Larval occurrence, oviposition behavior and biting activity of potential mosquito vectors of dengue on Samui Island, Thailand (original) (raw)
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This study investigated key breeding sites of Aedes aegypti (L.) and Ae. albopictus (Skuse) in high and low risk dengue haemorrhagic fever (DHF) areas. Ae. aegypti and Ae. albopictus larvae were found in 11 out of 29 types of water containers in both high and low risk DHF areas. Ae. aegypti larvae were found most in outdoor area containers in high risk DHF areas and in metal boxes in low risk DHF areas. On the other hand, Ae. albopictus larvae were found most in indoor earthen jars in low risk DHF areas and in areca containers in high risk DHF areas. The number of Ae. albopictus larvae found in the earthen jars and metal or plastic boxes in low risk areas were higher than in high risk DHF areas. Larval indices (i.e. HI and BI) in both high and low risk DHF areas were greater than 10 % and 50 %, respectively, which indicated high risks of DHF transmission.
Asia-Pacific Journal of Science and Technology, 2015
The objectives were to survey Aedes aegypti larval breeding habitats and analyze dengue vector indices. This larval vector survey was conducted in Dongklang village in Ubon Ratchathani province over two years in 2012 and 2013. During each year, dengue vector indices, House Index (HI), Container Index (CI), and Breteau Index (BI), were collected for two periods, dry season (January-April) and wet season (May-August). The number of households infested with larvae in the different years and periods were compared using chi-square test. The results showed in 2012, HI, CI, and BI were 52.7%, 19.9%, and 135.1% respectively in the dry season. In the wet season, the indices decreased. In 2013, dengue vector indices again tended to decrease from dry seasonal to wet seasonal periods. The numbers of households that were infested by Aedes larvae did not differ between years and seasons. Dengue vector indices are alternative methods to predict Aedes mosquito distribution and can be used in the m...
BMC Public Health
Background Controlling sites where mosquitos breed is a key strategy in breaking the cycle of infectious transmission of the dengue virus. Preventive behaviors, such as covering water containers with lids and adding temephos (commercially named Abate sand) in water containers are needed to reduce and control mosquito breeding sites. This study aimed to investigate the impact of dengue-preventive behaviors on Aedes immature production. Methods This cross-sectional study used in-person interviews to record occurrence of dengue-preventive behaviors in Bang Kachao, Samut Prakan Province, Thailand. Larval mosquitos in and around houses were observed and recorded, and covered 208 households. Results It was found that 50% of these households had containers for drinking water and 94% used water containers. Covering water containers with effective lids showed the best success among dengue-preventive behaviors for reducing Aedes immature production. Adding temephos in water containers also wa...
2018
Key containers are various kinds of water reservoirs where most of dengue vector breeding in them. Identification of key containers is important in order to know what dengue vector population control's target. This study aimed to know the type of containers in the dengue endemic areas of Banten Province and determine the key containers as the main target in vector control. A survey has been done in Cilegon (Bendungan, Panggung Rawi, and Samangraya), Serang (Cipare, Banjaragung, and Unyur), South Tangerang (Bendabaru, Baktijaya, Jalupang). Larvae survey conducted on 100 houses in each location by observing the presence or absence of mosquito larvae in water reservoirs (containers) act as potential breeding sites of Aedes aegypti both inside and outside of the house. The survey results were the types of containers, container number, container number with positive mosquito larvae, the key container, and entomology indices in each area. Various types of containers found in nine ende...
Dengue hemorrhagic fever is a severe and fatal infection that occurs in tropical regions such as Indonesia. In 2014, recorded that dengue morbidity rate was 5.17 per 100,000 inhabitants (approximately 13031 cases) with mortality rate of 0.84% (110 deaths). Demographic and societal changes such as population growth, urbanization, and modern transportation appear to play an important role in the increased incidence and geographical spread of dengue virus. Aedes Aegypti, the urban yellow fever mosquito, is also the principal dengue-carrying vector. The Aedes Aegypti mosquitoes as a vector of dengue virus normally live and breed in clean water reservoirs that are not directly related to the land such as: bath, bird drinks, water pot, water jars / barrel, cans, old tires, etc. In Indonesia, dengue outbreaks often occur when the seasons change from dry to rain or vice versa (1) This study aimed to figure out the influence of natural environment and the existence of the vector's larva. A logistic regression was performed to ascertain the effects of temperature, humidity, waste management and the existence of water reservoir on the likelihood of the existence of the vector's larva. The logistic regression model was statistically significant, p < .005 and the model explained the predictors of mosquito's larva by 52%. This finding shows that the existence of the mosquito's larva, influenced by temperature, waste management and the existence of water reservoir. Health education about waste management and environmental control are necessary to break the chain of mosquito breeding. .
International Journal of Tropical Insect Science, 2013
Dengue has become the fastest-growing mosquito-borne disease in Sri Lanka and the control of the vectors, Aedes aegypti Linnaeus and Ae. albopictus Skuse, is the most effective way of controlling the disease. A detailed study on vector prevalence has not been recorded from Sri Lanka. Therefore, the present study was undertaken to study the prevalence of both vectors in four semi-urban study sites in two of the most affected districts, namely Kandy (wet zone) and Kurunegala (intermediate zone), by conducting egg surveys (using ovitraps) and larval surveys from June 2007 to May 2008. A total of 82,524 eggs and 2658 larvae of Ae. aegypti and Ae. albopictus were collected. A total of 3699 potential breeding habitats were examined. Ovitrap and larval indices (house, container and Breteau) showed that all four areas are at epidemic risk, especially due to a high abundance of Ae. albopictus. The highest numbers for both the species were from the Kandy sites where dense vegetation, high rainfall and low temperature prevailed. The results showed a high mortality rate during the egg-to-larva transition, suggesting that conducting an egg survey alone would overestimate the vector abundance and the disease risk. For Ae. albopictus, the monthly mean number of eggs showed positive relationships with relative humidity in both districts and with rainfall in the Kandy District. The number of dengue cases in the area had no positive relationships with the abundance of eggs or larval density indices. Discarded receptacles were the most preferred breeding habitat for these dengue vectors. Since the attractiveness (inferred by the calculated risk factors) of most of the breeding habitats was very high, elimination of these breeding sites is essential for the success of dengue control programmes.
Entomological Investigation of Dengue Vectors
Intensive entomological investigations were carried out in seven dengue epidemic-prone districts of Pakistan, classifying them into three geographical regions, viz. southern, central and northern Pakistan. A total of 5132 water habitats from 2136 households in and around dengue-positive houses were sampled. Additionally, 264 samples each at least 30 metres away from dengue-positive houses were also collected from outdoor habitats. Only indoor samples data were used for the estimation of entomological indices. House Index, Container Index and Breteau Index were estimated at 39.42%, 27.96% and 67.2 respectively. Underground water tanks showed the highest (42.38%) positivity, followed by earthen pots (36.97%), drums (33.38%) and the least (4.58%) from discarded containers. From outdoor sites, only 5.05% (n=14) samples were found positive. Aedes aegypti and Aedes albopictus species exhibited a distinct association with different geographical regions. In the south of the country only Ae....
Malaysian Journal of Public Health Medicine, 2022
An entomological index is widely used for determining dengue transmission and mosquito populations. In this study, we determined the association between Aedes albopictus mosquito counts in three areas with different topographical features from six districts in Nakhon Si Thammarat and infected patients reported by the Ministry of Public Health's Department of Disease Control, using entomological indices, such as the sticky pad index and the sweep net index. The sampling region was selected from the top six districts of the province based on the number of reported dengue cases per 100,000 people. The regions were Khanom, Mueang, Pak Phanang, Phrom Khiri, Thung Song, and Thung Yai. They were divided into three categories of geographical features, including city, beach, and mountain. The mosquitos were collected by walking in a star form inside a 5 m diameter circle. The mosquitoes were separated into groups based on their species, and the percentile of the index was computed. We found that the number of mosquitoes was the highest in Pak Phanang and lowest in Khanom. The two indices and the number of A. albopictus collected from the six sampling locations were not significantly different (t = 1.31, p > 0.05). The coastline region had the highest number of mosquitoes and was substantially different from the other two regions (cosmopolitan and mountain) (F = 4.30; p < 0.05). By performing Pearson's correlation analysis, we found a negative correlation between dengue cases and the entomological index (r =-0.472; N = 36). Similarly, the number of patients showed a negative correlation with relative humidity (r =-0.355) but a positive correlation with temperature (r = 0.064). The epidemic pattern shifted throughout the year, and the number of cases then increased 2-4 weeks after the insect was found.
Dengue fever (DF), one of the most important emerging arboviral diseases, is transmitted through the bite of container breeding mosquitoes Aedes aegypti and Aedes albopictus. A household entomological survey was conducted in Dhaka from August through October 2000 to inspect water-holding containers in indoor, outdoor, and rooftop locations for Aedes larvae. The objective of this study was to determine mosquito productivity of each container type and to identify some risk factors of households infested with Aedes larvae. Of 9,222 households inspected, 1,306 (14.2%) were positive for Aedes larvae. Of 38,777 wet containers examined, 2,272 (5.8%) were infested with Aedes larvae. Containers used to hold water, such as earthen jars, tanks, and drums were the most common containers for larval breeding. Tires in outdoor and rooftop locations of the households were also important for larval breeding. Although present in abundance, buckets were of less importance. Factors such as independent household, presence of a water storage system in the house, and fully/partly shaded outdoors were found to be significantly associated with household infestation of Aedes larvae. Identification and subsequent elimination of the most productive containers in a given area may potentially reduce mosquito density to below a level at which dengue transmission may be halted.
Parasites & Vectors
Background The lack of information on behavioural patterns of Aedes aegypti and Aedes albopictus has become a significant limitation in vector control and disease management programmes. Therefore, the current study was focused on determining some bionomics aspects: breeding, resting, host-seeking and feeding preferences of Ae. aegypti and Ae. albopictus in Sri Lanka. Methods Larval and adult surveys were conducted from April 2017 to April 2019 monthly in six selected Medical Officer of Health (MOH) areas in Gampaha Distinct, Western province, Sri Lanka, representing urban, suburban and rural settings. Resting preferences of adult mosquitoes were observed from indoor and outdoor places using a Prockopack aspirator. The information on resting height, surface, material and locality was recorded. Human-baited double-net traps were used to determine the host-seeking time of Aedes mosquitoes. Statistical differences in the spatial distribution of mosquitoes in selected MOH areas and preva...