Resurgence of malaria after discontinuation of indoor residual spraying of insecticide in a previously high transmission intensity area of Uganda
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Date
2016
Journal Title
Journal ISSN
Volume Title
Publisher
The Lancet Global Health
Abstract
Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) are the primary tools for malaria prevention
in Africa. It is not known whether reductions in malaria can be sustained after IRS is discontinued. Our aim in this study was
to assess changes in malaria morbidity in an area of Uganda with historically high transmission where IRS was discontinued after a
4-year period followed by universal LLIN distribution.
Methods. Individual-level malaria surveillance data were collected from 1 outpatient department and 1 inpatient setting in
Apac District, Uganda, from July 2009 through November 2015. Rounds of IRS were delivered approximately every 6 months from
February 2010 through May 2014 followed by universal LLIN distribution in June 2014. Temporal changes in the malaria test
positivity rate (TPR) were estimated during and after IRS using interrupted time series analyses, controlling for age, rainfall, and
autocorrelation.
Results. Data include 65 421 outpatient visits and 13 955 pediatric inpatient admissions for which a diagnostic test for malaria
was performed. In outpatients aged <5 years, baseline TPR was 60%–80% followed by a rapid and then sustained decrease to 15%–
30%. During the 4–18 months following discontinuation of IRS, absolute TPR values increased by an average of 3.29% per month
(95% confidence interval, 2.01%–4.57%), returning to baseline levels. Similar trends were seen in outpatients aged ≥5 years and
pediatric admissions.
Conclusions. Discontinuation of IRS in an area with historically high transmission intensity was associated with a rapid increase
in malaria morbidity to pre-IRS levels.
Description
Keywords
IRS, Malaria, Resurgence, LLIN, Uganda
Citation
Raouf, S., Mpimbaza, A., Kigozi, R., Sserwanga, A., & Dorsey, G. (2016). Resurgence of malaria after discontinuation of indoor residual spraying of insecticide in a previously high transmission intensity area of Uganda. The Lancet Global Health, 4, S9. DOI: 10.1093/cid/cix251