Building the evidence base for dengue vector control: searching for certainty in an uncertain world

Abstract

This review discusses biological and chemical methods for dengue vector control, using recently emerging summary evidence, meta-analyses and systematic reviews to conclude on practical public health recommendations for Aedes control, which is increasingly relevant in an era of widespread Chikungunya, yellow feer and Zika outbreaks. The analysis follows an a priori framework of systematic reviews by the authors on vector control methods, distinguishing vector control methods into biological, chemical and environmental methods. Findings of each published systematic review by the authors, following each individual vector control method, are summarised and compared in the discussion against the findings of existing meta-analyses covering all vector control methods. Analysing nine systematic reviews and comparing to two existing meta-analyses provided low-to-moderate evidence that the control of Aedes mosquitoes can be achieved using 1) chemical methods, particularly indoor residual spraying and insecticide treated materials, and 2) biological methods, where appropriate. The level of efficacy and community effectiveness of the methods in most studies analysed is low, as was the overall assessment of study quality. Furthermore, the results show that too optimise results, larvae and adults should be targeted simultaneously. The quality of service delivery is probably one of the most important features of this analysisand including high coverage. The analysis also highlights the urgent need for standards to guide the design and reporting of vector control studies, ensuring the validity and comparability of results. These studies should aim to include measurements of human transmission datawhere and when possible.

Successful suppression of a field population of Ae. aegypti mosquitoes using a novel biological vector control strategy is associated with significantly lower incidence of dengue

“…Due to the near absence of dengue cases in the treated area, no such reactive intervention was required. Our study directly demonstrates that these highly common reactive measures that are utilized all over the world [26][27][28][29] were ineffective in preventing the continued spike in the number of dengue cases in the control region. Together, these data provide strong evidence that near prevention of dengue transmission in the treated area is exclusively due to NVC male mosquito releases.…”

“…Towards the end of March 2019, they began intervention in a series of reactive actions to try to thwart the outbreak and prevent an epidemic, including massive spraying of the organophosphate Malathion and 'blocking' (an intervention of seeking out larvae in breeding sites in a 100-meter radius around the infected case) of every resident dengue-case reported. This may have impacted the results and led to a certain reduction of the adult and subsequent larvae population in the control region ( Figure 4F, weeks [27][28][29]. Indeed, the incidence of dengue in the control area may have been even graver had the authorities not intervened at all.…”

“…CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. was not certified by peer review) (which The copyright holder for this preprint this version posted November 6, 2019. ; https://doi.org/10.1101/19010678 doi: medRxiv preprint demonstrates that these highly common reactive measures that are utilized all over the world [26][27][28][29] were ineffective in preventing the continued spike in the number of dengue cases in the control region. Together, these data provide strong evidence that near prevention of dengue transmission in the treated area is exclusively due to NVC male mosquito releases.…”

Scientific achievements and reflections after 20 years of vector biology and control research at the Pu Teuy mosquito field research station, Thailand

“…The long-term effectiveness of current approaches to malaria control such as artemisinin-based combination therapy, indoor residual spraying and insecticide-treated materials are undermined by increasing antiparasitic drug resistance, physiological resistance and behavioural responses of mosquito vectors to insecticides [ 1 , 2 ]. Controlling Aedes species, a cosmo tropical vector of dengue, yellow fever, Chikungunya and Nipah viruses remains difficult due to weak evidence from appropriately designed trials to reach a conclusion about any of the control methods available [ 3 , 4 ] Consequently, there is an increasing need for new strategies that exploit novel aspects of vector genetics, physiology, behaviour and ecology. These innovations must be drawn from an understanding of vector biology within natural transmission settings if they are to yield rapid, locally appropriate strategies for disease control [ 5 ].…”

“…Despite decades of organized vector control efforts, vector-borne diseases remain persistent threats and continue to impose a public health burden to vulnerable populations in receptive areas of Thailand [ 8 ]. Among these areas, Kanchanaburi Province is endemic for malaria and dengue, the two most commonly notifiable infections along with a few cases of lymphatic filariasis, Zika, and Chikungunya [ 4 ].…”