Objective To formulate a catalogue of alien vectors and pathogenic organisms for early warning and effective prevention of alien species invasion. Methods The authors searched literature, online databases, and published catalogues for alien vectors and pathogens that can seriously threaten the health of human and animals and agricultural and ecological security. They were evaluated for the risk of invasion to China by using a suitable habitat prediction model and a comprehensive evaluation system of multiple indicators. Candidate species with the potential of invasion were included in this catalogue. Results A total of 304 alien species were screened out and listed in this catalogue for China, including 69 vectors and 235 pathogenic organisms. Among them, 275 species (47 vectors and 228 pathogens) had high probability of invading China. Conclusion This catalogue can be used as an early warning directory to prevent alien vectors and pathogenic organisms from invading China, which provides a reference for relevant departments to formulate preventive management strategies and measures.

Objective To determine the current and future suitable areas of Elizabethkingia anophelis, and to provide a reference for preventing its outbreak and spread in China. Methods With 21 pieces of information on the geographical distribution of E. anophelis and data on 56 climatic factors, a MaxEnt model was used to estimate the suitable areas of E. anophelis in the world and China. R 4.2.2 software was used to adjust model parameters, and construct the receiver operating characteristic curve. The area under the curve was calculated to evaluate the accuracy of the model. The results were visualized using ArcGIS 10.5 software. Results Annual precipitation (bio12, 27.0%) and the minimum temperature in January (tmin01, 22.2%) contributed most to the distribution of E. anophelis. Under current climatic conditions, the highly suitable areas for E. anophelis were mainly distributed in the southeastern United States, northern South America, western Europe, central Africa, and parts of southeastern Asia; in China, they were mainly distributed in the wet regions south of the Qinling-Huaihe Line. Under future climatic conditions, climate changes of varying intensities generally promoted the suitable areas of E. anophelis in the world and China, especially under high radiative forcing. Conclusions There are large suitable areas for E. anophelis in the world and China under both current and future climate conditions, which are expected to be promoted with the change of climate in the future. Authorities should take measures to control greenhouse gas emissions to limit the increase of E. anophelis’ suitable areas. Provinces with its highly suitable areas should strengthen surveillance, risk assessment and response.

Objective To predict the potential distribution of Euglandina rosea in China under current and future climatic conditions via an optimized maximum entropy (MaxEnt) model, and to provide a theoretical basis for the prevention and control of invasion of E. rosea in China. Methods The global occurrence records of E. rosea were collected and screened using ENMtool. Maxent 3.4.1 and GraphPad Prism 8 were used to screen environmental variables according to the contribution rate of environmental variables, the jackknife method, and the correlation analysis of variables. The "kuenm" package was run in R 4.0.4 software to calculate and adjust the model parameters by means of regularization multipliers and feature combinations. The optimized MaxEnt model was used to predict the potential distribution of E. rosea in China under current and future climate scenarios. ArcGIS 10.7 was used to process the results and map the images. Results A total of 780 E. rosea occurrence records were identified, and four environmental variables were used to construct the MaxEnt model. The area under the curve (AUC) of the model was 0.963. The most influential environmental factors on the distribution of E. rosea were precipitation of the driest quarter and the highest temperature in February. The MaxEnt model predicted that the current potential areas of E. rosea were distributed in the southeast of China, concentrated in Fujian province, Guangdong province, and central Guangxi Zhuang Autonomous Region. It would gradually expand northward to Hunan province, Jiangxi province, central Anhui province, eastern Hubei province, and some areas of Zhejiang province in the future. Conclusions E. rosea has potential distribution in China. With global warming, its potential habitat areas will gradually expand, while at lower latitudes in the southeast they will slightly shrink. As a result, the overall center of potential areas shifts northward.

In 2021, the national surveillance of rodent-borne pathogens of disease vectors had been started up, and a total of 123 prefectures were selected as national surveillance sites. Sampling was completed at 95 surveillance sites. A total of 17 910 rodent specimens were collected, and 16 891 of them were tested. The completion rate of pathogen detection was 94.31%. The overall infection rate of eight monitored rodent-borne pathogens around China was 2.43% (407/16 716) for Hantavirus, 0.02% (4/16 154) for Dabie bandavirus (i.e., severe fever with thrombocytopenia syndrome virus), 5.75% (624/10 850) for Leptospira interrogans, 0.11% (5/4 470) for Rickettsia mooseri, 0.05% (5/10 790) for Orientia tsutsugamushi, 2.39% (75/3 136) for Bartonella, and 0.04% (2/5 075) for Anaplasma phagocytophilum. Francisella tularensis was not detected. More than ten species of rodents were found to be infected with different pathogens in 18 provinces across China. The infection rates of pathogens in rodents in southern regions were relatively high, and the positive rates of pathogens carried by various rodents differed. Rattus norvegicus and Apodemus agrarius were the species in which the most pathogens were detected.

Objective To assess the risk of alien pathogen invasion in China, and to reduce their harms. Methods The alien pathogens that might invade China since the year of 2000 were identified through consulting the literature, domestic and alien invasive species databases, and experts, and the risk assessment index system and risk assessment standard for alien pathogen invasion that adapt to the local ecological environment and economic and social development were established. Results Through the above method, the status description and risk assessment of 22 pathogens were carried out. It was found that 17 pathogens were high-risk invasion, 5 pathogens were medium risk invasion, among which 8 pathogens had invaded China. Conclusions China is facing a large risk of invasion of foreign pathogenic bacteria, and the monitoring and warning should be strengthened in time to prevent and control foreign pathogens.

Objective To assess the risk of Anopheles barbirostris invading China under future climate change scenarios, and to provide a basis for monitoring and early warning. Methods The maximum entropy model was used to predict the recent global potential distribution and project the future potential distribution of An. barbirostris in China. The main environmental factors affecting the distribution of An. barbirostris were analyzed based on the contribution rate of environmental factors. The vector risk assessment index system was established to calculate the comprehensive risk value of invasive species. Results A total of 99 effective distribution points of An. barbirostris were identified. The rainfall in September played a leading role in affecting the distribution of potential suitable areas of An. barbirostris. The omission rate of model training was roughly the same as the theoretical omission rate, and the area under the receiver operating characteristic curve was 0.988. Under the current climate scenario, the potential suitable areas of An. barbirostris in China were mainly in Guangdong province, Guangxi Zhuang Autonomous Region, and Hainan province as well as the eastern Sichuan Basin. In 2081-2100, China has the largest potential suitable area (207.51×10⁴ km²) under the shared socioeconomic pathway 585 climate scenario, and the area of suitable area will show an increasing trend under various climate scenarios. Through the risk assessment index system, it was calculated that the comprehensive risk value of An. barbirostris was 0.57, so An. barbirostris belonged to the medium-risk invasive species. Conclusions An. barbirostris is a species with a medium invasion risk. In the future, the mosquito vector surveillance system should be improved according to the distribution of its suitable areas, and scientific prevention and control strategies should be formulated.

Objective To analyze the epidemiological characteristics (temporal, spatial, and demographic distributions) of indigenous and imported cases of dengue fever reported in Chinese mainland from 2005 to 2020.Methods The seasonal characteristics of dengue fever were analyzed using Excel 2010. Trend analysis was performed on the annual median age of disease onset using the Mann-Kendall test with the use of R 4.0.2. The map visualization and spatial analysis of cases were conducted using ArcGIS 10.3 software.Results A total of 81 648 indigenous cases of dengue fever were reported in 14 provinces (autonomous regions or municipalities) of Chinese mainland from 2005 to 2020. The indigenous cases were reported between May and December, concentrated between August and November (98.26%), and were distributed south from 35°36?N, mainly in Guangdong (74.01%) and Yunnan (13.74%) provinces, indicating seasonal and regional characteristics. Two major outbreaks of dengue fever occurred in 2014 and 2019, with 46 033 and 15 376 indigenous cases, respectively, adding up to 75.21% of the total indigenous cases. Among the local cases from 2005 to 2020, the male-to-female ratio was 0.99∶1; 54.93% were aged between 25 and <55 years; the top three frequent occupations were engagement in housework or unemployment (21.40%), service workers (12.46%), and retirees (11.71%). The median age of the total indigenous cases was 40 years (interquartile range [IQR]: 27-54). The difference of overall trend of the median age of indigenous cases since 2005 was not statistically significant (Z=1.510, P=0.131). There were a total of 12 701 imported cases in 30 provinces (autonomous regions or municipalities) except the Tibet Autonomous Region in Chinese mainland from 2005 to 2020. The imported cases were reported throughout a year, frequently between June and November (81.81%), and were mainly distributed in Yunnan, Guangdong, Fujian, and Zhejiang provinces, suggesting seasonal and regional characteristics. The imported cases were mainly from Southeast Asian countries including Myanmar and Cambodia. In 2019, the number of imported cases reached a peak of 5 813, accounting for 45.77% of the total imported cases. Among the imported cases from 2005 to 2020, the male-to-female ratio was 2.05∶1; 73.29% were aged between 25 and 54 years; the top three frequent occupations were farmers (24.13%), service workers (19.34%), and engagement in housework or unemployment (13.91%). The median age of the total imported cases was 33 years (IQR: 26-44). The overall trend of the median age of imported cases since 2005 was not statistically different (Z=0.413, P=0.679). A total of 15 376 indigenous cases and 5 813 imported cases reported in 2019, and the number of indigenous and imported cases reported were dramatically decreased to 616 and 158 in 2020, respectively.Conclusions Dengue fever outbreaks in Chinese mainland are still caused by imported cases, with significant seasonal and regional characteristics. The indigenous cases were mainly distributed in Guangdong and Yunnan provinces, while the imported cases were mainly from Southeast Asian countries including Myanmar and Cambodia. There was no significant change in the median age of dengue fever cases from 2005 to 2021.

Objective To determine the species and positive rate of Rickettsia carried by gamasid mites on the body surface of rodents in Inner Mongolia Autonomous Region (Inner Mongolia), China, and to provide a basis for the prevention and control of local infectious diseases. Methods DNAs of gamasid mites on the body surface of rodents in different areas of Inner Mongolia were extracted, and the 17 kDa gene sequence was amplified by nested polymerase chain reaction (PCR). The outer membrane protein A (ompA) sequence was amplified for samples positive for the 17 kDa gene. The PCR products obtained by amplification were sequenced, and the phylogenetic tree was constructed after homology comparison between the sequencing results and the sequences from the National Center for Biotechnology Information, USA. Results Rickettsia was detected in 11 of 536 gamasid mites, and the total positive rate was 2.05%. The species of Rickettsia included R. heilongjiangensis, a sibling species of R. felis, and an unknown species of Rickettsia. Their host mites included Haemogamasus mandschuricus, Eulaelaps cricetuli, Hg. kitanoi, Haemolaelaps glasgowi, and deutonymphs of Parasitus sp., with the positive rates of 8.89%, 3.39%, 2.22%, 0.68%, and 12.50%, respectively. The hosts that carried gamasid mites positive for Rickettsia included Spermophilus dauricus, Allactaga sibirica, and Lasiopodomys brandtii. Conclusion Gamasid mites on the body surface of rodents in Inner Mongolia carry a variety of Rickettsia, including the species that are human pathogen.

Objective To investigate the species and prevalence of viruses carried by sandfly specimens in Wuxiang county, Shanxi province, China. Methods Sandfly specimens were collected in Wuxiang county, Shanxi province in June 2018, and virus isolation was conducted using two cell lines of golden hamster kidney cells (BHK-21 cells) and Aedes albopictus egg cells (C6/36 cells) preserved in the laboratory. The positive isolate was subjected to viral RNA extraction and cDNA library preparation, followed by viral gene amplification, nucleotide sequence determination, and phylogenetic analysis. Results The SXWX1816-2 strain caused cytopathic effects in mammalian cells (BHK-21 cells), but no cytopathic effect in insect cells (C6/36 cells). The results of nucleotide sequence determination and analysis of the virus genome showed that the lengths of nucleotide sequences in the coding region of M and S genes of the virus were 4 089 and 1 611 nt; the results of nucleotide and amino acid sequence homology and phylogenetic analysis of M and S genes of the virus showed that the SXWX1816-2 strain belonged to the Phlebovirus genus from the Phenuiviridae family, which shared the highest homology and closest phylogenetic relationship with Wuxiang virus (WUXV) previously isolated in China. Conclusions This study clarifies the taxonomic status of the virus (SXWX1816-2) isolated from natural sandflies in China. The results provide important basic data for the research on viruses carried by blood-sucking insects in China, especially the virus carried and transmitted by sandflies.

Objective To investigate the influencing factors of dengue fever and the existing problems in prevention and control efforts against dengue fever in the representative areas of Yunnan and Guangdong provinces, China through in-depth interviews, and to put forward targeted recommendations for local prevention and control strategies against dengue fever.Methods Using a self-designed interview outline, one-to-one interviews with 25 professionals engaged in dengue fever prevention and control research, epidemiological investigations, and treatment from the cities and prefectures with severe dengue fever outbreaks in Yunnan and Guangdong provinces were conducted. Electronic interview documents were obtained and imported into MAXQDA 2020 software for thematic framework analysis, including categorization, coding, analysis, and charting.Results Through the analysis of the interview data, a total of four first-level themes were obtained: (1) the current situation of dengue fever prevention and control, i.e., the current prevention and control strategies and measures, which were summarized in four measures attributed to routine response and seven to response strategies and measures against outbreaks; (2) factors affecting dengue fever prevention and control, including two climatic factors and six social factors, among which social factors could be controlled through human intervention to control the spread of dengue fever; (3) problems in dengue fever prevention and control, including inadequate government’s attention, unbalanced and insufficient financial investment, low public participation, and a lack of assessment and supervision mechanisms, which were most frequently mentioned by experts, along with six other problems, according to the interview data; (4) key points of response to dengue fever, which were summarized in ten key points of response.Conclusions The representative areas of dengue fever in Yunnan and Guangdong provinces should establish a long-term response mechanism led by the government with multi-sectoral cooperation to fully mobilize residents to participate in prevention and control, reasonably allocate funds for prevention and control, strengthen the control of Aedes vectors, and provide a scientific basis for the sustainable and precise control of dengue fever and other Aedes vector-borne diseases in China.

Objective To establish a duplex droplet digital polymerase chain reaction (ddPCR) detection method for Japanese encephalitis virus (JEV) and West Nile virus (WNV).Methods Based on the designed primers and probes of JEV and WNV, a duplex ddPCR detection system for JEV and WNV was established. Its sensitivity, specificity, and repeatability were explored. The sensitivity was compared with the number of cycles required for the fluorescent signal to cross the threshold in each reaction tube of dual quantitative PCR.Results The detection sensitivity of the duplex ddPCR detection system could reach 10² copies/μl for both JEV and WNV, with good specificity and repeatability. No cross-reactivity was observed with the Dengue virus, Chikungunya virus, Zika virus, Tick-borne encephalitis virus, and human genome.Conclusion The established duplex ddPCR method shows high sensitivity and specificity for JEV and WNV detection, which provides a solution for detection for the two viruses in different scenarios.

Objective: To investigate the rodents species, density, and pathogens they carry in Zunyi, Guizhou Province, China. Methods: A total of 70 sampling points were set in 14 counties/districts of Zunyi, with five points in the east, south, west, north, and center of each county/district. Small mammals were monitored through night trapping in Zunyi from October 2021 to October 2022, followed by species identification and pathogen detection. Excel 2021 was used for data organization. SPSS 26.0 was used to analyze the density, species, and pathogen-carrying status of small mammals through rate or constituent ratio comparison with the Chi-square test (P < 0.05 indicates a statistically significant difference). Results: A total of 9 969 effective traps were placed at all the surveillance points, capturing 549 small mammals in total, of which 522 were rodents. The total density of small mammals was 5.51%. The total density of rodents was 5.24%. The rodent density was highest in Honghuagang District (12.94%), followed by Fenggang County (12.34%), and lowest in Chishui City (1.80%). There was a statistical difference in rodent density between the counties/districts (χ²=195.619, P < 0.001). Rattus norvegicus was the dominant rodent species in urban residential areas, rural residential areas, and key industries, while Apodemus agrarius was the dominant species in farming areas. The composition of rodent species statistically differed in different regions (the center, north, east, and west) of Zunyi (χ²=117.357, P < 0.001). Each small mammal was examined for Leptospira interrogans and Orientia tsutsugamushi in the liver, spleen, and kidney; Dabie bandavirus in the liver, spleen, and lung; and Hantavirus in the lung. Among 343 samples tested, 27 were positive, all for L. interrogans, with a pathogen detection rate of 7.87%. Shrews had the highest detection rate (16.00%), followed by A. agrarius (12.35%), and R. norvegicus had the lowest detection rate (1.64%). There was a significant difference in the detection rates of different species of small mammals (χ²=14.372, P=0.002). The detection rate was 9.66% (26/269) in farming areas, which was highest, and 2.94% (1/34) in key industries, with negative detection results in urban and rural residential areas. There were no differences in detection rates between different habitats (χ²=5.171, P=0.160). The detection rate was 27.03% in Meitan County, followed by 25.00% in Suiyang County, and zero in Renhuai City, Fenggang County, and Yuqing County, with a statistical difference between different counties/cities/districts (χ²=35.409, P=0.001). Conclusions: The density of rodents was relatively high in Zunyi. The detection of L. interrogans should be a warning of the possibility of related diseases. Local authorities should strengthen rodent control in spring and autumn and take comprehensive control measures according to actual situation and dominant rodent species and pathogen detection status in different habitats, so as to reduce the density of rodents and prevent the occurrence of rodent-borne diseases.

Objective To analyze the epidemiological characteristics of hemorrhagic fever with renal syndrome (HFRS) in China from 2006 to 2021, to investigate the influence of non-pharmaceutical intervention against coronavirus disease 2019 (COVID-19) on HFRS prevalence, and to provide a scientific basis for the subsequent formulation of relevant policies. Methods Descriptive epidemiological methods were utilized to statistically analyze the epidemiological characteristics of HFRS in China from 2006 to 2021. The data of HFRS cases from 2006 to 2019 were used to establish an autoregressive integrated moving average (ARIMA) model to predict the number of HFRS cases in 2020-2021, and the predicted values were compared with the actual observed values. Results The number of HFRS cases in China was relatively stable in 2006-2021, and the number of deaths were significantly reduced. HFRS had obvious seasonality, with two peaks of incidence in a year, i.e., May-June and November. The number of cases in northeast China decreased, but the affected areas in the whole country expanded, and some areas were still at risk of outbreak. The number of male cases was significantly higher than that of female cases. The peak age group of onset was 35-49 years for males and 45-59 years for females, and there was a significant difference in the age composition between males and females (χ²=2 802.807, P<0.001). Farmers were the main affected population, accounting for more than half of the total cases. The seasonal ARIMA model was established by fitting the data of HFRS cases from 2006 to 2019 with R 4.0.4 software, which was (2,0,2)(1,1,0)₁₂ and was well fitted. The actual observed value of HFRS cases in 2020-2021 was close to the predicted value, within its 95% confidence interval. Conclusion HFRS is an important public health problem in China and the overall trend of its prevalence is relatively stable. It is necessary to strengthen the surveillance and implement more accurate prevention and control measures. The measures for COVID-19 prevention and control in China have no significant impact on the prevalence of HFRS during 2020-2021.

Objective: To investigate the density distribution of Aedes mosquitoes in different habitats and seasonal fluctuation in Hangzhou, Zhejiang Province, China from 2017 to 2021, so as to provide a scientific basis for effective prevention and control, risk assessment, and early warning of dengue fever. Methods: According to the National Vector Surveillance Implementation Plan and the Zhejiang Provincial Vector Surveillance Plan, Aedes mosquitoes were monitored in 15 districts (counties and cities) in Hangzhou. Adult mosquitoes were monitored using the double-layered mosquito net method, and larvae were monitored using the Breteau index (BI) method. The surveillance time was set during April to November. The mosquito surveillance data of the 15 districts (counties and cities) were collected. Excel 2019 software was used for data analysis. The net trap index, BI, and container index (CI) were calculated. Categorical data were compared using the Chi-squared test. One-way analysis of variance was used for quantitative data. Results: From 2017 to 2021, the density of Ae. albopictus in Hangzhou by the double-layered mosquito net method was 2.54 mosquitoes/net·h, and no Ae. aegypti mosquitoes were captured. The density of adult mosquitoes was lowest in 2017 and highest in 2020. There was a statistical difference in the net trap index between different years (F=5.117, P=0.017). The seasonal distribution generally presented a bimodal pattern, with the peaks of mosquito densities mainly in July and October. The average BI from 2017 to 2021 was 9.18, and the peak period of the BI was during May to October. The CI showed that Ae. albopictus larvae were distributed in all kinds of water bodies. The CI differed statistically between different water bodies in the same year (all P < 0.001) and between different years in the same water body (all P < 0.001). Conclusions: Ae. albopictus density was high in Hangzhou, indicating a risk of dengue fever outbreaks and regional epidemics. It is recommended that the counties (cities, districts) take timely mosquito control measures according to the density, distribution, and seasonal fluctuation of mosquitoes.

Objective To investigate the distribution of ticks and the carrying status of (SFTSV) in Dongyang, Zhejiang Province, China, so as to provide a basis for the prevention and control of severe fever with thrombocytopenia syndrome.Methods In 2019-2020, two towns (subdistrict) were set as monitoring sites in each of the mountainous, hilly, and basin areas of Dongyang. The artificial drag-flag method was used to collect free-living ticks in the wild. Parasitic ticks on the body surface of host animals, such as domestic animals (sheep, cattle, and dog) and field mice, were collected by tick inspection on the body surface of animals. Tick specimens were identified. Real-time quantitative reverse transcription polymerase chain reaction was used to detect SFTSV. The difference in rates was analyzed by the Chi-square test. The difference in the number of captured ticks was analyzed by the Fisher’s exact test.Results There were 10 species of ticks belonging to 4 genera and 1 family in Dongyang. There was statistically difference in the number of free-living ticks caught in different seasons in mountainous, hilly and basin areas (P<0.001 by Fisher’s exact test), which was significantly higher in mountainous areas than in basin areas, and the tick density in the first and second quarters was significantly higher than that in the third and fourth quarters. The average density of free-living ticks was 30.83 ticks/flag·100 m. The average tick infection rate of domestic animals was 18.72%, with a tick index of 0.94, and the average tick infection rate of rodents was 8.59%, with a tick index of 0.22. The dominant populations of free-living ticks and parasitic ticks on the body surface of domestic animals and rodents were Haemaphysalis longicornis, Rhipicephalus haemaphysaloides, and Ixodes granulatus, respectively. No SFTSV was detected in 771 tick specimens from 251 groups.Conclusions Ticks are commonly found in the wild and on the body surface of animals in Dongyang, and the species are relatively rich. The density of ticks is high in spring and summer, suggesting that spring is the best time to kill ticks.