ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
Objective: To elucidate the density distribution and spatiotemporal clustering characteristics of Aedes albopictus in Anhui Province from 2015 to 2024, so as to provide a scientific basis for the surveillance, early warning, risk assessment, and precise prevention and control of Aedes-borne diseases in the province. Methods: Surveillance data for the vector Ae. albopictus were collected from 16 prefecture-level cities in Anhui Province annually from May to October during the period 2015-2024. The Breteau index (BI) was used as the evaluation metric for descriptive analysis, and the Kruskal-Wallis H test was used for comparisons among different habitats. Spatial autocorrelation analysis and spatiotemporal scan analysis were conducted using QGIS 3.30.0, GeoDa 1.16.0.16, and SaTScan 10.1.2 softwares. Results: The density of Ae. albopictus in Anhui Province did not show a continuous linear trend. The average BI value was 10.28, which suggests the risk of dengue fever clustering epidemics, and the BI value peaked in 2017 at 12.13. The three cities with the highest average BI values were Huangshan (17.29), Tongling (16.67), and Huainan (14.65). Among different habitats, waste tires exhibited the highest BI value (15.13), and the differences in BI across habitats were statistically significant (H=54.663, P < 0.001). The results of spatial autocorrelation analysis showed that the density of Ae. albopictus exhibited global spatial autocorrelation only in 2015 (Moran's I=-0.319, P=0.006), and Chizhou was a persistent local high-density cluster and hotspot area. Spatiotemporal scan analysis identified one ClassⅠcluster encompassing Anqing, Chizhou, Tongling, Wuhu, Xuancheng, and Huangshan cities, with a clustering period spanning from May to September 2024 (relative risk=3.72, P < 0.001). Conclusions: From 2015 to 2024, the density of Ae. albopictus in Anhui Province consistently remained at levels that suggest the risk of clustering epidemics in most years. Its spatiotemporal clustering was mainly concentrated in six cities in southern Anhui, namely Anqing, Chizhou, Tongling, Wuhu, Xuancheng, and Huangshan cities, among which Chizhou was the core hotspot area. The high-incidence period of Ae. albopictus was from May to September each year, and precise prevention and control strategies should be formulated targeting these regions and periods.
Objective: To investigate the resistance levels of Culex pipiens pipiens in the Karamay City, Xinjiang Uygur Autonomous Region in 2025 to four commonly used insecticides (beta-cypermethrin, permethrin, deltamethrin, and propoxur), so as to provide a scientific basis for the rational and effective application of chemical insecticides in local mosquito control. Methods: The insecticide resistance of mosquito larvae was determined by the larval immersion method, and that of adult mosquitoes was detected by the WHO tube test at diagnostic doses. SPSS 20.0 software was used for statistical analysis, and probability unit (Probit) analysis was used to calculate regression equations. Results: In 2025, larvae of Cx. pipiens pipiens in the Karamay City exhibited moderate resistance to permethrin and deltamethrin, with resistance ratios of 36.38 and 17.35, respectively, while remaining susceptible to beta-cypermethrin and propoxur, with resistance ratios of 2.05 and 1.16, respectively. Adult mosquitoes demonstrated resistance to all four insecticides (0.025% beta-cypermethrin, 0.25% permethrin, 0.025% deltamethrin, and 0.1% propoxur), with mortality rates of 7.78%, 26.85%, 7.37% and 22.52%, respectively. Conclusions: Cx. pipiens pipiens in the Karamay City exhibits a distinct pattern of insecticide resistance to the four commonly used insecticides, characterized by highly differentiated resistance in larvae and resistance to all four insecticides in adult mosquitoes. It is recommended that a long-term monitoring mechanism for mosquito insecticide resistance be established locally. The use of permethrin and deltamethrin should be reduced or suspended, and insecticide rotation or mixture application strategies should be implemented. Furthermore, an integrated control system should be developed combining environmental management, physical control, and biological control to delay the emergence and development of insecticide resistance in mosquitoes.
Objective: To investigate the density, species composition, and seasonal fluctuation patterns of rodents in Xi'an City, so as to provide a scientific basis for guiding rodent prevention and control. Methods: From 2020 to 2025, rodent surveillance was conducted in all districts and counties of Xi'an City using the night-trapping method in odd-numbered months. Four habitat types, namely urban residential areas, rural villages, key industries, and other habitats, were selected for the surveillance. The surveillance data were collated and analyzed using Excel 2010 and SPSS 12.0 softwares. Chi-square tests were used for the comparison of capture rates and composition percentages, and trend analysis was performed using the Cochran-Armitage trend test. Results: A total of 138 365 effective traps were set in Xi'an from 2020 to 2025, and 356 rodents were captured, with an average rodent density of 0.26%. Rodent density differed significantly across years (χ2=38.221, P < 0.001). From 2020 to 2025, the rodent density in rural villages showed a fluctuating upward trend (Z=2.732, P=0.049). Rodent density in rural villages (0.56%) was significantly higher than that in other habitats, and rodent density showed a significant difference in different types of habitats (χ2=38.222, P < 0.001). The dominant rodent species were Mus musculus (52.53%), Rattus norvegicus (21.91%), and Apodemus agrarius (18.82%), and the species composition varied significantly across years (χ2=128.763, P < 0.001). Rodent density exhibited a bimodal seasonal distribution, with peaks in May (0.37%) and November (0.29%). M. musculus density peaked in May (0.20%) and September (0.18%), R. norvegicus and R. tanezumi densities peaked in May (0.10% and 0.04%), and A. agrarius density peaked in November (0.10%) and January (0.08%). In rural villages, rodent density peaked in May (0.96%). A slight increase in rodent density was observed throughout the year in key industries and other habitats, while rodent density in urban residential areas showed no obvious seasonal variation. Conclusions: Rodent density in Xi'an from 2020 to 2025 was lower than that from 2015 to 2019. However, rodent density has increased since 2024. It is therefore necessary to continuously strengthen rodent surveillance and control. Particular emphasis should be placed on rodent surveillance and deratization in rural areas, with additional attention directed to urban areas and key industries, in order to interrupt the transmission of rodent-borne diseases.
Objective: To investigate the population distribution, density levels, seasonal fluctuation patterns, and pathogen carriage status of ticks in Anji County, Zhejiang Province, so as to provide scientific evidence for the prevention and control of tick-borne diseases. Methods: From March to October in 2024 and 2025, the host body tick checking method and the flagging-dragging method were employed to monitor on-host and questing ticks, respectively. Tick species were identified using morphological methods. Fluorescent quantitative real-time PCR was used to detect eight pathogens, including Severe fever with thrombocytopenia syndrome virus, spotted fever group rickettsiae (SFGR), Borrelia burgdorferi, Anaplasma phagocytophilum, Ehrlichia chaffeensis, Bartonella, Babesia, and Theileria. The Chi-square test or Fisher's exact test was used to compare the tick infestation rate, composition ratio, and pathogen positivity rate. Results: A total of 2 673 parasitic ticks and 1 786 questing ticks were captured, belonging to 10 species across 4 genera within 1 family. Haemaphysalis longicornis was the dominant species in both, accounting for 97.23% and 95.07% of the collections, respectively. In the on-host tick surveillance, a total of 511 animals were examined. The overall tick index was 5.23, the overall infestation rate was 50.49%, and the overall tick density index was 10.36. The difference in infestation rates of different animals was statistically significant (P < 0.001), with hedgehogs showing the highest infestation rate (2/2). In the questing tick surveillance, the overall tick density was 2.00 ticks/(flag·100 m). The on-host tick index was higher in the first half of the year than in the second half of the year, with relatively high tick densities from April to June. The density of questing ticks showed three peaks throughout the year, with the highest peak in May, the second highest peak in September, and the third peak in March. In the on-host tick surveillance, the proportions of larvae, nymphs, and adults were highest in October, March, and June, respectively. In the questing tick surveillance, the proportions of larvae, nymphs, and adults were highest in September, March, and June, respectively. The results of pathogen detection showed that the pool positivity rate of total ticks was 87.64%(78/89), and the minimum infection rate was 6.96%(78/1 120), among which the detection rate of spotted fever group rickettsiae was the highest (75/89, 84.27%). The pool positivity rate of parasitic ticks was 86.76%(59/68), with a minimum infection rate of 8.51%(59/693), and the difference in pool positivity rates among larvae, nymphs, and adult ticks was statistically significant (P < 0.001). The pool positivity rate of questing ticks was 90.48%(19/21), with a minimum infection rate of 4.45%(19/427). Conclusions: The tick population in Anji County shows high tick species diversity, relatively high tick density, and carriage of diverse pathogens, indicating a high risk of tick-borne diseases. Comprehensive prevention and control measures against ticks and tick-borne diseases should be strengthened in rural areas and outdoor work environments.
Objective: To analyze the results of tick ecological surveillance in Ninghai County, Zhejiang Province, clarify the seasonal activity pattern, stage-specific distribution characteristics, and host infestation status of ticks in Ninghai County, and to provide a scientific basis for the precise prevention and control of ticks and tick-borne diseases. Methods: From 2020 to 2024, three types of surveillance habitats, namely rural residential areas, rural outdoor environments, and scenic areas, were set up in Ninghai County and ticks were monitored every March, May, July, and September. The flagging-dragging method was used to monitor questing ticks, and the animal body tick checking method was adopted to monitor on-host ticks. Excel 2013 software was used for data collation, and R 4.5.0 software was used for statistical analysis. The Mann-Whitney U test was adopted for the comparison of questing tick densities among different habitat types. The Kruskal-Wallis H test was applied to compare tick indices and tick density indices among different host animals. The Chi-square test was used to compare the tick infestation rates among different host animals. Results: A total of 7 tick species belonging to 4 genera and 1 family were collected in Ninghai County from 2020 to 2024. Haemaphysalis was the dominant genus in surroundings of human settlements, accounting for 85.21% (1 204/1 413). Tick density exhibited a bimodal seasonal distribution pattern (the density of questing ticks peaked in March and September, and the tick index of on-host ticks peaked in May and September). The density of questing ticks was 2.36 ticks/(flag·100 m), with larvae as the dominant developmental stage, accounting for 49.42%(341/690). The density of questing ticks was 2.36 ticks/(flag·100 m), with larvae as the dominant developmental stage, accounting for 49.42%(341/690). The average questing tick density in rural outdoor environments was 3.57 ticks/(flag·100 m), exceeding the 0.23 ticks/(flag·100 m) observed in scenic areas. The density of questing ticks differed significantly among habitat types (Z=3.327, P < 0.001). Questing ticks were predominantly larvae in March (64.13%), July (71.88%), and September (85.00%), while nymphs dominated in May (77.95%). The density of adult questing ticks remained low across all months. For on-host ticks, the average infestation rate was 36.98%, the average tick index was 2.14, and the average tick density index was 5.78. Adults represented the dominant developmental stage, accounting for 53.94%(390/723), and H. longicornis was the dominant species, accounting for 47.69% (186/390). Among different host animals, sheep had the highest average tick infestation rate (51.33%) and average tick index (2.43), while dogs had the highest average tick density index (7.71). There was a statistically significant difference in tick infestation rates among different host animals (χ2=26.693, P < 0.001). However, there were all no statistically significant differences in the tick index and tick density index among different host animals (H=1.534, P=0.489; H=1.857, P=0.666). On-host ticks were predominantly nymphs in March (65.52%), adult ticks dominated in May (74.70%), July (71.96%) and September (45.66%). Conclusions: Ticks were active from March to September in Ninghai County, Zhejiang Province, and with Haemaphysalis being the dominant genus in surroundings of human settlements. Tick infestation varies among different host animals, with relatively severe infestations observed in sheep and dogs.
Objective: To investigate the current resistance status of adult mosquitoes to commonly used insecticides in Yunnan Province, and to provide a scientific basis for the prevention and control of mosquito-borne infectious diseases such as dengue fever and Japanese encephalitis. Methods: In accordance with the National Vector Surveillance Implementation Plan, mosquitoes were captured from 2023 to 2025 in eight prefectures/cities of Yunnan Province, including Dehong Dai and Jingpo Autonomous Prefecture (Dehong Prefecture), Xishuangbanna Dai Autonomous Prefecture (Xishuangbanna Prefecture), Baoshan City, Kunming City, Yuxi City, Lincang City, Pu'er City, and Qujing City. Insecticide resistance of adult Culex tritaeniorhynchus, Cx. pipiens quinquefasciatus, Aedes albopictus, and Ae. aegypti was determined using WHO tube bioassay. Mortality of adult mosquitoes was calculated using Excel 2019, and the resistance level of adult mosquitoes was evaluated based on diagnostic doses. Results: During 2023-2024, Cx. tritaeniorhynchus populations from Baoshan, Pu'er and Yuxi exhibited resistance to all three pyrethroid insecticides (mortality: 5.38%-45.33%). For malathion, only the Pu'er population showed resistance (mortality: 28.16%). For fenitrothion, only the Pu'er population was tested and found resistant (mortality: 44.73%). For propoxur, only the Yuxi population was susceptible. For Cx. pipiens quinquefasciatus (Baoshan, Kunming, Qujing and Yuxi city, 2023-2025), all populations were resistant to the three pyrethroid insecticides (mortality: 0.00%-23.04%). No susceptible population was observed against propoxur (Yuxi population was not tested) and their mortalities were 59.33%-93.68%. Only the 2025 Baoshan population was susceptible to 5% malathion. Ae. albopictus (Dehong Prefecture, Kunming, Pu'er and Xishuangbanna Prefecture, 2023-2025) showed variable resistance to pyrethroids (mortality: 6.83%-100.00%). Among 9 bioassay results from four surveillance sites, 2 were susceptible, 1 indicated possible resistance, and 6 showed resistance. Of six propoxur bioassays, four yielded susceptible outcomes. Susceptible responses to malathion accounted for 2 out of all 4 test results. For Ae. aegypti (Dehong Prefecture, Mohan, Lincang and Xishuangbanna Prefecture, 2023-2025), 23 out of 24 pyrethroid bioassays demonstrated resistance (mortality: 2.33%-73.33%) and 1 showed susceptibility. Among nine propoxur tests, 1-ninth were resistant (mortality: 79.73%) and 4-ninths were susceptible. Only the Lincang population was tested against fenitrothion and was susceptible. Possible resistant responses to malathion accounted for 4 out of all 7 test results (mortality: 88.04%~96.91%). Conclusions: The four major vector mosquito species in Yunnan Province have developed widespread and stable resistance to pyrethroid insecticides, and their use should be reduced in mosquito prevention and control. Organophosphate and carbamate insecticides still retain certain application value against Ae. albopictus and Ae. aegypti. For Cx. tritaeniorhynchus and Cx. pipiens quinquefasciatus, insecticide rotation or integrated vector management strategies should be adopted.
Objective: To investigate the temporal and spatial distribution, species composition, and habitat distribution of flies in Yuxi City, Yunnan Province, and explore the influence of meteorological factors on fly density, and to provide a scientific basis for fly control. Methods: From March to October each year from 2018 to 2024, the density of flies in six counties (cities and districts) of Yuxi City was monitored using the cage-trap method. Seasonal fluctuations of density were analyzed using a linear mixed-effects model. Differences in fly density and species composition among different years, regions, and habitats were evaluated using ANOVA or Kruskal-Wallis H test and Chi-square test or Fisher's exact test. A generalized additive model was used to analyze the relationship between fly density and meteorological factors. Results: From 2018 to 2024, a total of 9 659 flies were captured in Yuxi City, with an overall fly density of 3.07 flies/cage. Musca domestica and M. sorbens were the dominant species, accounting for 73.89% (7 137/9 659) and 12.42% (1 200/9 659) of the total, respectively. There was no significant difference in fly density among different years (χ2=0.075, P=0.785), and the fly density peaked from June to July. The highest annual average fly densities were observed in Xinping Yi and Dai Autonomous County and Hongta District, which were 9.70 and 5.55 flies/cage, respectively. Among various habitats, farmers' markets had the highest fly density, which was 4.79 flies/cage. There were significant differences in fly density (H=14.650, P=0.002) and the species composition of flies (P < 0.001) among different habitats. Fly density exhibited a significant non-linear association with the current-month average surface air pressure (χ2=23 332.548, P < 0.001) and the 1-month-lagged average temperature (χ2=32.157, P=0.006). Overall, lower current monthly average surface pressure and higher 1-month-lagged average temperature were associated with an increased risk of elevated fly density. Conclusions: The fly density in Yuxi City remains relatively stable, with M. domestica and M. sorbens as the dominant species. The density of flies in farmers' markets is the highest, and the peak activity period for flies occurrs from June to July. It is recommended to implement comprehensive prevention and control measures for flies in key settings prior to the peak fly activity period in summer.
Objective: To analyze the spatiotemporal distribution characteristics of the chikungunya fever epidemic during its peak period in Nanhai District, Foshan City, Guangdong Province in 2025, and to identify different transmission modes to support targeted prevention and control. Methods: Information on 755 confirmed cases of chikungunya fever reported in Nanhai District from July 10 to August 26, 2025, was collected to analyze the temporal, spatial, and demographic distribution characteristics. Moreover, natural villages with ≥3 cases and a time interval of ≤22 days between the onset of the first and last cases were defined as clustered epidemic foci. The spatial distances between cases were calculated using the Haversine formula, and a progressive time-period division method was employed to analyze the spatial transmission characteristics of epidemic foci under different observation durations. Furthermore, the K-means clustering method was applied to identify different transmission modes. The comparison of count data such as incidence rates was performed using the Chi-square test, and the comparison of measurement data such as time intervals and distances was performed using analysis of variance or Kruskal-Wallis H test. Results: The epidemic involved seven townships (subdistricts), with Guicheng Subdistrict reporting the highest number of cases (484 cases, 64.11%). A total of 50 clustered epidemic foci were identified, of which 37 were located in Guicheng Subdistrict (74.00%). In the progressive observation, as the observation period extended from 15 days to 46 days, the average transmission distance between cases increased significantly by 75.64% (t=-2.476, P=0.040), and the growth primarily occurred during the later phase of observation (from day 30 to day 46). In addition, cluster analysis identified three transmission modes: point-clustered transmission (30 foci, 60.00%), uniform diffusion transmission (8 foci, 16.00%), and jump transmission (12 foci, 24.00%). Significant differences were observed among the three types of epidemic foci in terms of spatial distance (F=43.640, P < 0.001) and time interval (F=57.676, P < 0.001). Conclusions: The chikungunya fever epidemic in Nanhai District exhibited significant spatiotemporal clustering during its peak period, with point-clustered transmission being the dominant mode. It is recommended to implement differentiated prevention and control measures based on different transmission modes.
Objective: To analyze the epidemiological characteristics of dengue fever cases in Guizhou Province, identify the epidemic risk of dengue fever, and provide a scientific basis for the prevention and control of its local transmission. Methods: Field epidemiological investigation data on dengue fever cases in Guizhou Province from 2018 to 2025 were systematically reviewed, and relevant case information was supplemented from the China Information System for Disease Control and Prevention. Descriptive epidemiological methods were used to analyze the cases, the distribution of gender, age, and clinical symptoms of cases from different input sources through Chi-square test, and the Mann-Whitney U rank sum test was used for statistical analysis on the change in case distribution of differences between different importation sources and across different years. Results: From 2018 to 2025, a total of 162 imported dengue fever cases were reported in Guizhou Province. Of these, 77 (47.53%) were international imported cases, and 85 (52.47%) were domestic imported cases, and no local case reported. International imported cases originated predominantly from Southeast Asia, while domestic imported cases were mainly from Guangdong Province. The cases were distributed across 61 counties (districts) in 9 cities (prefectures) of the province. The peak for international imported cases occurred in August, while the peak for domestic imported cases occurred in October. There were 116 male and 46 female cases. There was no statistically significant differences in gender composition among cases from different importation sources (χ2=0.002, P=0.958). The age of cases ranged from 8 to 65 years, with a mean age of (36.76±11.97) years. The highest number of cases was observed in the 20- < 40 age group (91/162, 56.17%), followed by the 40- < 60 age group (61/162, 37.65%). There was no statistically significant differences in age distribution between international and domestic imported cases (χ2=7.307, P=0.057). The main clinical manifestations of the cases included fever, muscle pain, headache, fatigue, and rash. The median time interval from onset to diagnosis was 6 days. There was no significant differences in the time interval from onset to diagnosis between cases from 2018 to 2019 and those from 2023 to 2025 (Z=0.070, P=0.944), and between cases from different importation sources (Z=0.570, P=0.569). Conclusions: From 2018 to 2025, imported dengue fever cases in Guizhou Province exhibited seasonal and geographic characteristics. The cases were predominantly young and middle-aged males, and the time interval between onset to diagnosis was relatively long. Therefore, we should strengthen residents' awareness of seeking medical treatment and medical institutions' awareness of diagnosis, in order to achieve early detection and early isolation of dengue fever cases, thereby blocking its local transmission.
Objective: To investigate the species, composition, and distribution of tick resources in the Gansu Dunhuang West Lake National Nature Reserve, provide key data for understanding the interactions among organisms in desert ecosystems, and offer a theoretical basis for the scientific formulation of ecological protection strategies. Methods: A combination of non-invasive trapping method (using fresh beef and animal feces as bait) and traditional flagging-dragging method was employed to collect tick specimens in the reserve in April 2025 and identified morphologically. Meanwhile, DNA was extracted from morphologically ambiguous specimens, and molecular identification was performed based on the tick 16S rRNA and cytochrome c oxidase subunit Ⅰ(COⅠ) genes. Tick collection was performed simultaneously in the same habitat using both methods to evaluate capture efficiency, and the difference in capture rates was analyzed using the Chi-square test. Results: A total of 1 842 tick specimens were collected and assigned to three species in three genera of the family Ixodidae, namely Dermacentor nuttalli, Hyalomma asiaticum kozlovi, and Rhipicephalus turanicus. Among them, Hy. asiaticum kozlovi was the most abundant, accounting for 52.72% of the total specimens. The trapping method captured 1 621 specimens, the flagging-dragging method only captured 221 specimens, and the capture rate of the trapping method was higher than that of the flagging-dragging method (χ2=42.372, P < 0.001). Conclusions: Three species of ticks were found in the Gansu Dunhuang West-Lake National Nature Reserve, and the dominant species was Hy. asiaticum kozlovi. This study enriches the baseline data on tick resources in arid desert regions and provides a basis for ecological conservation in the reserve. The collection of a large number of tick specimens indicates a potential risk of tick-borne diseases, warranting continuous investigation in the future.
Objective: To clarify the species composition, morphological characteristics, and geographical distribution of Haemaphysalis in Zhejiang Province, and establish a regional taxonomic identification system for the genus, so as to provide a scientific basis and technical support for tick fauna surveys, vector surveillance, and the early warning and prevention and control of tick-borne diseases in Zhejiang Province. Methods: Tick specimens of the genus Haemaphysalis collected during the surveillance program on tick ecology and etiology in Zhejiang Province from 2020 to 2025 were used in this study. Information on the collected tick specimens, and relevant literature on tick taxonomy and faunal surveys in Zhejiang Province were collected and integrated. Morphological examination and identification were performed using a stereomicroscope, and digital microscopy was utilized for detailed feature imaging. Results: A total of 9 Haemaphysalis species were recorded in Zhejiang Province in this study. Significant differences were observed in the species composition of Haemaphysalis among prefecture-level cities. The highest species richness was found in Jinhua and Taizhou cities, with 8 species recorded in each, followed by Ningbo City with 6 species. Considerable variation was also detected in the geographical distribution of different Haemaphysalis species. Specifically, H. longicornis had the widest distribution, covering 10 prefecture-level cities; H. hystricis was distributed in 8 prefecture-level cities; and H. goral showed the narrowest distribution, being recorded only in Taizhou City. The identification characteristics, hosts, and geographical distribution of the 9 tick species were described and recorded. Textual and illustrated dichotomous keys for both females and males were compiled. Conclusions: This study systematically compiled a checklist, identification characteristics, hosts, and geographical distribution data of Haemaphysalis ticks in Zhejiang Province. Based on morphological descriptions combined with photographs of actual specimens, scientific and practical textual and illustrated keys to the genus Haemaphysalis in Zhejiang Province were developed. This study can provide essential technical support for tick fauna surveys, vector surveillance, and the early warning and prevention and control of tick-borne diseases in Zhejiang Province, effectively improving the accuracy and operability of tick identification.
Objective: To establish a rapid, sensitive, and specific loop-mediated isothermal amplification (LAMP) assay for the detection of Chikungunya virus (CHIKV) and evaluate its clinical application value. Methods: Specific LAMP primers were designed targeting the conserved region between the RNA-dependent RNA polymerase (RdRp) and E2 glycoprotein (E2) genes of CHIKV, covering the three major genotypes: the East/Central/South African (ECSA) lineage (including its Central African lineage and Indian Ocean lineage), the Asian lineage and the West African lineage. A detection system was subsequently established, and its sensitivity and specificity were systematically validated, followed by further verification using clinical samples. Results: A rapid LAMP assay for CHIKV was successfully established, with the optimal reaction conditions being isothermal amplification at 65 ℃ for 40 min. The established method could detect all three genotypes of CHIKV with a sensitivity of 1 000 copies/ml, and showed no cross-reactivity with Dengue virus serotypes 1-4, Zika virus, or Yellow fever virus. In testing 19 clinical samples from ports, the positive agreement, negative agreement, and total agreement rates between the LAMP assay and real-time RT-PCR were all 100% (15/15, 4/4, and 19/19, respectively). Conclusion: The LAMP assay established in this study is convenient to operate and enables rapid, sensitive, and specific detection of CHIKV, demonstrating important application value in the early diagnosis of chikungunya fever and epidemic prevention and control.
Objective: Field studies were conducted using intelligent mosquito vector surveillance devices to characterize the diurnal activity rhythm of Aedes albopictus under natural conditions, and to examine the correlations between key environmental parameters (i.e., temperature, relative humidity, wind speed, and light intensity) and the activity intensity of this vector species. Methods: The intelligent mosquito surveillance device was deployed in residential areas and urban parks in Bao'an District and Nanshan District of Shenzhen, China, from October 13 to 19 and October 23 to 29, 2025 for continuous mosquito trapping. The number of captured mosquitoes was counted on an hourly basis to construct the diurnal activity rhythm graph of Ae. albopictus. Differences in capture counts between time periods were compared using the independent-samples Mann-Whitney U test. Environmental parameters at the time of capture—temperature, humidity, wind speed, and illumination—were recorded synchronously. Spearman rank correlation, Pearson correlation, and principal component analysis (PCA) were applied to explore the relationships between mosquito abundance and environmental factors, as well as the interactions among these factors. Results: Two intelligent surveillance devices operated continuously for two monitoring cycles, each lasting 7 days. A total of 458 adult mosquitoes were captured, including 89 Ae. albopictus specimens (19.43%). Ae. albopictus exhibited a bimodal diurnal activity rhythm, with two activity peaks occurring at 7:00-9:00 and 14:00-17:00. The afternoon (13:00-18:00) peak was significantly higher than the morning (6:00-11:00) peak (U=0.500, P=0.002). The most frequently recorded temperature during mosquito capture was 27 ℃, with a minimum of 22 ℃ and a maximum of 38 ℃. Spearman's correlation analysis indicated that, when the temperature was at or below 27 ℃, mosquito abundance showed a weak positive correlation with temperature (rs= 0.143, P=0.787), whereas a strong negative correlation was observed when the temperature exceeded 27 ℃ (rs=-0.775, P=0.014). Within the relative humidity range of 44%-100%, mosquito capture peaked at a relative humidity of 63%. At or below this threshold, mosquito abundance was strongly positively correlated with humidity (rs=0.835, P < 0.001), while above 63% it showed a significant negative correlation (rs=-0.744, P < 0.001). Within the ranges of 0~1.5 m/s for wind speed and 0~107 064 lx for illumination intensity, the captured abundance of Ae. albopictus was significantly negatively correlated with wind speed (rs=-0.807, P=0.001) and illumination intensity (rs=-0.301, P=0.015). Environmental factors presented significant correlations (temperature negatively correlated with humidity and positively correlated with light intensity, and humidity negatively correlated with wind speed, all P < 0.05). Principal component analysis extracted two components named the "temperature-humidity-light comprehensive factor" and "wind factor", cumulatively explaining 69.63% of environmental variance; the majority of captures (79.78%) occurred in habitats with moderate temperature-humidity-light conditions and low wind speed. Conclusions: The intelligent mosquito surveillance device enables stable continuous mosquito trapping, identification, and quantification under field conditions. Ae. albopictus exhibits all-day activity with two distinct daily peaks, with the afternoon peak being more pronounced than the morning peak. A temperature of 27 ℃ and a relative humidity of 63% represent optimal environmental thresholds for Ae. albopictus activity. Calm and low-light conditions are more favorable for its activity.
Objective: To investigate the distribution and seasonal fluctuation of questing ticks in park environments and their correlation with meteorological factors in Pudong New Area, Shanghai, so as to provide a basis for tick control. Methods: From March to November 2024, questing ticks in parks with different types of vegetation were collected using the manual flagging-dragging method within the areas under the jurisdiction of 46 communities and Yangsi Hospital in Pudong New Area. The Chi-square test was used to analyze the differences in tick distribution among parks of different types and habitats with different types of vegetation. Meteorological data for Pudong New Area during the same period were collected. Spearman rank correlation analysis was used to explore the association between tick density and meteorological factors. Results: A total of 204 questing ticks were collected, among which larvae and nymphs accounted for 80.39% in total and all belonged to the genus Haemaphysalis. Haemaphysalis was the dominant genus in this survey. Among the adult ticks identified to species, the dominant species was Rhipicephalus sanguineus (24/40, 60.00%). The tick density was highest in country parks, reaching 0.43 ticks/(flag·100 m). The difference in the composition ratio of questing ticks at different developmental stages among different types of parks was statistically significant (χ2=120.565, P < 0.001). The tick density was highest in habitats with arbor vegetation, which was 0.42 ticks/(flag·100 m), and the difference in the distribution of questing ticks at different developmental stages among habitats with different types of vegetation was statistically significant (χ2=25.415, P < 0.001). The peak density of larvae occurred in July, which was 0.18 ticks/(flag·100 m), while gentle seasonal fluctuations without single peaks were observed for adult and nymphal tick densities. Spearman rank correlation analysis showed that the density of larvae was negatively correlated with the monthly average atmospheric pressure (rs=-0.707, P=0.033), and positively correlated with the monthly average temperature (rs=0.759, P=0.018), monthly average maximum temperature (rs=0.759, P=0.018), and monthly average minimum temperature (rs=0.828, P=0.006). Conclusions: In the park environments of Pudong New Area, Shanghai, Haemaphysalis is the dominant genus of questing ticks, and R. sanguineus is the dominant adult tick species. The peak density of larvae occurs in July, and the larval density is susceptible to meteorological factors such as temperature and atmospheric pressure.
Objective: To investigate the composition characteristics of gut microbiota in field Anopheles mosquitoes from the high-altitude region of Weixi Lisu Autonomous County (Weixi County), Yunnan Province, and to analyze the effects of different Anopheles species and their blood-feeding status on gut microbiota structure. Methods: From July to August 2023, Anopheles mosquitoes were collected from rural cattle sheds in six townships (towns) of Weixi County, Yunnan Province, including Pantiange, Yongchun, Badi, Yezhi, Kangpu, and Tacheng. After morphological identification, An. sinensis, An. kunmingensis, and An. peditaeniatus were included in the analysis. Blood-feeding status was determined based on whether the midgut was engorged with blood. Each mosquito species was assigned to an blood-fed group and a non-blood-fed group (only an blood-fed group set for An. peditaeniatus). Total DNA of the Anopheles midgut was extracted using the phenol-chloroform method, and high-throughput sequencing was performed based on the V3-V4 region of the 16S rRNA gene. Sequence quality control, denoising, amplicon sequence variant generation, and taxonomic annotation were performed using the QIIME2 (v2020.6) platform. Statistical analyses and visualization were conducted using R software (v4.5.1). Analytical indicators included alpha diversity, beta diversity, microbial community composition at the phylum and genus levels, the number of detected genera in each sample, and differential genera. Inter-group comparisons of alpha diversity and the number of detected genera were analyzed using the Kruskal-Wallis H test. Beta diversity was assessed using PERMANOVA/adonis2 based on Bray-Curtis distances. For the selection of differential genera, the Kruskal-Wallis H test was used for comparisons involving ≥3 groups, and the Wilcoxon rank-sum test was used for two-group comparisons. The Kruskal-Wallis H test was followed by comparison between two groups using the Wilcoxon rank-sum test. The Benjamini-Hochberg method was used for multiple testing corrections. Results: A total of approximately 2.4×106 high-quality sequences were obtained, yielding 3 815 amplicon sequence variants. Alpha diversity analysis showed no significant differences in Shannon and Simpson indices among mosquito groups (Shannon: H=4.468, P=0.346; Simpson: H=3.951, P=0.413). However, compared with non-blood-fed mosquitoes, blood-fed mosquitoes generally exhibited lower Shannon and Simpson indices. PERMANOVA/adonis2 analysis based on Bray-Curtis distances showed no significant difference in microbial community structure among the three blood-fed mosquito groups (R2=0.157, F=1.118, P=0.074) or between non-blood-fed An. sinensis and An. kunmingensis samples (R2=0.107, F=0.954, P=0.369). However, within the same mosquito species, gut microbial composition differed significantly between blood-fed and non-blood-fed samples. Significant differences in microbial composition were observed between the blood-fed and the non-blood-fed groups (An. sinensis: R2=0.165, F=1.586, P=0.023; An. kunmingensis: R2=0.131, F=1.206, P=0.045). At the phylum level, based on mean relative abundance across all samples, Proteobacteria, Bacteroidota, and Firmicutes were the dominant phyla, with Proteobacteria having the highest mean relative abundance (31.44%-86.61%). At the genus level, Pseudomonas, Bacteroides, Chryseobacterium, Asaia, and Serratia were the dominant genera, with their highest relative abundances in some samples reaching 97.34%, 35.75%, 85.89%, 96.53%, and 96.15%, respectively. The number of detected genera did not differ significantly among groups (H=7.280, P=0.122). Selection of differential genera showed that Pseudomonas (H=8.060, P=0.017) and Anaplasma (H=9.976, P=0.007) differed significantly among blood-fed An. sinensis, An. kunmingensis, and An. peditaeniatus. The relative abundance of Pseudomonas differed significantly between blood-fed An. sinensis and An. kunmingensis (Padjusted=0.024), with mean relative abundances of 0.01% and 47.50%, respectively. The relative abundance of Anaplasma differed significantly between blood-fed An. peditaeniatus and An. sinensis, as well as between blood-fed An. peditaeniatus and An. kunmingensis (both Padjusted=0.011), with mean relative abundances of 0% (An. peditaeniatus), 8.58% (An. sinensis), and 25.54% (An. kunmingensis). In addition, Rickettsia was detected in one blood-fed An. sinensis sample, with a relative abundance of 86.23%. Conclusions: The gut microbiota of field Anopheles mosquitoes from Weixi County, Yunnan Province, showed relatively consistent composition at the phylum level, whereas microbial composition and relative abundance at the genus level varied substantially among samples. Blood-feeding status was closely associated with changes in gut microbial community structure of Anopheles mosquitoes. Under the blood-feeding status, differences in gut microbial community structure among different Anopheles species were not significant.
Objective: To investigate the species composition, density distribution, and carriage of spotted fever group rickettsiae (SFGR) in ticks in Tongliao City, so as to provide scientific evidence for the targeted prevention and control of tick-borne diseases. Methods: Tick surveillance was carried out in 6 banners (districts) of Tongliao City in April, May, June, July, and September 2025. Ticks parasitizing domestic animals were collected using the host body tick checking method. Morphological identification of tick species was performed under a stereomicroscope. PCR was adopted to detect SFGR. Microsoft Excel 2021 software was used for data collation, and SPSS 26.0 software was applied for statistical analysis. The Chi-square test was used to compare tick composition ratios and SFGR positive rates, while the negative binomial regression or Kruskal-Wallis H test was adopted for the comparison of tick densties among groups. Results: A total of 956 domestic animals were investigated across 6 banners (districts) in Tongliao City, among which 193 animals were tick-infested, and 1 190 on-host ticks were captured. The overall tick index was 1.25, and the tick density index was 6.17. Statistically significant differences were observed in tick indices (χ2=921.40, P < 0.001) and tick density indices (H=14.234, P=0.014) among different regions. The tick indices of Kulun Banner (2.43, 270/111) and Zhalute Banner (2.92, 567/194) were relatively high, while Horqin District had the lowest tick index (0.01, 2/254). Among all host animals, yellow cattle presented the highest tick density index (8.22, 625/76). The tick index peaked in July. A total of 568 tick specimens collected from key habitats were tested for SFGR, with an overall positive rate of 28.17%. Rhipicephalus microplus showed a relatively high positive rate (10/15, 66.67%), followed by Dermacentor silvarum (130/270, 48.15%). Conclusions: The tick indices of on-host ticks on domestic animals were relatively high in Kulun Banner and Zhalute Banner of Tongliao City, with yellow cattle as the dominant host, and July as the peak activity period. The overall SFGR positive rate of ticks was higher than that in surrounding areas, and the dominant tick species, D. silvarum, showed a relatively high positive rate, indicating a high potential risk of SFGR transmission in Tongliao City. Targeted prevention and control measures should be strengthened in key regions, for key host animals, and during key seasons.
Objective: To investigate the carriage of Japanese encephalitis virus (JEV) in mosquitoes from livestock sheds in Mengbin Village, Lancang Lahu Autonomous County (Lancang County), Yunnan Province, located on the China-Myanmar border, to characterize the diversity of viruses carried by these mosquitoes, assess the co-circulation of major pathogenic arboviruses, and to provide a scientific basis for the prevention and control of arboviral diseases in border areas. Methods: Mosquito samples were collected using an electric mosquito aspirator in cattle sheds and pigsties in Mengbin Village, Menglang Town, Lancang County, Pu'er City, Yunnan Province, in July 2025. Following morphological identification, the mosquitoes were grouped by collection site, time, and species (30 individuals per pool) and tested for JEV by RT-qPCR. All JEV-positive mosquito samples were combined to construct a sample pool, and metavirome sequencing was performed using the Illumina NovaSeq 6000 platform. Bioinformatic analyses were conducted using software including Fastp (v0.23.2), Bowtie2 (v2.4.5), and MEGAHIT (v1.2.9) to characterize the viral community composition. For key arboviruses detected, phylogenetic trees were constructed using the neighbor-joining method in MEGA 7.0 software. Results: A total of 6 120 mosquitoes were captured, with Culex tritaeniorhynchus being the dominant species (6 000 individuals, accounting for 98.04%). RT-qPCR screening for JEV revealed a pool positivity rate of 12.75% among 204 mosquito pools, with all positive samples originating from Cx. tritaeniorhynchus. Metavirome sequencing yielded 178 viral contigs, which were annotated to 37 viral species across 21 families, with insect-specific viruses being predominant. At the species level, in addition to JEV, pathogenic viruses including Banna virus (BAV) and Getah virus (GETV) were detected, along with various insect-specific viruses such as Quang Binh virus and Hubei mosquito virus 2. Phylogenetic analysis revealed that the JEV sequence identified in this study belonged to genotype Ⅰa (based on the E gene), GETV sequence belonged to genotype Ⅳ (based on the E2 gene), BAV sequence belonged to genotype A1 (based on segment 12), and Quang Binh virus sequence was most closely related to a 2015 Yunnan isolate (based on the NS5 gene). Conclusion: Mosquitoes in livestock sheds in Mengbin Village, Lancang County, Yunnan Province harbor a rich diversity of viruses, with co-circulation of multiple pathogenic arboviruses including JEV, BAV, and GETV.
Objective: To investigate the viruses carried by mosquitoes collected in Anyang City, Henan Province, and provide a basis for assessing the local transmission risk of mosquito-borne viruses and formulating prevention and control strategies. Methods: Mosquitoes were collected using light traps, and species identification was conducted through a combination of morphological examination and molecular identification based on the mitochondrial cytochrome c oxidase subunit Ⅰ gene. The collected mosquito samples were screened for nucleic acids of Japanese encephalitis virus, Culex flavivirus, Sindbis virus, Tahyna virus, Liaoning virus (LNV), West Nile virus, Getah virus, and Banna virus using real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR). Positive samples were subjected to viral gene amplification, sequencing, phylogenetic analysis, and homology analysis. Results: A total of 5 712 mosquitoes were collected, comprising 4 427 Armigeres subalbatus (77.50%) and 1 285 Aedes vexans (22.50%). RT-qPCR showed that only one A. subalbatus sample (HNAY_2025_87) collected from a sheepfold in Linzhou City (cycle threshold value was 25.98) tested positive for LNV nucleic acid, while all other samples were negative. Phylogenetic analysis based on the segment 10 gene of LNV revealed that this strain (HNAY_2025_87) was genetically close to the 1997 Liaoning strain NE9731 and the 2022 Japanese strain 22WN03, which all belonged to genotype Ⅱ, but was distantly related to genotype Ⅰ viruses isolated from regions such as Xinjiang Uygur Autonomous Region and Qinghai Province. Homology analysis indicated that HNAY_2025_87 differed from the genotype Ⅱ reference strain NE9731 by only 3 amino acid residues. Conclusion: For the first time, LNV was detected in A. subalbatus in Anyang City, Henan Province, revealing the presence of the virus in the region and providing basic data for the surveillance and control of mosquito-associated viruses in this area.
Objective: To evaluate the seasonal population density dynamics and spatial distribution characteristics of the dengue vector Aedes albopictus in Hangzhou City in 2024, and determine the resistance levels of adult mosquitoes to five commonly used chemical insecticides, and to provide a basis for the development of prevention and control strategies. Methods: From April to November 2024, the double-layer net trap method and Breteau index (BI) melthod were used to conduct surveillance on the adult and larval densities of Ae. albopictus. From April to June 2024, field populations of Ae. albopictus were collected from 11 counties (county-level cities, districts) across the city and reared to the F1 generation in the laboratory. The susceptibility of female adult mosquitoes to 0.05% propoxur, 0.5% malathion, 0.4% permethrin, 1.4% alpha-cypermethrin, and 0.7% lambda-cyhalothrin was determined using the WHO tube bioassay method. R 4.3.1 software was used for statistical analysis, a linear mixed-effects model was used to analyze regional differences in mosquito density, non-parametric tests were performed on mortality data, and the Kruskal-Wallis H test and Dunn's test were used for between-group comparisons. Results: The density of Ae. albopictus in Hangzhou showed obvious seasonal fluctuations. The larval density peaked in May (BI=12.58), and the adult density peaked in June [net trap index=5.97 mosquitoes/(net·h)]. The differences in adult and larval mosquito densities among counties (county-level cities, districts) were statistically significant (Fnet trap index=16.349, P < 0.001; FBI=12.473, P < 0.001). Regional epidemic risk for dengue fever (all with BI≥20) appeared in Shangcheng District (May), Xiaoshan District (May), and Chun'an County (April). Local outbreak risk (10≤BI < 20) was observed in Lin'an District, Qiantang District, Tonglu County, Yuhang District, and Binjiang District over multiple months. Adult mosquito resistance testing showed that populations in all regions of Hangzhou developed high-level resistance to 0.4% permethrin (median mortality: 2.67%). Regarding 1.4% alpha-cypermethrin and 0.7% lambda-cyhalothrin, resistance levels were highest and widely distributed in the central and eastern urban areas (5 monitoring values showed resistance and 3 showed possible resistance), while populations in the southern and western urban areas were highly susceptible to these insecticides (1 monitoring value showed resistance, 7 showed possible resistance, and 2 showed susceptibitity). Resistance to 0.5% malathion and 0.05% propoxur mainly appeared in the central urban area, while populations in the remaining areas were susceptible or possibly resistant to these insecticides. Conclusions: Ae. albopictus infestation in Hangzhou in 2024 showed clear seasonal peaks and regional differences, and Ae. albopictus populations had developed resistance to commonly used insecticides, especially pyrethroids. It is recommended to combine the temporal dynamics of mosquito density and the spatial pattern of insecticide resistance in prevention and control, and to implement a precision integrated control strategy of "source reduction in early season and area-specific interventions".
As one of the most important disease vectors, mosquitoes transmit a variety of arboviruses that pose a severe threat to global public health. Single-cell RNA sequencing (scRNA-seq), distinguished by its high resolution in deciphering cellular heterogeneity at the single-cell level, has been widely applied in various biological disciplines. In recent years, scRNA-seq has been increasingly applied to research on mosquito physiology and mosquito-virus interactions, including the construction of mosquito single-cell atlases, the elucidation of mosquito immune responses to viruses and infection dynamics, and the characterization of viromes in mosquito single cells. This article systematically reviews the recent advances and challenges of whole-cell-based scRNA-seq in research on mosquitoes and mosquito-virus interactions, aiming to provide references for advancing the understanding of mosquito physiology and mosquito-virus interaction mechanisms and facilitating the prevention and control of arboviral infectious diseases.
