ABSTRACT
To demonstrate the effect of indoor spraying and window screens on Aedes aegypti mosquito density after space spraying. Methods: A total of 141 households (the study houses) in six communities of Songkhla City, located in Songkhla Province of southern Thailand, were randomly selected and the adult Ae. aegypti populations were assessed pre- and post-insecticide spraying from March to October, 2014. Houses close to (within a 20 m radius) the study houses were analyzed using spatial analysis tools. The Aedes aegypti density in the study houses and house density index were compared with the density in the neighbouring houses, based on three spraying conditions: (i) unsprayed (ii) only outdoor sprayed and (iii) indoor plus outdoor sprayed. Results: Only spraying houses indoors was the most effective (P<0.05). There was insufficient evidence that the source of the increase in the number of mosquitoes in unsprayed houses was due to their migration from neighbouring houses which had been sprayed. However, the study houses without screens on their windows were found to have a likely higher dengue vector population after spraying, but the difference was not significant. Conclusions: In dengue endemic areas, all houses should be fully screened and the number of houses ultra-low volume sprayed indoor plus outdoor should be increased with the cooperation of householders and communities during epidemics.
ABSTRACT
Objective:To examine the resurgence rate, house density index (HDI) and parous rate of the Aedes aegypti vector after space spraying carried out by the routine spraying team, and compare with the rates after standard indoor ultra low volume (SID-ULV) spraying carried out by the trained research spraying team. Methods:Between March and September 2014, a cluster randomized controlled trial including 12 clusters (6 regular ULV, 6 SID-ULV) with totally 4 341 households was conducted, and around 20–31 houses in each cluster were selected for assessment. The parous rate and HDI of collected mosquitoes 2 days before and 1, 2 and 6 days after spraying were obtained and compared. Results:The HDI dropped significantly from the baseline 1 and 2 days after spraying to a non-zero value in the SID-ULV treated locations but not in the regular ULV group locations. However, by 6 days after spraying, the HDI of both groups had returned to the base value measured 2 days before spraying. There were no statistically significant differences in the parous rate between groups. Conclusions: SID-ULV is more effective in reducing Aedes aegypti populations. However, rapid resurgence of dengue vector after spraying in urban areas was observed in both groups.
ABSTRACT
Objective: To examine the resurgence rate, house density index (HDI) and parous rate of the Aedes aegypti vector after space spraying carried out by the routine spraying team, and compare with the rates after standard indoor ultra low volume (SID-ULV) spraying carried out by the trained research spraying team. Methods: Between March and September 2014, a cluster randomized controlled trial including 12 clusters (6 regular ULV, 6 SID-ULV) with totally 4. 341 households was conducted, and around 20-31 houses in each cluster were selected for assessment. The parous rate and HDI of collected mosquitoes 2 days before and 1, 2 and 6 days after spraying were obtained and compared. Results: The HDI dropped significantly from the baseline 1 and 2 days after spraying to a non-zero value in the SID-ULV treated locations but not in the regular ULV group locations. However, by 6 days after spraying, the HDI of both groups had returned to the base value measured 2 days before spraying. There were no statistically significant differences in the parous rate between groups. Conclusions: SID-ULV is more effective in reducing Aedes aegypti populations. However, rapid resurgence of dengue vector after spraying in urban areas was observed in both groups.
ABSTRACT
This study aimed to demonstrate the effectiveness of impregnated shirt with Bifenthrin 2% EC to prevent mosquito biting in the rubber plantation. The three kinds of shirts included shirt worn on daily basis, shirt with dry latex, and shirt with impregnated Bifenthrin 2% EC. These shirt were worn by 6 people and rotate to wear these shirts one by one during 07.00-08.30 am. Mosquitoes will be collected for 4 days during the research period. The result is the mosquitoes (Aedes albopictus) landing-biting people who wore all three kinds of shirts. The mosquito landing-biting rates of wearing shirt without Bifenthrin 2% EC, shirt with dry latex, and shirt with dry latex and impregnated Bifenthrin 2% EC were 18, 8.89, and 2 mosquitoes/person/hour, respectively which had statistical significant difference. (p-value
ABSTRACT
The present study aimed to delineate the key containers, breeding sites of Aedes mosquitoes in suburban and rural areas where Chikungunya outbreak occurred. The survey was carried out at Ampur Muang and Hui-Yod, Trang Province during July-August 2009. Both containers with and without water were surveyed, mosquito larva index were calculated and all the larvae were identified to species. The results revealed the house index of 73 and 75 were obtained from 26 and 12 surveyed houses of suburban area and rural area, respectively. The key containers in houses were cement tanks in toilet (CI = 24.1) and all collected larvae were Aedes aegypti. The key containers in areas surrounding houses were coconut shells, plastic bottles, plant saucers and discarded tyres while in rubber plantations were broken rubber pots, coconut shells and coconut rubber pots. All the collected larvae in these areas were Aedes albopictus. The breeding sites found in areas surrounding houses had density more than one and in rubber plantations around 5.4 times. This study suggests that we should control the key breeding sites of Aedes mosquitoes such as discarded containers by big cleaning campaign. The activities should emphasize on in house and area surrounding house and followed by in rubber plantation.Key words : breeding sites, Aedes albopictus, Chikungunya
ABSTRACT
The objective of this study was to describe the biting time of Aedes albopictus in the rubber plantations and the orchards. It was performed in epidemic areas of Chikungunya of Songkhla and Satun Province in June and August 2009. Mosquitoes were induced by human bait. Two volunteers collected mosquitoes by sweep nets during 06.00 am to 06.00 pm. then caught mosquitoes were kept for species identification. The results revealed that 110 female mosquitoes with rate of 4.58 per man-hour were caught in the rubber plantation while 172 female mosquitoes with rate of 7.17 per man-hour were caught in the orchard. The biting rate of Ae. albopictus in the rubber plantation showed 2 peaks, the first peak was at the sun rise and the second main peak was at before sun set while in the orchard, the biting rate was high and reached the peak during 06.00-11.00 am. The biting rates in the rubber plantation and in the orchard were the lowest during 12.00-01.00 pm. However, biting behavior of female mosquitoes may be influenced by daily human activities and also temperature in their environment.Key words : Biting time, Aedes albopictus, Rubber Plantations, Orchards