Evaluation of personal protection afforded by repellent-treated sandals against mosquito bites in south-eastern Tanzania.
Background Outdoor and early evening mosquito biting needs to be addressed if malaria elimination is to be achieved. While indoor-targeted interventions such as insecticide-treated nets and indoor residual spraying remain essential, complementary approaches that tackle persisting outdoor transmission are urgently required to maximize the impact. Major malaria vectors principally bite human hosts around the feet and ankles. Consequently, this study investigated whether sandals treated with efficacious spatial repellents can protect against outdoor biting mosquitoes.
Methodology Sandals affixed with hessian bands measuring 48cm 2 treated with 6 ml, 10 ml and 12 ml of transfluthrin were tested in large cage semi-field and full field experiments. Sandals affixed with hessian bands measuring 240cm 2 and treated with 10 ml and 12ml of transfluthrin were also tested semi field experiments. Human landing catches (HLC) were used to assess reduction in biting exposure by comparing proportions of mosquitoes landing on volunteers wearing treated and untreated sandals. Sandals were tested against insectary reared Anopheles arabiensis mosquitoes in semi-field experiments and against wild mosquito species in rural Tanzania.
Results In semi-field tests, sandals fitted with hessian bands measuring 48cm 2 and treated with 12 ml, 10ml and 6ml transfluthrin reduced mosquito landings by 45.9%, (95% confidence interval (C.I.) = 28–59%), 61.1% (48%–71%), and 25.9% (9% - 40%) respectively compared to untreated sandals. Sandals fitted with hessian bands measuring 240cm 2 and treated with 12 ml and 10ml transfluthrin reduced mosquito landings by 59% (43 - 71%) and 64% (48 - 74%) respectively. In field experiments, sandals fitted with hessian bands measuring 48cm 2 and treated with 12 ml transfluthrin reduced mosquito landings by 70% (60% - 76%) against Anopheles gambiae s.l and 66.0% (59% - 71%) against all mosquito species combined.
Conclusion Transfluthrin-treated sandals conferred significant protection against mosquito bites in semi-field and field settings. Further evaluation is recommended for this tool as a potential complimentary intervention against malaria. This intervention could be particularly useful for protecting against outdoor exposure to mosquito bites. Additional studies are necessary to optimize treatment techniques and substrates, establish safety profiles and determine epidemiological impact in different settings.
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On 26 Mar, 2020
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On 25 Mar, 2020
Posted 18 Mar, 2020
On 19 Mar, 2020
On 13 Mar, 2020
On 12 Mar, 2020
On 12 Mar, 2020
On 04 Mar, 2020
Received 01 Mar, 2020
On 12 Feb, 2020
Invitations sent on 28 Jan, 2020
On 22 Jan, 2020
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On 21 Jan, 2020
Evaluation of personal protection afforded by repellent-treated sandals against mosquito bites in south-eastern Tanzania.
On 26 Mar, 2020
On 25 Mar, 2020
On 25 Mar, 2020
Posted 18 Mar, 2020
On 19 Mar, 2020
On 13 Mar, 2020
On 12 Mar, 2020
On 12 Mar, 2020
On 04 Mar, 2020
Received 01 Mar, 2020
On 12 Feb, 2020
Invitations sent on 28 Jan, 2020
On 22 Jan, 2020
On 21 Jan, 2020
On 21 Jan, 2020
On 21 Jan, 2020
Background Outdoor and early evening mosquito biting needs to be addressed if malaria elimination is to be achieved. While indoor-targeted interventions such as insecticide-treated nets and indoor residual spraying remain essential, complementary approaches that tackle persisting outdoor transmission are urgently required to maximize the impact. Major malaria vectors principally bite human hosts around the feet and ankles. Consequently, this study investigated whether sandals treated with efficacious spatial repellents can protect against outdoor biting mosquitoes.
Methodology Sandals affixed with hessian bands measuring 48cm 2 treated with 6 ml, 10 ml and 12 ml of transfluthrin were tested in large cage semi-field and full field experiments. Sandals affixed with hessian bands measuring 240cm 2 and treated with 10 ml and 12ml of transfluthrin were also tested semi field experiments. Human landing catches (HLC) were used to assess reduction in biting exposure by comparing proportions of mosquitoes landing on volunteers wearing treated and untreated sandals. Sandals were tested against insectary reared Anopheles arabiensis mosquitoes in semi-field experiments and against wild mosquito species in rural Tanzania.
Results In semi-field tests, sandals fitted with hessian bands measuring 48cm 2 and treated with 12 ml, 10ml and 6ml transfluthrin reduced mosquito landings by 45.9%, (95% confidence interval (C.I.) = 28–59%), 61.1% (48%–71%), and 25.9% (9% - 40%) respectively compared to untreated sandals. Sandals fitted with hessian bands measuring 240cm 2 and treated with 12 ml and 10ml transfluthrin reduced mosquito landings by 59% (43 - 71%) and 64% (48 - 74%) respectively. In field experiments, sandals fitted with hessian bands measuring 48cm 2 and treated with 12 ml transfluthrin reduced mosquito landings by 70% (60% - 76%) against Anopheles gambiae s.l and 66.0% (59% - 71%) against all mosquito species combined.
Conclusion Transfluthrin-treated sandals conferred significant protection against mosquito bites in semi-field and field settings. Further evaluation is recommended for this tool as a potential complimentary intervention against malaria. This intervention could be particularly useful for protecting against outdoor exposure to mosquito bites. Additional studies are necessary to optimize treatment techniques and substrates, establish safety profiles and determine epidemiological impact in different settings.
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