Outdoor residual spraying for malaria vector-control in Kayin (Karen) state, Myanmar: A cluster randomized controlled trial
2
Issued Date
2022-09-01
Resource Type
eISSN
19326203
Scopus ID
2-s2.0-85137656153
Pubmed ID
36083983
Journal Title
PLoS ONE
Volume
17
Issue
9 September
Rights Holder(s)
SCOPUS
Bibliographic Citation
PLoS ONE Vol.17 No.9 September (2022)
Suggested Citation
Chaumeau V., Kajeechiwa L., Kulabkeeree T., Sawasdichai S., Haohankhunnatham W., Inta A., Phanaphadungtham M., Girond F., Herbreteau V., Delmas G., Nosten F. Outdoor residual spraying for malaria vector-control in Kayin (Karen) state, Myanmar: A cluster randomized controlled trial. PLoS ONE Vol.17 No.9 September (2022). doi:10.1371/journal.pone.0274320 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/86480
Title
Outdoor residual spraying for malaria vector-control in Kayin (Karen) state, Myanmar: A cluster randomized controlled trial
Other Contributor(s)
Abstract
Outdoor and early biting by mosquitoes challenge the efficacy of bed nets and indoor residual spraying against malaria in the Greater Mekong Subregion. The objective of this study was to assess the efficacy of outdoor residual spraying (ORS) for malaria vector-control in this region. A cluster randomized controlled trial was conducted between July 2018 and April 2019 in twelve villages in Karen (Kayin) state, Myanmar. Villages were randomly assigned to receive either a single round of ORS with a capsule suspension of lambda-cyhalothrin for two days in October or no intervention (six villages per group). The primary endpoint was the biting rate of malaria mosquitoes assessed with human-landing catch and cow-baited trap collection methods, and was analyzed with a Bayesian multi-level model. In the intervention villages, the proportion of households located within the sprayed area ranged between 42 and 100% and the application rate ranged between 63 and 559 g of active ingredient per hectare. At baseline, the median of Anopheles biting rate estimates in the twelve villages was 2 bites per person per night (inter-quartile range [IQR] 0–5, range 0–48) indoors, 6 bites per person per night (IQR 2–16, range 0–342) outdoors and 206 bites per cow per night (IQR 83–380, range 19–1149) in the cow-baited trap. In intention-to-treat analysis, it was estimated that ORS reduced biting rate by 72% (95% confidence interval [CI] 63–79) from Month 0 to Month 3 and by 79% (95% CI 62–88) from Month 4 to Month 6, considering control villages as the reference. In conclusion, ORS rapidly reduces the biting rates of malaria mosquitoes in a Southeast Asian setting where the vectors bite mostly outdoors and at a time when people are not protected by mosquito bed nets.