Mosquito nets and impregnated fabrics
Without a vaccine or etiological treatment, the main means of controlling the chikungunya epidemic on Reunion Island is vector control, the measures of which aim to reduce the density of the Aedes albopictus vector; these mosquito control operations must also be accompanied by personal protection measures to protect the general population from mosquito bites.
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Recommendations encouraging the use of mosquito nets or impregnated clothing have been issued by several organisations (Afssaps, InVS, etc.), especially to protect children under 30 months of age and pregnant women. The conditions for using these protective means had to be specified and the short, medium and long term toxicity of using them repeatedly needed to be assessed. |
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General points & contextual elements:
Within the framework of managing the chikungunya epidemic on Reunion Island, on 22 August 2006 the Director General for Health (DGS-French Ministry of Health and Solidarities) and Director of Risk and Pollution Prevention (DPPR-French Ministry of Ecology and Sustainable Development) sent a solicited request to Afsset on the assessment of risks associated with the use of insecticide products for impregnating mosquito nets and clothing.
This solicited request forms part of the research already completed or currently under way by Afsset on the assessments of vector control products in the framework of managing the chikungunya crisis on Reunion Island: 
Solicited request of 26 January 2006 from the DGS and DPPR, on the assessment of dangers and risks associated with the use of the biocidal active substance temephos, with regard to an essential use application; Solicited request of 10 February 2006 from the DGS, Directorate of Work Relations (DRT) and DPPR, on the comparative assessment of the dangers and risks associated with the use of adulticide vector control products, and complementary application of 24 August 2006 to assess the effectiveness of potential substrates, Solicited request of 24 August 2006 from the DGS, DRT and DPPR, on the comparative assessment of the dangers and risks associated with the use of larvicide products for vector control. 
Working method:
Following the presentation of the 2006/7 solicited request to the Assessment of risks associated with biocidal products and substances committee of specialised experts (CSE) on 21 September 2006, it seemed necessary that this assessment be entrusted to a dedicated working group, in view of the specific nature of the request.
The group was composed so as to gather the skills of the toxicologists from the Biocides CSE and of the entomologists from the IRD, World Health Organization (WHO) and French army health services.
The group met on three occasions (30 October 2006, 18 December 2006 and 31 January 2007).
During the meeting of 18 December 2006, the InVS presented the group with epidemiological data concerning the chikungunya epidemic on Reunion Island and in Mayotte. During the meeting of 31 January 2007, the DGS compiled a list of the recommendations formulated in terms of the personal protection of the population from mosquito bites. 
On the basis of the literature and international recommendations (particularly from WHO), the experts identified the products available on the market and the associated dangers. Scenarios of use were then proposed and the corresponding exposures assessed.
Permethrin and deltamethrin are two commonly used active substances for impregnating fabrics.
Although the effectiveness of a mosquito net to protect against mosquitoes acting during the day, such as Aedes, may be surprising at first, the experts showed that the interest in terms of disease transmission was major.
The isolation of patients suspected of being infected by the chikungunya virus under mosquito nets helps to prevent mosquitoes which come to feed on their blood from becoming contaminated and infecting other people.
Mosquito nets also protect vulnerable populations such as young children who do not yet walk, bedridden people and pregnant women.
The experts recommended using longlife industrially impregnated mosquito nets, the assessment of which has not revealed any risk in particular.
Lastly, experts showed that the use of impregnated clothing could also provide additional protection, particularly for populations whose activity did not enable them to stay under a mosquito net. This scientific expert assessment was accompanied by recommendations for use so as to guarantee the safety of users.
Lastly, the experts stressed that these recommendations could be applicable to other epidemic contexts than the one on Reunion Island, when the behaviour of the vector mosquito was comparable to the Aedes.
More information:
Chikungunya epidemic on Reunion Island 
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