Dengue Vector Control Research Articles

Impact of Nanoparticles Synthesized From Azadirachta indica (A. Juss) for Targeted Control of Malarial, Dengue, and Filariasis Vectors With Minimized Aquatic Toxicity

ABSTRACTIn the present study, biogenic silver nanoparticles (AgNPs) synthesized using Azadirachta indica leaf extract were evaluated for their toxic effects on both target and non‐target species. The botanical synthesized nanoparticles were tested against Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus and non‐targeted species Artemia salina and Eudrilus eugeniae at 24 h posttreatment. AgNPs were characterized using the following analytical techniques: UV‐Vis spectroscopy, FT‐IR, x‐ray diffraction (XRD), energy‐dispersive x‐ray spectroscopy (EDX), and scanning electron microscope (SEM) analysis. Results showed that AgNPs caused larvicidal activity with 90.66% mortality in An. stephensi, 97.33% in Ae. aegypti, and 93.33% in Cx. quinquefasciatus at 24 h posttreatment. A. indica‐derived AgNPs had lower LC50 (lethal concentration 50) and LC90 (lethal concentration 90) values of 44.803 and 252.886 ppm/mL in An. stephensi, 18.358 and 189.553 ppm/mL in Ae. Aegypti, and 36.492 and 219.800 ppm/mL in Cx. quinquefasciatus, respectively. Furthermore, AgNPs demonstrated lower toxicity effects with 50.66% mortality in A. salina and 38.66% mortality in E. eugeniae at 24 h posttreatment. Additionally, they exhibited lower LC50 and LC90 values of 240.996 and 533.618 ppm/mL in A. salina and 301.122 and 548.944 ppm/kg in E. eugeniae at 24 h posttreatment, respectively. The findings conclude that green‐synthesized AgNPs from plants offer a promising, cost‐effective, and target‐specific alternative for eco‐friendly mosquito larvicides. Future work should focus on developing these plant‐based agents with minimal non‐target toxicity to support sustainable pest control. Further research may explore large‐scale applications and assess the long‐term environmental impacts of AgNPs in integrated vector management programs.

Use of Ovitrap for The Spatial Mapping of Aedes spp. in The Endemic Area of Dengue Fever of Baitussalam District Aceh Besar

The strategy for controlling dengue vector through periodic monitoring is an effective mitigation effort. Periodic monitoring of dengue vectors is generally more often conducted in the larval stage rather than the egg stage. Monitoring Aedes eggs periodically using ovitraps is more effective because it is not restricted by season. The objective of this study is to conduct spatial mapping of Aedes spp. distribution using ovitraps in Baitussalam Subdistrict, Aceh Besar. This study used observational methods and purposive sampling to determine the sample houses for ovitrap placement. A total of 50 houses in 5 gampong/village were observed. Analysis was conducted using the GPS Essentials application and Google Earth Pro software. The results showed that there were 4 gampong with Aedes spp. egg distribution in Baitussalam Subdistrict, Aceh Besar, namely Gampong Blang Krueng, Gampong Baet, Gampong Kajhu, and Gampong Cadek, while in Gampong Lam Ujong, no ovitraps positive for Aedes eggs. Ovitraps are an effective method for mapping Aedes spp. in efforts to control dengue. Keyword: Aedes spp; Dengue fever; ovitrap; spatial mapping.

Predatory Potential of Nymphal Odonates on Aedes aegypti Developing in Freshwater and Brackish Water Habitats.

Aedes aegypti, the primary vector of dengue, undergoes preimaginal development in brackish water (BW). However, dengue vector control exclusively targets freshwater (FW) habitats. The present study evaluated the predatory efficacy of nymphal odonates that can develop in both FW and BW. Nymphs of three damselfly and three dragonfly species from FW and BW habitats were identified and acclimatized to FW (<0.5 gL-1 salt) and BW (10 gL-1 salt) mesocosm conditions. The experiment was repeated nine times with nine different individual predators per species under both salinity conditions. One hundred L3 Ae. aegypti from FW and BW laboratory colonies were introduced to determine the predatory rate (PR) and clearance rate (CR) after 24, 48, and 72 h, and one hundred L3 larvae were introduced every 24 h. The dragonfly nymph Hydrobasileus croceus and the damselfly nymph Paracercion hieroglyphicum showed the highest PR and CR under both rearing conditions at all times. However, damselfly and dragonfly nymphs significantly (p < 0.05) differed in their CR under both FW and BW conditions. Thus, all six odonate species have predatory potential and this suggests that they could be used as biological control agents to eliminate preimaginal stages of Ae. aegypti developing in both FW and BW habitats.

Entomological surveys and insecticide susceptibility profile of Aedes aegypti during the dengue outbreak in Sao Tome and Principe in 2022.

The first dengue outbreak in Sao Tome and Principe was reported in 2022. Entomological investigations were undertaken to establish the typology of Aedes larval habitats, the distribution of Ae. aegypti and Ae. albopictus, the related entomological risk and the susceptibility profile of Ae. aegypti to insecticides, to provide evidence to inform the outbreak response. Entomological surveys were performed in all seven health districts of Sao Tome and Principe during the dry and rainy seasons in 2022. WHO tube and synergist assays using piperonyl butoxide (PBO) and diethyl maleate (DEM) were carried out, together with genotyping of F1534C/V1016I/V410L mutations in Ae. aegypti. Aedes aegypti and Ae. albopictus were found in all seven health districts of the country with high abundance of Ae. aegypti in the most urbanised district, Agua Grande. Both Aedes species bred mainly in used tyres, discarded tanks and water storage containers. In both survey periods, the Breteau (BI > 50), house (HI > 35%) and container (CI > 20%) indices were higher than the thresholds established by WHO to indicate high potential risk of dengue transmission. The Ae. aegypti sampled were susceptible to all insecticides tested except dichlorodiphenyltrichloroethane (DDT) (9.2% mortality, resistant), bendiocarb (61.4% mortality, resistant) and alpha-cypermethrin (97% mortality, probable resistant). A full recovery was observed in Ae. aegypti resistant to bendiocarb after pre-exposure to synergist PBO. Only one Ae. aegypti specimen was found carrying F1534C mutation. These findings revealed a high potential risk for dengue transmission throughout the year, with the bulk of larval breeding occurring in used tyres, water storage and discarded containers. Most of the insecticides tested remain effective to control Aedes vectors in Sao Tome, except DDT and bendiocarb. These data underline the importance of raising community awareness and implementing routine dengue vector control strategies to prevent further outbreaks in Sao Tome and Principe, and elsewhere in the subregion.

Cost of controlling the dengue vector Aedes aegypti in the Peruvian amazon.

Motivation for the study. Dengue prevention and control is based on the control of its vector. This study was conducted because of the need to know the costs associated with Aedes aegypti control in a region that carries out planned vector control activities. Main findings. The costs incurred in dengue vector control in the Loreto region in 2017 and 2018 amounted to PEN 4,066,380.25 and PEN 3,807,858.73, respectively. Implications. Knowing the cost of vector control activities will allow us to better plan these activities and have a basis for cost-effectiveness studies with other methods of prevention and control of dengue. To estimate the costs incurred in the control of Aedes aegypti in the Loreto region, during the years 2017 and 2018. We conducted a partial retrospective economic evaluation of the costs of Aedes aegypti control of the Regional Health Directorate Loreto, during the implementation of the Regional Plan for Surveillance and Control of Aedes aegypti. Documentation such as plans, intervention reports and payment slips were reviewed, and interviews were conducted with professional personnel involved in vector control, on the costs of control interventions. We found that the costs incurred in dengue vector control in the Loreto Region in the two years were: PEN 3,807,858 and PEN 4,066,380 during 2017 and 2018, respectively (USD 1,175,264 and USD 1,1210,232 at the 2017 and 2018 exchange rate). However, the effect of control activities is short-lived. The high cost involved in vector control with the methods currently used and the short duration of its effect make it unsustainable. Studies should be conducted in order to find other more efficient methods for dengue control.

Metabolic Resistance and Not Voltage-Gated Sodium Channel Gene Mutation Is Associated with Pyrethroid Resistance of Aedes albopictus (Skuse, 1894) from Cambodia.

(1) Background: In Cambodia, Aedes albopictus is an important vector of the dengue virus. Vector control using insecticides is a major strategy implemented in managing mosquito-borne diseases. Resistance, however, threatens to undermine the use of insecticides. In this study, we present the levels of insecticide resistance of Ae. albopictus in Cambodia and the mechanisms involved. (2) Methods: Two Ae. albopictus populations were collected from the capital, Phnom Penh city, and from rural Pailin province. Adults were tested with diagnostic doses of malathion (0.8%), deltamethrin (0.03%), permethrin (0.25%), and DDT (4%) using WHO tube assays. Synergist assays using piperonyl butoxide (PBO) were implemented before the pyrethroid assays to detect the potential involvement of metabolic resistance mechanisms. Adult female mosquitoes collected from Phnom Penh and Pailin were tested for voltage-gated sodium channel (VGSC) kdr (knockdown resistance) mutations commonly found in Aedes sp.-resistant populations throughout Asia (S989P, V1016G, and F1534C), as well as for other mutations (V410L, L982W, A1007G, I1011M, T1520I, and D1763Y). (3) Results: The two populations showed resistance against all the insecticides tested (<90% mortality). The use of PBO (an inhibitor of P450s) strongly restored the efficacy of deltamethrin and permethrin against the two resistant populations. Sequences of regions of the vgsc gene showed a lack of kdr mutations known to be associated with pyrethroid resistance. However, four novel non-synonymous mutations (L412P/S, C983S, Q1554STOP, and R1718L) and twenty-nine synonymous mutations were detected. It remains to be determined whether these mutations contribute to pyrethroid resistance. (4) Conclusions: Pyrethroid resistance is occurring in two Ae. albopictus populations originating from urban and rural areas of Cambodia. The resistance is likely due to metabolic resistance specifically involving P450s monooxygenases. The levels of resistance against different insecticide classes are a cause for concern in Cambodia. Alternative tools and insecticides for controlling dengue vectors should be used to minimize disease prevalence in the country.

Dengue hospitalizations and in-hospital mortality changes in trend in Ecuador: a nationwide study from 2015 to 2022

During recent years, dengue infection has spread rapidly within countries and between regions. Rapid rise in the global burden has been related to sociodemographic changes. Objective This study aimed to analyze dengue hospitalizations and in-hospital mortality trends in Ecuador, along with sociodemographic factors influencing adverse outcomes. Methods This study included 31,616 dengue hospitalizations in Ecuador during 2015–2022, of which 115 (0.36%) died. Data were extracted from national hospital registries. Age adjusted rates were calculated, and for the analysis of changes in trend, a Joinpoint regression was performed. Multivariate binary and multinomial logistic regressions were performed for assessing sociodemographic factors influencing dengue adverse outcomes. Results During 2015–2022, the mean age adjusted dengue hospitalization rate was 22.3 per 100,000 inhabitants with 49.41% annual decrease during 2015–2017 and 31.73% annual increase during 2017–2022 with higher rates in 2020 with 31.61, 2021 with 34.42, and 2022 with 25.81. The mean dengue in-hospital mortality rate was 0.08, mortality rates did not show significant changes during 2015–2022. Higher probability of death was observed in ages ≥50 years and ethnic minorities. People living in rural areas exhibited a 64% higher risk for complicated dengue hospitalization. Conclusions It was observed as an important accomplishment in Ecuador’s ongoing efforts to improve healthcare regarding dengue. 0.36% of dengue hospitalizations ended in death which is below the recommended 1%. The increase in dengue hospitalizations in Ecuador during recent years remains a concern. The COVID-19 pandemic might have influenced dengue prevention and vector control to be neglected leading to an increase in cases.

Stage-specific insecticide susceptibility and life-table analysis of the dengue vector mosquitoes &lt;em&gt;Aedes aegypti&lt;/em&gt; and &lt;em&gt;Ae. albopictus&lt;/em&gt;

Vector resistance to insecticides is a significant challenge in the control of mosquito-borne diseases such as dengue. Analysis of the growth rate and survivorship of the immature stages of larvae has been important in formulating effective vector control strategies. The present study aimed to assess insecticide resistance in both larvae and adults of Aedes aegypti and Ae. albopictus, and the life tables of their immature stages.Mosquito eggs collected from Kurunegala and Colombo districts of Sri Lanka from January to March 2023 were reared under laboratory conditions. Larval bioassays were carried out with temephos (0.0125 ppm, 0.0625ppm and 0.125ppm) and, the adult bioassays were with pyrethroids (0.03% deltamethrin, 0.05% and 0.08% lambdacyhalothrin, 0.04% permethrin) and malathion (1%and 5%). Biochemical assays were used to evaluate the activity of insecticide-detoxifying enzymes and the insensitivity of the organophosphate target site acetylcholinesterase. Survivorship of immature stages under laboratory conditions and semi-field conditions i.e., bamboo stumps, tyres and clay pots, were studied using Kaplan-Meier survival analysis.Larvae and adults of both species from Kurunegala were susceptible to all the insecticides tested, whereas Colombo populations were resistant. Acetylcholinesterases were largely sensitive in all vector populations. Higher activities of esterases, glutathione s-transferases and monooxygenases were found in Colombo populations. Results indicated that Ae. aegypti larvae were more resistant to insecticides than Ae. albopictus larvae. Also, the mechanisms of insecticide resistance were well developed in adults than in larvae.Aedes aegypti larval development time (5 days) was significantly shorter than that of Ae. albopictus (9 days) under laboratory conditions. Survival probabilities of them were 76-80%. Egg hatching to adult emergence period was 8 days for Ae. aegypti and 13 days for Ae. albopictus. This period, under semifield conditions were; bamboo stumps 7-7.2 days, tyres 10-11.3 days, and clay pots 13.8-14 days with survival rates varied from 28.8 to 63% for both species. This study highlights stage specific response of dengue vectors to insecticides and survivorship of their immature stages in different habitats. This knowledge can be effectively used in future dengue vector control programmes.

Bamboo stumps that are artificially in use put pressure on dengue and chikungunya vector control in Dhaka city, Bangladesh.

Aedes aegypti and Ae. albopictus mosquitoes breed in natural and artificial containers, and they transmit dengue and chikungunya. A study was conducted to identify the contribution of bamboo stumps to these disease vectors that were used in the flower garden as pillars to hold the bamboo flex fence. Two sizes of whole bamboo were used to hold fences around gardens at Dhaka University, Bangladesh, and were painted red and green. Mosquito larvae and pupae were collected from bamboo stumps between July and August, and vectors were identified up to the species level. The data were analyzed using the STATA/MP 14.2 version. 83.5% and 0.2% were Ae. albopictus and Ae. aegypti, respectively, and the remaining were Culex and Ar-migeres species. Ae. albopictus, Ae. aegypti, and both species-positive bamboo stumps were 46.9, 0.7, and 47.1%, respectively. 54.5% of the bamboo stumps had at least one mosquito species. The average stump depth for Aedes positive stumps (mean=11.7 cm, SE = 0.5) was significantly (p <0.001) higher than the Aedes negative stumps (mean = 9.5 cm, SE = 0.4). 53.8% and 38.0% stumps were found Aedes positive on the ground and upper sides of fences, respectively, and found significant (p<0.01) differences between both sides. A zero-inflated negative binomial count model is significant at a 5% level of significance, χ2(4) = 11.8, p = 0.019 (<0.05) for Ae. albopictus. Stump depth is found to have a significant positive effect on the number of Aedes-positive stumps. Artificially used natural containers are adding pressure to current mosquito control activities as mosquitoes are breeding on them, which needs additional attention.

Utilization of herbivore defensive latex from the weed Calotropis procera L in the green synthesis of silver nanoparticles and its potential application in the control of dengue vector Aedes aegypti

Milky latex produced by few and not all the plants are the treasure chest of various bioactive compounds with defensive potential against herbivores, insects and pathogens. Mankind have utilized latices in the preparation of novel plant-based therapies for centuries. Therefore, an attempt has been made to synthesis silver nanoparticles (AgNPs) using AgNO3 as a precursor and latex from C. procera as a reducing agent. The surface plasmon absorption peak at 430 nm confirmed AgNPs formation. The sharp peak with narrow width illustrated the homogenous nature. The face centre cubic structure of AgNPs was confirmed by the XRD pattern. FT-IR analysis deduced that the bio-molecules in the latex of C. procera are responsible for the reduction of AgNO3 to AgNPs. Biosynthesised L-AgNPs possessed well pronounced antibacterial activity against P. aeruginosa and K. pneumoniae. Anti-inflammatory activity of the nanoparticle determined by membrane stabilization and proteinase inhibitory assay was found to be in dose-dependent. LC50 value of L-AgNPs was found to be 63.09 µg/mL against IV instar larvae of A. aegypti. Distinct morphological changes were observed in the mosquito larva on exposure to various concentrations of L-AgNPs.

Efficacy of the insect growth regulator novaluron in the control of dengue vector mosquitoes Aedes aegypti and Ae. albopictus

Insect Growth Regulator (IGR) novaluron is an alternative to synthetic neuro-inhibitory insecticides. Present study was designed to assess appropriate dosages of novaluron for dengue vector control. Larvae of Aedes aegypti and Ae. albopictus were exposed to a concentration series of novaluron (Rimon EC10) for two fixed exposure periods of 7-days and 14-days to determined LC50 and LC99 values. Inhibition of adult emergence (IE50 and IE99) was determined by a 14-day exposure. Semi-field experiments were conducted by exposing cohorts of Ae. aegypti larvae to IE99, 2 × IE99 and 10 × IE99 novaluron concentrations in water storage buckets (10 L) and plastic barrels (200 L). For the 7-day exposure, LC50 values were 0.047–0.049 ppm and LC99 were 0.144–0.151 ppm. For 14-day exposure, these values were 0.002–0.005 ppm and 0.006–0.01 ppm respectively. For both species, IE99 was 0.001 ppb under semi-field conditions, and was effective for nearly 2 months. Novaluron concentration 0.01 ppb was effective up to 3 months, with an IE of 89–95%. Authorities should critically review a reduction of the presently recommended field dosage of 200 ppm novaluron by × 100 or more. This would provide the same efficacy but mitigate environmental pollution, development of vector resistance, and financial losses.

Bamboo stumps that are artificially in use put pressure on Dengue and Chikungunya vector control in Dhaka City, Bangladesh.

Aedes aegypti and Ae. albopictus mosquitoes breed in natural and artificial containers, and they transmit dengue and chikungunya. Therefore, a study was conducted to identify the contribution of bamboo stumps to these disease vectors that were used in the flower garden as pillars to hold the bamboo flex fence. Two sizes of whole bamboo were used to hold fences around gardens at Dhaka University, Bangladesh, and they were painted red and green. Mosquito larvae and pupae were collected from bamboo stumps between July and August, and vectors were identified up to the species level. The data were analyzed using the STATA/MP 14.2 version. We found 83.5% and 0.2% were Ae. albopictus and Ae. aegypti, respectively, and the rest were Culex and Armigeres species. Ae. albopictus, Ae. aegypti, and both species-positive bamboo stumps were 46.9, 0.7, and 47.1 percent, respectively. 54.5% of bamboo stumps had at least one mosquito species. The average stump depth for Aedes positive stumps (mean =11.7 cm, SE = 0.5) was significantly (p <0.001) higher than the Aedes negative stumps (mean = 9.5 cm, SE = 0.4). 53.8% and 38.0% stumps were found Aedes positive on the ground and upper sides of fences, respectively, and found significant (p<0.01) differences between both sides. A zero-inflated negative binomial count model is significant at a 5% level of significance, χ2(4) = 11.8, p = 0.019 (<0.05) for Ae. albopictus. Stump depth is found to have a significant positive effect on the number of Aedes-positive stumps. Artificially used natural containers are adding pressure to current mosquito control activities as mosquitoes are breeding on them, which needs additional attention.

COMMUNITY PERSPECTIVE ON PREVENTION AND CONTROL STRATEGIES OF DENGUE INFECTION IN MALAYSIA

Dengue is a vector-borne disease caused by a rapidly-spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards control measures of mosquitoes and the utilisation of biocontrol. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: Knowledge of biological control, respondent profiles, knowledge of dengue fever prevention, and the utilisation of insecticide for mosquito control. Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and ABATE (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel and successful community programmes is significantly influenced by the perception of control measures for mosquitoes.

COMMUNITY PERSPECTIVE ON PREVENTION AND CONTROL STRATEGIES OF DENGUE INFECTION IN MALAYSIA

Dengue is a vector-borne disease caused by a rapidly-spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards control measures of mosquitoes and the utilisation of biocontrol. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: Knowledge of biological control, respondent profiles, knowledge of dengue fever prevention, and the utilisation of insecticide for mosquito control. Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and ABATE (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel and successful community programmes is significantly influenced by the perception of control measures for mosquitoes.

School and community driven dengue vector control and monitoring in Myanmar: Study protocol for a cluster randomized controlled trial.

Dengue is the most common and widespread mosquito-borne arboviral disease globally estimated to cause >390 million infections and >20,000 deaths annually. There are no effective preventive drugs and the newly introduced vaccines are not yet available. Control of dengue transmission still relies primarily on mosquito vector control. Although most vector control methods currently used by national dengue control programs may temporarily reduce mosquito populations, there is little evidence that they affect transmission. There is an urgent need for innovative, participatory, effective, and locally adapted approaches for sustainable vector control and monitoring in which students can be particularly relevant contributors and to demonstrate a clear link between vector reduction and dengue transmission reduction, using tools that are inexpensive and easy to use by local communities in a sustainable manner. Here we describe a cluster randomized controlled trial to be conducted in 46 school catchment areas in two townships in Yangon, Myanmar. The outcome measures are dengue cases confirmed by rapid diagnostic test in the townships, dengue incidence in schools, entomological indices, knowledge, attitudes and practice, behavior, and engagement. The trial involves middle school students that positions them to become actors in dengue knowledge transfer to their communities and take a leadership role in the delivery of vector control interventions and monitoring methods. Following this rationale, we believe that students can become change agents of decentralized vector surveillance and sustainable disease control in line with recent new paradigms in integrated and participatory vector surveillance and control. This provides an opportunity to operationalize transdisciplinary research towards sustainable health development. Due to the COVID-19 pandemic and political instability in Myanmar the project has been terminated by the donor, but the protocol will be helpful for potential future implementation of the project in Myanmar and/or elsewhere.Registration: This trial was registered in the ISRCTN Registry on 31 May 2022 ( https://doi.org/10.1186/ISRCTN78254298).

Effectiveness of Ovitrap as a Control Tool Population Aedes Spp. In Areas Endemic to Dengue Fever Ternate City

The mosquito ovitrap is often used in dengue fever (DF) vector surveillance, but it has never been reported in control programs to reduce the vector population. This study aims to determine the ovitrap effectiveness as a vector control instrument for DF. The research was carried out from January to March 2021 in Bastiong Talangame Village, one of the DF endemic villages, which is a densed settlement in Ternate City. This research was a quantitative pre-experimental design type one group pre-test and post-test . Measurement of the density of Aedes spp. larvae presented in the House Index (HI), Container Index (CI), and Breteau Index (BI) were carried out four times before and after ovitrap installation. The installation of ovitraps was carried out in 100 houses, where four ovitraps were installed in each house with an installation time of four weeks. The results showed that the ovitrap index value decreased until it reached the moderate category in the last week of observation. The density of larvae based on the calculation of HI, CI, BI showed a significant decrease (p = 0.0001) before and after ovitrap installation, with the density figure value of the high category being the medium category. The use of ovitrap was effective in reducing the population of Aedes spp. so it should be considered in the dengue vector control strategy

Dengue Infection Survey on Prevention and Control Strategies Among Community in Malaysia

Dengue is a vector-borne disease caused by a rapidly spreading virus. Dengue vector control is considered the most efficient way for limiting and curbing the spread of the dengue virus. This study aimed to determine the perception of the Malaysian community towards prevention and control measures of Dengue infection. A total of 402 respondents in Putrajaya and Selangor participated in the survey. The questionnaire was broadly divided into three sections: i) respondent profile ii) knowledge about prevention of Dengue Fever and insecticide use for mosquito control iii) knowledge about biological control.Most of the respondents (83.0%) expressed concern regarding the effects of fogging activities on their health, whereas slightly more than half (56.0%) posited that fogging activities may have adverse environmental effects. The fogging method was reported as the most frequent method (29.2%) employed in controlling the mosquito population. Biocontrol with guppy fish scored (15.5%) and Abate® (mosquito larvae insecticide) (28.9%) were the other control measures utilised. Community perspectives revealed that 5.0% of the respondents were aware of biocontrol as a control method for the mosquito population. The biological method was considered safe for public health while guppy was reported as the most effective biocontrol agent. The introduction of novel biocontrol and successful community programmes is significantly influenced by the perception of prevention and control measures for mosquitoes.

Phylogenetic analysis of Aedes species distributed in Taif Province, Saudi Arabia, based on mitochondrial COX1 sequences

AbstractAs Aedes mosquitoes are the predominant carriers of arboviruses responsible for global dengue fever and chikungunya outbreaks, understanding their genetic diversity and population structure can enhance dengue prevention and vector control efforts. Although sympatric cryptic species have been acknowledged in Aedes species subgroups in Southeast Asia, little information is available regarding the occurrence and dispersal of cryptic Aedes species in Saudi Arabia. In the present investigation, we intend to analyze genetic variations and perform a phylogenetic study of sympatric Aedes samples collected from various locations in Taif Province, Saudi Arabia. The locus of mitochondrial DNA cytochrome c oxidase subunit 1 (COX1, analyzed with DNA barcoding) was utilized to determine genetic variance and to build phylogenetic trees. For species identification, the COX1 sequences of Aedes samples from Taif Province were compared with those of Aedes samples from GenBank (National Center for Biotechnology Information, NCBI). To identify phylogenetic relationships and genetic variability, phylogenetic trees were created using Taif Province samples, GenBank A. albopictus samples, and GenBank A. aegypti samples. The phylogenetic analysis revealed that some Taif samples (A3, A7, F2, F4, F1, A4, A1, F9 and F6) were closer to A. aegypti and A. albopictus samples from Africa and East Asia, especially Kenya and Malaysia. Whereas other samples (F9, F6, A4, F1 and A1) were closer to the GenBank A. aegypti samples KP843383 (Thailand), HM399357(Australia), MK533632 (Kenya), KX420460 (Kenya), KU495081 (Australia) and MF179160 (China) than the remaining Taif samples. Overall, our findings demonstrate that examining the genetic diversity and phylogenetic linkages of Aedes samples can aid in understanding the evolution of Aedes cryptic species in the western regions of Saudi Arabia.

Spatial analysis for risk assessment of dengue in Spain

IntroductionThe establishment of Aedes albopictus in new areas in Europe has changed the risk of local dengue transmission represented by imported human cases. The risk of transmission is determined by the distribution of travelers arriving from dengue-endemic areas and the distribution of Ae. albopictus as potential vectors of dengue in Spain. MethodsEnvironmental, entomological, epidemiological, demographic, tourism and travel data were analyzed to produce a series of maps to represent: the distribution of Ae. albopictus across municipalities; the risk of expansion of Ae. albopictus based on a species distribution model; the calculated index of travelers from dengue-endemic areas (IDVZE) per province; the percentage contribution of each municipality to the total number of cases in Spain. The maps were then added using map algebra, to profile the spatial risk of autochthonous dengue in Spain at a municipal level from 2016 to 2018. ResultsAe. albopictus was detected in 983 municipalities. The calculated IDVZE varied from 0.23 to 10.38, with the highest IDVZE observed in Madrid. The overall risk of autochthonous cases oscillated between 0.234 and 115, with the very high risk and high risk areas detected in the Mediterranean region, mainly in the Levantine coast and some parts of the Balearic Islands. Most of the interior of the peninsula was characterized as low risk. ConclusionPrevention and control measures to mitigate the risk of autochthonous dengue should be prioritized for municipalities in the high risk areas integrating early detection of imported dengue cases and vector control.

The Potential of Srigading Plants (Nyctanthes arbor-tristis) as Aedes aegypti Larvicides

Dengue Hemorrhagic Fever (DHF) is an endemic disease that causes high morbidity and mortality rates. The prevalence of DHF in Indonesia (2018) reached 24.75 per 100,000, and in South Kalimantan (2019) was 56.83 per 100,000 population. One of the efforts to control dengue vectors is the use of larvicides. The purpose of this study was to determine the potential of Srigading Plants (Nyctanthes arbor-tristis) as Aedes aegypti larvae as vectors of DHF in Wetlands. This study used a true experimental research design using the post-test-only controlled group design to determine the effectiveness of Srigading extract (Nyctanthes arbor-tristis) against the death of Aedes aegypti instar IV mosquito larvae. Based on the results, a significance value or p-value of 0.0001 0.05 was obtained. It indicated a significant difference between the number of mosquito larvae deaths and the concentration of Srigading extract given.