantes, Hector Halloran, M. Elizabeth Vazquez-Prokopec, Gonzalo M. Longini, Ira M. PLoS Negl Trop Dis Research Article BACKGROUND: Historically, mosquito control programs successfully helped contain malaria and yellow fever, but recent efforts have been unable to halt the spread of dengue, chikungunya, or Zika, all transmitted by Aedes mosquitoes. Using a dengue transmission model and results from indoor residual spraying (IRS) field experiments, we investigated how IRS-like campaign scenarios could effectively control dengue in an endemic setting. METHODS AND FINDINGS: In our model, we found that high levels of household coverage (75% treated once per year), applied proactively before the typical dengue season could reduce symptomatic infections by 89.7% (median of 1000 simulations; interquartile range [IQR]:[83.0%, 94.8%]) in year one and 78.2% (IQR: [71.2%, 88.0%]) cumulatively over the first five years of an annual program. Lower coverage had correspondingly lower effectiveness, as did reactive campaigns. Though less effective than preventative campaigns, reactive and even post-epidemic interventions retain some effectiveness; these campaigns disrupt inter-seasonal transmission, highlighting an off-season control opportunity. Regardless, none of the campaign scenarios maintain their initial effectiveness beyond two seasons, instead stabilizing at much lower levels of benefit: in year 20, median effectiveness was only 27.3% (IQR: [-21.3%, 56.6%]). Furthermore, simply ceasing an initially successful program exposes a population with lowered herd immunity to the same historical threat, and we observed outbreaks more than four-fold larger than pre-intervention outbreaks. These results do not take into account evolving insecticide resistance, thus long-term effectiveness may be lower if new, efficacious insecticides are not developed. CONCLUSIONS: Using a detailed agent-based dengue transmission model for Yucatán State, Mexico, we predict that high coverage indoor residual spraying (IRS) interventions can largely eliminate transmission for a few years, when applied a few months before the typical seasonal epidemic peak. However, vector control succeeds by preventing infections, which precludes natural immunization. Thus, as a population benefits from mosquito control, it gradually loses naturally acquired herd immunity, and the control effectiveness declines; this occurs across all of our modeled scenarios, and is consistent with other empirical work. Long term control that maintains early effectiveness would require some combination of increasing investment, complementary interventions such as vaccination, and control programs across a broad region to diminish risk of importation. Public Library of Science 2018-06-25 /pmc/articles/PMC6042783/ /pubmed/29939983 http://dx.doi.org/10.1371/journal.pntd.0006570 Text en © 2018 Hladish et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Hladish, Thomas J.
Pearson, Carl A. B.
Patricia Rojas, Diana
Gomez-Dantes, Hector
Halloran, M. Elizabeth
Vazquez-Prokopec, Gonzalo M.
Longini, Ira M.
Forecasting the effectiveness of indoor residual spraying for reducing dengue burden
title Forecasting the effectiveness of indoor residual spraying for reducing dengue burden
title_full Forecasting the effectiveness of indoor residual spraying for reducing dengue burden
title_fullStr Forecasting the effectiveness of indoor residual spraying for reducing dengue burden
title_full_unstemmed Forecasting the effectiveness of indoor residual spraying for reducing dengue burden
title_short Forecasting the effectiveness of indoor residual spraying for reducing dengue burden
title_sort forecasting the effectiveness of indoor residual spraying for reducing dengue burden
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6042783/
https://www.ncbi.nlm.nih.gov/pubmed/29939983
http://dx.doi.org/10.1371/journal.pntd.0006570
work_keys_str_mv AT hladishthomasj forecastingtheeffectivenessofindoorresidualsprayingforreducingdengueburden
AT pearsoncarlab forecastingtheeffectivenessofindoorresidualsprayingforreducingdengueburden
AT patriciarojasdiana forecastingtheeffectivenessofindoorresidualsprayingforreducingdengueburden
AT gomezdanteshector forecastingtheeffectivenessofindoorresidualsprayingforreducingdengueburden
AT halloranmelizabeth forecastingtheeffectivenessofindoorresidualsprayingforreducingdengueburden
AT vazquezprokopecgonzalom forecastingtheeffectivenessofindoorresidualsprayingforreducingdengueburden
AT longiniiram forecastingtheeffectivenessofindoorresidualsprayingforreducingdengueburden