Zika virus: mosquito control works if implemented well; new control tools in the pipeline

18 March 2016

WHO convened a consultation of its Vector Control Advisory Group (VCAG) on 14-15 March 2016 to review existing tools and five potential tools to effectively control the Aedes mosquito populations capable of transmitting Zika virus. The Group concluded that well implemented vector control programmes using existing tools are effective in reducing the transmission of Zika virus by Aedes mosquitoes and should be promoted. The Group further concluded that full-scale deployment is not recommended currently for any of the five new tools reviewed. However, two of the new tools warrant time-limited pilot deployment, accompanied by rigorous monitoring and evaluation, to reinforce the arsenal of available tools.

Mosquito control works if implemented well

Vector control is the most effective way to stop the transmission of Zika virus, chikungunya, dengue and yellow fever which are transmitted by Aedes mosquitoes. If current methods are implemented well—i.e. in an expedient, comprehensive and sustained way—they are effective.

Current tools include: targeted residual spraying of adult Aedes mosquitoes in and around houses; space spraying/indoor fogging where Aedes mosquitoes rest and bite (effective) and outside (less effective); elimination of the Aedes mosquito breeding sites to control the larval stage; personal protection measures (foremost wearing clothes—preferably light-coloured—that cover as much of the body as possible and using insect repellents that contain DEET, IR 3535 or Icaridin).

WHO recommends approaches that tackle all life stages of the Aedes mosquito (egg, larva/pupa and the adult) with full community participation.

New methods to control mosquito populations transmitting Zika virus in the pipeline

The VCAG recommended the carefully planned pilot deployment of two new tools, accompanied by rigorous independent monitoring and evaluation. They include the release of mosquitoes carrying Wolbachia bacteria which propagates itself in the population (symbiotic bacteria suppress the development of the virus in the mosquito and control transmission) and OX513A transgenic male mosquitoes which should be released periodically to suppress the wild population (Aedes larvae carrying the OX513A gene develop normally, but die before becoming an adult).

The Group further concluded that more evidence is required before pilot deployment of the other three tools could be considered. These include sterile insect technique, vector traps and attractive toxic sugar baits (to attract and kill mosquitoes).

Note to editors:

WHO convened the consultation of the WHO Vector Control Advisory Group (VCAG) following the Second meeting of the International Health Regulations (IHR) Emergency Committee on Zika virus held on 8 March, which recommended to: 1) enhance the surveillance of Aedes mosquito populations; 2) promote control measures and personal protective measures; and 3) strengthen vector control measures in the long term.

WHO has established the VCAG, which comprises independent senior experts in entomology (the study of insects) and vector control, in 2013.

For more information please contact:

Ashok Moloo
Telephone: +41 22 791 1637
Mobile phone: +41 79 540 50 86

Saira Stewart
Telephone: +41 22 791 4217
Mobile phone: +41 79 500 65 38

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