Table of Content

02 November 2021, Volume 33 Issue 5

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Establishment of a deep learning⁃visual model for intelligent recognition of Oncomelania hupensis

SHI Liang, XIONG Chun⁃Rong, LIU Mao⁃Mao, WEI Xiu⁃Shen, WANG Xin⁃Yao, WANG Tao, HUANG Yi⁃Xin, HONG Qing⁃Biao, LI WEI, YANG Hai⁃Tao, ZHANG Jian⁃Feng, YANG Kun

2021, 33(5):  445. 

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Objective　To establish a deep learning⁃based visual model for intelligent recognition of Oncomelania hupensis, the intermediate host of Schistosoma japonicum, and evaluate the effects of different training strategies for O. hupensis image recognition. Methods　A total of 2 614 datasets of O. hupensis snails and 4 similar snails were generated through field sampling and internet capture, and were divided into training sets and test sets. An intelligent recognition model was created based on deep learning, and was trained and tested. The precision, sensitivity, specificity, accuracy, F1 score and Youden index were calculated. In addition, the receiver operating characteristic (ROC) curve of the model for snail recognition was plotted to evaluate the effects of “new learning”, “transfer learning” and “transfer learning + data enhancement” training strategies on the accuracy of the model for snail recognition. Results　Under the “transfer learning + data enhancement” strategy, the precision, sensitivity, specificity, accuracy, Youden index and F1 score of the model were 90.10%, 91.00%, 97.50%, 96.20%, 88.50% and 90.51% for snail recognition, which were all higher than those under both “new learning” and “transfer learning” strategies. There were significant differences in the sensitivity, specificity and accuracy of the model for snail recognition under “new learning”, “transfer learning” and “transfer learning + data enhancement” training strategies (all P values < 0.001). In addition, the area under the ROC curve of the model was highest (0.94) under the “transfer learning + data enhancement” training strategy. Conclusions　 This is the first visual model for intelligent recognition of O. hupensis based on deep learning, which shows a high accuracy for snail image recognition. The “transfer learning + data enhancement” training strategy is helpful to improve the accuracy of the model for snail recognition.

Development of a fluorescent recombinase⁃aided isothermal amplification⁃based nucleic acid assay for detection of Leishmania

LIN Hong, ZHAO Song, LIU Yan⁃Hong, SHAO Lei, YING Qing⁃Jie, YANG Kun

2021, 33(5):  452. 

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Objective　To develop a fluorescent recombinase⁃aided isothermal amplification (RAA)⁃based nucleic acid assay for detection of Leshimania. Methods　Specific primers and probes were designed targeting Leishmania internal transcribed spacer 1 (ITS1) gene for RAA assay, and a fluorescent RAA assay was developed for detection of Leishmania following screening of primer pairs and optimization of primer and probe concentrations. The sensitivity of RAA assay for detection of Leishmania was evaluated using recombinant plasmid containing Leishmania ITS1 gene sequences at different copies and Leshimania genomic DNA at different concentrations as templates, and the specificity of RAA assay for detection of Leishmania was evaluated using the genomic DNA of transfusion⁃transmitted parasites, including Babesia microti, Toxoplasma gondii, Plamodium vivax, P. ovale, P. falciparum, P. malariae, L.donovani and L. infantum. Results　After the optimal primer pair was screened from 9 pairs of primer combinations, the final primer and probe concentrations were optimized as 0.3 μmol/L and 0.08 μmol/L, respectively. Nucleic acid detection of Leishmania was completed by the fluorescent RAA assay at an isothermal temperature of 39 ℃ within 20 min. Remarkable florescent signals were seen within 5 min following RAA detection of genomic DNA of L. donovani and L. infantum, and no cross⁃reactions were observed with B. microti, T. gondii, P. vivax, P. ovale, P. falciparum or P. malariae. The lowest limitation of detection of the fluorescent RAA assay was 10 copies/μL recombinant plasmid containing Leishmania ITS1 gene sequences and 1 fg/μL Leishmania genomic DNA. Conclusions　A rapid, simple, sensitive and specific fluorescent RAA assay is successfully developed for detection of L. donovani and L. infantum, which is effective for field screening of leishmaniasis.

Identification of factors affecting Oncomelania hupensis density in Eastern Dongting Lake regions

ZHENG Ying⁃Yan, ZHANG Na, WANG Zheng⁃Zhong, XIONG Ying, SHI Ying, LI Chun⁃Lin, TONG Yi⁃Xin, JIANG Feng, ZHOU Jie, HE Zhong, JIANG Jie, GUO Wen, JIANG Qing⁃Wu, ZHOU Yi⁃Biao

2021, 33(5):  457. 

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Objective　To evaluate the impact of water pollutants, water levels and meteorological factors on the Oncomelania hupensis density in Eastern Dongting Lake regions, so as to provide insights into schistosomiasis control. Methods　O. hupensis snails were surveyed using a systematic sampling method in snail⁃infested marshlands in Eastern Dongting Lake regions from 2007 to 2014, and data pertaining to water pollutants, water levels and meteorological factors were collected. The duration of submergence and the date of the start of submergence were calculated. The snail density and its influencing factors were descriptively analyzed, and a linear mixed model was generated to examine the impacts of variables on the snail density. In addition, smooth curves were fitted to investigate the relationship between snail density and variables. Results　The snail density appeared a fluctuation in Eastern Dongting Lake regions during the period from 2007 to 2014, with the highest density on October, 2010 (52.79 snails/0.1 m2) and the lowest density on January 2009 (2.15 snails/0.1 m2). Linear mixed⁃model analysis showed that permanganate index, total phosphorus and the date of the start of submergence affected the snail density (t = 6.386, -2.920 and -3.892, all P values < 0.01). Smooth curve analysis revealed that the associations of the snail density with the permanganate index and total phosphorus appeared an approximately quadratic curve. After the end of April, the earlier date of the start of submergence resulted in a higher snail density. Conclusion　Permenganate index, total phosphorus and the date of the start of submergence affect the O. hupensis snail density in Eastern Dongting Lake regions.

Establishment of a fluorescent recombinase⁃aided isothermal amplification assay for nucleic acid detection of Paraginiumus skrjabini and preliminary evaluation of its detection efficiency

DENG Yan, LIU Yan⁃Hong, CHEN Wei⁃Qi, ZHANG Ya⁃Lan, JIANG Tian⁃Tian, LI Su⁃Hua, AI Lin, CAI Mao⁃Rong, YING Qing⁃Jie, LIU Ying, ZHANG Hong⁃Wei

2021, 33(5):  464. 

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Objective　To establish a nucleic acid assay for detection of Paragonimus skrjabini based on the recombinase⁃aided isothermal amplification (RAA) technique, and to preliminarily evaluate its detection efficiency. Methods　The metacercariae of P. skrjabini, P. westermani and Euparagonimus cenocopiosus were isolated from crabs, and genomic DNA was extracted for molecular characterization. The cytochrome c oxidase 1 (cox1) gene sequence of P. skrjabini was selected as the target gene fragment, and the primers and probes were designed, screened and synthesized for RAA assay. The genomic DNA of P. skrjabini metacercariae from Jiyuan City and Yiyang County of Luoyang City, Henan Province were used as templates for verification of the fluorescent RAA assay. The fluorescent RAA assay was performed to detect different concentrations of plasmids containing target gene fragment and P. skrjabini metacercariae genomic DNA to determine the sensitivity. Fluorescent RAA assay was performed with recombinant plasmids containing P. skrjabini cox1 gene sequences at different concentrations and P. skrjabini genomic DNA as templates to evaluate its sensitivity, and the genomic DNA of P. westermani, E. cenocopiosus, Clonorchis sinensis and Schistosoma japonicum was detected with fluorescent RAA assay to evaluate its specificity. Results　P. skrjabini, P. westermani and E. cenocopiosus metacercariae were isolated from crabs, respectively. Molecular characterization and phylogenetic analysis confirmed their homology with the genes sequences of standard Paragonimus strains in GenBank. A fluorescent RAA assay was successfully established for nucleic acid detection of P. skrjabini, and the genomic DNA of P. skrjabini metacercariae from Jiyuan City and Yiyang County of Luoyang City, Henan Province was amplified using the fluorescent RAA assay within 5 min, while the negative control was not amplified. If the recombinant plasmid containing P. skrjabini cox1 gene sequences was used as templates, the fluorescent RAA assay showed the lowest detection limit of 10 copies/µL, and positive amplification was observed within 5 min. If genomic DNA was used as templates, the fluorescent RAA assay showed the lowest detection limit of 10 pg/µL, and all positive amplifications were found within 5 to 10 min. In addition, the fluorescent RAA assay was tested negative for P. westermani, E. cenocopiosus, C. sinensis and S. japonicum. Conclusions　A rapid, sensitive and specific fluorescent RAA assay is successfully established for nucleic acid detection of P. skrjabini, which has potential values in rapid field detection and species identification in freshwater crabs in areas endemic for P. skrjabini.

Effect of Echinococcus multilocularis infections on mitochondrial functions of macrophages

DENG Jun, HUANG Deng⁃Liang, ZHANG Yao⁃Gang, LI Jian⁃Hua, HOU Jing, JIANG Yuan, TIAN Mei⁃Yuan, SUN Li, ZHANG Tao, ZHANG Xuan, DONG Yun, FAN Hai⁃Ning, MA Yan⁃Yan

2021, 33(5):  470. 

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Objective　To investigate the changes of mitochondrial metabolic functions of macrophages following Echinococcus multilocularis infections， so as to provide insights into the pathogenesis of alveolar echinococcosis. Methods　Two groups were assigned according to different treatment methods. In the culture group， mouse leukemic monocyte macrophage RAW264.7 cells were cultured with 2 000 E. multilocularis at a ratio of 500∶1， while RAW264.7 cells in the control group were given no treatment. Then， both the culture and control groups were further divided into the 24 h and 72 h subgroups. Mitochondria were stained with MitoTracker® Deep Red FM and the mean fluorescence intensity of macrophage mitochondria was measured with the Cytation 5 Cell Imaging Multi⁃Mode Reader. The mitochondrial DNA copy number was quantified using the quantitative real⁃time PCR （qPCR） assay， and the mitochondrial energy metabolism was monitored using the Seahorse XF assay. In addition， the mitochondrial reactive oxygen species and mitochondrial membrane potential were detected using flow cytometry. Results　The mean fluorescence intensities of macrophage mitochondria were significantly lower in the 24 h （15 341 ± 2 532 vs. 17 823 ± 3 429； t = 6.379， P < 0.01） and 72 h （18 102 ± 3 505 vs. 21 511 ± 5 144； t = 17.680， P < 0.01） culture subgroups than in the corresponding control subgroups， and lower mitochondrial DNA copy numbers were measured in the 72 h culture subgroup than in the 72 h control group [ （3.23 × 109 ± 1.78 × 107） vs. （4.39 × 109 ± 3.70 × 107）； t = 8.85， P < 0.001]. The oxygen consumption rates were significantly greater in the 24 h [ （241.70 ± 73.13） pmol/min vs. （69.05 ± 52.30） pmol/min； t = 7.89， P < 0.01] and 48 h culture groups [ （249.50 ± 42.06） pmol/min vs. （60.28 ± 40.66） pmol/min； t = 8.64， P < 0.01] than in the corresponding control groups， and a higher extracellular acidification rate was seen in the 48 h culture group than in the 48 h control group [ （111.6 ± 17.49） mpH/min vs. （35.05 ± 7.569） mpH/min； t = 16.90， P < 0.01]. In addition， flow cytometry detected higher mean fluorescence intensity of mitochondrial reactive oxygen species （58 264 ± 10 087 vs. 4 307 ± 97； t = 12.930， P < 0.01） and lower mitochondrial membrane potential （9.833% ± 2.285% vs. 2.667% ± 0.208%； t = 6.645， P < 0.01） in the 72 h culture group than in the control group. Conclusions　E. multilocularis infection may impair mitochondrial functions and inhibit oxidative phosphorylation of macrophages， resulting in increased macrophage glycolysis. It is speculated that the alteration of macrophage metabolic states may contribute to the mechanisms underlying the development and progression of alveolar echinococcosis.

Analysis of components of proteins from Echinococcus granulosus cyst fluid

WANG Shu⁃Ying, YANG Xiao⁃Di, GAO Hong⁃Yu, XING Jing⁃Yu, HU Qi, HUANG Ting⁃Ting, WU Pei, ZHAO Yi⁃Ting, LIU Hao⁃Wei, LIU Wei⁃Yue, WANG Hui⁃Na, ZHOU Rui, CHU Liang

2021, 33(5):  476. 

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Objective　To analyze the components of proteins from Echinococcus granulosus cyst fluid using the shotgun method, and to identify the active components with potential regulatory effects for immune dysregulation diseases. Methods　The   E. granulosus cyst fluid was collected aseptically from the hepatic cysts of patients with cystic echinococcosis, and characterized by liquid chromatography （LC） tandem mass spectrometry （MS/MS） following digestion with trypsin. The protein data were searched using the software MaxQuant version 1.6.1.0 and the cellular components, molecular functions, and biological processes of the identified proteins were analyzed using the Gene Ontology （GO） method. Results　The E. granulosus cyst fluid separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS⁃PAGE） had a relative molecular mass of 25 to 70 kDa. LS⁃MS/MS analysis identified 37 proteins, including 32 known proteins and 5 unknown proteins. At least 4 proteins were preliminarily found to exhibit potential regulatory effects for immune dysregulation diseases, including antigen B, glutathione⁃S⁃transferase （GST）, thioredoxin peroxidase （TPX） and malate dehydrogenase （MDH）. GO enrichment analysis showed that the identified proteins had 149 molecular functions and were involved in 341 biological processes. Conclusions 　E. granulosus cyst fluid has a variety of protein components, and four known proteins are preliminarily identified to be associated with immune dysregulation diseases.



Identification of potential targets and synergistic mechanism of Kushen Decoction for the treatment of cryptosporidiosis

ZHAN Na, LIU Xing⁃Hai, TANG Fang⁃Ying, ZHANG Jian⁃Yong

2021, 33(5):  483. 

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Objective　To explore the potential targets and synergistic mechanisms of Kushen Decoction for the treatment of cryptosporidiosis using network pharmacology and molecular docking methods. Methods　The main active ingredients of Kushen Decoction were captured from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) and the Universal Protein Resource (UniProt) database, and the potential targets were predicted. In addition, the active ingredients of Kushen Decoction that were not included in the TCMSP database were retrieved in CNKI, WanFang Data, CBM, PubMed and Web of Science databases, and the target genes of all supplemented active ingredients were predicted using the online TargetNet database. Network construction and analysis were performed using the Cytoscape software, and cryptosporidiosis⁃related targets were retrieved in the Comparative Toxicogenomics Database and GeneCards database. The protein⁃protein interaction (PPI) network was created using the STRING database, and the DAVID database was used for GO enrichment and KEGG pathway analyses. The tissue distribution of key targets was investigated using the BioGPS database, and the AutoDockTools software was employed to verify the molecular docking results. Results　A total of 38 active ingredients of Kushen Decoction were screened, and the core ingredients included quercetin, (+)⁃14α⁃hydroxymatrine and apigenin. A total of 831 targets of Kushen Decoction and 512 cryptosporidiosis⁃related targets were predicted, and PPI network analysis revealed 69 key targets, including AKT1, TNF and IL⁃6. There were 303 biological processes, 46 molecular functions and 29 cellular components involved in the treatment of cryptosporidiosis with Kushen Decoction, and 13 KEGG pathways played a therapeutic role in the synergistic mechanisms of multiple targets, such as Toll⁃like receptor (TLR), nuclear factor kappa B(NF)⁃ĸB, nucleotide binding oligomerization domain like receptor (NLR) signal pathways. The core targets were mainly distributed in the hematologic and immune systems. Molecular docking analysis showed that the binding energy between active ingredients and key targets were all less than 0 kJ/mol, indicating the strong binding of ligands to receptors. Conclusions　The active ingredients of Kushen Decoction, such as quercetin, (+)⁃14α⁃hydroxymatrine and apigenin, may act on targets like AKT1, TNF, IL⁃6 to modulate TLR, NLR and NF⁃κB signaling pathways to play a synergistic role in the treatment of cryptosporidiosis in the hematologic and immune system.

Analysis of laboratory re⁃examination results in Sichuan Provincial Malaria Diagnostic Reference Laboratory from 2014 to 2020

ZOU Yan, LI Li, YU Tao, GE Li, HUO Fang, LIU Yang

2021, 33(5):  496. 

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Objective　To re⁃examine the diagnosis results of reported malaria cases in Sichuan Province from 2014 to 2020, so as to assess the malaria diagnostic capability of Sichuan Provincial Malaria Diagnostic Reference Laboratory. Methods　The blood and blood smear samples from reported malaria cases were collected by Sichuan Provincial Malaria Diagnostic Reference Laboratory from 2014 to 2020, and subjected to re⁃examinations using microscopy and nested PCR assay. The re⁃examination results were compared. Results　A total of 1 710 samples from reported malaria cases were re⁃examined by Sichuan Provincial Malaria Diagnostic Reference Laboratory from 2014 to 2020, and 1 634 samples were identified positive, with a positive coincidence rate of 95.56% （1 634/1 710） and a 92.29% (1 508/1 634) total coincidence rate of the Plasmodium species. The coincidence rates with P. falciparum, P. vivax, P. malariae and P. ovale were 99.48% (961/966), 97.07% (430/443), 83.05% (98/118) and 67.86% (19/28), respectively, and the coincidence rate was 91.81%（1 513/1 648） between microscopic and nested⁃PCR results. Conclusions　The capability of microscopists remains weak at grassroot medical institutions in Sichuan Province. Further training is required among microscopists to improve the malaria surveillance capability in Sichuan Province during the post⁃elimination stage.

Susceptibility of Anopheles sinensis to insecticides in Puyang City, Henan Province

HU Ya⁃Bo, HE Zhi⁃Quan, LIU Ying, QIAN Dan, YANG Cheng⁃Yun, LU De⁃Ling, ZHANG Qun⁃Qun, ZHANG Hong⁃Wei

2021, 33(5):  501. 

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Objective　To investigate the susceptibility of Anopheles sinensis to malathion, deltamethrin and lambda⁃cyhalothrin in Puyang City, Henan Province, so as to provide the scientific basis for local malaria vector control. Methods　An. sinensis was captured from Puyang County, Puyang City of Henan Province in September 2018 and July 2020, and the susceptibility of field captured An. sinensis to malathion, deltamethrin and lambda⁃cyhalothrin was tested using the filter⁃paper bioassay recommended by WHO. The insecticide resistance level was assessed based on the WHO criteria. Results　In 2018 and 2010, the half knock⁃down times (KT50) of malathion were 91.08 min and 40.95 min for An. sinensis, with knock⁃down rates of 37.50% and 60.87% 60 min post⁃exposure to malathion and 24⁃hour mortality rates of 90.91% and 100%, respectively, and the insecticide resistance levels were moderately resistant (M) and susceptible (S). The KT50 of deltamethrin were 415.56 min and 341.19 min for An. sinensis in 2018 and 2020, with knock⁃down rates of 22.92% and 16.98% 60 min post⁃exposure to malathion and 24⁃hour mortality rates of 22.92% and 16.98%, and the insecticide resistance levels were all resistant (R). The KT50 of lambda⁃cyhalothrin were 164.22 min and 236.22 min for An. sinensis in 2018 and 2020, with knock⁃down rates of 30.39% and 38.30% 60 min post⁃exposure to malathion and 24 h mortality rates of 19.60% and 21.28%, respectively, and the insecticide resistance levels were all R. Conclusion　An. sinensis is relatively susceptible to malathion but has developed high⁃level resistance to deltamethrin and lambda⁃cyhalothrin in Puyang City, Henan Province.

Studies on resistance of Schistosoma to praziquantel XⅧ Sensitivity to praziquantel in filial generations of praziquantel⁃resistant and ⁃sensitive Schistosoma japonicum mixed infections

QU Guo⁃Li, LIANG You⁃Sheng, DAI Jian⁃Rong, SHI Feng, XING Yun⁃Tian, SHEN Xue⁃Hui, GUO Na

2021, 33(5):  505. 

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Objective　To investigate the sensitivity of adult worms of filial generations from praziquantel⁃resistant and ⁃sensitive Schistosoma japonicum mixed infections to praziquantel. Methods　Mice were infected with the cercariae of an; experimentally generated praziquantel⁃resistant S. japonicum isolate [median effective dose (ED50) = 277.4 mg/kg] and a laboratory⁃maintained praziquantel⁃sensitive S. japonicum isolate (ED50 = 99.6 mg/kg) at a mixture ratio of 1∶1 and 2∶1, which was maintained in the laboratory via the mouse⁃snail cycle for 8 generations. Then, mice were infected with the cercariae of the 8th filial⁃generation parasite, and grouped 35 days post⁃infection. Mice in the 5 treatment groups were given praziquantel treatment by gavage at a single oral dose of 37.5, 75, 150, 300 mg/kg and 600 mg/kg, while animals in the control group was administered orally with 2.5% cremophor EL. All mice were sacrificed 14 days post⁃treatment and adult worms were collected by perfusion of the portal vein. The worm burden reductions and praziquantel ED50 values were calculated. The praziquantel⁃resistant S. japonicum isolate generated from experimental induction with 12 rounds of praziquantel treatment with sub⁃curative doses was maintained in the laboratory via the mouse⁃snail cycle, and mice were infected with the cercariae of the 8th filial⁃generation parasite. The praziquantel ED50 value against the 8th filial⁃generation adults was measured. Results　After mice were infected with the mixture of cercariae of PZQ⁃resistant and ⁃sensitive S. japonicum isolates at a ratio of 1∶1, the praziquantel ED50 was 135.2 mg/kg against the adults of the 8th filial⁃generation parasite. After mice were infected with the mixture of cercariae of PZQ⁃resistant and ⁃sensitive S. japonicum isolates at a ratio of 2∶1, the praziquantel ED50 was 129.2 mg/kg against the adults of the 8th filial⁃generation parasite. In addition, the praziquantel ED50 was 208.4 mg/kg against the adults of the 8th filial⁃generation S. japonicum without the selection pressure of praziquantel. Conclusions　Compared with the experimentally induced praziquantel⁃resistant S. japonicum isolate, the adult worms of the filial⁃generation S. japonicum show a reduced sensitivity to praziquantel in the same host following infection with the mixture of cercariae of praziquantel⁃resistant and ⁃sensitive S. japonicum isolates. The adult worms of the filial generation of the praziquantel⁃resistant S. japonicum isolate without the selection pressure of praziquantel may still maintain the resistance to praziquantel.

Surveillance of Culex mosquitoes in Jiangsu Province from 2018 to 2019

LI Ju⁃Lin, TANG Jian⁃Xia, WU Jing⁃Yao, YANG Meng⁃Meng, LIANG Cheng, ZHANG Mei⁃Hua, LI Ya⁃Shu, WANG Guan⁃Xi, ZHOU Hua⁃Yun, ZHU Guo⁃Ding, CAO Jun

2021, 33(5):  510. 

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bjective　To investigate the distribution and density of Culex mosquito populations and the resistance of Culex pipiens pallens to insecticides in Jiangsu Province in 2018 and 2019. Methods　During the period from June to October in 2018 and 2019, six counties (districts, cities) were sampled in southern, northern and central Jiangsu Province as surveillance sites. The density of Culex mosquitoes was measured overnight using the light trapping technique. In addition, Culex pipiens pallens mosquitoes were collected from Hai’an of Nantong City and Yandu District of Yancheng City, central Jiangsu Province, and the sensitivity of female first filial generations to dichlorodiphenyltrichloroethane (DDT), malation, proposur, beta cypermethrin and deltamethrin was tested using the standard WHO insecticide susceptibility test assay. Results　A total of 104 423 Culex mosquitoes were captured in six surveillance sites of Jiangsu Province in 2018 and 2019, and Culex quinquefasciatus (49.11%), Culex pipiens pallens (28.38%), and Culex tritaeniorhynchus (21.04%) were predominant species. The density of Culex mosquitoes started to increase since early June, peaked in July and tended to be low in late October. Culex pipiens pallens mosquitoes captured from Hai’an was susceptible to malation, while those from Yandu District were moderately resistant to malation. Culex pipiens pallens mosquitoes from both Yandu and Hai’an were moderately resistant to proposur, and were resistant to DDT, beta cypermethrin and deltamethrin. Conclusions　Culex quinquefasciatus, Culex pipiens pallens and Culex tritaeniorhynchus are predominant Culex species in Jiangsu Province. Culex pipiens pallens is resistant to DT, beta cypermethrin and deltamethrin in central Jiangsu Province.

Prevalence of human soil⁃borne nematode infections in Yunnan Province: a cross⁃sectional study in 2015

WU Fang⁃Wei, WANG Li⁃Bo, LI Ben⁃Fu, YAN Xin⁃Liu, ZI Jin⁃Rong, PENG Jia, CAI Xuan, BAO Xue⁃Ying, YANG Ya⁃Ming

2021, 33(5):  513. 

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Objective　To investigate the current prevalence of human soil⁃borne nematode infections in Yunnan province, so as to provide the scientific evidence for formulating the soil⁃borne nematodiasis control strategy in the province. Methods　In 2015, a total of 20 survey sites were sampled in 10 counties (cities) of Yunnan Province using the stratified cluster random sampling method. Stool samples were collected from all local permanent residents at ages of one year and older in each survey site, and the soil⁃borne nematode eggs were identified using the modified Kato⁃Katz technique and the egg number was counted. In addition, the hookworm species was identified using the filter⁃paperculture method, and Enterobius vermicularis eggs were detected using the cellophane tape method in children at ages of 3 to 6 years. Results　A total of 5 067 residents received stool examinations, and 950 residents were detected with soil⁃borne nematode infections, with an overall prevalence rate of 18.75%. The prevalence of Ascaris lumbricoides, Trichuris trichura and hookworm was 7.52%, 8.47% and 9.02%, respectively. Among 446 children detected using the cellophane tape method, 5 children were detected with E. vermicularis infections. Among the 160 residents with hookworm infections, there were 139 residents with Necator americanus infections (86.88%), 16 with A. duodenale infections (10.00%) and 5 with mixed infections (3.12%). Mild A. lumbricoides (67.98%, 259/381), T. trichura (88.58%, 380/429) and hookworm infections (94.53%, 432/457) were predominant. Among the four ecological zones, the highest prevalence of human soil⁃borne nematode infections was found in the East Tibet⁃South Sichuan Ecological Zone (31.79%), and among the 10 survey counties (cities), the greatest prevalence was seen in Gongshan Derung and Nu Autonomous County (50.13%), while the lowest prevalence was found in Ninglang Yi Autonomous County (0.40%). The prevalence of human soil⁃borne nematode infections was 5.67% (43/759), 26.67% (610/2 287) and 14.70% (297/2 021) in high⁃, moderate⁃ and low⁃economic⁃level regions, respectively. There were no significant differences in the prevalence of human soil⁃borne nematode infections in terms of ecological regions, survey counties (cities) or economic development levels (χ2 = 342.20, 814.60 and 201.34, all P < 0.05). There was no significantdifference in the prevalence of human soil⁃borne nematode infections between male (18.21%, 441/2 422) and female residents (19.24%, 509/2 645) (χ2 = 0.89, P > 0.05), and soil⁃borne nematode infections were detected in residents at all age groups, with the greatest prevalence found in residents at ages of 1 to 9 years (25.88%). In addition, the highest prevalence of soil⁃borne nematode infections was seen in residents with the Dulong Ethnic Minority (82.09%), in preschool children (25.06%) and in illiterate residents (24.80%), and there was no age⁃, ethnicity⁃, occupation⁃ or education level⁃specific prevalence of soil⁃borne nematode infections detected (χ2 = 46.50, 1 016.96, 36.33 and 52.43, all values P < 0.05). Conclusions　Theprevalence of human soil⁃borne nematode infections remains high in Yunnan Province. The management of soil⁃borne nematodiasis requires to be reinforced among low⁃age children, farmers, old people and residents with low educations levels or ethnic groups.

Schistosomiasis control in the evolution of China’s international discourse power

ZHOU Li⁃Ying, ZHANG Jian⁃Feng, LI Wei, YANG Kun

2021, 33(5):  518. 

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As a successful example of global public health, Chinese schistosomiasis control technology and experiences have been included in global public health governance. Chinese schistosomiasis control program progresses with China’s international discourse power. During the period from the initial stage of the founding of the People’s Republic of China to China’s Reform and opening⁃up, the national schistosomiasis control program of China achieved great successes through mobilizing multi⁃sectorial resources under the policy of Independence and Self⁃reliance. Following China’s Reform and opening⁃up, all advantageous opportunities were captured to solve problems pertaining to schistosomiasis control in the context of complex international situations. As a consequence, transmission control of schistosomiasis was achieved across China in 2015. Since the Eighteenth National Congress of the Communist Party of China, China has contributed the discourse system with distinct Chinese characteristics to the world, and has actively participated in health cooperation projects between China and other “Belt and Road” countries, which has contributed China’s wisdom to global schistosomiasis control program and conveyed China’s voice to the world.

Opportunities and challenges of schistosomiasis control during the construction of the Chengdu⁃Chongqing economic circle

HUANG Yan, YU Xiao⁃Ping, LIU Yang, XU Liang, MENG Xian⁃Hong, WU Zi⁃Song

2021, 33(5):  523. 

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Chengdu⁃Chongqing economic circle is centered on Chengdu City and Chongqing Municipality, with aims to build the "fourth growth pole" of China's economy. During this circle, elimination of schistosomiasis had been achieved in 82.5% of the endemic counties (districts) of Sichuan Province, and schistosomiasis is not historically endemic in Chongqing Municipality; however, there is still a risk of schistosmiasis transmission in Sichuan Province and Chongqing Municipality because the natural and social factors affecting schistosomiasis transmission have not been completely eliminated in these areas. Based on the endemic situation of schistosomiasis in Sichuan Province and Chongqing Municipality, we analyzed the opportunities and challenges of schistosomiasis control during the construction of Chengdu⁃Chongqing economic circle, and proposed the corresponding suggestions, so as to provide insights into the sustainable development of schistosomiasis control in the context of the Chengdu⁃Chongqing economic circle construction.

Effectiveness and cost analysis of two chemical molluscicides in hilly schistosomiasis⁃endemic regions

ZHOU Xing, YUAN Min, WU Xia, LI Zong⁃Guang, LI Jian⁃Ren, LÜ Shang⁃Biao

2021, 33(5):  527. 

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Objective　To investigate the effectiveness and cost of 50% and 80% wettable powder of niclosamide ethanolamine salt (NESWP) and 26% metaldehyde and niclosamide suspension concentrate (MNSC) in hilly schistosomiasis⁃endemic regions, so as to provide insights into the selection of chemical molluscicides in hilly regions. Methods In September 2020, a wasteland in Guanshanqiao Village, Yanrui Township, Yushan County of Jiangxi Province was selected as the experimental region, which was sectioned into five blocks and defined as four experimental groups (A1, A2, B, C) and a blank control group (D). 80% NESWP were given at doses of 1 g/m2 and 1.5 g/m2 in groups A1 and A2 using the spraying method, 50% NESWP was given at a dose of 2 g/m2 in Group B using the spraying method, and 26% MNSC was at a dose of 4 g/m2 in Group C using the spraying method, while no chemical treatment was given in Group D. Snail survey was performed using a systematic sampling method before chemical treatment and 1, 3, 7 d and 15 d post⁃treatment to examine the molluscicidal effect, and all molluscicidal costs were estimated to calculate the cost of chemical treatment per 1 m2 and the cost of the reduction in the mean density of living snails per 1%. Results　The highest mortality of snails was 78.95% and the lowest density of living snails was 0.238 8 snails/0.1 m2 in the experimental groups within 7 d of chemical treatment, and the highest mortality of snails was 94.74% and the lowest density of living snails was 0.058 0 snails/0.1 m2 7 d post⁃treatment. There were no significant differences in the snail mortality among the A1, A2, B and C groups 1 ([χ2] = 2.250, P > 0.05), 3 ([χ2] = 1.779, P > 0.05) or 15 d post⁃treatment ([χ2] = 2.286, P > 0.05), while a significant difference was detected in the snail mortality among the four groups 7 d post⁃treatment ([χ2] = 7.990, P = 0.046). In addition, there were no significant differences in the snail mortality between A1 and A2 groups 1 ([χ2] = 0.724, P > 0.05), 3 ([χ2] = 0.584, P > 0.05), 7 ([χ2] = 0.400, P > 0.05) or 15 d post⁃treatment ([χ2] = 0.251, P > 0.05). The costs of chemical treatment per 1 m2 were 0.58, 0.60, 0.64 Yuan and 0.73 Yuan in groups A1, A2, B and C, and the costs of the mean density of living snail per 1% reduction were 19.29, 20.44, 21.68 Yuan and 23.53 Yuan in groups A1, A2, B and C, respectively. Conclusion　80% NESWP shows a high molluscicidal efficacy and low cost in hilly schistosomiasis⁃endemic regions.

Effects of urban construction on Oncomelania snails control in Wuhan City

JIN Xian⁃Ling, LUO Hua⁃Tang, YUAN Yi

2021, 33(5):  531. 

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Objective　To evaluate the effectiveness of urban construction projects on Oncomelania snails control in Wuhan City, so as to provide insights into the development of an integrated control strategy for urban schistosomiasis. Methods　The data pertaining to the endemic situation of schistosomiasis, schistosomiasis control data, the construction of the Yangtze River Bridge, marshland management and park constructions were collected from Wuhan City from 1990 to 2020. The changes of areas of snail habitats and high⁃risk settings were compared before and after implementation of these urban construction projects to evaluate the effectiveness of urban construction projects on Oncomelania snails control. Results　The number of schistosomiasis cases decreased by 97.35%, and the number of cattle with schistosomiasis decreased by 100% in Wuhan City from 1990 to 2020, with a 41.99% reduction in areas of snail habitats, including 94.97% and 34.40% reductions in snail habitats inside and outside the embankment decreased. During the period from 1990 through 2020, a total of 10 Yangtze River bridges were built in Wuhan City, and areas of snail habitats around the bridges reduced from 11 699.05 hm2 before the bridge building to 8 726.14 hm2 after the building (a 25.41% reduction), while the areas of high⁃risk settings reduced from 411.69 hm2 before the bridge building to 276.78 hm2 after the building (a 32.77% reduction). Following treatment of three marshlands in Hankou, Hanyang and Wuchang, the areas of snail habitats reduced from 225.80 hm2 before the management to 199.47 hm2 after the management (a 11.66% reduction), and the areas of high⁃risk settings reduced from 23.14 hm2 before the treatment to 17.73 hm2 after the building (a 23.38% reduction). Following the building of 5 parks in snail⁃infested settings, the areas of snail habitats reduced from 319.61 hm2 before the construction to 280.80 hm2 after the construction (a 12.14% reduction), and the areas of high⁃risk settings reduced from 35.00 hm2 before the construction to 27.73 hm2 after the construction (a 20.77% reduction). Conclusion　Simultaneous implementation of urban construction projects and schistosomiasis control measures is effective to shrink snail⁃infested setting and high⁃risk settings and control the endemic situation of schistosomiasis in endemic foci in Wuhan City.

Advances in the research of comorbidity of Blastocystis hominis infections and other diseases

CHEN Hui⁃Hui, LIU Qin, DENG Yan, ZHANG Hong⁃Wei, TIAN Li⁃Guang

2021, 33(5):  535. 

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Blastocystis hominis is a common intestinal protozoan parasite. Most individuals with B. hominis infections have no apparent clinical symptoms; however, a few patients, notably those with co⁃infections or impaired immune system function may present abdominal pain, diarrhea, nausea, vomiting, and even death. This paper reviews the co⁃infections of B. hominis and other pathogens and comorbidity of B. hominis infections and other diseases, so as to provide insights into the management of B. hominis infections.

Progress of researches on the actions of praziquantel against hepatic fibrosis

YUAN Xuan, DAI Jian⁃Rong

2021, 33(5):  540. 

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Praziquantel not only has broad⁃spectrum anti⁃trematode and anti⁃tapeworm effects, but also has pharmacological effects such as regulating inflammatory response and anti⁃fibrosis. Hereby, the anti⁃fibrosis effect of praziquantel and its mechanism were reviewed in order to provide theoretical basis for the treatment of liver fibrosis.

Progress of researches on symbionts in the management of mosquito⁃borne infectious diseases

LU Jia⁃Chen, SHEN Fei⁃Hu, Lei Yao, Xu Qin⁃Wen, Yang Bo, CHENG Yang

2021, 33(5):  544. 

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Mosquitoes are the main vectors of many infectious diseases, including malaria and yellow fever, which seriously threaten human health across the world. In addition to the use of chemical insecticides, genetic control is a new attempt to currently available interventions used for mosquito vector control. In terms of ecological safety, however, symbiotic control as a novel approach has been proposed for mosquito control. Since there are multiple symbiotic microflora inhabiting in a variety of tissues of mosquitoes, including the digestive tract, they may affect the transmission of mosquito⁃borne infectious diseases through affecting the lifespan, reproductive competence, and vector competence of the host. In this review, the interactions between symbionts in mosquitoes were summarized, and the research progress of mosquito⁃associated symbionts in the management of mosquito⁃borne infectious diseases was reviewed.