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    25 June 2023, Volume 35 Issue 3
    Progress of schistosomiasis control in People’s Republic of China in 2022
    ZHANG Lijuan, HE Junyi, YANG Fan, DANG Hui, LI Yinlong, GUO Suying, LI Shizhen, CAO Chunli, XU Jing, LI Shizhu, ZHOU Xiaonong
    2023, 35(3):  217-224,250. 
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    This report presented the endemic status of schistosomiasis and analyzed the data collected from the national schistosomiasis prevention and control system and national schistosomiasis surveillance program in the People’s Republic of China in 2022. Among the 12 provinces (municipality and autonomous region) endemic for schistosomiasis, Shanghai Municipality, Zhejiang Province, Fujian Province, Guangdong Province and Guangxi Zhuang Autonomous Region continued to maintain the achievements of schistosomiasis elimination, and Sichuan and Jiangsu provinces maintained the criteria of transmission interruption, while Yunnan, Hubei, Anhui, Jiangxi and Hunan provinces maintained the criteria of transmission control by the end of 2022. A total of 452 counties (cites, districts) were found to be endemic for schistosomiasis in China in 2022, with 27 434 endemic villages covering 73 424 400 people at risk of infections. Among the 452 endemic counties (cities, districts), 75.89% (343/452), 23.45% (106/452) and 0.66% (3/452) achieved the criteria of elimination, transmission interruption and transmission control of schistosomiasis, respectively. In 2022, 4 317 356 individuals received serological tests for schistosomiasis, and 62 228 were sero⁃positive. A total of 208 646 individuals received stool examinations for schistosomiasis, with one positive and another two cases positive for urine microscopy, and these three 3 cases were imported schistosomiasis patients from Africa. There were 28 565 cases with advanced schistosomiasis documented in China by the end of 2022. Oncomelania hupensis snail survey was performed in 18 891 endemic villages in China in 2022 and O. hupensis snails were found in 6 917 villages (36.62% of all surveyed villages), with 8 villages identified with emerging snail habitats. Snail survey was performed at an area of 655 703.01 hm2 and 183 888.60 hm2 snail habitats were found, including 110.58 hm2 emerging snail habitats and 844.35 hm2 re⁃emerging snail habitats. There were 477 200 bovines raised in the schistosomiasis endemic areas of China in 2022, and 113 946 bovines received serological examinations for schistosomiasis, with 204 sero⁃positives detected. Among the 131 715 bovines received stool examinations, no positives were identified. In 2022, there were 19 726 schistosomiasis patients receiving praziquantel chemotherapy, and expanded chemotherapy was performed in 714 465 person⁃time for humans and 234 737 herd⁃time for bovines in China. In 2022, snail control with chemical treatment was performed at an area of 119 134.07 hm2, and the actual area of chemical treatment was 65 825.27 hm2, while environmental improvements were performed at an area of 1 163.96 hm2. Data from the national schistosomiasis surveillance program of China showed that the mean prevalence of Schistosoma japonicum infections was both zero in humans and bovines in 2022, and no S. japonicum infection was detected in O. hupensis snails. These data demonstrated that the endemic status of schistosomiasis continued to decline in China in 2022, with 3 confirmed schistosomiasis patients that had a foreign nationality and all imported from Africa, and the areas of snail habitats remained high. Further improvements in the construction of the schistosomaisis surveillance and forecast system, and reinforcement of O. hupensis survey and control are required to prevent the re⁃emerging schistosomiasis.
    Risk predictive models of healthcare⁃seeking delay among imported malaria patients in Jiangsu Province based on the machine learning
    ZHANG Yuying, CAO Yuanyuan, YANG Kai, WANG Weiming, YANG Mengmeng, CHAI Liying, GU Jiyue, LI Mengyue, LU Yan, ZHOU Huayun, ZHU Guoding, CAO Jun, LU Guangyu
    2023, 35(3):  225-235,243. 
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    Objective To create risk predictive models of healthcare⁃seeking delay among imported malaria patients in Jiangsu Province based on machine learning algorithms, so as to provide insights into early identification of imported malaria cases in Jiangsu Province. Methods Case investigation, first symptoms and time of initial diagnosis of imported malaria patients in Jiangsu Province in 2019 were captured from Infectious Disease Report Information Management System and Parasitic Disease Prevention and Control Information Management System of Chinese Center for Disease Control and Prevention. The risk predictive models of healthcare⁃seeking delay among imported malaria patients were created with the back propagation (BP) neural network model, logistic regression model, random forest model and Bayesian model using thirteen factors as independent variables, including occupation, species of malaria parasite, main clinical manifestations, presence of complications, severity of disease, age, duration of residing abroad, frequency of malaria parasite infections abroad, incubation period, level of institution at initial diagnosis, country of origin, number of individuals travelling with patients and way to go abroad, and time of healthcare⁃seeking delay as a dependent variable. Logistic regression model was visualized using a nomogram, and the nomogram was evaluated using calibration curves. In addition, the efficiency of the four models for prediction of risk of healthcare⁃seeking delay among imported malaria patients was evaluated using the area under curve (AUC) of receiver operating characteristic curve(ROC). The importance of each characteristic was quantified and attributed by using SHAP to examine the positive and negative effects of the value of each characteristic on the predictive efficiency. Results A total of 244 imported malaria patients were enrolled, including 100 cases (40.98%) with the duration from onset of first symptoms to time of initial diagnosis that exceeded 24 hours. Logistic regression analysis identified a history of malaria parasite infection [odds ratio (OR) = 3.075, 95% confidential interval (CI): (1.597, 5.923)], long incubation period [OR = 1.010, 95% CI: (1.001, 1.018)] and seeking healthcare in provincial or municipal medical facilities [OR = 12.550, 95% CI: (1.158, 135.963)] as risk factors for delay in seeking healthcare among imported malaria cases. BP neural network modeling showed that duration of residing abroad, incubation period and age posed great impacts on delay in healthcare⁃seek among imported malaria patients. Random forest modeling showed that the top five factors with the greatest impact on healthcare⁃seeking delay included main clinical manifestations, the way to go abroad, incubation period, duration of residing abroad and age among imported malaria patients, and Bayesian modeling revealed that the top five factors affecting healthcare⁃seeking delay among imported malaria patients included level of institutions at initial diagnosis, age, country of origin, history of malaria parasite infection and individuals travelling with imported malaria patients. ROC curve analysis showed higher overall performance of the BP neural network model and the logistic regression model for prediction of the risk of healthcare⁃seeking delay among imported malaria patients (Z = 2.700 to 4.641, all P values < 0.01), with no statistically significant difference in the AUC among four models (Z = 1.209, P > 0.05). The sensitivity (71.00%) and Youden index (43.92%) of the logistic regression model was higher than those of the BP neural network (63.00% and 36.61%, respectively), and the specificity of the BP neural network model (73.61%) was higher than that of the logistic regression model (72.92%). Conclusions Imported malaria cases with long duration of residing abroad, a history of malaria parasite infection, long incubation period, advanced age and seeking healthcare in provincial or municipal medical institutions have a high likelihood of delay in healthcare⁃seeking in Jiangsu Province. The models created based on the logistic regression and BP neural network show a high efficiency for prediction of the risk of healthcare⁃seeking among imported malaria patients in Jiangsu Province, which may provide insights into health management of imported malaria patients.
    Single⁃cell RNA sequencing deciphers transcriptional profiles of hepatocytes in mouse with hepatic alveolar echinococcosis
    YANG Qingqing, JIA Wanzhong, WANG Xiangqian, CAI Qigang, GE Xin, WANG Wei, HAN Xiumin
    2023, 35(3):  236-243. 
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    Objective To investigate the cell composition and the transcriptional characteristics in microenvironments of hepatic tissues in mice at late stage of Echinococcus multilocularis infection at a single⁃cell level. Methods Peri⁃lesion and paired distal hepatic specimens were collected from two BALB/c mice (6 to 8 weeks old) infected with E. multilocularis for single⁃cell RNA sequencing. The Seurat package in the R software was employed for quality control of data, multi⁃sample integration and correction of batch effects, and uniform manifold approximation and projection (UMAP) algorithm was used for cell clustering. Cell types were annotated using classical marker genes. Differentially expressed genes were screened in each cell type through differential gene expression analysis, and the biological roles of cells were predicted using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Results A total of 43 710 cells from peri⁃lesion and distal hepatic tissues of E. multilocularis⁃infected mice were analyzed, and were classified into 11 cell types, including neutrophils, T cells, macrophages, granulocyte⁃monocyte progenitor cells, B cells, plasma cells, basophils, hepatic stellate cells, endothelial cells, hepatocytes, and platelets. T cells were the largest population of immune cells in the microenvironment of hepatic tissues, including five CD4+ T cell subsets, two CD8+ T cell subsets and phosphoantigen⁃reactive γδT cells. The proportions of CD4+ helper T cells and cytotoxic CD4+ T cells decreased and the proportion of T helper 2 (Th2) cells increased in peri⁃lesion tissues relative to distal hepatic tissues. In addition, the differentially expressed genes in Th2 cells were associated with negative regulation of the immune system, and the highly expressed genes in cytotoxic CD4+ T cells correlated with activation of the immune system. Conclusions Single⁃cell RNA sequencing deciphers the cell composition and distribution in microenvironments of hepatic tissues from mice infected with E. multilocularis, and the increased proportion of Th2 cells in peri⁃lesion hepatic tissues may be associated with formation of immunosuppressive microenvironments.
    Bioinformatics analysis and prokaryotic expression of Strongyloides stercoralis serine protease inhibitor 1
    HAN Xue, BI Xianglian, ZHAO Hongying, SHI Yunliang, WEN Qing, LÜ Jiayin, SUN Jiayue, FU Xiaoyin, LIU Dengyu
    2023, 35(3):  244-250. 
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    Objective To predict the structure and antigenic epitope of the Strongyloides stercoralis serine protease inhibitor 1 (Ss⁃SRPN⁃1) protein using bioinformatics tools, and to construct prokaryotic expression plasmids for expression of recombinant Ss⁃SRPN⁃1 protein, so as to provide the basis for unraveling the function of the Ss⁃SRPN⁃1 protein. Methods The amino acid sequence of the Ss⁃SRPN⁃1 protein was downloaded from the NCBI database, and the physicochemical properties, structure and antigenic epitopes of the Ss⁃SRPN⁃1 protein were predicted using bioinformatics tools, including ExPASy, SWISS⁃MODEL and Protean. Primers were designed according to the nucleotide sequences of Ss⁃SRPN⁃1, and the Ss⁃SRPN⁃1 gene was amplified, cloned and sequenced with genomic DNA extracted from the infective third⁃stage larvae of S. stercoralis as a template. The Ss⁃SRPN⁃1 protein sequence was cloned into the pET28a (+) expression vector and transformed into Escherichia coli BL21 (DE) cells for induction of the recombinant Ss⁃SRPN⁃1 protein expression. The recombinant Ss⁃SRPN⁃1 protein was then purified and identified using Western blotting and mass spectrometry. Results Bioinformatics analysis showed that the Ss⁃SRPN⁃1 protein, which was composed of 372 amino acids and had a molecular formula of C1948H3046N488O575S16, was a stable hydrophilic protein, and the subcellular localization of the protein was predicted to be extracellular. The Ss⁃SRPN⁃1 protein was predicted to contain 11 dominant B⁃cell antigenic epitopes and 20 T⁃cell antigenic epitopes. The Ss⁃SRPN⁃1 gene with a length of 1 119 bp was successfully amplified, and the recombinant plasmid pET28a (+)/Ss⁃SRPN⁃1 was constructed and transformed into E. coli BL21(DE) cells. The expressed recombinant Ss⁃SRPN⁃1 protein had a molecular weight of approximately 43 kDa, and was characterized as a Ss⁃SRPN⁃1 protein. Conclusions The recombinant Ss⁃SRPN⁃1 protein has been expressed successfully, and this recombinant protein may be a potential vaccine candidate against strongyloidiasis.
    Effects of angiotensin⁃converting enzyme on reproduction of Culex pipiens pallens
    WANG Huan, LIU Jin, KAILIMAI Aini, ZHENG Junnan, SHEN Bo, SUN Yan, ZHOU Dan
    2023, 35(3):  251-257. 
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    Objective To investigate the role of angiotensin⁃converting enzyme (ACE) in the reproduction of Culex pipiens pallens, so as to provide insights into selection of targets for controlling mosquito vector populations. Methods Cx. pipiens pallens was collected from Tangkou County, Shandong Province in 2009. Female and male mosquitoes were selected at 72 hours post⁃eclosion, and quantitative real⁃time reverse transcription PCR (qPCR) assay was used to detect the expression of ACE gene in the whole body and reproductive tissues of male mosquitoes and fertilized female mosquitoes before (0 h) and after blood meals (24, 48, 72 h), respectively. Then, 150 female and 150 male mosquitoes at 0 to 4 hours post⁃eclosion were selected and divided into the wild⁃type group (WT group), small interfering RNA⁃negative control group (siNC group) and small interfering RNA⁃ACE group (siACE group), of 50 mosquitoes in each group. Mosquitoes in the WT group were given no treatment, and mosquitoes in the siNC and siACE groups were given microinjection of siNC and siACE into the hemolymph at a dose of 0.3 μg per mosquito. The knockdown efficiency was checked using qPCR assay, and the reproductive phenotype of mosquitoes was observed. Results The relative ACE gene expression was higher in the whole body of male mosquitoes (5.467 ± 1.006) relative to females (1.199 ± 0.241) (t = 5.835, P = 0.004) at 72 h post⁃eclosion, and the highest ACE expression was seen in reproductive tissues of male mosquitoes (199.100 ± 24.429), which was 188.3 times higher than in remaining tissues (1.057 ± 0.340) (t = 6.602, P = 0.002). Blood meal induced high ACE expression in all body tissues of fertilized female mosquitoes, with peak expression at 24 h after blood meals (14.957 ± 2.815), which was 14.8 times higher than that before blood meals (1.009 ± 0.139) (P = 0.002). The transcriptional level of ACEs continued to increase in the ovaries of female mosquitoes after blood meals during the vitellogenesis phase, peaking at 48 h after blood meals (5.500 ± 0.734), which was 5.1 times higher than that before blood meals (1.072 ± 0.178) (P = 0.002). Small RNA interference targeting ACE resulted in a 57.2% reduction in ACE expression in female mosquitoes in the siACE group (0.430 ± 0.070) relative to the siNC group (1.002 ± 0.070) (P = 0.001), and a 41.1% reduction in male mosquitoes in the siACE group (0.588 ± 0.067) relative to the siNC group (1.008 ± 0.131) (P = 0.016). Knockdown of ACE expression resulted in a 48.0% decrease in the number of eggs laid by female mosquitoes in the siACE group [(94.000 ± 27.386) eggs] relative to the siNC group [(180.800 ± 27.386)] (P < 0.001), and a 45.0% decrease in the number of eggs laid by wild female mosquitoes mated with males in the siACE group [(104.500 ± 20.965) eggs] relative to the siNC group [(190.050 ± 10.698) eggs] (P < 0.001). Conclusions  Reduced ACE expression may inhibit the fecundity of male and female mosquitoes, and ACE may be as a potential target for mosquito vector population suppression.
    Prevalence and genotyping of Cryptosporidium spp. and Giardia lamblia in dogs and cats from a pet hospital in Shanghai Municipality
    ZHANG Jing, QIN Yuan, SHEN Yujuan, WANG Yaxue, CAO Jianping, SU Yaxin, LIU Hua
    2023, 35(3):  258-262. 
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    Objective To investigate the prevalence and genotypes of Cryptosporidium spp. and Giardia lamblia in dogs and cats from a pet hospital in Shanghai Municipality. Methods A total of 145 fresh fecal samples were collected from pet dogs and cats in a pet hospital in Shanghai Municipality during the period from November 2021 to June 2022, including 99 dog fecal samples and 46 cat fecal samples. The small subunit ribosomal ribonucleic acid (SSU rRNA) gene of Cryptosporidium and the triose phosphate isomerase (TPI) gene of G. lamblia were amplified using nested PCR assay, and the positive amplification products were sequenced from both directions. The sequence assembly was performed using the software Clustal X 2.1, and sequence alignment was conducted using BLAST. A phylogenetic tree was created with the Neighbor⁃Joining method using MEGA 11.0 to identify parasite species or genotype. Results The overall prevalence of Cryptosporidium and G. lamblia was 20.00% (29/145) in 145 pet dog and cat fecal samples, with the prevalence of 0.69% (1/145) and 19.31% (28/145) in Cryptosporidium and G. lamblia, respectively. G. lamblia was only detected in dog fecal samples, with prevalence of 18.18% (18/99), while the detection rates of Cryptosporidium and G. lamblia were 2.17% (1/46) and 21.74% (10/46) in cat fecal samples. Nucleotide sequence analysis showed that one Cryptosporidium positive sample was characterized as C. felis, and 28 G. lamblia positive samples were all characterized as Giardia assemblage A, which showed 100% sequence homology with human isolates of Giardia. Phylogenetic analysis revealed that the sequences obtained in this study belonged to the same branch with the reported Giardia assemblage A. Conclusions Cryptosporidium and G. lamblia infection was prevalent in pet dogs and cats from the study pet hospital in Shanghai Municipality, and there is a zoonotic risk for the species and genotype. Intensified surveillance of Cryptosporidium and Giardia infection is recommended in pets and their owners, and improved management of pet keeping is required.
    Prediction of potential suitable habitats of Haemphysalis concinna in Heilongjiang Province based on the maximum entropy model
    ZHANG Yaming, WANG Yue, YUAN Shuang, TANG Lei, ZHANG Wenjia, CHEN Qu, CHEN Shulin, YU Yang, JIA Yuehui
    2023, 35(3):  263-270. 
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    Objective To predict the potential suitable habitat of Haemaphysalis concinna in Heilongjiang Province under different climatic scenarios. Methods The geographic locations of ticks in Heilongjiang Province from 1980 to 2022 were captured from literature review and field ticks monitoring data from Harbin Center for Disease Control and Prevention in Heilongjiang Province, and the tick distribution sites with spatial correlations were removed using the software ArcGIS 10.2. The environment data under historical climatic scenarios from 1970 to 2000 and the climatic shared socioeconomic pathways (SSP) 126 scenario model from 2021 to 2040 and from 2041 to 2060 were downloaded from the WorldClim website, and the elevation (1 km, 2010), population (1 km grid population dataset of China, 2010) and annual vegetation index (1 km, 2010) data were downloaded from the Resource and Environmental Science and Data Center, Institute of Geographical Sciences and Natural Resources, Chinese Academy of Sciences. The contribution of environmental factors to H. concinna distribution was evaluated and environmental variables were screened using the software MaxEnt 3.4.1 and R package 4.1.0, and the areas of suitable habitats of H. concinna and changes in center of gravity were analyzed using the maximum entropy model in Heilongjiang Province under different climatic scenarios. In addition, the accuracy of the maximum entropy model for prediction of H. concinna distribution was assessed using the area under curve (AUC) of the receiver operating characteristic curve. Results A total of 79 H. concinna distribution sites and 24 environmental variables were collected, and 70 H. concinna distribution sites and 9 environmental factors that contributed to distribution of the potential suitable habitats of H. concinna in Heilongjiang Province were screened. The three most significant contributing factors included precipitation seasonality, annual precipitation, and mean temperature of the driest quarter, with cumulative contributions of 60.7%. The total area of suitable habitats of H. concinna was 29.05 × 104 km2 in Heilongjiang Province under historical climatic scenarios, with the center of gravity of suitable habitats located at (47.31° N, 129.16° E), while the total area of suitable habitats of H. concinna reduced by 0.97 × 104 km2 in Heilongjiang Province under the climatic SSP126 scenario from 2041 to 2060, with the center of gravity shifting to (47.70° N, 129.28° E). Conclusions The distribution of suitable habitats of H. concinna strongly correlates with temperature and humidity in Heilongjiang Province. The total area of potential suitable habitats of H. concinna may appear a tendency towards a decline with climatic changes in Heilongjiang Province, and high⁃, medium⁃ and low⁃suitable habitats may shift.
    Dermatophagoides farinae induces conjunctival epithelial cell damage to promote neutrophil migration and neutrophil extracellular traps formation 
    WU Meili, YAN Ru, ZHAO Wenjun
    2023, 35(3):  271-278. 
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    Objective To investigate the mechanisms underlying allergic conjunctivitis caused by conjunctival epithelial cell damage, neutrophil migration and neutrophil extracellular traps (NETs) formation induced by crude extracts of Dermatophagoides farinae mite (CDM). Methods Human conjunctival epithelial cells were stimulated with 500, 1 000, 2 000, 4 000 ng/mL, and the expression levels of interleukin⁃6 (IL⁃6), tumor necrosis factor⁃α (TNF⁃α), interferon⁃γ (IFN⁃γ) and IL⁃8 were detected using quantitative real⁃time PCR (qPCR) assay and enzyme⁃linked immunosorbent assay (ELISA). The culture supernatant of human conjunctival epithelial cells was collected and co⁃cultured with neutrophils. Neutrophil migration was measured using Transwell migration assay, and the expression of NETs markers myeloperoxidase (MPO) and citrullinated histone H3 (CitH3) was quantified using immunofluorescence staining. Neutrophils were stimulated with phorbol 12⁃myristate 13⁃acetate (PMA), and then NETs were collected for treatment of human conjunctival epithelial cells. Cell apoptosis was detected using flow cytometry, and the levels of IL⁃6, TNF⁃α, IFN⁃γ and IL⁃8 were measured in the cell culture supernatant using ELISA. Results Treatment with CDM at concentrations of 2 000 ng/mL and 4 000 ng/mL up⁃regulated IL⁃6, TNF⁃α, IFN⁃γ and IL⁃8 expression in human conjunctival epithelial cells. Following treatment with CDM at concentrations of 2 000 ng/mL and 4 000 ng/mL, the culture supernatant of human conjunctival epithelial cells promoted neutrophil migration and induced increases in the staining intensity of MPO and CitH3. In addition, increased NETs triggered the apoptosis of human conjunctival epithelial cells and IL⁃6, TNF⁃α, IFN⁃γ and IL⁃8 secretion in the culture supernatant of human conjunctival epithelial cells. Conclusions CDM induces human conjunctival epithelial cell damages, thereby promoting neutrophil migration and NETs formation, while the release of NETs further aggravates human conjunctival epithelial cell damages.
    Interpretation of Detection and identification standard of hookworm—Hookworm larvae coproculture techniques (WS/T 791—2021)
    DENG Yan, JIANG Tiantian, CHEN Weiqi, ZHANG Yalan, ZHANG Hongwei, ZHAO Dongyang
    2023, 35(3):  279-281,285. 
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    Detection and identification standard of hookworm—Hookworm larvae coproculture techniques (WS/T 791—2021) is the first recommended technical standard for hookworm detection and species identification using the hookworm larvae coproculture technique in China. This standard was issued on November 23, 2021, and had been in effect since May 1, 2022. This article provides a detailed interpretation pertaining to the background, drafting process, main contents, and dos and don’ts for better understanding and application of this standard among professionals working in disease control and prevention institutions and medical institutions.
    Prevalence of Angiostrongylus cantonensis infection in snails in Fujian Province from 2017 to 2021
    XIE Xianliang, CHEN Yunhong, LI Yanrong, XIE Hanguo
    2023, 35(3):  282-285. 
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    Objective To investigate the prevalence of Angiostrongylus cantonensis infection in market⁃sold and field⁃captured snails in Fujian Province, so as to provide the scientific basis for the formulation of the angiostrongyliasis control measures. Methods In each month from May to October during the period from 2017 through 2021, Pomacea snails were collected from two field fixed surveillance sites and Bellamya aeruginosa collected from one agricultural product market in Fuzhou City, while Pomacea and B. aeruginosa snails were collected from two agricultural product markets and four restaurants in Xiamen City. At least 50 Pomacea snails and 500 g B. aeruginosa were sampled each time. A. cantonensis infection was detected in Pomacea snails using lung microscopy, and in B. aeruginosa using a tissue homogenate method. Results A total of 9 531 Pomacea snails were detected for A. cantonensis infection in two cities of Fuzhou and Xiamen, and the overall prevalence of A. cantonensis infection was 4.40%, with the highest prevalence in 2017 (6.82%, 116/1 701) and the lowest prevalence in 2019 (3.46%, 83/2 400). The prevalence of A. cantonensis infection was significantly higher in Pomacea snails sampled from Fuzhou City (11.23%, 326/2 903) than from Xiamen City (1.40%, 93/6 628) ([χ2] = 461.48, P < 0.01). A. cantonensis larvae were detected in larval Pomacea snails in two cities of Fuzhou and Xiamen each month. The prevalence of A. cantonensis infection in Pomacea snails appeared an overall tendency towards a rise with month in Fuzhou City, with the highest prevalence in October (15.24%), and there was a significant difference among month ([χ2] = 14.56, P < 0.05), while the prevalence of A. cantonensis infection in Pomacea snails was low in Pomacea snails sampled from Xiamen City each month, with the highest prevalence in June (2.64%), and there was a significant difference among month ([χ2] = 23.17, P < 0.05). A total of 18 966 B. aeruginosa snails were detected for A. cantonensis infection in two cities of Fuzhou and Xiamen, and the overall prevalence of A. cantonensis infection was 0.01%. Conclusions A. cantonensis infection was identified in Pomacea and B. aeruginosa snails in Fujian Province from 2017 to 2021, and there is a potential risk of human A. cantonensis infection.
    Prevalence and influencing factors of human soil⁃transmitted nematode infections in Ningbo City from 2016 to 2021
    YE Zehao, CHU Kun, ZHANG Jienan, SUN Yawei, LU Feng
    2023, 35(3):  286-290,298. 
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    Objective To investigate the prevalence and influencing factors of soil⁃transmitted nematode infections in Ningbo City from 2016 to 2021, so as to provide insights into the development of targeted control measures against soil⁃transmitted nematodiasis. Methods Permanent residents at ages of 3 years and older were sampled in Ningbo City using a multi⁃stage sampling method each year during the period from 2016 to 2021. Soil⁃transmitted nematode eggs were detected in stool samples using a modified Kato⁃Katz thick smear method (two slides for each stool sample), and Enterobius vermicularis eggs were additionally identified among children at ages of 3 to 12 years using the adhesive cellophane⁃tape perianal swab method. The time⁃ and regions⁃specific prevalence of soil⁃transmitted nematode infections was calculated, and the factors affecting hookworm infections were identified using a multivariate logistic regression model. Results A total of 11 573 person⁃times were detected for soil⁃transmitted nematode infections in Ningbo City from 2016 to 2021, and 296 egg⁃positives were detected, with a mean prevalence rate of 2.56% [95% confidential interval (CI): (2.28%, 2.87%)]. Hookworm was the predominant species of soil⁃transmitted nematode among egg⁃positives in Ningbo City (98.31%, 291/296), and there was a significant difference in the prevalence of hookworm infections among years ([χ2] = 190.27, P < 0.01). The highest prevalence of hookworm infections was observed in Ninghai County (4.06%), and there was a region⁃specific prevalence rate of hookworm infection in Ningbo City ([χ2] = 148.43, P < 0.01). Multivariate logistic regression analysis showed that elderly residents at ages of over 60 years [odds ratio (OR)= 1.94, 95% CI: (1.07, 3.54), P < 0.05], males [OR = 2.19, 95% CI: (1.72, 2.80), P < 0.01], farmers [OR = 6.94, 95% CI: (3.37, 14.29), P < 0.01] and residents with a low education level [illiteracy or semi⁃illiterate: OR = 3.82, 95% CI: (1.56, 9.35), P < 0.05; primary school: OR = 2.70,95% CI: (1.11, 6.59), P < 0.05] were at a higher risk for hookworm infections. Conclusions The overall prevalence of soil⁃transmitted nematode infections was low among residents in Ningbo City from 2016 to 2021. The surveillance and health education for human hookworm disease remain to be reinforced among male farmers with a low education level at ages of over 60 years in Ninghai County.
    Prevalence of parasitic infections in human stool samples from a hospital in Chenzhou City of Hunan Province
    PENG Yufeng, LIAO Xiaomei, ZHU Lepan, ZHANG Yangnan
    2023, 35(3):  291-293. 
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    Objective To investigate the prevalence of parasitic infections in human stool samples from a hospital in Chenzhou City, Hunan Province, so as to provide insights into the management of intestinal parasitic diseases. Methods Stool samples were collected from patients admitted to a hospital in Chenzhou City from September 2020 to March 2021, subjected to physiological saline smearing and microscopy for detection of intestinal parasites. The prevalence of parasitic infections and the species of parasites were descriptively analyzed. Results The overall prevalence of intestinal parasitic infections was 1.61% in the 10 728 stool samples, and there were 3 samples with mixed infections of two parasite species. A total of seven parasite species were identified, including Blastocystis hominis (162 cases, 1.55%), Giardia lamblia (5 cases, 0.05%), Dientamoeba fragilis (5 cases, 0.05%), Endolimax nana (one case, 0.01%), Iodamoeba bütschlii (one case, 0.01%), Strongyloides stercoralis (one case, 0.01%) and Trichomonas hominis (one case, 0.01%). The prevalence of intestinal parasitic infection was significantly higher among women than in men (2.14% vs. 1.25%; [χ2] = 13.01, P < 0.01), and a high prevalence rate was seen among patients at ages of 20 to 30 years (2.99%) and 80 years and older (2.86%); however, no age⁃specific prevalence of intestinal parasitic infection was detected ([χ2] = 12.45, P > 0.05). Conclusions The overall prevalence of intestinal parasitic infection was low among patients admitted to a hospital in Chenzhou City, and gender⁃specific prevalence was found. Food⁃borne and opportunistic parasites were predominant intestinal parasites, including B. hominis, G. lamblia and D. fragilis.
    Epidemiological characteristics of imported malaria cases after malaria elimination in Yixing City of Jiangsu Province
    LIANG Jing, XUE Zhiqiang, LI Xuebing
    2023, 35(3):  294-298. 
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    Objective To analyse the epidemiological characteristics of imported malaria cases after malaria elimination in Yixing City, Jiangsu Province, so as to provide reference for malaria prevention and control in grassroots healthcare institutions. Methods All data pertaining to malaria cases reported in Yixing City from 2016 to 2022 were retrieved from Chinese Disease Control and Prevention Information System, and the data pertaining to vector monitoring and human malaria parasite infections from 2016 to 2022 were collected for a descriptive statistical analysis. Results A total of 14 imported malaria cases were reported in Yixing City from 2016 to 2022, including 12 cases with Plasmodium falciparum malaria, one case with P. vivax malaria and one case with P. ovale malaria, and all cases acquired infections in Africa and then returned to Yixing City. Malaria cases were reported across 2016 to 2022 except in 2020 and 2021. Malaria cases were predominantly reported during the period between December and February of the next year, and workers were the predominant occupation. The institutions where malaria was initially diagnosed included county⁃level general hospitals, county⁃level disease prevention and control institutions and grassroots healthcare centers, and there were 10 cases with definitive diagnosis of malaria on the day of initial diagnosis, with a 64.29% (9/14) correct rate of initial diagnosis. There were 5 cases diagnosed with severe malaria, and the standardized response rate was 100.00% following the “1⁃3⁃7” surveillance and response strategy. Of all malaria vectors, only Anopheles sinensis was monitored in Yixing City from 2016 to 2022, and all humans were tested negative for blood smears except imported malaria cases. Conclusions The correct rate of initial malaria diagnosis was not high in healthcare institutions in Yixing City from 2016 to 2022, and there are still multiple challenges for prevention of re⁃establishment of imported malaria.
    Progress in methodology of the Global Burden of Disease Study and its impact on the disease burden of parasitic diseases
    ZENG Ting, JIA Tiewu
    2023, 35(3):  299-306. 
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    Currently, the Global Burden of Disease Study (GBD) is the most comprehensive, systematic, and largest-scale global observational epidemiological project, which measures the national, regional and global mortality and disability of diseases, injuries and risk factors that threaten human health using unified indicators, such as disability-adjusted life year. This review describes the development history, assessment process and methodological advances of GBD, and discusses the impact of GBD on the burden of parasitic diseases, aiming to provide insights into the widespread use of GBD.
    Progress of international and national researches on disease burden of echinococcosis
    MIAO Liyuan, TIAN Tian, ZHOU Xiaonong
    2023, 35(3):  307-312. 
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    As a neglected tropical disease defined by the World Health Organization (WHO), echinococcosis causes a huge public health burden. Understanding the disease burden due to echinococcosis facilitates the progress towards elimination of the disease. This review analyzes the advances in disease and economic burdens of echinococcosis, describes the status quo disease burden due to echinococcosis in different areas of the world, compares the difference between international and national studies on disease and economic burdens of echinococcosis, and discusses the shortcomings of the current international and national studies on disease burden of echinococcosis. Currently, the studies on disease burden of echinococcosis suffer from problems of few field survey data and lack of authoritative disability weights for echinococcosis, while the studies on economic burden of echinococcosis suffer from problems of lack of comprehensive study populations and indicators.
    Progress of researches on techniques for detection of Angiostrongylus cantonensis in intermediate host snails
    ZHAO Yongbo, LI Tianmei, GUO Yunhai
    2023, 35(3):  313-316. 
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    Angiostrongyliasis cantonensis is an emerging infectious disease in China. Snails are intermediate hosts of Angiostrongylus cantonensis and play a critical role in the transmission of angiostrongyliasis cantonensis. Detection of A. cantonensis in snails is an important part of epidemiological surveys. Currently, the rapid developments in the techniques for detection of A. cantonensis in snails facilitate the surveillance of angiostrongyliasis cantonensis and provide an important support for angiostrongyliasis cantonensis prevention and control. This review summarizes the advances in the techniques for detection of A. cantonensis in snails.
    Application of machine learning in clinical predictive models for infectious diseases: a review
    ZHENG Ruiying, LIU Genyan
    2023, 35(3):  317-321. 
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    Infectious diseases are one of the major threats to global public health. Inconvenience of diagnosis and treatment frequently causes misdiagnosis, missing diagnosis or overtreatment, resulting in serious clinical outcomes. As an important branch of artificial intelligence, machine learning has been widely used in multiple fields. Predictive models created based on patients’ clinical characteristics, laboratory tests, and imaging examinations are effective for prediction and evaluation of clinical diagnosis, therapeutic efficacy and prognosis, as well as detection of outbreaks. Machine learning modeling has the advantages of high efficiency, high accuracy and interpretability as compared to traditional modeling approaches, which provides a new tool for diagnosis and treatment of infectious diseases. This review summarizes the advances of applications of machine learning in clinical predictive models for infectious diseases.
    Cystic echinococcosis misdiagnosed as hepatic cyst: a case report
    PANG Chongmin, ZHANG Bo, CHEN Yao
    2023, 35(3):  322-324. 
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    This case report presents the diagnosis and treatment of a case of cystic echinococcosis misdiagnosed as hepatic cyst. The case had anaphylactic shock caused by extravasation of cyst fluid during extraction of hepatic cyst and suffered from postoperative recurrence of echinococcosis. This case report may provide insights into diagnosis and treatment of cystic echinococcosis among healthcare workers in non⁃endemic areas.