The World Health Organization recommends certain deltamethrin-impregnated mosquito nets to avoid the transmission of vector-borne diseases spread by mosquitoes. In France, these mosquito nets are not covered by any marketing authorisation, so they cannot be used in compliance with biocide regulations. In the context of the current Zika epidemic in the French départements of the Americas, the French High Council for Public Health recommends that France request a waiver from the European Union for the use of long-lasting deltamethrin-impregnated mosquito nets. In this context, ANSES has been asked by the Ministry of Ecology to urgently publish an opinion on the appropriateness of derogatory use of long-lasting deltamethrin-impregnated mosquito nets as provided for under Article 55.2 of the Biocidal Products Regulation. On the basis of available data, ANSES concludes that the use of such mosquito nets may be authorised. However, the Agency recommends attaching the net around the bed of infants and children so that it is difficult for them to reach, to ensure that they cannot put it into their mouths. It also recommends using mosquito nets whose efficacy has been validated by the World Health Organization and to restrict washes to a minimum given the toxicity of deltamethrin for the aquatic environment.
Deltamethrin is an active biocidal substance approved within Europe to combat insects, mites and other arthropods. Deltamethrin-impregnated mosquito nets are recommended by the World Health Organization (WHO) to avoid the transmission of vector-borne diseases spread by mosquitoes.
In France, long-lasting deltamethrin-impregnated mosquito nets are not covered by any marketing authorisation and cannot, therefore, be used.
In the context of the current Zika epidemic in the French départements of the Americas, the French High Council for Public Health published an opinion on 18 January 2016 recommending that the competent French authority allow the derogatory use of deltamethrin-impregnated mosquito nets. ANSES was therefore requested by the French Ministry of Ecology to urgently publish an opinion on the appropriateness of derogatory use of deltamethrin-impregnated mosquito nets as provided for under Article 55.2 of the Biocidal Products Regulation.
ANSES based its work on WHO assessments as regards the technical characteristics and efficacy of long-lasting deltamethrin-impregnated mosquito nets. The use of nets meeting all WHO criteria should be preferred. These mosquito nets meet criteria of efficacy and resistance to washing, having proven effective after three years of use in the field.
ANSES furthermore considers that despite mosquito resistance to deltamethrin, widely accepted in the literature and demonstrated in the French overseas départements, mosquito nets impregnated with a long-lasting insecticide still remain favourably effective to repel adult mosquitoes.
The Agency’s recommendations
On the basis of available data, in the opinion published today, ANSES considers that the risk related to the use of mosquito nets is acceptable for human health insofar as, for infants and young children, the mosquito net is attached around the bed so that children cannot grasp it and put it in their mouths.
In addition, in the light of the highly toxic nature of deltamethrin for the aquatic environment, the Agency strongly recommends restricting the washing of nets to a minimum.
As no data are available on the risk for human health and the environment and the efficacy of re-impregnation of nets with deltamethrin, ANSES does not recommend this practice.
Finally, the Agency considers it necessary for the services responsible for distributing mosquito nets to inform users on the precautions to be taken as to their use and ensure the correct application of management measures.
Currently, very few active larvicide and adulticide substances are used for vector control in France. The widespread use of deltamethrin, without alternating between other active substances, has led to the emergence of proven resistance among mosquitoes in the overseas départements. The agricultural and veterinary use of this compound accentuates this issue. There is therefore a vital need for a broader range of active substances not only in the short term but the medium term, because vector control actions against arbovirus and other pathogens are bound to spread throughout the French territory. Although authorised exceptionally by European regulations, the derogatory use of prohibited substances or products no longer appears a suitable and sustainable strategy.
ANSES was asked on 3 June 2009 by the French Ministries of Ecology, Health and Labour to help select active substances that might be useful for vector control. In 2012, ANSES put forward a short-list of 32 active substances following multi-criteria analysis combining toxicity, eco-toxicity, exposure and environmental fate. These substances were then grouped into three classes corresponding to use in the short-, medium- or long-term.
ANSES is today publishing an updated list of active substances that might be used for vector control with respect to their known usage and regulatory status within Europe. This is not a risk assessment but a list of active substances of interest that might be useful for vector control, upon which efforts should be concentrated in order to encourage manufacturers and foster research. ANSES also recommends developing efficacy trials and exposure models designed to estimate the exposure for operators, the general population and the environment, dedicated to the specific uses involved in vector control so as to conduct a detailed risk assessment and compare the different products.