Malaria control programme utilizing indoor residual spraying of chemical insecticide is only effective if a high coverage of targeted area is achieved. The effectiveness of the residual spraying, on the other hand, re...Malaria control programme utilizing indoor residual spraying of chemical insecticide is only effective if a high coverage of targeted area is achieved. The effectiveness of the residual spraying, on the other hand, relies on the efficacy and residual activity of the insecticides applied, which to a certain extent are influenced by the nature of the sprayed surfaces. The bioefficacy of indoor residual-sprayed deltamethrin wettable granule (WG) formulation for the control of malaria was compared with the current dose of deltamethrin wettable powder (WP) in malaria endemic areas in Balai Ringin, Sarawak. Doses of 20 mg/m2 WP (control), 20 mg/m2 WG, 30 mg/m2 WG and 40 mg/m2 WG were sprayed separately on different surfaces namely, wooden, rough-bamboo, smooth-bamboo and brick surfaces. Residual activity of WP and WG formulations was tested against lab-bred Anopheles maculatus using WHO standard procedure. Deltamethrin at 30 mg/m2 WG exhibited the highest sustainable level of effectiveness against An. maculatus (An. maculatus mortality was between 95% - 100%) up to week 60 post-spraying when sprayed on smooth- bamboo surface. These results indicated that 30 mg/m2 WG could be an ideal concentration for controlling malaria vector effectively up to 15 months of which long-lasting residual spraying was envisaged. The usual two spraying cycles per year with 20 mg/m2 deltamethrin WP could be replaced with 30 mg/m2 deltamethrin WG since the long residual activity was achieved by employing a single spraying only.展开更多
Knowledge of the composition and biting habits of mosquito associated with endemic areas is important in establishing sound vector control programmes and understanding the epidemiology of vector borne diseases. The bi...Knowledge of the composition and biting habits of mosquito associated with endemic areas is important in establishing sound vector control programmes and understanding the epidemiology of vector borne diseases. The biting activity cycle of several mosquito species in Serian, Sarawak was observed and described. Collections were carried out indoors and outdoors for 12 hours from 6.00 pm to 6.00 am using human landing catch techniques. A total of 7271 mosquitoes comprising 27 species belonging to sixgenera were collected. Mansonia bonneae (23.6%) was the predominant species caught in the study areas followed by Culex vishnui (22.3%), Culex pseudovishnui (19.6%) and Culex tritaenorhynchus (13.7%). A high rate of human biting activity by Ma. bonneae was detected during November but the activity was low during January.The biting activity of Ma.bonneae was found higher outdoor compared to indoorand peaked at 7.00 pm-8.00 pm.Cx.vishnui also exhibited similar biting activity peak while Anopheles letiferex-hibited biting activity peaked at 12.00 am-1.00 am.Cx.pseudovishnui showed biting patterns which were almost similar between indoor and outdoor activity and could be considered active throughout the 12 hour period.展开更多
The incidence of dengue in Malaysia has shown an increasing trend since the year 2000. Vector control is the primary approach for dengue control in Malaysia. There is an urgent need for new or modified approaches such...The incidence of dengue in Malaysia has shown an increasing trend since the year 2000. Vector control is the primary approach for dengue control in Malaysia. There is an urgent need for new or modified approaches such as the residual spraying on the outer walls that can potentially last long enough to control the Aedes population, particularly in the outbreak-prone areas. In this field study, we conducted outdoor residual spraying (ORS) using a newly formulated polymer-enhanced suspension concentrate (SC-PE) of deltamethrin. The objectives of this study were to evaluate the efficacy of ORS using deltamethrin SC-PE and its effect on wild Aedes populations and to assess its residual bio-efficacy on painted cement walls against the pyrethroid-susceptible strains of laboratory-reared Aedes mosquitoes. Three rounds of spraying in a four-month cycle were conducted between 2014 and 2015 in four residential areas (low-rise and high-rise housing types) in Hulu Langat, Selangor. The bio-efficacy of the insecticide was evaluated by assessing its impact on vector population using ovitrap surveillance. Standard WHO wall deposit bioassay was adapted to determine bio-efficacy of deltamethrin, i.e. post 30 min knockdown and post 24 h mortality after exposure. During the treatment period, we observed significant reductions in the population of Ae. albopictus in the sprayed low-rise housing in both semi-indoor and outdoor environments, while in the high-rise housing, there was also a significant decline in Ae. aegypti population in the semi-indoor environment. The evaluation of the residual bio-efficacy of deltamethrin SC-PE against laboratory-reared Aedes mosquitoes showed that the insecticide lasted longer in the high-rise housing compared to the low-rise housing with >80% mortality achieved continuously for 16 weeks. We provide initial evidence on residual efficacy of deltamethrin SC-PE in reducing Aedes population size in the low-rise and high-rise housing. Our results showed that ORS is a promising tool in the dengue vector control and like IRS in malaria control;it is a powerful and effective method if conducted correctly. However, large scale and well-designed studies with entomological and epidemiological endpoints are still warranted before its routine use in dengue control.展开更多
文摘Malaria control programme utilizing indoor residual spraying of chemical insecticide is only effective if a high coverage of targeted area is achieved. The effectiveness of the residual spraying, on the other hand, relies on the efficacy and residual activity of the insecticides applied, which to a certain extent are influenced by the nature of the sprayed surfaces. The bioefficacy of indoor residual-sprayed deltamethrin wettable granule (WG) formulation for the control of malaria was compared with the current dose of deltamethrin wettable powder (WP) in malaria endemic areas in Balai Ringin, Sarawak. Doses of 20 mg/m2 WP (control), 20 mg/m2 WG, 30 mg/m2 WG and 40 mg/m2 WG were sprayed separately on different surfaces namely, wooden, rough-bamboo, smooth-bamboo and brick surfaces. Residual activity of WP and WG formulations was tested against lab-bred Anopheles maculatus using WHO standard procedure. Deltamethrin at 30 mg/m2 WG exhibited the highest sustainable level of effectiveness against An. maculatus (An. maculatus mortality was between 95% - 100%) up to week 60 post-spraying when sprayed on smooth- bamboo surface. These results indicated that 30 mg/m2 WG could be an ideal concentration for controlling malaria vector effectively up to 15 months of which long-lasting residual spraying was envisaged. The usual two spraying cycles per year with 20 mg/m2 deltamethrin WP could be replaced with 30 mg/m2 deltamethrin WG since the long residual activity was achieved by employing a single spraying only.
文摘Knowledge of the composition and biting habits of mosquito associated with endemic areas is important in establishing sound vector control programmes and understanding the epidemiology of vector borne diseases. The biting activity cycle of several mosquito species in Serian, Sarawak was observed and described. Collections were carried out indoors and outdoors for 12 hours from 6.00 pm to 6.00 am using human landing catch techniques. A total of 7271 mosquitoes comprising 27 species belonging to sixgenera were collected. Mansonia bonneae (23.6%) was the predominant species caught in the study areas followed by Culex vishnui (22.3%), Culex pseudovishnui (19.6%) and Culex tritaenorhynchus (13.7%). A high rate of human biting activity by Ma. bonneae was detected during November but the activity was low during January.The biting activity of Ma.bonneae was found higher outdoor compared to indoorand peaked at 7.00 pm-8.00 pm.Cx.vishnui also exhibited similar biting activity peak while Anopheles letiferex-hibited biting activity peaked at 12.00 am-1.00 am.Cx.pseudovishnui showed biting patterns which were almost similar between indoor and outdoor activity and could be considered active throughout the 12 hour period.
文摘The incidence of dengue in Malaysia has shown an increasing trend since the year 2000. Vector control is the primary approach for dengue control in Malaysia. There is an urgent need for new or modified approaches such as the residual spraying on the outer walls that can potentially last long enough to control the Aedes population, particularly in the outbreak-prone areas. In this field study, we conducted outdoor residual spraying (ORS) using a newly formulated polymer-enhanced suspension concentrate (SC-PE) of deltamethrin. The objectives of this study were to evaluate the efficacy of ORS using deltamethrin SC-PE and its effect on wild Aedes populations and to assess its residual bio-efficacy on painted cement walls against the pyrethroid-susceptible strains of laboratory-reared Aedes mosquitoes. Three rounds of spraying in a four-month cycle were conducted between 2014 and 2015 in four residential areas (low-rise and high-rise housing types) in Hulu Langat, Selangor. The bio-efficacy of the insecticide was evaluated by assessing its impact on vector population using ovitrap surveillance. Standard WHO wall deposit bioassay was adapted to determine bio-efficacy of deltamethrin, i.e. post 30 min knockdown and post 24 h mortality after exposure. During the treatment period, we observed significant reductions in the population of Ae. albopictus in the sprayed low-rise housing in both semi-indoor and outdoor environments, while in the high-rise housing, there was also a significant decline in Ae. aegypti population in the semi-indoor environment. The evaluation of the residual bio-efficacy of deltamethrin SC-PE against laboratory-reared Aedes mosquitoes showed that the insecticide lasted longer in the high-rise housing compared to the low-rise housing with >80% mortality achieved continuously for 16 weeks. We provide initial evidence on residual efficacy of deltamethrin SC-PE in reducing Aedes population size in the low-rise and high-rise housing. Our results showed that ORS is a promising tool in the dengue vector control and like IRS in malaria control;it is a powerful and effective method if conducted correctly. However, large scale and well-designed studies with entomological and epidemiological endpoints are still warranted before its routine use in dengue control.
