OBJECTIVE: To analyze the density, distribution and insecticide resistance of Aedes albopictus in Ningbo City in 2021, so as to provide insights into formulation of dengue fever control strategies. METHODS: Four administrative villages were randomly selected from each county (district) in Ningbo City from April to November, 2021, to investigate the indoor population density of Aedes larvae, and the Breteau index (BI) was calculated. The population density of adult mosquitoes was investigated in residential areas, parks/bamboo forests, waste tire stacking sites/waste stations/construction sites in each county (district). On June 2021, larvae of the natural strain A. albopictus were collected from epidemic sites of dengue fever in Ningbo City in 2018, and raised in laboratory. Then, larvae and female mosquitoes without blood feeding were selected for insecticide resistance bioassays, while insecticide-sensitive strains of A. albopictus served as controls. The resistance of A. albopictus larvae to deltamethrin, beta-cypermethrin, propoxur, temephos and dichlorvos using the impregnation method, and the medium lethal concentration (LC₅₀) and resistance ratio (RR) were calculated. The resistance of adult A. albopictus to beta-cypermethrin, permethrin, deltamethrin, propoxur and malathion was determined using the tube bioassay, and the mosquito mortality was calculated. RESULTS: A total of 10 072 small water containers from 9 935 households were investigated in Ningbo City in 2021, and there were 1 276 containers with Aedes larvae detected, with an average BI of 12.89. Totally 1 422 mosquito nets were allocated and 954 female A. albopictus were captured, with an average net trapping index of 1.34 mosquitoes/(net·hour). Both larval and adult A. albopictus mosquitoes were found from April to November, and the density of larval A. albopictus peaked in September (BI = 21.21), while the density of adult A. albopictus peaked in August, with a net trapping index of 2.38 mosquitoes/(net·hour). The LC₅₀ values of delta-methrin, beta-cypermethrin, propoxur, temephos and dichlorvos were 0.017 4, 0.000 9, 0.364 1, 0.038 1 mg/L and 0.001 6 mg/L against larvae of natural strains of A. albopicchus, with RRs of 49.66, 25.53, 9.65, 2.24 and 6.06, and the mortality rates of adult mosquitoes were 66.00% (66/100), 69.39% (68/98), 25.00% (25/100), 98.97% (96/97) and 100.00% (98/98) 24 hours post-treatment with 0.08% beta-cypermethrin, 0.03% deltamethrin, 0.4% permethrin, 0.05% propoxur, and 0.5% malathion for 24 h, respectively. CONCLUSIONS A. albopictus is widely distributed in Ningbo City, with a high population density and presents high-level resistance to common pyrethroid insecticides. The population density and insecticide resistance of A. albopictus requires to be reinforced.
Animals ; Female ; Malathion ; Temefos ; Aedes ; Propoxur ; Permethrin ; Dichlorvos ; Mosquito Vectors ; Larva ; Dengue/prevention & control*

Objectives: This scoping review aimed to support a landscape analysis to identify lessons learned about intersectoral collaborations (ISCs) by describing their existing models in the context of dengue, malaria and yellow fever. Methods: A scoping review following the methodology of Joanna Briggs Institute was performed using the following inclusion criteria: studies involving humans; studies discussing intersectoral collaborations, malaria/dengue/yellow fever, and prevention or control at any level; and studies in countries endemic for the aforementioned diseases. Studies were screened using Covidence, while data were extracted using NVivo. Results: Of the 7,535 records retrieved, 69 were included in the qualitative analysis. Most ISCs were initiated by multilateral organizations and ministries of health, and none by communities. Strategies included advocacy, health education, research, public health measures, resource mobilization, service delivery and training; mostly employed on a community level. Monitoring and evaluation were mostly formative, ongoing, and participatory. Gaps included administrative and policy barriers, resource shortages, and inadequate research and training. Conclusions Multiple models of ISC exist in the literature. There is a need to develop a comprehensive framework for an effective and sustainable multisectoral approach for the prevention and control of VBDs ensuring adequate resources, active stakeholders, and strategies that span the entire socio-ecological spectrum.
Dengue ; Disease Vectors ; Intersectoral Collaboration ; Malaria ; Vector Borne Diseases

BACKGROUND: International Health Regulations controls international travel including human movement, disease vector, and imported items to prevent the spread of dengue, especially in seaports, airports, and border crossing posts. This study aimed to determine dengue Transovarial Transmission Index (TTI) and distribution of dengue virus in the areas around Adisucipto Airport of Yogyakarta, Indonesia. METHODS: The study was a descriptive analytic study with cross sectional design, conducted by mapping the spread of the dengue virus and identifying TTI in Adisucipto Airport. A total of 145 ovitraps were installed in both perimeter and buffer areas of the airport. Positive Ovitrap Index (OI), TTI, and serotype of dengue virus were examined. The TTI was identified using immunocytochemistry immunoperoxidase streptavidin biotin complex (IISBC) method in mosquito head squash preparations. RESULTS: OI in the buffer area was 32 (45.1%), whereas OI in the perimeter area was 24 (32.4%). The TTI in the buffer and perimeter areas were 21 (18.3%) and 11 (18.9%), respectively. The TTI was found greater in the Aedes aegypti population compared to the Aedes albopictus population, both in the perimeter area (20% versus 16.7%) and the buffer area (20.3% versus 16.1%). Dengue virus serotype-2 (DENV-2) and dengue virus serotype-3 (DENV-3) were predominantly found in Ae. aegypti and Ae. albopictus. CONCLUSIONS Buffer areas of Adisucipto Airport of Yogyakarta have higher risk as breeding sites for Aedes spp., predominantly DENV-2 and DENV-3 serotypes. High OI shows that the areas are likely to have higher risk of developing dengue outbreak.
Aedes ; virology ; Air Travel ; Airports ; Animals ; Cross-Sectional Studies ; Dengue ; transmission ; virology ; Dengue Virus ; classification ; isolation & purification ; Female ; Indonesia ; Mosquito Vectors ; virology ; Ovum ; virology ; Serotyping

In light of global climate change, the seasonal and geographical distribution of vector species, especially mosquitoes, chigger mites, and ticks, are of great importance for human beings residing in rural and urban environments. A total of 12 species belonging to 4 genera have been identified as vector mosquitoes in the Republic of Korea. The most common of the 56 mosquito species in this country from 2013 through 2015 was found to be a malaria vector, Anopheles sinensis s.l. (species ratio [SR] 52%); followed by a potential vector of West Nile virus, Aedes vexans nipponii (SR 38%); a Japanese encephalitis vector, Culex tritaeniorhynchus (SR 6%); a West Nile virus vector, Culex pipiens (SR 3%); and a dengue and Zika virus vector, Ae. albopictus (SR 0.3%). Of the scrub typhus vectors, Leptotrombidium scutellare is the predominant chigger mite in Gyongnam province and Jeju island, whereas L. pallidum is the predominant species in other areas of Korea. Ticks were found to be prevalent in most environmental conditions, and high levels of their activity were consistently observed from May to September. Haemaphysalis species of ticks were mostly collected in grasslands, whereas Ixodes species were frequently found in coniferous forests. Haemaphysalis longicornis, known as the main vector of severe fever with thrombocytopenia syndrome, was the predominant species and was widely distributed throughout the country.
Aedes ; Anopheles ; Climate Change ; Communicable Diseases* ; Coniferophyta ; Culex ; Culicidae ; Dengue ; Disease Vectors* ; Encephalitis, Japanese ; Fever ; Forests ; Globus Pallidus ; Grassland ; Humans ; Ixodes ; Korea* ; Malaria ; Mites ; Republic of Korea ; Scrub Typhus ; Seasons ; Thrombocytopenia ; Ticks ; Trombiculidae ; West Nile virus ; Zika Virus

OBJECTIVETo construct dengue virus-specific full-length fully human antibody libraries using mammalian cell surface display technique.

METHODSTotal RNA was extracted from peripheral blood mononuclear cells (PBMCs) from convalescent patients with dengue fever. The reservoirs of the light chain and heavy chain variable regions (LCκ and VH) of the antibody genes were amplified by RT-PCR and inserted into the vector pDGB-HC-TM separately to construct the light chain and heavy chain libraries. The library DNAs were transfected into CHO cells and the expression of full-length fully human antibodies on the surface of CHO cells was analyzed by flow cytometry.

RESULTSUsing 1.2 µg of the total RNA isolated from the PBMCs as the template, the LCκ and VH were amplified and the full-length fully human antibody mammalian display libraries were constructed. The kappa light chain gene library had a size of 1.45×10(4) and the heavy chain gene library had a size of 1.8×10(5). Sequence analysis showed that 8 out of the 10 light chain clones and 7 out of the 10 heavy chain clones randomly picked up from the constructed libraries contained correct open reading frames. FACS analysis demonstrated that all the 15 clones with correct open reading frames expressed full-length antibodies, which could be detected on CHO cell surfaces. After co-transfection of the heavy chain and light chain gene libraries into CHO cells, the expression of full-length antibodies on CHO cell surfaces could be detected by FACS analysis with an expressible diversity of the antibody library reaching 1.46×10(9) [(1.45×10(4)×80%)×(1.8×10(5)×70%)].

CONCLUSIONUsing 1.2 µg of total RNA as template, the LCκ and VH full-length fully human antibody libraries against dengue virus have been successfully constructed with an expressible diversity of 10(9).

Animals ; Antibodies, Viral ; CHO Cells ; Cell Surface Display Techniques ; Cricetinae ; Cricetulus ; Dengue Virus ; immunology ; Gene Library ; Genetic Vectors ; Humans ; Immunoglobulin Heavy Chains ; immunology ; Transfection

Animals ; Climate Change ; Dengue ; transmission ; Disease Vectors ; Humans

OBJECTIVE: Dengue fever remains a public health problem in the Philippines. Eliminating key container artificial breeding sites of mosquito vectors is a vital part of dengue control. The objective of this descriptive cross-sectional study was to conduct an entomological survey of artificial container breeding sites of Aedes mosquitoes in households of two puroks in Batasan Hills, Quezon City.

METHODS: All potential artificial container breeding sites of dengue in each household were inspected for mosquito larvae. Water was sampled from all containers that had mosquito larvae. Water was sampled from all containers that had mosquito larvae and the larval species determined through microscopic examination. Using the World Health Organization list of recognized containers, each container was classified as recognized or an unrecognized container.

RESULTS: The larval indices computed were: container index = 6.4%, household index = 23.9% and Breteau index = 29%. The proportion of containers positive for A. aegypti larvae was significantly higher for the unrecognized containers (9.9%) than that of the recognized containers (3.9%) (p=0.002).

CONCLUSION: The high household index and Breteau index indicate that the potential for dengue transmission is high in the study area. Unrecognized artificial containers contributed significantly to the number of Aedes breeding sites. "Search-and-destroy" campaigns in the community should be expanded to include these containers. Crafting specific vector control messages that address the problem of particular unrecognized containers as well as those of recognized containers with the highest proportion positive for Aedes larvae will also aid dengue control and prevention. Repeat surveys to monitor larval indices may be used to help ascertain the effectiveness of these messages in decreasing mosquito breeding sites.

Animal ; Aedes ; Larva ; Water ; Public Health ; Mosquito Vectors ; Dengue ; Cities ; Breeding

OBJECTIVETo assess the larvicidal and irritant activities of the hexane extracts of leaves of Citrus sinensis (C. sinensis) against the early fourth instars and female adults of Aedes aegypti (Ae. aegypti).

METHODSThe larvicidal potential of the prepared leaf extract was evaluated against early fourth instar larvae of Ae. aegypti using WHO protocol. The mortality counts were made after 24 h and LC50 and LC90 values were calculated. The efficacy of extract as mosquito irritant was assessed by contact irritancy assays. Extract-impregnated paper was placed on a glass plate over which a perspex funnel with a hole on the top was kept inverted. Single female adult, 3-day old unfed/blood-fed, was released inside the funnel. After 3 min of acclimatization time, the time taken for the first take-off and total number of flights undertaken during 15 min were scored.

RESULTSThe citrus leaf extracts from hexane possessed moderate larvicidal efficiency against dengue vector. The bioassays resulted in an LC50 and LC90 value of 446.84 and 1 370.96 ppm, respectively after 24 h of exposure. However, the extracts were proved to be remarkable irritant against adults Ae. aegypti, more pronounced effects being observed on blood-fed females than unfed females. The extract-impregnated paper was thus proved to be 7-11 times more irritable as compared with the control paper.

CONCLUSIONSThe hexane extracts from C. sinensis leaves are proved to be reasonably larvicidal but remarkably irritant against dengue vector. Further studies are needed to identify the possible role of extract as adulticide, oviposition deterrent and ovicidal agent. The isolation of active ingredient from the extract could help in formulating strategies for mosquito control.

Aedes ; drug effects ; Animals ; Citrus sinensis ; metabolism ; Dengue ; transmission ; Disease Vectors ; Female ; Insecticides ; pharmacology ; Larva ; drug effects ; Mosquito Control ; methods ; Plant Extracts ; pharmacology ; Plant Leaves ; metabolism

OBJECTIVETo achieve secretory and extracellular production of recombinant dengue virus serotypes I-IV envelope glycoprotein domain III (DENV-1-4 EDIII) in Pichia pastoris.

METHODSEDIII genes of DENVI-IV were amplified and cloned into vector pPIC9K, respectively. These recombinant plasmids were then linearized and transferred into Pichia pastoris strain GS115. Clones highly produced in 4.0 mg/ml G418 were amplified and induced by methanol to achieve the secreted recombinant proteins. Ni-NTA agarose beads were used for purification, while SDS-PAGE and Western blotting were used for identification.

RESULTSThe recombinant plasmids pPIC9K-DENV-1-4 EDIII were constructed and successfully transferred into Pichia pastoris strain GS115. The recombinant EDIII proteins were expressed in a secretory way with the molecular weight about 12 × 10(3) and specifically identified by anti-His monoclonal antibody and anti-DENVI-IV mice sera.

CONCLUSIONDENVI-IV EDIII proteins are successfully achieved from Pichia pastoris expression system and could be used for development of dengue vaccines, diagnostic reagents and study of biological function of the E protein.

Dengue Virus ; genetics ; Genetic Vectors ; Pichia ; metabolism ; Recombinant Proteins ; genetics ; Viral Envelope Proteins ; secretion

OBJECTIVETo express the domain III of DENV II envelop protein in Escherichia coli, obtain the purified recombinant protein and identify its immunoreactivity.

METHODSSuckling mice were inoculated with live DENV II in the brain. The total RNA was extracted from the brain of the infected mice, and the envelope protein DNA fragment was amplified by RT-PCR and ligated into pMD 18-T to construct pMD 18-T-DV2-E. The domain III DNA fragment of the envelope protein was amplified by PCR with pMD 18-T-DV2-E as the template and cloned into pET-32a(+) to construct the expression plasmid pET-32a(+)-DV2-E-DIII. The recombinant plasmid was transformed into E.coli BL21(DE3) and induced by IPTG, and the expressed products were analyzed by SDS-PAGE and Western blotting.

RESULTSAfter RT-PCR amplification, a specific DNA fragment of about 1.5 kb was obtained and ligated into pMD 18-T to construct pMD 18-T-DV2-E. With pMD 18-T-DV2-E as the template, the domain III DNA fragment about 320 bp in length was amplified and the expression plasmid pET-32a(+)-DV2-E-DIII was successfully constructed. After induction with IPTG, a specific soluble protein with a relative molecular mass of 29000 was obtained and the expression product accounted for 52.50 percent; of the total protein of the cell lysate. Western blotting demonstrated reactivity of the recombinant protein with His-Tag McAb and DENV (Type I-IV) McAb.

CONCLUSIONThe recombinant plasmid can be highly expressed in E.coli BL21(DE3) in a soluble form and the recombinant protein can react with DENV (Type I-IV) McAb.

Animals ; Dengue Virus ; genetics ; isolation & purification ; Escherichia coli ; metabolism ; Genetic Vectors ; Mice ; Mice, Inbred Strains ; Plasmids ; Protein Interaction Domains and Motifs ; Viral Envelope Proteins ; genetics ; isolation & purification