Residual insecticidal activity of long-lasting deltamethrin-treated curtains after 1 year of household use for dengue control.
OBJECTIVE
To evaluate the residual insecticidal activity of the PermaNet(®) curtains on Aedes aegypti after 1 year of use in Thai households and to assess the influence of sun and dust exposure, washing practices and detergent use.


METHODS
We sampled UV-protected PermaNet(®) curtains made of a long-lasting deltamethrin-[55 mg/m(2)] treated polyester netting, before (10 curtains) and after 8 (10 curtains) and 12 months (66 curtains) of household use in a field site in Chon Buri, Thailand. We assessed the residual insecticidal activity of the curtains by standard WHO bioassay, using a deltamethrin-susceptible insectarium Aedes aegypti strain.


RESULTS
Mosquito mortality was 100% before distribution, 100% at 8 months and 98.2% (95% CI 97.9-98.5) at 12 months of use. Sunlight, hand-washing and detergent use had no effect on the residual insecticidal activity after 12 months. However, the mosquito survival rate increased by a factor of 6.4 (95% CI 3.5-11.8) on machine-washed curtains and by a factor of 2.0 (95% CI 1.4-2.9) on curtains not covered by dust.


CONCLUSIONS
The residual insecticidal activity of PermaNet® curtains remains high after 12 months use under field conditions.
Vanlerberghe
V
V
Epidemiology and Disease Control Unit, Institute of Tropical Medicine, Antwerp, Belgium. vvanlerberghe@itg.be
Trongtokit
Y
Y
Cremonini
L
L
Jirarojwatana
S
S
Apiwathnasorn
C
C
Van der Stuyft
P
P
D000330:Aedes / Q000187:drug effects*; D000818:Animals; D001512:Bedding and Linens; D003715:Dengue / Q000517:prevention & control*; D003902:Detergents; D004391:Dust; D006801:Humans; D007306:Insecticides / Q000032:analysis* / Q000494:pharmacology; D007846:Laundering; D009032:Mosquito Control / Q000379:methods*; D009570:Nitriles / Q000032:analysis* / Q000494:pharmacology; D011722:Pyrethrins / Q000032:analysis* / Q000494:pharmacology; D013472:Sunlight; D013785:Thailand; D013997:Time Factors
D003902:Detergents; D004391:Dust; D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin