ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
Objective: To investigate the prevalence of Wolbachia infection among the dengue vectors Aedes aegypti and Ae. albopictus in a dengue-endemic area, Jinghong, Yunnan Province, China, so as to provide a scientific basis for the application of Wolbachia for mosquito control. Methods: The female and male adults and larvae of Ae. aegypti and Ae. albopictus were collected in Jinghong. Genomic DNA was extracted from single mosquito samples. Based on the Wolbachia surface protein gene (wsp), universal primers were designed for polymerase chain reaction (PCR) amplification and detection to calculate the infection rate of Wolbachia; and for positive samples, wAlbA and wAlbB genotypes were identified through PCR amplification with the specific primers to analyze the status of co-infection. For all positive samples, the wsp gene was sequenced for a phylogenetic analysis. The Chi-square test or Fisher's exact test was used to compare the infection rate of Wolbachia by species, development stage, and sex of Ae. aegypti and Ae. albopictus. Results: A total of 480 Ae. aegypti samples were collected, 17 of which tested positive for Wolbachia, indicating a natural infection rate of 3.54%. Among the 96 Ae. albopictus samples, 89 were positive for Wolbachia, resulting in a natural infection rate of 92.71%. The natural Wolbachia infection rate of Ae. aegypti was significantly different from that of Ae. albopictus (χ2=423.581, P < 0.001). In Ae. aegypti, Wolbachia natural infection rates did not differ significantly between females (2.50%) and males (4.38%) (χ²=0.847, P=0.357) or between adults (3.44%) and larvae (3.75%) (χ²=0.030, P=1.000). In Ae. albopictus, no significant difference was observed in the Wolbachia natural infection rates between females (96.86%) and males (90.63%) (χ²=1.067, P=0.302) or between adults (93.75%) and larvae (90.63%) (χ²=0.308, P=0.579). Aedes aegypti had a significantly lower natural Wolbachia infection rate than Ae. albopictus in both adults (χ2=288.638, P < 0.001) and larvae (χ2=135.018, P < 0.001) as well as in both female (χ2=185.350, P < 0.001) and male adults (χ2=185.492, P < 0.001). For 17 Wolbachia-positive Ae. aegypti samples, 6 were positive for wAlbA, 3 were positive for wAlbB, and 8 were positive for wAlbA+wAlbB, with a co-infection rate of 47.06% (8/17). Among 89 positive Ae. albopictus samples, 9, 2, and 78 were positive for wAlbA, wAlbB, and wAlbA+wAlbB, respectively, with a co-infection rate of 87.64% (78/89). The co-infection rate was significantly lower in Ae. aegypti than in Ae. albopictus (χ2=15.356, P < 0.001). In the analysis of the wsp gene sequence of 106 samples, a total of 21 haplotypes were found, including 5 shared haplotypes and 16 private haplotypes (4 in Ae. aegypti and 12 in Ae. albopictus); the ratio of samples with shared haplotypes to those with private haplotypes was 13∶4 in Ae. aegypti and 74∶15 in Ae. albopictus; H2 was the major haplotype, involving 39 Wolbachia sequences (8 in Ae. aegypti and 31 in Ae. albopictus), which showed a dispersive geographical distribution and was detected in all the positive samples. Conclusion: Natural Wolbachia infection is present in both Ae. aegypti and Ae. albopictus populations in Jinghong, with a significantly lower infection rate in Ae. aegypti than in Ae. albopictus, consistently observed across both larval and adults stages, but with no significant difference in the infection rates between larvae and adults within the same species. The development stage and sex do not influence the natural infection rate of Wolbachia in the same species of Aedes mosquitoes. Aedes albopictus harbors more diverse Wolbachia haplotypes than Ae. aegypti, indicating a higher degree of gene differentiation in Ae. albopictus.
Objective: To compare the differences between hot steam and hot air in eradicating adult bed bugs through a quantitative study on the efficacy of the two heat treatment methods. Methods: The lethal time of adult bed bugs under hot steam and hot air at 50, 55, and 60 ℃, and the lethal temperature for adult bed bugs with exposure times of 1, 2, and 3 s under hot steam and hot air were measured by bioassay. Probit regression analysis was used to calculate lethal time of 50% (LTime50), lethal time of 99% (LTime99), lethal temperature of 50% (LTemp50), and lethal temperature of 99% (LTemp99). Results: The LTime50 for killing adult bed bugs with hot steam at 50 and 55 ℃ were 10.6 and 4.7 s, respectively, and the LTime99 were 28.3 and 28.0 s, respectively. All adult bed bugs were killed by hot steam at 60 ℃ within 2 s. The LTime50 for killing adult bed bugs with hot air at 50, 55, and 60 ℃ were 32.9, 13.3, and 3.6 s, respectively, and the LTime99 were 92.7, 57.3, and 17.8 s, respectively. The LTemp50 for adult bed bugs treated by hot steam for 1, 2, and 3 s were 69.7, 57.7, and 55.5 ℃, respectively, and the LTemp99 were 100.4, 60.7, and 61.3 ℃, respectively. The LTemp50 for adult bed bugs treated by hot air for 1, 2, and 3 s were 102.3, 82.7, and 70.7 ℃, respectively, and the LTemp99 were 150.7, 140.0, and 103.8 ℃, respectively. Conclusions: Both hot steam and hot air at 50, 55, and 60℃ can kill adult bed bugs. At the same temperature, hot steam is faster in killing bed bugs. Hot steam quickly kills bed bugs within the treatment times of 1, 2, and 3 s, and can be used for the rapid treatment of adult bed bugs. Hot air is slower in killing adult bed bugs and requires a higher temperature. Even under the conditions of a temperature higher than 100℃ for 3 s, hot air cannot cause 100% mortality of bed bugs.
Objective: To investigate bacterial communities carried by Laelaps jettmari, so as to provide etiological information for the prevention and control of mite-borne diseases. Methods: Gamasid mites were collected from the body surface of Apodemus agrarius in Dandong, Liaoning Province, China. Among them, DNA was extracted from L. jettmari, the dominant mite species on the rodents across different habitats, to establish a metagenomic library for high-throughput sequencing through the Illumina NovaSeq sequencing platform. The composition of the bacterial flora present in the samples was analyzed. The dominant microbial populations carried by L. jettmari in different habitats were compared through the nonparametric analysis of similarities. Results: Across three habitats in Dandong, L. jettmari from the body surface of A. agrarius in woodland had the largest number of microorganism-specific genes, but with no significant difference in microbial community structure (P > 0.05). The analysis of the bacterial population structure of nine groups of L. jettmari samples revealed that at the phylum level, the dominant phyla carried by L. jettmari were Pseudomonadota, Bacillota, Campylobacterota, Bacteroidota, and Actinomycetota; at the class level, the dominant classes were Gammaproteobacteria, Alphaproteobacteria, Epsilonproteobacteria, Bacilli, and Actinomycetia; at the genus level, Escherichia, Acinetobacter, Campylobacter, and Anaplasma were detected; and at the species level, 814 bacterial species were identified, in which the dominant bacteria were E. coli, Thiothrix sp., Ac. baumannii, and C. jejuni. In addition, important pathogenic bacteria such as An. phagocytophilum and endosymbiotic bacteria such as Wolbachia were detected in small amount. Conclusions: L. jettmari mites have a similar bacterial community structure across different habitats, which carry a variety of pathogenic bacteria and unknown bacteria, posing a potential threat of disease transmission to local humans and animals. The role of gamasid mites in the transmission of zoonotic diseases should be further researched.
Objective: To analyze the species, density, seasonal variation, and biting habits of malaria-transmitting vector Anopheles in Hubei Province, China, so as to provide a reference for the prevention and control of local imported malaria re-transmission. Methods: The surveillance on Anopheles population was conducted once a year in three villages in Zaoyang City, Hubei Province in July to September from 2021 to 2023. Two mosquito-catching sites were selected in indoor environments (human house or livestock shed) and in outdoor environments (near the paddy field or pond), respectively. Mosquitoes were captured using the light-trap method (from 19:00 to 7:00 of the next day) for three consecutive days. From 2021 to 2023, additional six surveillance sites were selected for surveillance on Anopheles density once in early and late months of May to October each year, and mosquitoes were captured using the human-baited double net trap method (from 19:00 to 7:00 of the next day). The seasonal variation of density, activity characteristics at night, and population structure of Anopheles mosquitoes at different mosquito-catching sites were analyzed. Densities of Anopheles mosquitoes were compared by analysis of variance, and differences in Anopheles population composition were compared using the Chi-square test. Results: The surveillance on Anopheles population showed that a total of 42 275 mosquitoes were collected by the light-trap method from 2021 to 2023, including An. sinensis (1.13%, 477/42 275), Culex (98.86%, 41 791/42 275), Aedes (3), and Armigeres subalbatus (4). A total of 41 710 mosquitoes were collected in livestock sheds, including An. sinensis (0.93%, 387/41 710), Culex (99.06%, 41 318/41 710), Aedes (1), and Ar. subalbatus (4). A total of 290 mosquitoes were collected near the paddy field/pond, including An. sinensis (13.79%, 40/290), Culex (85.52%, 248/290), and Aedes (0.69%, 2/290). A total of 275 mosquitoes were collected in human houses, including An. sinensis (18.18%, 50/275) and Culex (81.82%, 225/275). In 2021, the composition of Anopheles mosquitoes at different mosquito-catching sites was not significantly different (χ2=2.823, P=0.091), while a significant difference was observed in 2022 and 2023 (χ2=6.024, P=0.013; χ2=24.970, P < 0.001), with the proportion of Anopheles mosquitoes collected near the paddy field/pond and from human houses higher than that in livestock sheds. The surveillance on Anopheles density showed that the density peak of An. sinensis at different surveillance sites in Hubei Province appeared from June to July in 2021-2023. From 2021 to 2023, the mean density peaks of An. sinensis were 7.73, 6.66, and 5.47 mosquitoes/person·h, respectively, all occurring in late July with no significant differences (F=0.071, P=0.932). Among the additional six surveillance sites, the mean density of Anopheles mosquitoes was the highest in Wuxue City (6.82 mosquitoes/person·h), followed by Enshi City (3.61 mosquitoes/person·h). There was a significant difference in the density of Anopheles mosquitoes at different surveillance sites (F=8.486, P < 0.001). Most active period of An. sinensis was 21:00- < 23:00 at night. From 2021 to 2023, the peak densities of An. sinensis at night were 5.31, 5.91, and 3.48 mosquitoes/person·h, respectively, and with no significant differences (F=0.365, P=0.700). Conclusions: In this surveillance, no An. lesteri mosquitoes were captured. Anopheles sinensis is still the main vector of malaria transmission in Hubei Province. In some areas, the density of Anopheles mosquitoes is still high, showing a potential risk of malaria transmission. Therefore, it is suggested to strengthen the surveillance on Anopheles mosquitoes in the malaria post-elimination stage to prevent re-transmission of malaria.
Objective: To investigate the level and distribution of housefly (Musca domestica) resistance to several common insecticides in different regions of China, so as to provide guidance for housefly control and insecticide resistance management in China. Methods: The housefly resistance surveillance data in 2023 were collected from the National Vector Surveillance System. The data were processed to analyze the distribution of housefly resistance levels by using descriptive methods with the use of WPS Excel 2021. ArcGIS 10.6 software was used to map the distribution of the resistance levels for different types of insecticides. Results: The housefly resistance data were collected from 83 surveillance sites across 26 provinces (autonomous regions and municipalities) in 2023, focusing on five insecticides (deltamethrin, beta-cypermethrin, permethrin, propoxur, and dichlorvos). Houseflies demonstrated medium-to-high resistance to deltamethrin at 91.23% (52/57) of the surveillance sites, to beta-cypermethrin at 91.55%(65/71) of the surveillance sites, to permethrin at 85.00% (17/20) of the surveillance sites, to propoxur at 40.00% (14/35) of the surveillance sites, and medium resistance to dichlorvos at 8.51% (4/47) of the surveillance sites. Conclusions: Houseflies at more than 80% of the surveillance sites have developed moderate-to-high resistance to pyrethroid insecticides. It is essential to enhance scientific insecticide management, discontinuing the use of pyrethroids or combining them with other types based on local conditions, with priority given to carbamate and organophosphate insecticides, and combining environmental management to effectively control houseflies and related infectious diseases, thereby improving the quality of life of residents.
Objective: To analyze the surveillance results of fly density in Zhejiang Province, China from 2019 to 2023, discuss the density distribution and seasonal variation of fly populations, so as to provide a reference for the establishment of surveillance and early warning indicators for abnormal fly population density and related infectious diseases. Methods: Surveillance sites were set up in all counties, cities, and districts across Zhejiang Province, and the fly trap method was used to monitor the fly density from April to November in 2019-2023. The surveillance data were organized and statistically analyzed using Excel 2021 and R 4.0.2 softwares. The Kruskal-Wallis H test was employed for comparing differences between groups. Results: From 2019 to 2023, a total of 33 665 fly traps were deployed in Zhejiang Province, capturing 88 713 flies, with a fly density of 2.64 flies/trap. The dominant fly species in Zhejiang Province were species of Sarcophagidae and Musca domestica, followed by Lucilia sericata and Muscina stabulans. The highest fly density was found in farmers' markets (3.38 flies/trap), followed by residential areas (2.57 flies/trap), then green belts (2.40 flies/trap), and outdoor environment of catering areas (the lowest, 2.18 flies/trap). The temporal distribution of fly density generally showed unimodal distribution, with an increase starting in April each year, peaking between June and August, and then gradually decreasing. In 2019-2023, there was no significant difference in fly density between different years in Zhejiang Province (F=5.962, P=0.202). Conclusions: The fly density in Zhejiang Province shows unimodal distribution, with little variation between different years. The density data from previous years can serve as a basis for establishing the reference range of early warning indicators for fly control in the future.
Objective: To investigate the species composition, density, distribution, and seasonality of mosquitoes in Ningbo, Zhejiang Province, China, so as to provide a basis for scientific prevention and control of mosquito-borne diseases. Methods: Between April and November from 2020 to 2024, mosquito surveillance was carried out using the light trapping method in five habitats (urban residential areas, parks, hospitals, farmhouses, and livestock sheds/farms) across ten counties (cities, districts) of Ningbo. Excel 2019, SPSS 22.0, and R 4.1.0 were used for statistical analysis. The long-term trend of mosquito density was analyzed through seasonal decomposition. Mosquito species composition in different years and habitats was compared using the Chi-square test, and multiple comparisons were performed using the Z test. Mosquito density levels in regions of different geomorphological types were compared using the Kruskal-Wallis H test, and pairwise comparisons were performed using the Mann-Whitney U test. The Bonferroni's method was adopted for multiple testing correction. The changes in mosquito species composition in the past 5 years were analyzed using the Mann-Kendall Z trend test. Results: The average density of adult mosquitoes was 4.78 mosquitoes/lamp∙night in Ningbo from 2020 to 2024. Culex pipiens pallens/quinquefasciatus were the dominant species, accounting for 75.90% of the total catches. By habitat, livestock sheds/farms had the highest mosquito density at 9.55 mosquitoes/lamp∙night, while hospitals had the lowest level at 2.95 mosquitoes/lamp∙night. The composition of mosquito species was significantly different across various habitats (χ2=21 432.869, P < 0.001) with Cx. tritaeniorhynchus (44.51%), Anopheles sinensis (5.37%), and Armigeres subalbatus (2.74%) captured from livestock sheds/farms being higher than those captured from other habitats; the composition ratio of Aedes albopictus was significantly higher in parks (7.84%) than in the other habitats; and farmhouses had significantly higher proportions of Ar. subalbatus (2.17%), An. sinensis (0.83%), and Cx. tritaeniorhynchus (1.44%) than urban residential areas (all P < 0.05). Mosquito density differed significantly in regions of different geomorphological types (H=7.504, P=0.023), which was significantly higher in mountainous-dominated areas (7.10 mosquitos/lamp·night) than in plain-dominated areas (4.10 mosquitoes/lamp∙night) (U=68.000, P=0.009). The seasonal fluctuation analysis revealed that the peak period of mosquito activity was from June to September, with the highest peak in July. The seasonal decomposition analysis detected no significant change in mosquito density in Ningbo from 2020 to 2024 (F=0.859, P=0.360). Conclusions: Culex pipiens pallens/quinquefasciatus are the dominant mosquito species in Ningbo, and livestock sheds/farms, farmhouses, and parks are key places for mosquito control. Specific strategies should be applied for mosquito control according to the characteristics of mosquito species composition in different habitats, and comprehensive prevention measures should be taken during the peak period to reduce their peak density level.
Objective: To investigate rodent species and density and their changes in different seasons and ecological environments in Zaozhuang, a national surveillance site for rodent ecology, Shandong Province, China, so as to provide scientific basis and decision support for rodent control, public health policy formulation, and public education. Methods: From 2021 to 2023, rodent density was monitored by night trapping in odd-numbered months in one county and one district of Zaozhuang, which included three types of habitats (urban residential areas, special industries, and rural villages). Excel 2010 and SPSS 26.0 softwares were used for statistical analysis. The Chi-square test was performed for rodent density comparison. Results: A total of 21 560 effective traps were retrieved in Zaozhuang from 2021 to 2023 and 97 rodents were caught, with an average rodent density of 0.45% during the three years. Rodent density differed significantly between the three years (χ2=25.508, P < 0.001). The density of rodents was significantly higher in rural villages (0.75%) than in urban residential areas (0.35%) and special industries (0.29%) (χ2=18.777, P < 0.001). The dominant rodent species monitored during the three years were Rattus norvegicus and Mus musculus, with the composition ratios being 45.36% and 50.52%, respectively. By season, rodent density showed a unimodal distribution in any year and any habitat, all peaking in May. Conclusions: The dominant rodent species in Zaozhuang are R. norvegicus and M. musculus, and the density of rodents in rural areas is higher than that in urban areas. Rodent control measures should be developed according to the habits of different rodent species and the seasonal trend of rodent density, so as to improve the effects of rodent prevention and control.
Objective: To analyze the epidemiological characteristics and spatiotemporal clustering features of severe fever with thrombocytopenia syndrome (SFTS) in Jinhua, Zhejiang Province, China, so to provide a basis for the prevention and control of SFTS. Methods: The data on SFTS cases in Jinhua from 2011 to 2023 were obtained from the China Information System for Disease Control and Prevention. Descriptive analysis, Joinpoint regression, spatial autocorrelation analysis, and spatiotemporal clustering analysis were performed to describe the epidemiological characteristics and spatiotemporal clusters of SFTS. Results: A total of 113 SFTS cases were reported in Jinhua from 2011 to 2023. The average annual incidence rate was 0.15/100 000, with no significant upward trend [annual percentage change (APC)=103.62%, P=0.127]. The overall case fatality rate was 26.55%. The majority of the cases (61.06%) occurred during May to July. All the counties (cities and districts) of Jinhua were affected, with the number of townships (sub-districts) reporting cases increasing from 1 in 2011 to 27 in 2021. The top three regions by average annual incidence rate were Dongyang City (0.30/100 000), Lanxi City (0.23/100 000), and Pujiang County (0.23/100 000). The geographical distribution of the SFTS epidemic was generally clustered, with a high-high cluster within Dongyang City (Moran's I=0.159, P < 0.05). Two spatiotemporal clusters were identified: the Class-Ⅰ cluster consisted of 9 townships (sub-districts) in Dongyang City and Pan'an County from August 2017 to July 2023 (P < 0.001); and the Class-Ⅱ cluster were composed of 16 townships (sub-districts) in Lanxi City, Pujiang County, Yiwu City, Jindong District, and Wucheng District from April 2020 to October 2021 (P < 0.001). Patients aged ≥60 years accounted for 69.03% of the total cases. Both the incidence rate and case fatality rate increased with age. By occupation, 88.50% of the cases were farmers. The median interval from onset to diagnosis was 4.0 (1.0, 7.5) days. Conclusions: The geographical distribution of SFTS in Jinhua is gradually expanding, with the northeastern and northwestern regions at high risk. The season peak is late spring to early summer. The middle-aged and elderly farmers are more vulnerable.
Objective: To analyze the overall temporal and spatial distribution characteristics of malaria in Yunnan Province, China from 2006 to 2022, so as to provide a reference for determining key regions, consolidating malaria elimination achievements, and optimizing health resource allocation in Yunnan Province. Methods: The data of malaria cases in Yunnan Province from 2006 to 2022 were collected. Descriptive epidemiological methods were used to analyze the epidemic situation of malaria in the pre-elimination stage (2006-2016) and post-elimination stage (2017-2022). With the use of ArcGIS 10.8 software, spatial autocorrelation and standard deviational ellipse methods were employed to analyze the spatiotemporal distribution pattern and spatial evolution trend of malaria in Yunnan Province over the long-term temporal scales. Results: A total of 35 568 malaria cases were reported in Yunnan Province from 2006 to 2022, and the average annual incidence rates before and after malaria elimination were 194.77/100 000 and 11.76/100 000, respectively, showing a downward trend. The incidence of malaria peaked during May to July, with distinct seasonality. The male-to-female sex ratio of the reported cases was 3.77∶1. Patients aged between 20 and < 45 years accounted for 64.71% (23 017 cases) of the total cases. By occupation, farmers were the main population, accounting for 53.35% (18 975 cases). In the past 17 years, the high-incidence areas for malaria in Yunnan Province were mainly concentrated in western Dehong Dai and Jingpo Autonomous Prefecture (Dehong Prefecture) (average annual incidence, 76.20/100 000) and Baoshan City (average annual incidence, 22.58/100 000). The global spatial autocorrelation analysis showed that the distribution of malaria cases in Yunnan Province was clustered in the pre-elimination stage and in the post-elimination stage from 2017 to 2021. The local spatial autocorrelation analysis showed that the local malaria hotspots in Yunnan Province before malaria elimination were Tengchong City, Ximeng Wa Autonomous County, and Menglian Dai Lahu Wa Autonomous County; and the hotspots after malaria elimination were basically the same as those of imported malaria before malaria elimination, including Mangshi City, Ruili City, Longchuan County, Yingjiang County, and Lianghe County in Dehong Prefecture and Tengchong City in Baoshan Prefecture-level City. According to the standard deviational ellipse analysis, malaria in Yunnan Province showed a general westward spatial evolution trend from 2006 to 2022, with a gradually decreasing case distribution area. The movement trajectory of the centroid revealed that the incidence of malaria in Yunnan Province had an overall trend of moving to the west from 2006 to 2022, with a distinct spatial expansion trend and an eastward shifting trend of the centroid in 2022. Conclusions: From 2006 to 2022, the incidence of malaria in Yunnan Province generally showed a downward trend, and the areas with high incidence were gradually concentrated in the western part of Yunnan Province. It is necessary to strengthen malaria surveillance and response capacity for Mangshi City, Ruili City, Longchuan County, Yingjiang County, Lianghe County, and Tengchong City, maintaining current malaria elimination achievements and preventing local re-transmission of imported cases.
Objective: To investigate the epidemiological characteristics of severe fever with thrombocytopenia syndrome (SFTS) and the gene characteristics of Dabie bandavirus (DBV) in Shaoxing, Zhejiang Province, China in 2023, so as to provide a scientific basis for the prevention and control of this disease. Methods: The data of SFTS cases from Shaoxing in 2023 were collected. Descriptive epidemiological methods were used to analyze the epidemiological characteristics of SFTS. Serum samples were collected from the cases to sequence the DBV S gene fragment by Sanger sequencing. Homologous alignment, genetic evolution, and amino acid variation analysis were performed using Clustal Omega, MEGA 11.0, and Megalign tools of DNAStar 11.1 softwares. Results: In 2023, a total of 102 cases of SFTS were reported in Shaoxing, including 13 deaths, with a fatality rate of 12.75%. The cases occurred in March to October, and the most cases distributed in April to May (48 cases, 47.06%). SFTS was reported in all the six counties (cities and districts) of Shaoxing, and the number of SFTS cases was largest in Xinchang County (61 cases, 59.80%). The male-to-female ratio was 1∶1.22. The patients were mainly distributed in the age groups of 60 to < 70 years and 70 to < 80 years (64 cases in total, 62.75%). The majority of the cases were farmers (79 cases, 77.45%). The multiple gene sequence alignment results showed that the nucleotide homology of the S segment of 16 DBV strains was 94.27%-100%. The genetic evolution analysis showed that the prevalent DBV genotypes in Shaoxing were C, E-3, F-1, and F-2, most of which were closely related to the strains from Ningbo (China), Japan, and Korea, and the distribution of the C type had distinct regional characteristics. The S segment-encoded nucleoprotein and nonstructural proteins had 5 and 18 amino acid mutation points, respectively. Conclusions: Shaoxing reported a substantial number of SFTS cases and a high fatality rate in 2023, with the highest incidence in summer and autumn and in Xinchang County, mostly affecting the elderly, women, and farmers. Prevalent DBV strains include multiple genotypes and numerous amino acid variation sites, so it is necessary to strengthen surveillance and pay attention to the virus' variation.
Objective: To investigate the incidence of dengue fever and mosquito density at the epidemic sites in Guangzhou, China in 2023, so as to provide a theoretical basis for optimizing prevention and control measures against dengue fever. Methods: The data about dengue cases and the vector mosquito density surveillance data of the epidemic sites were collected in Guangzhou in 2023 to analyze the epidemiological characteristics of dengue fever and assess the status of mosquito emergency surveillance at the epidemic sites. Mean comparisons and correlation tests were performed using the t-test and Spearman rank correlation analysis in SPSS 26.0. Results: In 2023, Guangzhou reported a total of 1 801 cases of dengue fever, including 1 716 local cases and 85 imported cases. Domestically imported cases were mainly from Yunnan Province, while overseas imported cases mainly originated from Southeast Asia. Local cases were concentrated in the central urban area, accounting for 81.76% (1 403/1 716) of the total number. The incidence of dengue peaked during October to November. The infected population mainly consisted of retired personnel, household workers and the unemployed, and commercial service workers. The municipal mosquito vector emergency team conducted emergency surveillance 616 times in 2023, with an average standard space index (SSI) of 2.10 and an average adult-mosquito density index(ADI) of 6.54 individuals / human∙hour for the first surveillance (before control). Within 3 days after epidemic reporting, the compliance rates of SSI and ADI were 44.00% and 20.00%, respectively. The number of local dengue cases was positively correlated with the SSI (rs=0.431, P < 0.001) and ADI (rs=0.470, P < 0.001). Conclusions: The scale of dengue fever epidemics in Guangzhou has rebounded to the level before the COVID-19 pandemic. The poor effectiveness of daily mosquito control leads to a high risk of dengue transmission. It is necessary to strengthen the daily management and surveillance of mosquito density, timely detect dengue fever cases in the early stage and effectively carry out emergency response, and improve the speed of emergency mosquito vector control.
Objective: To establish a model for predicting animal plague based on surveillance in the Gurbantunggut Desert of the Junggar Basin in Xinjiang Uygur Autonomous Region, China. Methods: Based on the plague surveillance and meteorological data of the Gurbantunggut Desert from 2005 to 2016, The biological and meteorological factors significantly influencing the positive rate of serum Yersinia pestis antibodies in great gerbils were identified through Spearman rank correlation analysis. Plague epizootic prediction models were constructed by using multiple linear stepwise regression (MSR) and back propagation neural network (BPNN) methods separately. The prediction accuracy of the models was evaluated using the coefficient of determination (R2), root mean square error (RMSE), and mean absolute percentage error (MAPE). Results: The positive rate of serum Y. pestis antibodies in great gerbils was positively correlated with great gerbil density, burrow cluster coverage, and 1-year-lagged average sunlight hours from late spring to autumn (all P < 0.05), while negatively correlated with 1-year-lagged average annual precipitation (ρ=-0.069, P=0.047). For the MSR model, the compliance rate of predicted plague epizootic intensity was 33.33% (4/12), with R2=0.496, RMSE=0.046, and MAPE=0.659 on the training set, while on the test set, the corresponding metrics were 0.167, 0.058, and 0.661, respectively. The BPNN model showed a compliance rate of 83.33% (10/12), with R2=0.790, RMSE=0.029, and MAPE=0.209 on the training set, while on the test set, the corresponding metrics were 0.892, 0.021, and 0.292. Conclusions: The BPNN model is superior to the MSR model with better prediction and higher accuracy, which can be used for the prediction of animal plague prevalence in the Gurbantunggut Desert of the Junggar Basin.
Objective: To visualize the evolution, current status, hotspots, and future directions of domestic and international research on mosquito-borne infectious diseases, so as to provide a reference for future research in the field of mosquito-borne diseases. Methods: A library of literature on mosquito-borne infectious diseases published from 1990 to 2024 in the China National Knowledge Infrastructure and Web of Science core collection was created. CiteSpace 6.3.R3 software was used for analysis and data visualization to obtain the distributions, visualizations, and cluster maps of countries, research institutions, authors, cited literature, and keywords of the included studies on mosquito-borne infectious diseases; significant works in this field was identified; and research frontiers and hotspots were determined through timeline analysis and keyword burst detection. Results: The number of publications on mosquito-borne infectious diseases from 1990 to 2024 exhibited a "stable-rising-declining" trend. The main research entities were primarily from North America, led by the United States, and European countries. Liu Qiyong and Jordi Figuerola were the most prolific authors in Chinese research and English language, respectively. Tropical medicine, preventive medicine, and basic medicine were dominant research fields. The key research institutions included the University of Florida, Southern Medical University, and Chinese center for disease control and prevention (China CDC) and the United States centers for disease control and prevention (US CDC). The Chinese research hotspots had gradually shifted from surveillance and insecticide resistance to dengue fever and arthropod-borne viruses, while the hotspots in foreign-language literature had transitioned from a broad focus on RNA viruses to Zika virus, climate change, and virome. Conclusions: Research on mosquito-borne infectious diseases has gained increasing attention. Current domestic research is primarily focused on dengue fever, mosquito ecology, and insecticide resistance, while international research hotspots are centered on Zika virus, climate change, and molecular biology related to mosquito-borne diseases. Domestic research exhibits characteristics including centralized research entities, limited collaboration, and regional imbalances, highlighting the need for enhanced communication and cooperation between research entities and countries.
Objective: To analyze the allocation of plague prevention professionals and laboratory testing capabilities in prefectural and county-level institutions for disease control and prevention (ICDs), including center for disease control and prevention and institute of endemic disease control, in Hebei Province, China, evaluate the plague prevention capability of disease control and prevention institutions, identify weaknesses, propose prevention and control suggestions, so as to enhance the plague response capability of the ICDs across the province, and establish a scientific evaluation methodology for plague control and prevention capacity. Methods: A combination of questionnaire survey and on-site verification was used to investigate the plague prevention professionals, laboratory setup, test items, and reagent reserves in 14 prefectural ICDs (covering the two provincially-administered county-level cities of Xinji and Dingzhou, and Xiongan New Area) and their respective county-level centers for disease control in Hebei Province in January 2025. Data were organized and analyzed using Excel 2010 and SPSS 26.0 softwares. Results: The workforces of IDCs in plague control key prefectures and counties (cities and districts) (hereinafter called key prefectural and county-level IDCs) demonstrated higher proportions of personnel with associate senior titles or above, bachelor's degree or higher, preventive medicine major and aged > 50 than in non-key prefectures and counties (cities and districts). The differences in the composition ratios of professional titles, educational backgrounds, majors, and age groups among personnel were statistically significant between key and non-key prefectural and county levels IDCs (χ2=11.372, P=0.008; χ2=7.860, P=0.020; χ2=8.230, P=0.016; χ2=15.467, P=0.001). No statistically significant difference existed in plague detection capabilities between key and non-key prefectural institutions (Z=1.722, P=0.085), whereas a significant difference was found between key and non-key county-level institutions (Z=4.865, P < 0.001), with key county-level institutions demonstrating higher plague detection capabilities. Conclusions: In 2025, 12 key prefectural and county-level ICDs for plague prevention in Hebei Province face issues of aging plague prevention professionals and reserve talent shortages. However, they have more laboratory test items for plague, more sufficient reagent reserves, and higher plague prevention capabilities compared with non-key institutions. The 176 non-key prefectural and county-level institutions face challenges such as insufficient plague prevention professionals, weak professional abilities, few test items for plague, and reagent shortages, necessitating the strengthening of plague prevention capability. It is recommended to further consolidate the plague prevention capabilities of prefectural and county-level institutions in Hebei Province by increasing talent reserve, optimizing resource allocation, and intensifying training.
Objective: To investigate the genotypes of the voltage-gated sodium channel (VGSC) gene and their distribution characteristics in the field populations of Aedes albopictus in high-risk areas for dengue fever in China, so as to understand the knockdown resistance (kdr) status of Ae. albopictus to inform dengue prevention and control. Methods: From April to October 2022, Aedes larvae were collected from Fuzhou (Fujian Province), Jinghong (Yunnan Province), and Guangzhou (Guangdong Province). The larvae were reared in the laboratory to adulthood. For the morphologically identified Ae. albopictus mosquitoes, individual genomic DNA was extracted for VGSC gene fragment amplification by PCR and sequencing. Descriptive statistical analysis was performed to characterize the kdr mutations of the Ae. albopictus mosquitoes. Results: A total of 540 Ae. albopictus mosquitoes were genotyped through VGSC fragment sequencing. At V1016, two alleles were identified: wild-type GTA/V (724, 67.04%) and mutant GGA/G (356, 32.96%); the V1016G mutation was detected in all the three high-risk areas, with the frequency ranging from 18.41% to 68.91%; three genotypes were observed: wild-type homozygote V/V (288, 53.33%), wild-type/mutant heterozygote V/G (148, 27.41%), and mutant homozygote G/G (104, 19.26%); and the overall mutation frequency ranged from 31.19% to 84.62%. At F1534, four alleles were identified: wild-type TTC/F (401, 37.13%), mutant TCC/S (399, 36.94%), mutant TGC/C (273, 25.28%), and mutant TTG/L (7, 0.65%), with the mutant allele frequencies ranging from 29.81% to 77.48%; seven genotypes were detected: wild-type homozygote F/F (109, 20.19%), wild-type/mutant heterozygotes F/S (117, 21.67%), F/C (59, 10.92%), and F/L (7, 1.30%), mutant heterozygote S/C (126, 23.33%), and mutant homozygotes S/S (78, 14.44%) and C/C (44, 8.15%); and the mutation frequency ranged from 49.36% to 94.56%. A total of 19 genotype combinations were identified, with the V/V+S/C combination being the most prevalent (119, 22.04%). Conclusions: Kdr mutations, predominantly V1016G and F1534S, are frequent in the three high-risk areas for dengue. Insecticides should be applied scientifically and rationally to delay the development of resistance.
Objective: To determine the Pulex irritans infestation in some towns of Hotan County, Xinjiang Uygur Autonomous Region (Xinjiang), China, and to evaluate the killing effect of 8% alpha-cypermethrin wettable powder by residual spraying. Methods: The electric sprayer was used for residual spraying of 8% alpha-cypermethrin wettable powder. Before and after spraying, the damage of free P. irritans fleas in some towns of Hotan, Xinjiang was investigated and quantified by the inquiry method and sticky trap method. The flea index, flea infestation rate, and biting rate before and after control were compared by the independent group sample t test or one-way analysis of variance and Chi-square test. Results: The survey covered 4 townships. The biting rate was 54.04 % before flea treatment, and decreased to 1.79% after treatment, with a statistically significant difference (χ2=731.366, P < 0.001). A total of 1 007 fleas were captured before treatment, with an infestation rate of 41.97 %, and 42 fleas were captured after treatment, with the infestation rate being decreased to 6.52% (χ2=499.607, P < 0.001). The total flea index significantly decreased from 0.53 before treatment to 0.01 after treatment (t=28.482, P < 0.001). The total flea control rate was 98.11%. Conclusions: Flea infestation is common in Hotan County. The 8% alpha-cypermethrin wettable powder can rapidly reduce flea density and significantly mitigate flea infestation. It is recommended to adopt integrated control strategies by combining resistance surveillance, seasonal population dynamics of fleas, and environmental management (e.g., improving ground hardening and sanitary conditions) to reduce the potential transmission risks of flea-borne diseases such as plague.
Objective: To investigate the prevalence of Bartonella henselae and B. quintana as well as related symptoms and risk factors among a patient population at a medical institution, so as to provide a reference for clinical surveillance and diagnosis of bartonellosis. Methods: Indirect immunofluorescence assay was used to detect IgG antibodies against B. henselae and B. quintana in 200 serum samples from different age cohorts of patients aged 0-95 years at a Beijing hospital in 2019. The infection rates were compared by age, sex, inpatient/outpatient source, symptoms, and underlying diseases using the Chi-square test or Fisher's exact test by SPSS 27.0 software, and logistic regression was perfermed to analyze the influencing factors of infection rates. Results: The median age of the tested population was 52.00 (28.75-67.75) years. Forty-nine cases (24.50%) were positive for B. henselae antibodies, 8 (4.00%) were positive for B. quintana antibodies, and 6 (3.00%) were positive for both B. henselae and B. quintana antibodies. There was a significant difference in the infection rates of B. henselae and B. quintana (χ2=8.821, P=0.003). The infection rates of the two pathogens were not significantly different by age, sex, fever status, outpatient/inpatient source, and the history of cardiovascular diseases (all P > 0.05). Conclusions: The patients attending this hospital had a significant proportion of previous infections with Bartonella, with the infection rate of B. henselae higher than that of B. quintana. Medical professionals should pay attention to the prevalence of Bartonella infection to ensure timely diagnosis and treatment.
Objective: To investigate the type, number, and distribution of mosquito and fly breeding sites in Guangzhou, China, so as to lay the foundation for developing mosquito and fly control measures and plans, and the prevention and control of vector-borne diseases. Methods: In March 2024, 50 households were selected respectively from the eastern, western, southern, northern, and middle of each sub-district/town in Guangzhou; and in each sub-district/town, the mosquito habitats were selected in different directions, including at least 10 outdoor environments in residential areas, 15 governmental and organizational units (government agencies, social organizations, and enterprises and public institutions), 10 construction sites, 5 parks/green places, 5 special industries, and 10 other environments. The mosquito breeding sites in indoor and outdoor environments was surveyed, and the shelter conditions of the breeding sites were recorded. In each sub-district/town, more than six habitat types were selected to investigate the breeding sites of flies, and whether there were covers on breeding containers were recorded. The Chi-square test was used to compare the positive rates of different breeding sites. Results: In March, the average Breteau index was 3.85, and the average standard space index was 0.26. The main breeding sites of Aedes albopictus were flowerpots, flowerpot trays, containers of various materials and aquatic plants; in residential areas, the proportions of the 4 types of breeding sites were 37.43%, 19.33%, 15.45% and 18.92%, respectively, with higher positive rates in bamboo tubes/tree holes (10.06%) and waste tires (7.20%); and in outdoor environments, the breeding sites proportions were 20.10%, 13.20%, 22.67% and 13.18%, respectively, with higher positive rates in waste tires (6.55%) and bamboo tubes/tree holes (6.18%). The positive rate of Ae. albopictus breeding sites without shelters (3.89%) was significantly higher than that with shelters (2.14%) (χ2=481.061, P < 0.001). The main Culex breeding sites were wells and ditches; in residential areas, the proportions of the two breeding sites were 35.18% and 29.68%, respectively, with the positive rate higher in ditches (8.87%); and in outdoor environments, the breeding sites proportions were 52.96% and 38.34%, respectively, with the positive rate higher in hollows (11.57%). The average positive rate of fly breeding sites was 4.33%. The main fly breeding sites were garbage (61.42%), with a highest positive rate in animal matter (6.82%). Among fly breeding sites, the positive rate of covered habitats (4.09%) was significantly lower than that of uncovered habitats (4.58%) (χ2=4.744, P=0.029). Conclusions: Guangzhou had low densities of mosquitoes and flies but abundant breeding sites in March 2024. The breeding sites of mosquitoes and flies differs by environmental type, and sheltering or covering can reduce their breeding. Control measures should be formulated according to the breeding sites of mosquitoes and flies.
Objective: To investigate the species, density, and Hantavirus infection status of rodents in the suburban counties of Xi'an, China, so as to provide a scientific basis for the control and prevention of rodents and hemorrhagic fever with renal syndrome. Methods: From January to December 2023, rodents were monitored by night-snap trapping with peanut baits at randomly selected sites in the suburban counties of Xi'an, which were divided into four survey areas in the east, south, west, and north. The monitored habitats included urban residential areas, rural residential areas, key places, farmland, and grassland/woodland. Rodents captured were taxonomically classified based on external morphological characteristics and ecological distribution. Lung tissues collected post-dissection were subjected to Hantavirus nucleic acid detection through reverse transcription real-time quantitative PCR (RT-qPCR). Excel 2021 software was used to establish the database, and R 4.3.2 were used for statistical analyses. Rodent species composition was compared using the Fisher's exact test. Results: A total of 15 146 effective snap traps were deployed, and 358 rodents were captured, with a rodents density of 2.36%. Rodent densities were highest in the southern region at 3.39% and in the grassland/woodland at 4.55%. The dominant species was Mus musculus in the northern region and Apodemus agrarius in the other regions, showing a significant difference in rodents species composition between different regions (P < 0.001). Apodemus agrarius was dominant in grassland/woodland, farmland, and key places, Rattus norvegicus was dominant in urban residential areas, and M. musculus was abundent among three species of rodents found in rural residential areas. The difference in rodent species composition between different habitats was statistically significant (P < 0.001). Hantavirus nucleic acid testing was performed on lung tissue samples for all the captured rodents; and 20 positive rodents were detected, all being A. agrarius, and all infected with Hantaan virus. Among the four regions, rodents in the southern region had the highest Hantavirus infection rate (10.38%), and among the different habitats, rodents in farmland had the highest infection rate (8.70%). Conclusions: Rodent density and Hantavirus infection rate are both high in the suburban counties of Xi'an, especially in the southern region, where the risk of rodent infestations should be paid attention to. Based on the investigation results, the government should carry out rodent control and the prevention of rodent-borne diseases, and establish a long-term management mechanism, so as to effectively control rodent density and reduce rodent-borne diseases.
Objective: To investigate the allocation of personnel, equipment, and pesticides and the operational status of disinfection stations for eliminating the four pests (disinfection and sterilization stations) and government-hired pest control operation (PCO) companies across the sub-districts/towns of Guangzhou, China, so as to provide a basis for formulating strategies to improve the vector control capacity of Guangzhou. Methods: A self-designed questionnaire was used to conduct on-site surveys and interviews with disinfection and sterilization stations and PCO companies across Guangzhou's sub-districts/towns to analyze factors affecting resource allocation. The analysis of variance and Kruskal-Wallis H test were performed for continuous variable comparison among multiple groups, and the Bonferroni method was applied for pairwise comparison. Results: Among 170 institutions, disinfection and sterilization stations, municipal management offices, urban appearance and environmental sanitation supervision and management offices, and other government subordinate agencies accounted for 68.24% (116/170), while PCO companies accounted for 31.76% (54/170). The sub-districts/towns with disinfection and sterilization stations responsible for daily management and dengue fever emergency response accounted for 55.62% (94/169). There was a significant difference in the composite scores of pest control stations, PCO companies, and other government agencies (χ2=35.012, P < 0.001). Between six vector control working models (including pest control station full responsibility, PCO company full responsibility, and pest control station combined with PCO company co-responsibility), the composite scores differed significantly (χ2=35.610, P < 0.001); and the pairwise comparisons revealed that the PCO company full responsibility group had a significantly higher composite score than the pest control station full responsibility group and the municipal management office and urban appearance and environmental sanitation supervision and management office group. Conclusion: Optimizing the vector control capacity of sub-districts/towns from the perspective of institutions requires promoting a long-term management mechanism that encourages healthy competition to stimulate the development and improvement of the industry and institutions.
Objective: To investigate the species composition and distribution of necrophagous flies in Shenyang, China, so as to provide a reference for using necrophagous flies to determine the time and place of death in criminal cases. Methods: From March to October 2021, necrophagous flies were collected by trapping in urban and rural areas of Shenyang, and their species were identified based on their morphological characteristics. The Shannon-Wiener index, evenness index, and Simpson's index were calculated using Excel 2013 software. Analysis of similarities was performed using R 4.3.1 software. Results: A total of 29 species of necrophagous flies under 18 genera in 8 families were collected in Shenyang, with Calliphoridae being the dominant population accounting for 41.06% of the total catches. In urban and rural areas, 27 species of 17 genera of 8 families each were trapped, with no significant difference in species distribution between the two types of areas (R=-0.083, P=0.692). There was a significant difference in species distribution among spring, summer, and autumn (R=0.387, P=0.001). Species diversity was highest in summer. Conclusions: Calliphorid flies are the dominant population of necrophagous flies in Shenyang. The species distribution of necrophagous flies is similar in urban and rural areas, and the species composition is greatly influenced by seasons.
