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Permethrin-Treated Clothing as Protection against the Dengue Vector, Aedes aegypti: Extent and Duration of Protection.

DeRaedt Banks S, Orsborne J, Gezan SA, Kaur H, Wilder-Smith A, Lindsey SW, Logan JG - PLoS Negl Trop Dis (2015)

Bottom Line: Washing duration and technique had a significant effect, with insecticidal longevity shown to be greater with machine washing (LW50 = 33.4) compared to simulated hand washing (LW50 = 17.6).Ironing significantly reduced permethrin content after 1 week of simulated use, with a 96.7% decrease after 3 months although UV exposure did not reduce permethrin content within clothing significantly after 3 months simulated use.However, our findings also suggest that clothing may provide only short-term protection due to the effect of washing and ironing, highlighting the need for improved fabric treatment techniques.

View Article: PubMed Central - PubMed

Affiliation: Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom.

ABSTRACT

Introduction: Dengue transmission by the mosquito vector, Aedes aegypti, occurs indoors and outdoors during the day. Personal protection of individuals, particularly when outside, is challenging. Here we assess the efficacy and durability of different types of insecticide-treated clothing on laboratory-reared Ae. aegypti.

Methods: Standardised World Health Organisation Pesticide Evaluation Scheme (WHOPES) cone tests and arm-in-cage assays were used to assess knockdown (KD) and mortality of Ae. aegypti tested against factory-treated fabric, home-dipped fabric and microencapsulated fabric. Based on the testing of these three different treatment types, the most protective was selected for further analysis using arm-in cage assays with the effect of washing, ultra-violet light, and ironing investigated using high pressure liquid chromatography.

Results: Efficacy varied between the microencapsulated and factory dipped fabrics in cone testing. Factory-dipped clothing showed the greatest effect on KD (3 min 38.1%; 1 hour 96.5%) and mortality (97.1%) with no significant difference between this and the factory dipped school uniforms. Factory-dipped clothing was therefore selected for further testing. Factory dipped clothing provided 59% (95% CI = 49.2%- 66.9%) reduction in landing and a 100% reduction in biting in arm-in-cage tests. Washing duration and technique had a significant effect, with insecticidal longevity shown to be greater with machine washing (LW50 = 33.4) compared to simulated hand washing (LW50 = 17.6). Ironing significantly reduced permethrin content after 1 week of simulated use, with a 96.7% decrease after 3 months although UV exposure did not reduce permethrin content within clothing significantly after 3 months simulated use.

Conclusion: Permethrin-treated clothing may be a promising intervention in reducing dengue transmission. However, our findings also suggest that clothing may provide only short-term protection due to the effect of washing and ironing, highlighting the need for improved fabric treatment techniques.

No MeSH data available.


Related in: MedlinePlus

Flow chart of study design and experiments performed.*Denotes that the treatment technique was not included in all efficacy evaluation tests. FDSU was not included in Arm-in-cage assays and HDC was not included in the cone assays.
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pntd.0004109.g001: Flow chart of study design and experiments performed.*Denotes that the treatment technique was not included in all efficacy evaluation tests. FDSU was not included in Arm-in-cage assays and HDC was not included in the cone assays.

Mentions: Following the initial cone and arm-in-cage tests to compare different treatment types, residual activity was evaluated on the FDC only. FDC materials were washed 1, 5, 10, 15, 20, 25, 30 times using a) the WHOPES bottle washing method [18] and b) machine washing. This comparison was important because some residents in Thailand hand-wash their clothes, whilst others use washing machines. Cone assays were then performed on these materials with KD and mortality recorded and HPLC analysis performed to quantify permethrin content within the washed fabrics. FDC clothing was also washed and exposed to ironing, ultraviolet light (UV) or both UV and ironing in combination, for varying degrees of time to simulate field use, then analysed by HPLC to quantify permethrin content. A summary of the testing is provided in Fig 1.


Permethrin-Treated Clothing as Protection against the Dengue Vector, Aedes aegypti: Extent and Duration of Protection.

DeRaedt Banks S, Orsborne J, Gezan SA, Kaur H, Wilder-Smith A, Lindsey SW, Logan JG - PLoS Negl Trop Dis (2015)

Flow chart of study design and experiments performed.*Denotes that the treatment technique was not included in all efficacy evaluation tests. FDSU was not included in Arm-in-cage assays and HDC was not included in the cone assays.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595206&req=5

pntd.0004109.g001: Flow chart of study design and experiments performed.*Denotes that the treatment technique was not included in all efficacy evaluation tests. FDSU was not included in Arm-in-cage assays and HDC was not included in the cone assays.
Mentions: Following the initial cone and arm-in-cage tests to compare different treatment types, residual activity was evaluated on the FDC only. FDC materials were washed 1, 5, 10, 15, 20, 25, 30 times using a) the WHOPES bottle washing method [18] and b) machine washing. This comparison was important because some residents in Thailand hand-wash their clothes, whilst others use washing machines. Cone assays were then performed on these materials with KD and mortality recorded and HPLC analysis performed to quantify permethrin content within the washed fabrics. FDC clothing was also washed and exposed to ironing, ultraviolet light (UV) or both UV and ironing in combination, for varying degrees of time to simulate field use, then analysed by HPLC to quantify permethrin content. A summary of the testing is provided in Fig 1.

Bottom Line: Washing duration and technique had a significant effect, with insecticidal longevity shown to be greater with machine washing (LW50 = 33.4) compared to simulated hand washing (LW50 = 17.6).Ironing significantly reduced permethrin content after 1 week of simulated use, with a 96.7% decrease after 3 months although UV exposure did not reduce permethrin content within clothing significantly after 3 months simulated use.However, our findings also suggest that clothing may provide only short-term protection due to the effect of washing and ironing, highlighting the need for improved fabric treatment techniques.

View Article: PubMed Central - PubMed

Affiliation: Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom.

ABSTRACT

Introduction: Dengue transmission by the mosquito vector, Aedes aegypti, occurs indoors and outdoors during the day. Personal protection of individuals, particularly when outside, is challenging. Here we assess the efficacy and durability of different types of insecticide-treated clothing on laboratory-reared Ae. aegypti.

Methods: Standardised World Health Organisation Pesticide Evaluation Scheme (WHOPES) cone tests and arm-in-cage assays were used to assess knockdown (KD) and mortality of Ae. aegypti tested against factory-treated fabric, home-dipped fabric and microencapsulated fabric. Based on the testing of these three different treatment types, the most protective was selected for further analysis using arm-in cage assays with the effect of washing, ultra-violet light, and ironing investigated using high pressure liquid chromatography.

Results: Efficacy varied between the microencapsulated and factory dipped fabrics in cone testing. Factory-dipped clothing showed the greatest effect on KD (3 min 38.1%; 1 hour 96.5%) and mortality (97.1%) with no significant difference between this and the factory dipped school uniforms. Factory-dipped clothing was therefore selected for further testing. Factory dipped clothing provided 59% (95% CI = 49.2%- 66.9%) reduction in landing and a 100% reduction in biting in arm-in-cage tests. Washing duration and technique had a significant effect, with insecticidal longevity shown to be greater with machine washing (LW50 = 33.4) compared to simulated hand washing (LW50 = 17.6). Ironing significantly reduced permethrin content after 1 week of simulated use, with a 96.7% decrease after 3 months although UV exposure did not reduce permethrin content within clothing significantly after 3 months simulated use.

Conclusion: Permethrin-treated clothing may be a promising intervention in reducing dengue transmission. However, our findings also suggest that clothing may provide only short-term protection due to the effect of washing and ironing, highlighting the need for improved fabric treatment techniques.

No MeSH data available.


Related in: MedlinePlus