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*

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: Dengue epidemic is a dynamic and complex phenomenon that has gained considerable attention due to its injurious effects. The focus of this study is to statically analyze the nature of the dengue epidemic network in terms of whether it follows the features of a scale-free network or a random network. METHODS: A multifarious network of Aedes aegypti is addressed keeping the viewpoint of a complex system and modelled as a network. The dengue network has been transformed into a one-mode network from a two-mode network by utilizing projection methods. Furthermore, three network features have been analyzed, the power-law, clustering coefficient, and network visualization. In addition, five methods have been applied to calculate the global clustering coefficient. RESULTS: It has been observed that dengue epidemic follows a power-law, with the value of its exponent γ = −2.1. The value of the clustering coefficient is high for dengue cases, as weight of links. The minimum method showed the highest value among the methods used to calculate the coefficient. Network visualization showed the main areas. Moreover, the dengue situation did not remain the same throughout the observed period. CONCLUSIONS: The results showed that the network topology exhibits the features of a scale-free network instead of a random network. Focal hubs are highlighted and the critical period is found. Outcomes are important for the researchers, health officials, and policy makers who deal with arbovirus epidemic diseases. Zika virus and Chikungunya virus can also be modelled and analyzed in this manner.
Administrative Personnel ; Aedes ; Arboviruses ; Chikungunya virus ; Critical Period (Psychology) ; Dengue Virus ; Dengue ; Humans ; Methods ; Zika Virus

OBJECTIVES: The Aedes mosquito is a vector for transmitting many arboviruses. Knowledge of the breeding habitat of this vector is vital for implementing appropriate interventions. Thus, this study was conducted to determine the breeding habitats and presence of Aedes mosquito species in the study areas.METHODS: A house-to-house cross-sectional survey of Aedes mosquito breeding habitats was carried out in Metema and Humera, Ethiopia, in August 2017. All available water-holding containers present in and around houses were inspected for the presence of immature stages of Aedes mosquitoes, and they were collected and reared to the adult stage for species identification. In the larval survey, the house index, container index, and Breteau index were computed as risk indices.RESULTS: Of the 384 houses surveyed for the presence of Aedes mosquito larval breeding, 98 were found to be positive for larvae. During the survey, a total of 566 containers were inspected, of which 186 were found to be infested with Aedes mosquito larvae, with a container index of 32.9, a house index of 25.5, and a Breteau index of 48.4. The most common Aedes mosquito breeding habitats were discarded tires (57.5%), followed by mud pots (30.0%). Of the 1,077 larvae and pupae collected and reared, Aedes aegypti (49.3%), Ae. vittatus (6.5%), and Culex species (44.2%) were identified.CONCLUSIONS: Discarded tires were the most preferred breeding habitats for Aedes mosquitoes. Moreover, Ae. aegypti, the main vector of dengue and other arboviruses, was identified for the first time in this region, suggesting a high potential for arbovirus transmission in the study areas.
Adult ; Aedes ; Arboviruses ; Breeding ; Cross-Sectional Studies ; Culex ; Culicidae ; Dengue ; Ecosystem ; Ethiopia ; Humans ; Larva ; Pupa

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

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

OBJECTIVES: The Aedes mosquito is a vector for transmitting many arboviruses. Knowledge of the breeding habitat of this vector is vital for implementing appropriate interventions. Thus, this study was conducted to determine the breeding habitats and presence of Aedes mosquito species in the study areas. METHODS: A house-to-house cross-sectional survey of Aedes mosquito breeding habitats was carried out in Metema and Humera, Ethiopia, in August 2017. All available water-holding containers present in and around houses were inspected for the presence of immature stages of Aedes mosquitoes, and they were collected and reared to the adult stage for species identification. In the larval survey, the house index, container index, and Breteau index were computed as risk indices. RESULTS: Of the 384 houses surveyed for the presence of Aedes mosquito larval breeding, 98 were found to be positive for larvae. During the survey, a total of 566 containers were inspected, of which 186 were found to be infested with Aedes mosquito larvae, with a container index of 32.9, a house index of 25.5, and a Breteau index of 48.4. The most common Aedes mosquito breeding habitats were discarded tires (57.5%), followed by mud pots (30.0%). Of the 1,077 larvae and pupae collected and reared, Aedes aegypti (49.3%), Ae. vittatus (6.5%), and Culex species (44.2%) were identified. CONCLUSIONS: Discarded tires were the most preferred breeding habitats for Aedes mosquitoes. Moreover, Ae. aegypti, the main vector of dengue and other arboviruses, was identified for the first time in this region, suggesting a high potential for arbovirus transmission in the study areas.
Adult ; Aedes* ; Arboviruses ; Breeding* ; Cross-Sectional Studies ; Culex ; Culicidae* ; Dengue ; Ecosystem* ; Ethiopia* ; Humans ; Larva ; Pupa

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

Zika virus (ZIKV) is an arthropod-borne member of the genus Flavivirus, closely related to the dengue, West Nile, Japanese encephalitis, and yellow fever viruses and is transmitted by Aedes spp. mosquitoes. It has emerged explosively since 2007 to cause a series of epidemics in Micronesia, the South Pacific, and most recently the Americas. Following the first detection of ZIKV on the American continent, autochthonous ZIKV transmission has been confirmed throughout Central and South America. The unprecedented numbers of people infected during recent outbreaks in the South Pacific and the Americas may have resulted in enough ZIKV infections to notice patterns of the associated incidence of congenital microcephaly, Gillain-Barre symdrome, and acute diffuse encephalomyelitis. Here we review the history, emergence, biology, transmission, and control strategies for the ongoing outbreak through vector-centric approaches on ZIKV to date.
Aedes ; Americas ; Arboviruses ; Biology ; Culicidae ; Dengue ; Disease Outbreaks ; Encephalitis, Japanese ; Encephalomyelitis ; Flavivirus ; Incidence ; Microcephaly ; Micronesia ; South America ; Yellow fever virus ; Zika Virus*

Zika virus was first isolated in from nonhuman primate in 1947. It is in the genus Flavivirus, closely related to other flavivirus like Dengue, West Nile, Yellow fever and Japanese encephalitis virus. Since 2007 epidemic in Yap island, zika virus infections had spread to the countries in Micronesia and South Pacific. In 2015, Zika virus outbreak occurred in Brazil and now more than 40 countries in American continents reported autochthonous infection. The virus is transmitted mainly by Ae. aegypti mosquito with many other Aedes mosquito species known as vector. Recently, Zika virus infection is known to cause severe neurological complications and congenital malformation. In this paper, we will review current knowledge on Zika virus history, biology, clinical characteristics and preventive method.
Aedes ; Biology ; Brazil ; Culicidae ; Dengue ; Encephalitis Virus, Japanese ; Flavivirus ; Methods ; Microcephaly ; Micronesia ; Primates ; Yellow Fever ; Zika Virus Infection* ; Zika Virus*