The study was conducted at five communes from regions (Hµ T©y, Thõa Thiªn HuÕ, §µ N½ng, Kh¸nh Hßa, and Kiªn Giang province). The results indicated that the key breeding places of Aedes aegypti is different from region to region. In the Northern field trial, key breeding sites of Aedes aegypti are concrete tanks (65.6%); aquarium tanks (10.0%); and flower vases (15%). In the Central region, key breeding sites of Aedes Aegypti are wells, drums, ant traps, aquariums, toilette tanks. In the South, Aedes aegypti larvae are concentrated in big-size jars (67%), small-breeding sites of dengue vectors was changed after applying the intervention methods. It is clearly that the identification of key breeding places of Aedes aegypti are useful to propose the appropriate, effective control methods, and to evaluate the success of intervention measures.
Dengue ; Aedes ; Dengue Hemorrhagic Fever

Aedes albopictus C6/36 cells are susceptible to Dengue virus. The C6/36 cell line was infected with type 1 Dengue virus (DEN 1). At different time after these cells infected, morphological observations with electron microscope were conducted with super thin slicing method and the ultrastructural characteristics of DEN 1 virus in infected cells were recorded.
Dengue Virus ; Aedes, Cells

Background: Dengue fever remains a major public health problem in Vietnam. It was transmitted through two main Aedes species, namely Aedes aegypti and Aedes albopictus in which Aedes aegypti played the predominant role in transmitting the dengue viruses (accounted for 94% of the Aedes genus).Different groups of insecticides have been widely used in the community. As a consequence, it increased the resistance level of Aedes vectors to the insecticides. Therefore, a new synthesized insecticide was required for future control and prevention of dengue epidemics. \r\n', u'Objectives: To evaluate the efficacy of Cynoff 25 ULV in suppressing Aedes species in Vietnam. \r\n', u'Subjects and methods: The study was conducted in the entomology laboratory and in the fields of Ha Tay province. ULV spraying was implemented in Hiengiang commune, Thuongtin district, in comparison with a control area, Van Mo commune in Ha Dong town.\r\n', u'Results and conclusions: : Cynoff 25 ULV had a high efficacy that kills over 90% of 2 dengue vector species, namely Aedes aegypti and Aedes albopicctus after 24 hours exposure at the distance of 30 meters from the brass nozzle of a STIHL SR 400 sprayer. In the field trials, Cynoff 25 ULV also had high efficacy in killing Aedes species, e.g. 100% of Aedes species were killed after spraying and the effects lasted for 3 months for Aedes aegypti and one month for Aedes albopictus species. The insecticide had no side-effects or any other adverse effects to humans, livestock and the environment in the intervention areas. \r\n', u'
cynoff 25 ULV ; aedes species ; dengue vectors

Dengue is a disease propagated by vectors namely Aedes spp. mosquitoes. One of the effective approaches to control dengue is through integrated vector management and intervention programs. COMBI or Communication for Behavioral Impact is a strategic approach to control the Aedes population as well as dengue cases. This study was conducted at Taman Desa Kolej, Nilai, Negeri Sembilan, an suburban residential area to determine the effectiveness of COMBI, by using questionnaire and entomological survey as well as implementation of an intervention program. We carried out activities such as the establishment of COMBI promoter team, clean up events, talk shows with the residential community and distributed pamphlets containing information about dengue. Results indicated significant difference (p<0.05) on the knowledge, opinion and practices about dengue among the residents, for the pre and post intervention program. The entomological survey showed that, the primary mosquito species in this area was Aedes albopictus which comprised of 78 (31%) of the total mosquitoes examined, followed by Culex gelidus of 58 (23%), Culex quinquefasciatus of 37 (14.7%) and Aedes aegypti of 21 (8.3%). The density of Aedes population did not show any significant difference. In conclusion, COMBI intervention was effective in controlling dengue cases in Taman Desa Kolej.
Dengue ; Aedes ; Data Collection ; Urban Population ; Malaysia

Field trials of Wolbachia-transinfected mosquitoes, as a biological approach to curb dengue transmission, have been initiated. This study aimed to determine the knowledge regarding dengue fever (DF), practice of vector control, and acceptance of Wolbachia as a dengue control method among Universiti Kebangsaan Malaysia Medical Centre (UKMMC) healthcare staff. A questionnaire assessing knowledge regarding DF, vector control practices, and acceptance of Wolbachia was conducted among 330 UKMMC healthcare staff via convenience sampling. More than 70% of the respondents had good knowledge regarding DF, good vector control practice, and good acceptance of Wolbachia. Being female and having household income >MYR3000 had higher odds of having good knowledge regarding DF [(aOR 2.40; 95%CI 1.13, 5.12) and (aOR 3.86; 95%CI 1.91, 7.80)]. Having household income >MYR3000 had higher odds of having good vector control practice (aOR 2.33; 95%CI 1.20, 4.54) while academicians were three times (1-0.24) less likely to have good vector control practice than non-academicians (aOR 0.24; 95%CI 0.13, 0.48). Good acceptance of Wolbachia was associated with being academicians (aOR 8.83; 95%CI 2.60, 29.96) and having good knowledge regarding DF (aOR 6.07; 95% CI 2.89, 12.74). Gender, different income level and type of occupation have significant association with either good knowledge regarding DF or practice on vector control. Different type of occupation and level of knowledge also were notably significantly associated with good acceptance on Wolbachia as dengue biological control. These factors may be the focus for future plan to enhance the knowledge, acceptance and practice regarding DF and its control.
Wolbachia ; Dengue, Aedes ; Knowledge ; Practice ; Acceptance ; Questionnaire ; Healthcare staff

Objective: To explore the impact of health management measures for entry personnel (entry management measures) against COVID-19 on the epidemiological characteristics of imported Dengue fever in Guangdong Province from 2020 to 2022. Methods: Data of imported Dengue fever from January 1, 2016 to August 31, 2022, mosquito density surveillance from 2016 to 2021, and international airline passengers and Dengue fever annual reported cases from 2011 to 2021 in Guangdong were collected. Comparative analysis was conducted to explore changes in the epidemic characteristics of imported Dengue fever before the implementation of entry management measures (from January 1, 2016 to March 20, 2020) and after the implementation (from March 21, 2020 to August 31, 2022). Results: From March 21, 2020, to August 31, 2022, a total of 52 cases of imported Dengue fever cases were reported, with an imported risk intensity of 0.12, which were lower than those before implementation of entry management measures (1 828, 5.29). No significant differences were found in the characteristics of imported cases before and after implementation of entry management measures, including seasonality, sex, age, career, and imported countries (all P>0.05). 59.62% (31/52) of cases were found at the centralized isolation sites and 38.46% (20/52) at the entry ports. However, before implementation of entry management measures, 95.08% (1 738/1 828) of cases were found in hospitals. Among 51 cases who had provided entry dates, 82.35% (42/51) and 98.04% (50/51) of cases were found within seven days and fourteen days after entry, slightly higher than before implementation [(72.69%(362/498) and 97.59% (486/498)]. There was significant difference between the monthly mean values of Aedes mosquito larval density (Bretto index) from 2020 to 2021 and those from 2016 to 2019 (Z=2.83, P=0.005). There is a strong positive correlation between the annual international airline passengers volume in Guangdong from 2011 to 2021 and the annual imported Dengue fever cases (r=0.94, P<0.001), and a positive correlation also existed between the international passenger volume and the annual indigenous Dengue fever cases (r=0.72, P=0.013). Conclusions: In Guangdong, the entry management measures of centralized isolation for fourteen days after entry from abroad had been implemented, and most imported Dengue fever cases were found within fourteen days after entry. The risk of local transmission caused by imported cases has reduced significantly.
Animals ; Humans ; COVID-19 ; Aedes ; Epidemics ; China/epidemiology* ; Dengue/epidemiology*

Dengue fever is a kind of viral disease which infects people through mosquito bite. It is present in 100 countries and about 5 million to 10 million people are inflicted with this disease every year. Since the 1980s, it has seen a dramatic increase across the globe. One of the reasons for the spread of the disease is that rapid industrialization and urbanization have destroyed the natural habitat of mosquitos. Additionally, dengue fever occurs mostly in underdeveloped countries. These countries have not implemented systematic epidemiological investigation and are yet to come up with effective methods in terms of prevention of mosquito bites. Moreover, more and more people have traveled the areas at risk of this disease. Global the incidence of dengue fever has increased and has also seen a rise in cases among the travelers. One can easily find a case in a clinical setting. On top of that, due to global warming and north warding of dengue occurring latitude in the northern hemisphere, Aedes albopictus which is the vector of dengue fever, has been found in JeJu island. This makes it a major concern that the mosquitos have inhabited the country. Prevention of dengue fever is important since antiviral agents and vaccinations are not still commonly used.
Aedes ; Antiviral Agents ; Culicidae ; Dengue* ; Ecosystem ; Global Warming ; Incidence ; Methods ; Severe Dengue ; Urbanization ; Vaccination ; Virus Diseases

BACKGROUND: The changing nature of dengue epidemiology and control makes dengue one of the challenging infectious disease problems in the present time with certain inadequacies in existing knowledge base becoming apparent.
OBJECTIVE: This quantitative and experimental study was conducted to provide recent local evidence that dengue virus transovarial transmission among field collected Aedes aegypti mosquitoes does occur and presents an important factor in the epidemiology and control of dengue.
METHODS: Households in Quezon City, Philippines, a known dengue infection hotspot in 2011, were randomly selected (H9 and H14) for Aedes aegypti egg and larval collection. Mosquito larvae were captured using standard ovitraps and reared to adulthood in the entomology unit of the Molecular Diagnostics and Genotyping Laboratory at the University of the Philippines (UP), College of Medicine, Manila. Whole organism homogenate of adult mosquitoes were prepared for subsequent dengue virus molecular characterization and virulence testing. Both egg samples and their infection profile for dengue virus was determined by serotype specific RT-PCR.
RESULTS: Molecular test results show that in each household and in each generation (parent, F1 and F2), there were detectable and strong dengue viral presence, predominantly the serotypes DEN-2, DEN-3 and DEN-4 in the Aedes aegypti mosquito homogenates.
CONCLUSIONS: These laboratory evidences indicate that thransovarial transmission of dengue virus does occur in a high urban city like Quezon City where incidence of dengue is high.Thus, it is important to consider the existence of this phenomenon in existing and future dengue control programs to ensure effectiveness of community-based intervention strategies.

Human ; Animal ; Male ; Female ; Dengue Virus ; Aedes ; Serogroup ; Larva ; Entomology ; Pathology, Molecular ; Virulence ; Genotype ; Dengue

BACKGROUND: Dengue Fever (DF) and Dengue Hemorrhagic Fever (DHF) are now considered as major health problems in the Philippines. N,N,-dietyl-3-toluamide (DEET) is recognized as the most effective against Aedes aegypti. However, the concern about its use have underscored the need to find a safer alternative repellent.
OBJECTIVES: This study aims to determine and compare the repellent activity of tea tree (Melaleuca alternifolia) oil against Aedes aegypti with 7% DEET using a double-blind controlled experimental trial
METHODOLOGY: Twenty healthy subjects were allocated systematically by alternate assignment into three treatment groups (Control vs. Tea Tree oil, control vs. 7 percent DEET, Tea Tree oil vs DEET). All subjects were exposed to Aedes aegypti for 5 minutes every hour for 8 hours and the number of mosquitoes biting/landing were recorded and compared for each treatment group
RESULTS: Fifty percent tea tree oil has a repellent activity against Aedes aegypti and its efficacy is comparable to 7% DEET. Both treatments were equally effective in repelling mosquitoes for 7 hours. No cutaneous reactions to both repellents were noted
CONCLUSION: The efficacy of tea tree oil is comparable to 7% DEET and is recommended as an alternative natural mosquito repellent.

Human ; Aedes ; Deet ; Dengue ; Healthy Volunteers ; Insect Repellents ; Melaleuca ; Severe Dengue ; Tea ; Tea Tree Oil ; Trees

OBJECTIVES: Aedes mosquitoes are responsible for transmitting the dengue virus. The mosquito lifecycle is known to be influenced by temperature, rainfall, and relative humidity. This retrospective study was planned to investigate whether climatic factors could be used to predict the occurrence of dengue in East Delhi. METHODS: The number of monthly dengue cases reported over 19 years was obtained from the laboratory records of our institution. Monthly data of rainfall, temperature, and humidity collected from a local weather station were correlated with the number of monthly reported dengue cases. One-way analysis of variance was used to analyse whether the climatic parameters differed significantly among seasons. Four models were developed using negative binomial generalized linear model analysis. Monthly rainfall, temperature, humidity, were used as independent variables, and the number of dengue cases reported monthly was used as the dependent variable. The first model considered data from the same month, while the other three models involved incorporating data with a lag phase of 1, 2, and 3 months, respectively. RESULTS: The greatest number of cases was reported during the post-monsoon period each year. Temperature, rainfall, and humidity varied significantly across the pre-monsoon, monsoon, and post-monsoon periods. The best correlation between these three climatic factors and dengue occurrence was at a time lag of 2 months. CONCLUSIONS: This study found that temperature, rainfall, and relative humidity significantly affected dengue occurrence in East Delhi. This weather-based dengue empirical model can forecast potential outbreaks 2-month in advance, providing an early warning system for intensifying dengue control measures.
Aedes ; Culicidae ; Dengue Virus ; Dengue* ; Disease Outbreaks ; Humidity* ; Incidence* ; Linear Models ; Retrospective Studies* ; Seasons ; Weather