Table of Content

14 March 2023, Volume 35 Issue 1

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Optimized pathway to schistosomiasis elimination in China: a scrutiny using a marginal benefit approach

LI Qin, YANG Guojing, ZHENG Jinxin, XU Jing, ZHOU Xiaonong

2023, 35(1):  1. 

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Following concerted efforts for over 7 decades, great achievements have been gained in the national schistosomiasis control program of China. Currently, China is moving towards the stage of schistosomiasis elimination, when the major task is to make full use of available resources to improve schistosomiasis surveillance and response to sustainably consolidate gained schistosomiasis control achievements and prevent re⁃emerging schistosomiasis. There is therefore an urgent need for optimization of interventions for schistosomiasis elimination. Based on analysis of socioeconomic features at different stages of the national schistosomiasis control program in China, this review discusses the relationship between the needs of assessment of schistosomiasis elimination interventions and the optimized strategy of schistosomiasis elimination at different stages of the national schistosomiasis control program using a marginal benefit approach and proposes the optimized schistosomiasis elimination strategy that allows the highest marginal benefit with currently available schistosomiasis elimination costs, so as to provide the optimal strategic pathway to schistosomiasis elimination and facilitate the achievement of the targets set in Healthy China 2030.

Temporal trends in disease burden of major human parasitic diseases in China from 1990 to 2019

ZENG Ting, LÜ Shan, TIAN Liguang, LI Shizhu, SUN Leping, JIA Tiewu

2023, 35(1):  7. 

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Objective　To analysize the temporal trends in the disease burden of major human parasitic diseases in China from 1990 to 2019, so as to provide the evidence for improving the parasitic disease control strategy in China. Methods　The disability⁃adjusted life years (DALYs) of malaria, intestinal nematode infections, schistosomiasis, food⁃borne trematodiases, cysticercosis and echinococcosis in China from 1990 to 2019 were captured from the Global Burden of Disease Study 2019 (GBD 2019), and age⁃ and gender⁃specific DALYs of parasitic diseases were estimated. The temporal trends in DALYs of malaria, intestinal nematode infections, schistosomiasis, food⁃borne trematodiases, cysticercosis and echinococcosis were evaluated in China from 1990 to 2019 using average annual percent change (AAPC) with Joinpoint regression analysis. Results　The DALYs were 643 836.42 person⁃years due to food⁃borne trematodiases, 156 853.03 person⁃years due to cysticercosis, 79 764.62 person⁃years due to schistosomiasis, 70 989.73 person⁃years due to intestinal nematode infections, 4 258.61 person⁃years due to echinococcosis and 264.86 person⁃years due to malaria in China in 2019, respectively. The overall DALYs of six parasitic diseases were higher among men (546 441.93 person⁃years) than among women (409 525.33 person⁃years), and were greater among adults at ages of 14 to 65 years (684 780.84 person⁃years) than among children at 14 years and lower (35 437.38 person⁃years) and the elderly at ages of 65 years and older (235 749.04 person⁃years). During the period from 1990 to 2019, food⁃borne trematodiases were the leading cause of DALYs among the six parasitic diseases, and cysticercosis shifted from the fourth leading cause in 1990 to the second leading cause of DALYs in China in 2019, while intestinal nematode infections shifted from the second leading cause in 1990 to the fourth leading cause of DALYs in 2019. The DALYs of major human parasitic diseases appeared an overall tendency towards a decline in China from 1990 to 2019, with the fastest drop seen in DALYs due to malaria (AAPC = -19.6%, P = 0.003), followed by due to intestinal nematode infections (AAPC = -8.2%, P < 0.001) and schistosomiasis (AAPC = -3.1%, P < 0.001), and a slow decline was seen in the DALYs of food⁃borne trematodiases (AAPC = -1.0%, P < 0.001), while there were no significant decrease in the DALYs of echinococcosis (AAPC = -0.5%, P = 0.264) and the DALYs of cysticercosis appeared a tendency towards a rise (AAPC = 0.7%, P < 0.001). Conclusions 　The disease burden of major human parasitic diseases appeared an overall tendency towards a decline in China from 1990 to 2019, with a high disease burden seen due to food⁃borne parasitic diseases, no remarkable reduction seen in echinococcosis, and a tendency towards a rise seen in cysticercosis. It is recommended to focus on echinococcosis control, and continue to consolidate the control achievements of other major human parasitic diseases in China; meanwhile, the surveillance and prevention of food⁃borne parasitic diseases should be reinforced.

Establishment and evaluation of a method for extracting exogenous short DNA fragments of Schistosoma japonicum from urine samples

ZHANG Qiaoqiao, ZHAO Song, YE Yuying, BI Niannian, WANG Xinyao, ZHANG Jianfeng, LI Wei, YANG Kun

2023, 35(1):  15. 

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Objective　To establish the method for extracting exogenous short DNA fragments of Schistosoma japonicum from urine samples, and to evaluate the efficiency of this method for extraction from urine samples treated with various methods. Methods　The S. japonicum SjG28 gene fragment was selected as a target sequence, and the 81 bp short DNA fragment was amplified on the target sequence using PCR assay. Following characterization using sequencing, the short DNA fragment was added into the urine samples as an exogenous short DNA fragment. Primers and probes were designed with SjG28 as a target gene, to establish the real⁃time fluorescent quantitative PCR (qPCR) assay. The sensitivity of this qPCR assay was evaluated with exogenous short DNA fragments that were diluted at a 1∶10 dilution ratio as the DNA template, and the specificity of the qPCR assay was evaluated with the genomic DNA of S. mansoni, S. haematobium, Babesia, Ancylostoma duodenale, Clonorchis sinensis, and Paragonimus westermani as DNA templates. Exogenous short DNA fragments were added into artificial and healthy volunteers’ urine samples, followed by pH adjustment, centrifugation and concentration, and the efficiency of extracting exogenous short DNA fragments from urine samples was compared with the QIAmp Viral RNA Mini Kit (Qiagen kit) and BIOG cfDNA easy kit (BIOG kit). Results　A 81 bp small DNA fragment of S. japonicum was successfully prepared, and the lowest detection limit of the established qPCR assay was 100 copies/μL of the 81 bp small DNA fragment of S. japonicum. If the genomic DNA of S. japonicum, S. mansoni, S. haematobium, Babesia, A. duodenale, C. sinensis, and P. westermani served as DNA templates, the qPCR assay only detected fluorescent signals with S. japonicum genomic DNA as the DNA template. If the pH values of artificial urine samples were adjusted to 5, 6, 7 and 8, the recovery rates were (49.12 ± 2.09)%, (84.52 ± 4.96)%, (89.38 ± 3.32)% and (87.82 ± 3.90)% for extracting the exogenous short DNA fragment of S. japonicum with the Qiagen kit, and were (2.30 ± 0.07)%, (8.11% ± 0.26)%, (13.35 ± 0.61)% and (20.82 ± 0.68)% with the BIOG kit, respectively (t = 38.702, 26.955, 39.042 and 29.571; all P values < 0.01). If the Qiagen kit was used for extracting the exogenous short DNA fragment from artificial urine samples, the lowest recovery rate was seen from urine samples with a pH value of 5 (all P values < 0.05), and there were no significant differences in the recovery rate from urine samples with pH values of 6, 7 and 8 (all P values > 0.05). Following centrifugation of artificial [(64.30 ± 1.00)% vs. (58.87 ± 0.26)%; t = 12.033, P < 0.05] and healthy volunteers’ urine samples [(31 165 ± 1 017) copies/μL vs. (28 471 ± 818) copies/μL; t = 23.164, P < 0.05]. In addition, concentration of artificial urine samples with the 10 kDa Centrifugal Filter and concentration of healthy volunteers’ urine samples with the 100 kDa Centrifugal Filter were both effective to increase the recovery of the Qiagen kit for extracting the exogenous short DNA fragment of S. japonicum (both P values < 0.01). Conclusions　A method for extracting exogenous short DNA fragments of S. japonicum from urine samples has been successfully established, and the Qiagen kit has a high extraction efficiency. Adjustment of urine pH to 6 to 8 and concentration of healthy volunteers’ urine samples with the 100 kDa Centrifugal Filter are both effective to increase the efficiency of extracting exogenous short DNA fragments of S. japonicum.

Genetic variations in four geographical isolates of Gohieria fusca based on cytochrome b and internal transcribed spacer genes

TAO Xianglin, MA Fei, LI Zheng, KAN Xinrui, YE Changjiang, SUN Entao

2023, 35(1):  22. 

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Objective　To investigate the genetic diversity and genetic differentiation of different geographical isolates of Gohieria fusca. Methods　G. fusca isolates were sampled from Wuhu (WH), Bengbu (BB) and Bozhou cities (BZ) of Anhui Province and Jiaxing City of Zhejiang Province (JX). Mitochondrial cytochrome b (Cytb) and ribosomal internal transcribed spacer (ITS) genes were amplified in WH, BB, BZ and JX isolates of G. fusca using PCR assay. The gene sequences were edited and aligned using the software Chromas 2 and DNASTAR 1.00, and the haplotype, haplotype diversity (Hd) and nucleotide polymorphism (Pi) of each isolate were calculated using the software DnaSP 5.10.00. The genetic differentiation among isolates (Fst) and gene flow value (Nm) were estimated using the software MEGA 10.2, and a phylogenetic tree was built. Tests of neutrality and analysis of molecular variance (AMOVA) were performed using the software Arlequin 3.1 and a haplotype network was built based on the Median⁃Joining network using the software Network 10.2. Results　PCR assay showed that the sizes of the Cytb and ITS genes were 372 bp and 1 301 to 1 320 bp, respectively. All four isolates of G. fusca presented high genetic diversity based on mitochondrial Cytb and ITS genes (Hd = 0.804，Pi = 0.006 91). AMOVA showed genetic differentiation among geographical isolates of G. fusca (Fst = 0.202 40, P < 0.05), and the genetic variation was mainly caused by intra⁃population variations (79.76%). Gene flow analysis showed a high level of gene flow among G. fusca isolates (Nm > 1). Tests of neutrality based on Cytb gene measured a Tajima’s D value of -1.796 31 (P < 0.05) and a Fu’s FS value of -3.293 98 (P < 0.05) in WH isolate of G. fusca, indicating population expansion in WH isolate of G. fusca. Haplotype network analysis and phylogenetic analysis revealed no remarkable geographical distribution pattern among different geographical isolates of G. fusca. All four isolates of G. fusca presented high genetic diversity (Hd = 0.985，Pi = 0.011 97). AMOVA showed moderate level of genetic differentiation between four isolates (Fst = 0.104 62, P < 0.05). The tests of neutrality based on ITS genes measured a Tajima’s D value of -6.088 20 and a Fu’s FS value of -1.935 99 (both P > 0.05) in the whole isolate of G. fusca, indicating no obviously population expansion. Conclusions　 The four geographical isolates of G. fusca have high genetic diversity and remarkable genetic differentiation. Since a high level of gene flow is detected among different geographical isolates of G. fusca, no obvious geographical distribution pattern of G. fusca is found.

Effect of Trichomonas vaginalis macrophage migration inhibitory factor on THP⁃1 macrophages

LIN Lin, HUANG Shuang, ZHANG Fengyuan, LI Jiazheng, JIANG Xugan, CHEN Shengxia

2023, 35(1):  29. 

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Objective　To investigate the effect of Trichomonas vaginalis macrophage migration inhibitory factor (TvMIF) on THP⁃1 macrophages. Methods　Recombinant TvMIF protein was prokaryotic expressed and purified, and endotoxin was removed after identification. Following exposure to TvMIF at concentrations of 0, 1, 5, 10, 50 and 100 ng/mL, the cytotoxicity of the recombinant TvMIF protein to THP⁃1 macrophages was tested using cell counting kit (CCK)⁃8 assay, and the apoptosis of THP⁃1 macrophages and reactive oxygen species (ROS) were detected using flow cytometry. The relative expression of nucleotide⁃binding oligomerization domain⁃like receptor protein 3 (NLRP3), caspase⁃1, interleukin⁃1β (IL⁃1β) and IL⁃18 genes was quantified using real⁃time fluorescent quantitative  PCR (qPCR) assay, and the expression of caspase⁃1, NLRP3, gasdermin D (GSDMD), gasdermin D N⁃terminal (GSDMD⁃NT) and pro⁃IL⁃1β proteins were determined using Western blotting assay. Results　Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS⁃PAGE) displayed successful expression and purification of the recombinant TvMIF protein with a molecular weight of 15.5 kDa, and the endotoxin activity assay showed the successful removal of endotoxin in the recombinant TvMIF protein (endotoxin concentration < 0.1 EU/mL), which was feasible for the subsequent studies on protein functions. Flow cytometry revealed that the recombinant TvMIF protein at a concentration of 10 ng/mL and less promoted the apoptosis of THP⁃1 macrophages, and the highest apoptotic rate of THP⁃1 macrophages was seen following exposure to the recombinant TvMIF protein at a concentration of 5 ng/mL, while the recombinant TvMIF protein at concentrations of 50 and 100 ng/mL inhibited the apoptosis of THP⁃1 macrophages. Exposure to the recombinant TvMIF protein at a concentration 1 ng/mL resulted in increased ROS levels in THP⁃1 macrophages. qPCR assay quantified significantly elevated caspase⁃1, NLRP3, IL⁃18 and IL⁃1β expression in THP⁃1 macrophages 8 hours post⁃treatment with the recombinant TvMIF protein at a concentration 1 ng/mL, and Western blotting determined increased caspase⁃1, NLRP3, pro⁃IL⁃1β, GSDMD and GSDMD⁃NT protein expression in THP⁃1 macrophages following exposure to the recombinant TvMIF protein at a concentration 1 ng/mL. Pretreatment with MCC950 significantly reduced GSDMD and GSDMD⁃NT protein expression. Conclusions　High⁃concentration recombinant TvMIF protein inhibits macrophage apoptosis, while low⁃concentration recombinant TvMIF protein activates NLRP3 inflammasome and promotes macrophage pyroptosis.

Establishment and preliminary evaluation of a fluorescent recombinase-aided amplification/CRISPR-Cas12a system for rapid detection of Plasmodium falciparum

HUANG Weiyi, WEI Huagui, WANG Chunfang, WANG Junli, CHEN Liying, CHEN Weizhong, LIU Yaqun, ZHENG Yuzhong, LIN Min

2023, 35(1):  38. 

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Objective　To establish a fluorescent assay for rapid detection of Plasmodium falciparum based on recombinase-aided amplification (RAA) and CRISPR-Cas12a system,and to preliminarily evaluate the diagnostic efficiency of this system. Methods　The 18S ribosomal RNA (rRNA) gene of P. falciparum was selected as the target sequence, and three pairs of RAA primers and CRISPR-derived RNA (crRNA) were designed and synthesized. The optimal combination of RAA primers and crRNA was screened and the reaction conditions of the system were optimized to create a fluorescent RAA/CRISPR-Cas12a system. The plasmid containing 18S rRNA gene of the P. falciparum strain 3D7 was generated, and diluted into concentrations of 1 000, 100, 10, 1 copy/μL for the fluorescent RAA/CRISPR-Cas12a assay, and its sensitivity was evaluated. The genomic DNA from P. vivax, P. malariae, P. ovum, hepatitis B virus, human immunodeficiency virus and Treponema pallidum was employed as templates for the fluorescent RAA/CRISPR-Cas12a assay, and its specificity was evaluated. Fifty malaria clinical samples were subjected to the fluorescent RAA/CRISPR-Cas12a assay and nested PCR assay, and the consistency between two assays was compared. In addition, P. falciparum strain 3D7 was cultured in vitro. Then, the culture was diluted into blood samples with parasite densities of 1 000, 500, 200, 50, 10 parasites/μL with healthy volunteers’ O-positive red blood cells for the RAA/CRISPR-Cas12a assay, and the detection efficiency was tested. Results　The Pf-F3/Pf-R3/crRNA2 combination, 2.5 μL as the addition amount of B buffer, 40 min as the RAA reaction time, 37 °C as the reaction temperature of the CRISPR-Cas12a system were employed to establish the fluorescent RAA/CRISPR-Cas12a system. Such a system was effective to detect the plasmid containing 18S rRNA gene of the P. falciparum strain 3D7 at a concentration of 1 copy/μL, and presented fluorescent signals for detection of P. falciparum, but failed to detect P. ovum, P. malariae, P. vivax, T. pallidum, hepatitis B virus or human immunodeficiency virus. The fluorescent RAA/CRISPR-Cas12a system and nested PCR assay showed completely consistent results for detection of 50 malaria clinical samples (kappa = 1.0, P < 0.001). Following 6-day in vitro culture of the P. falciparum strain 3D7, 10 mL cultures were generated and the fluorescent RAA/CRISPR-Cas12a system showed the minimal detection limit of 50 parasites/μL. Conclusion　The fluorescent RAA/CRISPR-Cas12a system is rapid, sensitive and specific for detection of P. falciparum, which shows promising value for rapid detection and risk monitoring of P. falciparum.

Malaria control knowledge and behaviors and their influencing factors among residents in Banlao Township, Cangyuan County, Yunnan Province

DING Chunli, XU Jianwei, LIN Zurui, XU Shiyan, CUI Xin, SUN Weijiang, TIAN Guangqiang, LI Chunhua, LUO Zhongsheng, ZHOU Yaowu, YANG Yaming

2023, 35(1):  44. 

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Objective　To investigate the awareness of malaria⁃related knowledge, the use of mosquito nets and their influencing factors among residents in Banlao Township, Cangyuan County, Yunnan Province. Methods　In August 2020, 19 settlement sites in Banlao Township, Cangyuan County, Lincang City, Yunnan Province were selected as study areas, and permanent residents at ages of 10 years and older were enrolled for a questionnaire survey, including residents’ demographics, family economic status, malaria control knowledge and use of mosquito nets. In addition, the factors affecting the use of mosquito nets in the night prior to the survey were identified using multivariate logistic regression analysis. Results　A total of 320 questionnaires were allocated, and all were recovered (a 100% recovery rate). There were 316 valid questionnaires, with an effective recovery rate of 98.75%. The 316 respondents included 152 men and 164 women and 250 Chinese respondents and 66 foreign respondents. The awareness of clinical syndromes of malaria was significantly higher among Chinese residents (71.60%) than among foreign residents (50.00%) ([χ2] = 11.03, P < 0.01), and the proportions of Chinese and foreign residents sleeping under mosquito nets were 46.00% and 69.70% on the night prior to the survey, respectively ([χ2] =11.73, P < 0.01). Multivariate logistic regression analysis identified ethnicity group and type of residence as factors affecting the use of mosquito nets in the night prior to the survey. Conclusions　The awareness of malaria control knowledge, the coverage and the use of mosquito nets were low among residents in Banlao Township, Cangyuan County, Yunnan Province. Targeted health education is recommended to improve the awareness of malaria control knowledge and self⁃protection ability. In addition, improving the allocation of long⁃lasting mosquito nets and health education pertaining to their uses and increasing the proportion of using mosquito nets correctly is needed to prevent re⁃establishment of imported malaria.

Expression of CD47 and its ligands in pregnant mice infected with Toxoplasma gondii during pregnancy

BI Xianglian, FU Xiaoyin, XUE Sa, HAN Xue, ZENG Yulu, SUN Jiayue, LIU Dengyu

2023, 35(1):  51. 

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Objective　To investigate the dynamic expression of cluster of differentiation 47 (CD47) and its ligands signaling regulatory protein α (SIRPα) and thrombospondin⁃1 (TSP⁃1) in mice infected with Toxoplasma gondii in the second and third trimesters. Methods　C57BL/6J mice (6 to 8 weeks old) were used for modeling T. gondii infection in the first trimester, and the pregnant mice were randomly divided into the normal control and infection groups, of 10 mice in each group. Pregnant mice in the infection group were intraperitoneally injected with 150 T. gondii tachyzoites on gestational day (Gd) 6.5, while pregnant mice in the normal control group were intraperitoneally injected with the same volume of physiological saline at the same time. The uterine and placental specimens were collected from all pregnant mice on Gd12.5 and Gd18.5, and the pregnant outcomes were recorded. The pathological damages of mouse uterine and placental specimens were observed using hematoxylin⁃eosin (HE) staining on Gd12.5 and Gd18.5. The relative expression of CD47, SIRPα, TSP⁃1, surface antigen 1 (SAG1), interferon⁃γ (IFN⁃γ), interleukin⁃2 (IL⁃2), IL⁃4 and IL⁃13 mRNA was quantified in mouse uterine and placental specimens using real⁃time fluorescence quantitative PCR (qPCR) assay, and the CD47, SIRPα, TSP⁃1 expression was determined in mouse uterine and placental specimens using immunohistochemical staining. Results　As compared with those in the normal control group, the pregnant mice in the infection group showed back arching, bristling, trembling and listlessness during pregnancy, and several mice presented virginal bleeding and abortion. Pathological examinations showed inflammatory cell infiltration, congestion and necrosis in uterine and placental specimens of pregnant mice in the infection group, a higher abortion rate of pregnant mice was seen in the infection group than in the normal control group on Gd12.5 ([χ2] = 20.405, P < 0.001) and Gd18.5 ([χ2] = 28.644, P < 0.001). qPCR assay showed significant differences in the expression of CD47, SIRPα, TSP⁃1, SAG1, INF⁃γ, IL⁃2, IL⁃4 and IL⁃13 genes in mouse placental specimens between the normal control and control groups on Gd12.5 and Gd18.5 [F′(F) = 37.511, 29.337, 97.343, 53.755, 67.188, 21.145, 8.658 and 13.930, all P values < 0.001]. Higher CD47, SIRPα and TSP⁃1 gene expression was quantified in mouse placental specimens in the infection group than in the normal control group on Gd12.5 (all P values < 0.01), and lower CD47, SIRPα and TSP⁃1 gene expression was quantified in the infection group than in the normal control group on Gd18.5 (all P values < 0.001), while higher SAG1 gene expression was detected in placental specimens of pregnant mice in the infection group than in the normal control group on Gd12.5 and Gd18.5 (both P values < 0.01). In addition, higher INF⁃γ and IL⁃2 expression and lower IL⁃4 and IL⁃13 expression was detected in mouse placental specimens in the infection group than in the normal control group on Gd12.5 and Gd18.5 (all P values < 0.001), and there were significant differences in the CD47, SIRPα, TSP⁃1, SAG1, INF⁃γ, IL⁃2, IL⁃4 and IL⁃13 gene expression in uterine specimens of pregnant mice between the normal control and infection groups on Gd12.5 and Gd18.5 [H(F′and F) = 14.951, 25.977, 18.711, 48.595, 39.318, 14.248 and 15.468, all P values < 0.01], and higher CD47 and TSP⁃1 expression was detected in mouse uterine specimens in the infection group than in the control group on Gd12.5 and Gd18.5 (all P values < 0.01); however, no significant difference was found in the SIRPα expression (P > 0.05). Higher SAG1 expression was detected in uterine specimens of pregnant mice in the infection group than in the normal control group on Gd12.5 and Gd18.5 (both P values < 0.01), and higher INF⁃γ and IL⁃2 gene expression and lower IL⁃4 and IL⁃13 gene expression was found in the placental specimens of pregnant mice in the infection group than in the normal control group on Gd12.5 and Gd18.5 (all P values < 0.001). Spearman correlation analysis showed that the CD47 gene expression correlated positively with IFN⁃γ (rs = 0.735, P < 0.05) and IL⁃2 (rs = 0.655, P < 0.05) and negatively with IL⁃4 (rs = -0.689, P < 0.05) and IL⁃13 expression (rs = -0.795, P < 0.05) in the placental specimens of pregnant mice in the infection group on Gd12.5, and the CD47 gene expression correlated negatively with IFN⁃γ (rs = -0.745, P < 0.05) and IL⁃2 expression (rs = -0.816, P < 0.05) and positively with IL⁃4 (rs = 0.704, P < 0.05) and IL⁃13 (rs = 0.802, P < 0.05) in the placental specimens of pregnant mice in the infection group on Gd18.5. Immunohistochemical staining showed mild CD47, SIRPα and TSP⁃1 expression in uterine and placental specimens of pregnant mice in the normal control group on Gd12.5 and Gd18.5, strong CD47, SIRPα and TSP⁃1 expression in the placental specimens of pregnant mice in the infection group on Gd12.5 and strong CD47 and TSP⁃1 expression in the uterine specimens of pregnant mice in the infection group on Gd12.5. Conclusions　T. gondii infection in the first trimester may cause abnormal expression of CD47 and its ligands SIRPα and TSP⁃1 in the maternal⁃fetal interface of pregnant mice in the second and third trimesters, which may be associated with the immune escape of T. gondii at the maternal⁃fetal interface.

Surveillance of Aedes populations in Jiangsu Province in 2020

LI Julin, TANG Jianxia, WU Jingyao, YANG Mengmeng, ZHANG Meihua, LIANG Cheng, ZHOU Huayun, ZHU Guoding, CAO Jun

2023, 35(1):  63. 

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Objective　To investigate the seasonal Aedes population fluctuation and the resistance of Aedes populations to common insecticides in Jiangsu Province in 2020, so as to provide insights into vector⁃borne infectious diseases control. Methods　One village was randomly sampled from each of Xinbei District of Changzhou City and Zhangjiagang County of Suzhou City in southern Jiangsu Province, Hai’an County of Nantong City and Yandu District of Yancheng City in Central Jiangsu Province, and Suining County of Xuzhou City and Sihong County of Suqian City in northern Jiangsu Province during the period between May and October, 2020. A small ponding container was sampled, and larval Aedes mosquitoes were collected using straws once each in early and late stages of each month. All larvae were bred in laboratory to adults for population identification. In addition, larval breeding were observed in all small ponding containers in and out of 30 households that were randomly sampled from six surveillance sites, and the larval mosquito density was estimated using Breteau index. Larval A. albopictus mosquitoes were sampled around Cuiyuan New Village in Jintan District of Changzhou City, and bred in laboratory to the first offspring generation, and the susceptibility of adult female mosquitoes to deltamethrin, lambda⁃cyhalothrin, malathion, and propoxur was tested using the filter⁃paper bioassay recommended by WHO. Results　A total of 1 165 larval Aedes mosquitoes were captured from small ponding containers in six surveillance sites of Jiangsu Province in 2020, and all were identified as A. albopictus following eclosion. The largest number of Aedes larvae captured was found in July. A total of 1 152 households were investigated in six surveillance sites, and the mean Breteau indexes were 9.58, 13.20, 13.71, 13.20, 12.18 and 5.58 from May to October, respectively, while a high Aedes transmission risk was seen in Xinbei District of Changzhou City, with a higher Breteau index than in Suining(H = 23.667, Padjusted = 0.001) and Sihong (H = 22.500, Padjusted = 0.003) counties. The field⁃captured A. albopictus from Cuiyuan New Village in Jintan District of Changzhou City remained sensitive to malathion, but was resistant to propoxur, and developed high⁃level resistance to deltamethrin and lambda⁃cyhalothrin. Conclusions　A. albopictus was present in southern, central and northern Jiangsu Province in 2020, and the larval density peaked in July. A. albopictus captured from Cuiyuan New Village in Jintan District of Changzhou City has developed high⁃level resistance to pyrethroid pesticides.

Prevalence and risk factors of hookworm infections among vegetable growers in Anhui Province from 2018 to 2019

WANG Min, MA Xiaohe, ZHANG Shiqing, GUO Jianduo, JIN Wei, WANG Tianping

2023, 35(1):  68. 

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Objective　To investigate the prevalence and risk factors of hookworm infections among vegetable growers in Anhui Province, so as to provide the evidence for formulating the control strategy and interventions for hookworm human infections. Methods　A total of 1 179 vegetable growers were randomly sampled from 7 counties in Anhui province according to the natural ecological function areas in 2018 and 2019, and the basic features and risk factors of hookworm infections were collected from all subjects using a self⁃designed questionnaire, including living environment, vegetable planting and fertilization, type of household crops, animal feeding, hygiene and labor habits. In addition, stool samples were collected from all participants, and each stool sample was subjected to twice tests with the Kato⁃Katz technique. The risk factors of hookworm infections were identified among vegetable growers with the Bayesian log⁃binomial regression model. Results　The prevalence of hookworm infection was 3.90% among the 1 179 vegetable growers. The prevalence of hookworm infection was 10.07% (15/149) among unemployed subjects, 5.32% (31/583) among farmers, and 0 among full⁃time vegetable growers (0/377) and subjects with other occupations (0/70), and there was a significant difference among subjects in terms of occupation ([χ2] = 36.37, P < 0.01). Bayesian log⁃binomial regression analysis showed that fertilization with human feces [relative risk (RR)= 18.25, 95% confidence interval (CI): (4.31, 77.17)], barefoot labor in vegetable fields [RR = 2.86, 95% CI: (1.43, 5.70)], and living in plain ecological areas along the middle and lower reaches of the Yangtze River [RR = 4.19, 95% CI: (1.19, 14.81)] were independent risk factors of hookworm infections among vegetable growers. Stratified analysis showed that fertilization with human feces, barefoot labor in vegetable fields, drinking well water or mountain spring, and living in plain ecological areas along the middle and lower reaches of the Yangtze River were independent risk factors of hookworm infection among farmers, and living in plain ecological areas along the middle and lower reaches of the Yangtze River and growing rice were independent risk factors of hookworm infection among unemployed individuals. Conclusions　The prevalence of hookworm infection is high among vegetable growers in Anhui Province, and fertilization with human feces, barefoot labor in vegetable fields and living in plain ecological areas along the middle and lower reaches of the Yangtze River are risk factors of hookworm infections among vegetable growers.

Prevalence and molecular characterization of Cryptosporidium in captive⁃bred Mustela putorius furo in Jiangsu Province

ZHANG Jinyang, ZHOU Yonghua, GUO Jie, LI Jiajia, WU Yanyan, ZHOU Zhenghai, ZHU Haiyun, LUO Xinyu, CHEN Dongqian, LI Qiaoqiao, LIU Xinchao, LI Wenchao

2023, 35(1):  73. 

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Objective　To investigate the prevalence and molecular features of Cryptosporidium in captive⁃bred Mustela putorius furo in Jiangsu Province. Methods　A total of 290 fresh stool samples were collected from a ferret farm in Jiangsu Province on May 2017, and the small subunit rRNA (SSU rRNA) gene of Cryptosporidium was amplified in stool samples using nested PCR assay. The actin, cowp and gp60 genes were amplified in positive samples and sequenced to characterize Cryptosporidium species/genotypes. Results　A total of 18 stool samples were tested positive for Cryptosporidium SSU rRNA gene, with a detection rate of 6.2%. Sequence and phylogenetic analyses of SSU rRNA, actin and cowp genes characterized Cryptosporidium isolated from captive⁃bred ferrets as Cryptosporidium sp. ferret genotype. In addition, gp60 gene was amplified in 10 out of 18 stool samples tested positive for Cryptosporidium. Conclusions　Cryptosporidium is widely prevalent in captive⁃bred ferrets in Jiangsu Province, and Cryptosporidium sp. ferret genotype is the only Cryptosporidium genotype in ferrets.

Prevalence of Anisakise infections in marine fishes in Eastern Fujian Fishing Ground of Fujian Province

CAI Wuwei, LIN Chenxin, ZHENG Dan, XIE Hanguo

2023, 35(1):  78. 

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Objective　To investigate the prevalence of Anisakis infection in marine fishes in Eastern Fujian Fishing Ground of Fujian Province, so as to provide insights into the development of the anisakiasis control strategy. Methods　Marine fish samples were randomly collected from Jiaocheng District, Fuding City and Xiapu County around Eastern Fujian Fishing Ground in Fujian Province from September to December, 2021. All fishes were dissected, and the abdominal contents were collected. Parasites were sampled under a stereomicroscope and the Anisakis species were identified through morphology. The prevalence and intensity of Anisakis infections were calculated. Results　A total of 177 marine fishes belonging to 24 species were dissected, and Anisakis was detected in 73 marine fishes (41.2%) belonging to 16 species (66.7%), with a mean infection intensity of 14.3 parasites per fish. High prevalence of Anisakis infection was found in Ilisha elongata (5/5), Miichthys miiuy (3/3), Plectorhynchus cinctus (2/2), Scomberomorus niphonius (12/13), Trichiurus lepturus (19/23), Pennahia argentata (6/11) and Ditrema temmincki (14/27), with mean infection intensities of 9.2, 2.7, 4.5, 10.9, 39.2, 4.5 parasites per fish and 2.1 parasites per fish. The Anisakis larvae were characterized as Anisakis and Hysterothylacium. Conclusions　High prevalence of Anisakis infection is detected in marine fishes in Eastern Fujian Fishing Ground of Fujian Province. The health education pertaining to food health is required to be reinforced to prevent the development of human anisakiasis.

Exploration and practice of process assessment in Human Parasitology teaching for international medical students

ZHOU Xia, LI Yuanyuan, XIA Chaoming

2023, 35(1):  82. 

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Teaching evaluation is an important measure to test the teaching quality. In order to better achieve the training objectives among international medical students based on the specific conditions of foreign students and the characteristics of Human Parasitology, a process⁃based assessment and evaluation system has been established for international medical students. The process assessment highlights the characteristics of assessment process, diversified forms and inquires of test questions. Following implementation of process assessment, the proportion of excellence (examination scores of 90 and higher) improved from 3.25% (10/308) to 13.09% (50/382) (t = 5.995, P < 0.001) and the proportion of good marks (examination scores of 80 to 89) increased from 18.83% (58/308) to 36.13% (138/382) (t = 7.505, P < 0.001) during the semester assessment among international medical students at five grades, while the proportion of failure in examination pass (examination scores of below 60) reduced from 12.34% (38/308) to 3.24% (10/382) (t = 7.303, P < 0.000 1), indicating that the process⁃based assessment and evaluation system improves the examination score of Human Parasitology among international medical students and the teaching quality of Human Parasitology.

Publication and citation analyses of Chinese Journal of Schistosomiasis Control from 2011 to 2020

PAN Li, ZHU Hongru, QIAN Yili, DENG Yao, YANG Kun

2023, 35(1):  86. 

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Objective　To investigate the publications and citations of Chinese Journal of Schistosomiasis Control from 2011 to 2020, so as to provide insights into improving the journal quality and impact. Methods　All publications were retrieved from 60 issues of 10 volumes of Chinese Journal of Schistosomiasis Control from 2011 to 2020, and publication and citation analyses were performed using a bibliometric method. Results　A total of 1 867 articles were published in Chinese Journal of Schistosomiasis Control from 2011 to 2020, with the largest number in 2012 (220 publications) and the lowest in 2020 (135 publications), and original article (36.48%), control experience (17.14%) and control study (10.34%) were the three most common article type. The overall proportion of grant⁃supported articles was 59.08% (1 103/1 867), and the number of grant per article was (2.34 ± 1.58) grants. The mean duration from submission to publication was (173.48 ± 105.84) days per article, and there was a significant difference in the mean duration from submission to publication among years (F = 30.883, P < 0.01). Jiangsu Province (492 publications, 26.35%), Shanghai Municipality (264 publications, 14.14%) and Hubei Province (230 publications, 12.32%) were the three most productive provinces where the first author lived, and disease control and prevention institutions were the predominant affiliations of the first author (67.22%), with Jiangsu Institute of Schistosomiasis Control, National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, and Wannan Medical College as the three most productive affiliations. The number of authors was 5.94 authors per publication, and the proportion of co⁃authored publications was 95.45% in Chinese Journal of Schistosomiasis Control from 2011 to 2020. Journal article was the predominant type of cited (89.97%), and the mean number of citations was (15.70 ± 11.56) citations per publication, with a significant difference in the mean number of citations per publication among years (F = 2.205, P < 0.05). The impact factors of Chinese Journal of Schistosomiasis Control ranged from 0.877 to 1.676 during the period from 2011 to 2020, and the overall Price index was 47.59%. Conclusions　Both the academic impact and national transmissibility of Chinese Journal of Schistosomiasis Control appeared a tendency towards a rise from 2011 to 2020. Seeking high⁃quality contributions, increasing interdisciplinary integration, shortening the duration from submission to publication, expanding the coverage of publication services and enhancing impact are the future priorities of the journal.

The role of sinusoidal endothelial cells in liver injury: a review

JIANG Tingting, HU Yuan, CAO Jianping

2023, 35(1):  92. 

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Liver sinusoidal endothelial cells (LSECs) locate on the surface of hepatic sinusoids. As the first line of defense between the liver and blood, LSECs are the most abundant non-parenchymal cells in the liver. Under physiological conditions, LSECs may induce liver immune tolerance through participating in substance transport and metabolic waste removal, thereby maintaining liver homeostasis, and under pathological conditions, LSECs may promote liver immune response via antigen presentation. LSECs have been found to play a crucial regulatory role in maintaining the balance between liver regeneration and liver fibrosis. This article reviews the progress of researches on LSECs functions, LSECs changes in liver injury, signal pathways associated with regulation of LSECs functions, and the interaction between LSECs and other types of cells in the liver, aiming to elucidate the function of LSECs and their roles in liver diseases

Application of CRISPR/Cas systems in the nucleic acid detection of pathogens: a review

LI Mengru, QIN Zhiqiang, YIN Kun, ZHENG Bin

2023, 35(1):  98. 

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Rapid, sensitive and specific detection tools are critical for the prevention and control of infectious diseases. The in vitro nucleic acid amplification assays, including polymerase chain reaction and isothermal amplification technology, have been widely used for the detection of pathogens. Recently, nucleic acid detection⁃based on clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR⁃associated proteins (Cas) have been developed, which are rapid, highly sensitive, highly specific, and portable. This review describes the classification and principle of CRISPR/Cas systems and their applications in pathogen detection, and discusses the prospects of CRISPR/Cas systems.

Progress of researches on albendazole for treatment of alveolar echinococcosis C

UI Ziyan, YE Gengbo, YU Wenhao, WANG Zhixin, KONG Fanyu, REN Li

2023, 35(1):  104. 

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Alveolar echinococcosis, caused by Echinococcus multilocularis infection, is a highly deadly zoonotic parasitic disease. As a benzimidazole compound, albendazole has a strong and broad⁃spectrum anti⁃parasitic action. For alveolar echinococcosis patients that are unwilling to receive surgical treatment, lose the timing for surgery, or are intolerant to surgery due to poor physical status, administration of albendazole may delay disease progression. Recently, a large number of advances have been achieved in experimental studies on alveolar echinococcosis. In order to increase the understanding of the therapeutic efficacy of albendazole for alveolar echinococcosis, this review summarizes the advances in albendazole treatment for alveolar echinococcosis, so as to provide insights into the clinical treatment of alveolar echinococcosis with albendazole.

A case with severe neurocysticercosis

HUANG Lin, CHEN Xingwang, LIU Yang, LI Tiaoying

2023, 35(1):  111. 

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This case report described the diagnosis and treatment of an ethnic Tibetan case with severe neurocysticercosis residing in agricultural areas of Sichuan province.