Table of Content

30 August 2021, Volume 33 Issue 4

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Concept and mechanism innovations provide a sustainable driver for echinococcosis control in China

XIAO Ning

2021, 33(4):  329. 

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China is one of the countries with the highest disease burden of echinococcosis in the world. China’s progress in echinococcosis control started with limited scientific research projects, followed by nationwide epidemiological surveys, and then launched a national echinococcosis control programme on the basis of a pilot intervention project. During this process, science-based control and technological innovations have been integrated into echinococcosis control in China. The concept and mechanism innovations-based echinococcosis control models and successful experiences in highly endemic foci promote the sustainable echinococcosis control achievements in China. In addition, the joint echinococcosis prevention and control and sharing of successful experiences with other echinococcosis-endemic countries will provide China’s wisdom, China’s strategy and China’s contributions to global echinococcosis control and the health of human beings.

Establishment of a nucleic acid dipstick test for detection of Schistosoma japonicum specific gene fragments based on the recombinase⁃aided isothermal amplification assay

YE Yu⁃Ying, ZHAO Song, LIU Yan⁃Hong, ZHANG Jian⁃Feng, XIONG Chun⁃Rong, YING Qing⁃Jie, YANG Kun

2021, 33(4):  334. 

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Objective　To develop a rapid test for detection of Schistosoma japonicum specific gene fragments based on the recombinase⁃aided isothermal amplification assay (RAA) and nucleic acid dipstick test. Methods　The S. japonicum SjG28 gene fragment was selected as the target gene fragment, and the primers and fluorescent probe were designed and synthesized. Then, a S. japonicum nucleic acid dipstick test was established. The sensitivity of this dipstick test was evaluated by detecting different copies of recombinant plasmids containing the S. japonicum SjG28 gene fragment and different concentrations of genomic DNA from adult worms of S. japonicum, and the specificity of the dipstick test was evaluated by detecting the genomic DNA from Clonorchis sinensis, S. mansoni, Ancylostoma duodenale, S. haematobium, Babesia and Paragonimus westermani. Results　The S. japonicum nucleic acid dipstick test based on the S. japonicum SjG28 gene fragment showed the minimum detectable limit of 10 copies/μL of the recombinant plasmid containing the S. japonicum SjG28 gene fragment and the minimum detectable limit of 1 pg/μL of S. japonicum genomic DNA, and the dipstick assay tested negative for the genomic DNA from C. sinensis, S. mansoni, A. duodenale, S. haematobium, Babesia and P. westermani. Conclusion　A rapid, simple, and visualized assay is established for detection of S. japonicum specific gene fragments based on RAA and nucleic acid dipstick test.

Establishment and preliminary application of a recombinase⁃aided isothermal amplification assay⁃based multiplex nucleic acid assay for detection of three Echinococcus species

ZHANG Xue⁃Yong, JIAN Ying⁃Na, GUO Zhi⁃Hong, DUO Hong, WEI Yan⁃Ming

2021, 33(4):  339. 

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Objective　To establish a multiplex nucleic acid assay for rapid detection of Echinococcus multilocularis, E. granulosus and E. shiquicus based on the recombinase⁃aided isothermal amplification assay (RAA) and to preliminarily assess its diagnostic efficiency. Methods　The mitochondrial genomic sequences of E. multilocularis (GenBank accession number: NC_000928), E. granulosus (GenBank accession number: NC_044548) and E. shiquicus (GenBank accession number: NC_009460) were used as target sequences, and three pairs of primers were designed based on the RAA primer design principle and synthesized for the subsequent multiple RAA amplification. The genomic DNA of E. multilocularis, E. granulosus and E. shiquicus at different concentrations and the recombinant plasmids containing the target gene at various concentrations were amplified to evaluate the diagnostic sensitivity of the multiplex RAA assay, and the genomic DNA of E. multilocularis, E. granulosus, E. shiquicus, Taenia multiceps, T. saginata, T. asiatica, Dipylidium caninum, T. hydatigena, Toxocara canis, Fasciola hepatica, T. pisiformis, Mesocestoides lineatus and Cryptosporidiumn canis was detected using the multiplex RAA assay to evaluate its specificity. In addition, the reaction condition of the multiplex RAA assay was optimized, and was then employed to detect the tissues with echinococcosis lesions, simulated canine fecal samples and field captured fox fecal samples to examine its application values. Results　The multiplex RAA assay was effective to specifically amplify the mitochondrial gene fragments of E. multilocularis, E. granulosus and E. shiquicus within 40 min at 39 ℃, with sequence lengths of 540, 430 bp and 200 bp, respectively. This multiplex RAA assay showed the minimum detection limits of 2.0, 2.5 pg/μL and 3.1 pg/μL for detection of the genomic DNA of E. multilocularis, E. granulosus and E. shiquicus, and presented the minimum detection limit of 200 copies/μL for detection of the recombinant plasmids containing E. multilocularis, E. granulosus and E. shiquicus target genes. This multiplex RAA assay was effective to simultaneously detect single and multiple infections with E. multilocularis, E. granulosus and E. shiquicus, but failed to amplify the genomic DNA of T. multiceps, T. saginata, T. asiatica, D. caninum, T. hydatigena, T. canis, F. hepatica, T. pisiformis, M. lineatus and C. canis. In addition, the optimized multiplex RAA assay was effective to detect all positive samples from the tissue samples with echinococcosis lesions, simulated canine fecal samples and field captured fox fecal samples, which was fully consistent with the detection of the single PCR assay. Conclusion　A sensitive and specific multiplex nucleic acid assay for rapid detection of E. multilocularis, E. granulosus and E. shiquicus has been successfully established.

Investigation on population dynamics and Echinococcus infections in small rodents around human settlement in Yushu City, Qinghai Province

WANG Xu, ZUO Qing⁃Qiu, YU Qing, SONG Cheng⁃Xi, WANG Zheng⁃Huan, XIAO Ning, WANG Yuan⁃Jia, WENG Xiao⁃Dong, WEI Xu, ZHOU Hong⁃Rang, CUI Xiao⁃Yu

2021, 33(4):  346. 

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Objective　To investigate the population dynamics and Echinococcus infections in small rodents around human settlement in Yushu City, Qinghai Province. Methods Rodents were captured using the mouse trap method in pastures from Batang Township and Longbao Township of Yushu City, Qinghai Province on May, August and October, 2018. The body weight and snout⁃vent length of all captured rodents were measured, and the species was identified according to the rodent morphology. Genomic DNA was extracted from rodent liver specimens and lesion specimens, and the mitochondrial cox1 gene of Echinococcus was amplified using PCR assay for identification of parasite species. In addition, the tissue specimens positive for PCR assay were sampled for pathological examinations. The prevalence of Echinococcus infections was estimated in rodents, and a phylogenetic tree was created based on Echinococcus cox1 gene sequences. Results　A total of 285 small rodents were captured, including 143 Ochotona curzoniae (50.2%), 141 Lasiopodomys fuscus (49.5%), and 1 Neodon irene (0.3%), and there was a remarkable variation in habitat selection among these three rodent species. The number of L. fuscus correlated positively with vegetation coverage (r = 0.350, P = 0.264), with the greatest number seen in August, and the number of O. curzoniae negatively with vegetation coverage（r = –0.371, P = 0.235), with the highest number seen in August and the lowest number in May. The female/male ratios of O. curzoniae and voles were 1∶0.96 and 0.82∶1, respectively. The body weight (r = 0.519, P < 0.01) and snout⁃vent length (r = 0.578, P < 0.01) of O. curzoniae showed a tendency towards a rise with month, while the body weight (r = –0.401, P < 0.01) and snout⁃vent length (r = –0.570, P < 0.01) of voles presented a tendency towards a reduction with month. No Echinococcus infection was detected in voles, while 2.1% prevalence of E. shiquicus infection was seen in O. curzoniae. Phylogenetic analysis revealed consistent sequences of cox1 gene from E. shiquicus in Yushu City of Qinghai Province and Shiqu County, Ganzi Tibetan Autonomous Prefecture of Sichuan Province. Conclusions　The small rodents around the human settlement in Yushu City of Qinghai Province mainly include O. curzoniae and L. fuscus, with the greatest numbers seen in May and August, respectively. Following the concerted efforts for echinococcosis control, the prevalence of Echinococcus infections is low in small rodents around the human settlement in Yushu City; however, there is still a risk of echinococcosis transmission.

Expression and significance of TGF⁃β1, p38MAPK and BMP⁃7 protein in liver specimens of patients with alveolar hepatic echinococcosis

CAO Tao, YANG Yu⁃Wen, YANG Xiao, ZHU Hai⁃Hong

2021, 33(4):  353. 

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Objective　To detect the expression of transforming growth factor⁃β1 (TGF⁃β1), p38MAPK and bone morphogenetic protein⁃7 (BMP⁃7) protein in the liver specimens of patients with hepatic alveolar echinococcosis, and to investigate the potential role of TGF⁃β1, p38MAPK and BMP⁃7 protein in hepatic fibrosis caused by hepatic alveolar echinococcosis. Methods　A total of 20 patients with hepatic alveolar echinococcosis were enrolled as study subjects, and hepatic specimens were sampled from the sites within 0.5 cm (Group A) and 0.5 to 1.5 cm from hepatic alveolar echinococcosis lesions (Group B), while normal liver specimens sampled from the sites 2 cm and greater from hepatic alveolar echinococcosis lesions served as controls (Group C). The fibrosis of liver specimens was pathological examined using HE and Masson staining, and the expression of TGF⁃β1, p38MAPK and BMP⁃7 protein was quantified in liver tissues using Western blotting. The associations of TGF⁃β1, p38MAPK and BMP⁃7 protein expression with hepatic fibrosis were assessed. Results　HE staining showed the malaligned structure of hepatocytes and destruction of the structure of hepatic lobules at various degrees in liver specimens in groups A and B, with hepatocyte degeneration, atrophy and necrosis, hyperplasia of fibrous tissues and eosinophilic granulocyte infiltration seen, while no abnormal pathological alterations of liver tissues, normal hepatocyte structure and morphology and uniform size, no malaligned structure of hepatocytes, clear structure of hepatic lobules, no or mild hepatocyte degeneration or necrosis, and no eosinophilic granulocyte infiltration were seen in Group C. Masson staining showed that there was hyperplasia of multiple fibrous connective tissues in the liver portal areas in groups A and B, with fibrosis seen in hepatic lobules, while no obvious pathological changes were seen in Group C. There were significant differences seen in TGF⁃β1 (P < 0.001), p38MAPK (P < 0.01) and BMP⁃7 protein (P < 0.05) expression in liver tissues in groups A, B and C, and higher TGF⁃β1, p38MAPK and BMP⁃7 protein expression was quantified in groups A and B than in Group C (all P values < 0.05), while greater TGF⁃β1, p38MAPK and BMP⁃7 protein expression was detected in Group B than in Group C (all P values < 0.05). The expression of TGF⁃β1, p38MAPK and BMP⁃7 protein correlated positively with the severity of hepatic fibrosis (r = 0.866, 0.702 and 0.801, all P values < 0.05), and there were significant differences in TGF⁃β1 (F = 72.580, P < 0.01), p38MAPK ([χ2] = 31.705, P < 0.01) and BMP⁃7 protein expression ([χ2] = 48.388, P < 0.01) among liver tissues with different degrees of fibrosis. The TGF⁃β1 protein expression correlated positively with p38MAPK and BMP⁃7 protein expression (r = 0.607 and 0.702, both P values < 0.001), and the BMP⁃7 protein expression also correlated positively with p38MAPK protein expression (r = 0.456, P < 0.001). Conclusion　The interaction among TGF⁃β1, p38MAPK and BMP⁃7 jointly participates in the development of hepatic fibrosis induced hepatic alveolar echinococcosis.

Potential suitable habitats of Haemaphysalis longicornis in China under different climatic patterns

CUN De⁃Jiao, WANG Qiang, YAO Xiao⁃Yan, MA Ben, ZHANG Yi, LI Lan⁃Hua

2021, 33(4):  359. 

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Objective　To evaluate the impact of environmental and climatic factors on the distribution of suitable habitats of Haemaphysalis longicornis, and to predict the potential distribution of H. longicornis under different climate patterns in China. Methods　Data pertaining to the distribution of H. longicornis were retrieved from public literatures. The effects of 19 climatic factors (annual mean temperature, annual mean temperature difference between day and night, isothermality, standard deviation of seasonal variation of temperature, maximum temperature of the warmest month, minimum temperature of the coldest month, temperature annual range, mean temperature of the wettest season, mean temperature of the driest season, mean temperature of the warmest season, mean temperature of the coldest season, annual mean precipitation, precipitation of the wettest month, precipitation of the driest month, coefficient of variance of precipitation, precipitation of the wettest season, precipitation of the driest season, precipitation of the warmest season and precipitation of the coldest season) and 4 environmental factors (elevation, slope, slope aspect and vegetation coverage) on the potential distribution of H. longicornis were assessed using the maximum entropy (MaxEnt) model based on the H. longicornis distribution data and climatic and environmental data, and the potential distribution of H. longicornis was predicted under the RCP 2.6 and 8.5 emissions scenarios. Results　Among the environmental and climatic factors affecting the geographical distribution of H. longicornis in China, the factors contributing more than 10% to the distribution of H. longicornis mainly included the precipitation of the driest month (26.0%), annual mean temperature (11.2%), annual mean precipitation (10.0%) and elevation (24.2%). Under the current climate pattern, the high⁃, medium⁃ and low⁃suitable habitats of H. longicornis are 1 231 900, 1 696 200 km2 and 1 854 400 km2 in China, respectively. The distribution of H. longicornis increased by 336 100 km2 and 367 300 km2 in 2050 and 2070 under the RCP 2.6 emissions scenario, and increased by 381 000 km2 and 358 000 km2 in 2050 and 2070 under the RCP 8.5 emissions scenario in China, respectively. Conclusions　Climatic and environmental factors, such as precipitation, temperature and elevation, greatly affect the distribution of H. longicornis in China, and the suitable habitats of H. longicornis may expand in China under different climate patterns in future.

Distribution and suitable habitats of ticks in the Yangtze River Delta urban agglomeration

LI Zhong⁃Qiu, LI Lan⁃Hua, YIN Hui⁃Jun, WEI Zi⁃Xin, GUO Yun⁃Hai, MA Ben, ZHANG Yi

2021, 33(4):  365. 

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Objective　To investigate the current distribution of ticks and predict the suitable habitats of ticks in the Yangtze River Delta urban agglomeration in 2017, so as to provide insights into tick control and management of tick⁃borne diseases in these areas. Methods　All publications pertaining to tick and pathogen distribution in the Yangtze River Delta urban agglomeration were retrieved, and the geographical location of tick distribution was extracted. The effects of 19 climatic factors on the distribution of ticks were examined using the jackknife method, including the mean temperature of the wettest quarter, precipitation of the coldest quarter, mean temperature of the driest quarter, maximum temperature of the warmest month, precipitation of the driest month, minimal temperature of the coldest month, annual precipitation, mean daily temperature range, precipitation seasonality, annual temperature range, temperature seasonality, annual mean temperature, mean temperature of the warmest quarter, precipitation of the wettest quarter, isothermality, mean temperature of the coldest quarter, precipitation of the wettest month, precipitation of the driest quarter and precipitation of the warmest quarter. The distribution of ticks was analyzed in 2020 using the maximum entropy (MaxEnt) model, and the potential suitable habitats of ticks were predicted in 2070 using the MaxEnt model based on climatic data. Results　A total of 380 Chinese and English literatures were retrieved, and 148 tick distribution sites were extracted, with 135 sites included in the subsequent analysis. There were 7 genera (Haemaphysalis, Rhipicephalus, Ixodes, Dermacentor, Boophilus, Hyalomma and Amblyomma) and 27 species of ticks detected in the Yangtze River Delta urban agglomeration. The climatic factors affecting the distribution of ticks in the Yangtze River Delta urban agglomeration mainly included the mean temperature of the wettest quarter and the precipitation of the coldest quarter, with 26.1% and 23.6% contributions to tick distributions. The high⁃, medium⁃ and low⁃suitable habitats of ticks were 20 337.08, 40 017.38 km2 and 74 931.43 km2 in the Yangtze River Delta urban agglomeration in 2020, respectively. The climate changes led to south expansion of the suitable habitats of ticks in the Yangtze River Delta urban agglomeration in 2070, and the total areas of suitable habitats of ticks was predicted to increase by 18 100 km2. In addition, the high⁃, medium⁃ and low⁃suitable habitats of ticks were predicted to increase to 24 317.84, 45 283.02 km2 and 83 766.38 km2 in the Yangtze River Delta urban agglomeration in 2070, respectively. Conclusions　Multiple tick species are widespread in the Yangtze River Delta urban agglomeration, and the future climate changes may lead to expansion of tick distribution in these areas.

Epidemic situation and diagnosis of imported malaria before and after malaria elimination in Nanjing City, Jiangsu Province

HE Yi⁃Sha, WANG Yu, LI Yan⁃Jing, XIE Chao⁃Yong

2021, 33(4):  373. 

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Objective　To analyze the epidemiological characteristics and diagnosis of imported malaria before and after malaria elimination in Nanjing City of Jiangsu Province, so as to provide the scientific evidence for formulating the malaria control strategy after malaria elimination. Methods　Data pertaining to the epidemic situation and individual investigation of malaria in Nanjing City before (from 2012 to 2016) and after malaria elimination (from 2017 to 2020) were captured from the National Notifiable Communicable Disease Reporting System and the Information System for Parasitic Diseases Control and Prevention and were analyzed statistically. Results　A total of 178 malaria cases were reported in Nanjing City from 2012 to 2020, and all were imported cases. There were 99 malaria cases reported before malaria elimination in Nanjing City, including 78 cases with Plasmodium falciparum malaria (78.79%), 5 cases with P. vivax malaria (5.05%), 10 cases with P. ovale malaria (10.10%), 3 cases with P. malariae malaria (3.03%) and 3 cases with mixed infections (3.03%), and 79 malaria cases reported after elimination, including 63 cases with P. falciparum malaria (79.75%), 5 cases with P. vivax malaria (6.33%), 9 cases with P. ovale malaria (11.39%), 2 cases with P. malariae malaria (2.53%). There was no significant difference in the proportion of each type of malaria cases in Nanjing City before and after malaria elimination ([χ2] = 2.400, P > 0.05). Malaria cases mainly acquired Plasmodium infections in African regions, and no significant difference was seen in the proportion of malaria cases returning to Nanjing City from African countries before and after malaria elimination ([χ2] = 0.093, P > 0.05). The number of malaria cases peaked in Nanjing City in January and during the period from May to July before elimination, and there was no apparent seasonal variation in the distribution of malaria cases after elimination. The proportion of malaria cases living in Nanjing City was significantly greater after malaria elimination than before elimination (72.15% vs. 55.56%; [χ2] = 5.187, P = 0.023). The proportions of businessmen and international students were both 5.05% before malaria elimination, and increased to 15.19% and 13.92% after elimination, respectively ([χ2] = 5.229 and 4.229, both P values < 0.05). The percentage of definitive diagnosis of malaria at initial diagnosis was 18.75% in county⁃level hospitals before malaria elimination and increased to 61.11% after elimination ([χ2] = 6.275, P = 0.012), while the proportion of malaria cases with definitive diagnoses in county⁃level hospitals was 4.04% before malaria elimination and increased to 13.92% after elimination ([χ2] = 5.562, P = 0.018). During the period from 2012 to 2020, the proportion of malaria cases with definitive diagnoses within 1 to 3 days post⁃admission increased from 27.27% in Nanjing City before malaria elimination to 45.57% after elimination ([χ2] = 6.433, P = 0.011). Conclusions　The epidemic situation of imported malaria remains serious in Nanjing City during the post⁃elimination stage, and malaria parasite infections predominantly occur in African regions. In addition, there are changes in regional and occupational distributions of malaria cases and the diagnostic capability of malaria increases in county⁃level hospitals in Nanjing City after malaria elimination. Further improvements in the malaria surveillance system and the diagnostic and treatment capability of malaria in medical institutions at each level are required to consolidate malaria elimination achievements in Nanjing City.

Construction of a cDNA library for Sparganum mansoni and screening of diagnostic antigen cadidates

LU Yan, CHEN Jia⁃Xu, SONG Peng, LI Hao, AI Lin, CAI Yu⁃Chun, CHU Yan⁃Hong, CHEN Shao⁃Hong

2021, 33(4):  380. 

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Objective　To construct a cDNA library of Sparganum mansoni and immunoscreen antigen candidates for immunodiagnosis of sparganosis mansoni. Methods　Total RNA was extracted from S. mansoni, and reversely transcribed into cDNA, which was ligated into the phage vector. These recombinant vectors were packaged in vitro to construct the SMART cDNA library of S. mansoni. Then, the cDNA library was immunoscreened with sera from patients with sparganosis mansoni to yield positive clones. The inserted fragments of positive clones were sequenced and subjected to homology analyses, and the structure and functions of the coding proteins were predicted. Results　The SMATR cDNA library of S. mansoni was successfully constructed. The titer of the cDNA library was 6.25 × 106 pfu/mL, with a recombinant efficiency of 100%, and the mean length of the inserted fragments in the library was larger than 1 100 bp. A total of 12 positive clones were obtained by immunoscreening, and were categorized into Sm⁃I (Sm60⁃1), Sm⁃II (Sm58⁃1), Sm⁃III (Sm20⁃1) and Sm⁃IV (Sm22⁃3), with 1 134, 1 063, 883 bp and 969 bp long inserted fragments. Their coding proteins were highly homologous with the Spirometra erinaceieuropaei antigenic polypeptide, cytoplasmic antigen, ribosomal protein S4⁃like protein and unnamed protein product, respectively. Conclusions　A SMART cDNA library of S. mansoni has been successfully constructed and 4 categories of positive clones have been identified, which provides a basis for further studies on diagnostic antigens for sparganosis mansoni.

Study on emergency metabolic changes of Anopheles sinensis larvae following exposure to deltamethrin

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

2021, 33(4):  387. 

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Objective　To analyze the changes of small molecular metabolites in the larvae of a deltamethrin⁃sensitive strain of Anopheles sinensis following exposure to deltamethrin, so as to provide the scientific basis for investigating the metabolic pathway and screening metabolic markers of deltamethrin in An. sinensis. Methods　The 50% and 75% lethal concentrations (LC50 and LC75) of deltamethrin against the larvae of a deltamethrin⁃sensitive strain of An. sinensis were calculated in laboratory. The type and content of An. sinensis larvae metabolites were detected using high performance liquid chromatography and mass spectrometry (LC⁃MS/MS) following exposure to deltamethrin at LC50 and LC75 for 30 min and 24 h, and the changes of metabolites were analyzed. Results　The LC50 and LC75 values of deltamethrin were 4.36 × 10-3 μg/mL and 1.12 × 10-2 μg/mL against the larvae of a deltamethrin⁃sensitive strain of An. sinensis. Following exposure of the larvae of a deltamethrin⁃sensitive strain of An. sinensis to deltamethrin at LC50 and LC75 for 30 min, the differential metabolites mainly included organic oxygen compounds, carboxylic acid and its derivatives, fatty acyl and pyrimidine nucleotides, with reduced glucose levels. Following exposure for 24 h, the differential metabolites mainly included organic oxygen compounds, carboxylic acid and its derivatives, aliphatic acyl and purine nucleotides, with increased glucose level detected. Conclusion　Carbohydrate, carboxylic acid and its derivatives, fatty acyls, amino acids and their derivatives may play important roles in deltamethrin metabolism in the larvae of a deltamethrin⁃sensitive strain of An. sinensis.

Drug⁃resistant gene polymorphisms in Plasmodium falciparum isolated from Bioko Island, Equatorial Guinea in 2018 and 2019

HE Jin⁃Quan, CHEN Jiang⁃Tao, LI Jing⁃He, CHEN Wei⁃Zhong, LIANG Xue⁃Yan, HUANG Hui⁃Ying, WEI Hua⁃Gui, HUANG Wei⁃Yi, WANG Jun⁃Li LIN Min, YANG Pei⁃Kui, CHEN Xin⁃Yao, LIU Xiang⁃Zhi

2021, 33(4):  396. 

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Objective　To investigate the genetic polymorphisms of Plasmodium falciparum multidrug resistance protein 1 (PfMDR1), chloroquine resistance transporter (PfCRT) and Kelch 13 (PfK13) genes in Bioko Island, Equatorial Guinea, so as to provide insights into the development of the malaria control strategy in local areas. Methods　A total of 85 peripheral blood samples were collected from patients with Plasmodium falciparum infections in Bioko Island, Equatorial Guinea in 2018 and 2019, and genomic DNA was extracted. The PfMDR1, PfCRT and PfK13 genes were amplified using a nested PCR assay. The amplification products were sequenced, and the gene sequences were aligned. Results　There were no mutations associated with artemisinin resistance in PfK13 gene in Bioko Island, Equatorial Guinea, while drug⁃resistant mutations were detected in PfMDR1 and PfCRT genes, and the proportions of PfMDR1_N86Y, PfMDR1_Y184F and PfCRT_K76T mutations were 35.29% (30/85), 72.94% (62/85) and 24.71% (21/85), respectively. Conclusion　There are mutations in PfMDR1, PfCRT and PfK13 genes in P. falciparum isolates from Bioko Island, Equatorial Guinea.

Surveillance of Enterobius vermicularis infections among children in Shandong Province from 2016 to 2020

BU Xiu⁃Qin, ZHAO Chang⁃Lei, YAN Ge, WANG Yong⁃Bin, WANG Long⁃Jiang, KONG Xiang⁃Li, XU Yan, ZHANG Ben⁃Guang

2021, 33(4):  401. 

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Objective　To investigate the prevalence and changing trend of Enterobius vermicularis infections among children in Shandong Province, so as to provide the scientific evidence for the adjustment and development of the enterobiasis control strategy. Methods　Soil⁃borne nematodiasis surveillance sites were assigned in 51 counties (districts, cities) in Shandong Province from 2016 to 2020, and the E. vermicularis infections were detected using a modified Kato⁃Katz technique and the cellophane tape method among children at ages of 3 to 9 years living in these surveillance sites. The epidemiological profiles of E. vermicularis⁃infected children were descriptively analyzed. Results　A total of 5 060 children at ages of 3 to 9 years were detected in 51 soil⁃borne nematodiasis surveillance sites in Shandong Province from 2016 to 2020, and the overall prevalence of E. vermicularis infections was 2.23%. The annual prevalence of E. vermicularis infections was 3.99% (26/651), 1.70% (14/824), 0.96% (8/837), 2.90% (45/1 552) and 1.67% (20/1 196) from 2016 to 2020, respectively, with a significant difference detected among years ([χ2] = 21.455, P < 0.01). The prevalence of E. vermicularis infections was 1.25% (15/1 198), 1.85% (14/755), 3.18% (84/2 640) and 0 (0/467) among children from central, eastern, southern and northern Shandong Province ([χ2] = 27.326, P < 0.01). In addition, there was no significant difference in the prevalence of E. vermicularis infections between male (1.98%, 56/2 831) and female children (2.56%, 57/2 229) ([χ2] = 1.916, P > 0.05); however, there was age⁃specific prevalence of E. vermicularis infections among children ([χ2] = 16.448, P < 0.05), with the greatest prevalence detected among children at ages of 6 years (3.18%, 25/786), and the lowest prevalence seen among children at ages of 3 years (0.75%, 6/800). Conclusions　The prevalence of E. vermicularis infections remained at a medium level among children at ages of 3 to 9 years in Shandong Province from 2016 to 2020, with region⁃specific prevalence found across the province. An integrated strategy is required for enterobiasis control.

Prevalence and influencing factors of Enterobius vermicularis infections among children in Fanxian County of Henan Province in 2019

SONG Chuan⁃Qing, JIAO Xue⁃Cheng, JIANG Tian⁃Tian, LIANG Gui⁃Hua, WANG Lan⁃Zhen, XU Yin⁃Huai, HUANG Shou⁃Hai, CHEN Wei⁃Qi, DENG Yan, ZHANG Ya⁃Lan

2021, 33(4):  406. 

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Objective　To investigate the prevalence and influencing factors of Enterobius vermicularis infections among children in Fanxian County, Henan Province in 2019, so as to provide insights into the management of enterobiasis. Methods　Five kindergartens were selected in urban and rural areas of Fanxian County, Henan Province using the stratified sampling method in 2019, and a census of E. vermicularis infections was performed among all children in the kindergartens. E. vermicularis eggs were detected using adhesive and scotch cellophane⁃tape anal swab methods, and the basic characteristics of children and their families, health habits and the kindergartens’ information were investigated with questionnaires. Logistic regression analysis was used to investigate the risk factors and protective factors of pinworm infection in children. Results　A total of 671 children were tested, and the mean prevalence of E. vermicularis infections was 15.50% (104/671). The prevalence of E. vermicularis infections was higher among children in rural kindergartens (28.13%, 72/256) than in urban kindergartens (7.71%, 32/415) ([χ2] = 50.380, P < 0.01), and greater in private kindergartens (32.26%, 60/186) than in public kindergartens (9.07%, 44/485) ([χ2] = 55.183, P < 0.01). There was no gender⁃specific prevalence of E. vermicularis infections among children ([χ2] = 1.442, P > 0.05), and the prevalence of E. vermicularis infections presented a tendency towards a rise with age ([χ2] trend = 8.373, P < 0.05) and school grade ([χ2] trend = 30.274，P < 0.05). Logistic regression analysis identified rural kindergartens and high grades as risk factors, and separate washing of children’s and adults’ cloths, frequent bathing and frequent dinnerware disinfection in kindergartens as protective factors for E. vermicularis infections among children. In addition, there was no significant difference in the detection of E. vermicularis infections among children by using adhesive (73.08%, 76/104) and scotch cellophane⁃tape anal swab methods (56.73%, 59/104) ([χ2] = 3.959, P > 0.05). Conclusions　The prevalence of E. vermicularis infection is high among children in Fanxian Country, Henan Province. Health education and surveillance of enterobiasis are required to be intensified among children in rural kindergartens and senior grades and their parents and teachers.

Epidemic situation of malaria in Jiangsu Province in 2019

WANG Wei⁃Ming, CAO Yuan⁃Yuan, YANG Meng⁃Meng, GU Ya⁃Ping, XU Sui, ZHOU Hua⁃Yun, ZHU Guo⁃Ding

2021, 33(4):  411. 

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Objective　To analyze the epidemic situation of malaria in Jiangsu Province in 2019, so as to provide the scientific basis for the development of the strategy for the prevention of re⁃introduction of imported malaria. Methods　The malaria case report information, epidemiological case investigation information, epidemic foci investigation and management report in Jiangsu Province in 2019 were collected, and all epidemiological data were descriptively analyzed. Results　A total of 244 malaria cases were reported in Jiangsu Province in 2019, and all cases were laboratory⁃confirmed overseas imported cases, including 4 cases with vivax malaria, 206 cases with falciparum malaria, 12 cases with malariae malaria and 22 cases with ovale malaria. In 2019, there were 12 malaria cases progressing into severe cases in Jiangsu Province, with one death. Nanjing, Nantong, Lianyungang, Taizhou and Changzhou cities contributed the largest number of malaria cases in 2019, with the number of malaria cases accounting for 59.84% of total cases in Jiangsu Province. The infections occurred in Papua New Guinea (2 cases), Pakistan (1 case) and 27 African countries (241 cases), including Angola, the Democratic Republic of the Congo, Nigeria, Equatorial Guinea, Cote d'Ivoire and so on. There were 77 cases (31.55%) with a visit to doctor on the day of onset, and 146 cases (59.84%) within 1 to 3 days after onset. In addition, there were 149 cases (61.06%) with definitive diagnosis at the first visit and 77 cases (31.55%) diagnosed within 1 to 3 days after the visit, and the mean duration from the visit to definitive diagnosis was (0.80 ± 1.59) d, which significantly shortened as compared to that (1.34 d ± 2.59 d) in 2018 (U = 2.53, P < 0.05). Conclusions　Intensifying the surveillance and management of imported malaria and improving the diagnostic capability of imported malaria and the treatment of severe malaria cases are required to consolidate the achievements of malaria elimination in Jiangsu Province.

Seroepidemiological survey of Toxoplasma gondii infections in patients with diabetes mellitus in Hangzhou City

XIA Jian⁃Ping, HUANG Jian⁃Feng

2021, 33(4):  414. 

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Objective　To investigate the seroprevalence of Toxoplasma gondii infections among patients with diabetes mellitus in Hangzhou City. Methods　A total of 337 patients with type 1 diabetes mellitus, 624 patients with type 2 diabetes mellitus and 384 patients with gestational diabetes mellitus living in Hangzhou City during the period from March 2017 through May 2020 were recruited as the study subjects, while age⁃ and gender⁃matched healthy volunteers and pregnant women without gestational diabetes mellitus served as controls. Enzyme⁃linked immunosorbent assay (ELISA) was employed to detect serum IgG and IgM antibodies against T. gondii in patients with diabetes mellitus and controls, and the seroprevalence of anti⁃T. gondii antibody was compared between diabetes mellitus patients and controls. Results　The overall seroprevalence of anti⁃T. gondii antibody(18.10% vs. 4.45%, [χ2] = 31.38, P < 0.01) and the seroprevalence of anti⁃T. gondii IgG antibody (14.54% vs. 2.97%, [χ2] = 28.28, P < 0.01) were both significantly higher in patients with type 1 diabetes mellitus than in healthy controls, while no significant difference was seen in the seroprevalence of anti⁃T. gondii IgM antibody between patients and controls (3.56% vs. 1.48%, [χ2] = 2.96, P > 0.05). The seroprevalence rates of serum anti⁃T. gondii (23.56% vs. 6.57%, [χ2] = 70.37, P < 0.01) and anti⁃T. gondii IgG antibodies (21.15% vs. 5.45%, [χ2] = 66.73, P < 0.01) were significantly higher in patients with type 2 diabetes mellitus than in healthy controls, while no significant difference was seen in the seroprevalence of anti⁃T. gondii IgM antibody between patients and controls (2.40% vs. 1.12%, [χ2] = 2.96, P > 0.05). In addition, the overall seroprevalence of serum anti⁃T. gondii antibody(26.30% vs. 19.53%, [χ2] = 4.98, P < 0.05) and the seroprevalence of anti⁃T. gondii IgG antibody (23.70% vs. 17.71%, [χ2] = 4.20, P < 0.05) were both significantly higher in patients with gestational diabetes mellitus than in pregnant women without gestational diabetes mellitus, while no significant difference was seen in the seroprevalence of anti⁃T. gondii IgM antibody between pregnant women with and without gestational diabetes mellitus (2.60% vs. 1.82%, [χ2] = 0.54, P > 0.05). Conclusions　The patients with diabetes mellitus present a higher seroprevalence rate of anti⁃T. gondii antibody than controls in Hangzhou City. Screening of T. gondii infections and health education pertaining to toxoplasmosis prevention and control knowledge should be reinforced in patients with diabetes mellitus.

Evaluation of the effect of the water⁃saving irrigation project on Oncomelania hupensis control in hilly regions of Yixing City, Jiangsu Province 

LIANG Jing, XUE Zhi⁃Qiang, LI Xue⁃Bing

2021, 33(4):  417. 

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Objective　To evaluate the effect of the water⁃saving irrigation project on Oncomelania hupensis snail control in hilly regions of Yixing City, Jiangsu Province. Methods　A retrospective survey combined with cross⁃sectional investigation was employed. The implementation of the water⁃saving irrigation development project in Yixing City from 2005 to 2007 was retrospectively collected, and the snail status was collected in regions where the water⁃saving irrigation project was located and the project⁃affected regions from 2003 to 2018, to examine the effect of the project on snail control. In addition, a cross⁃sectional survey was performed to investigate the destruction of the water⁃saving irrigation project in 2018. Results　A total of 22 water⁃saving irrigation projects were implemented in 5 townships in hilly regions of Yixing City from 2005 to 2007, where snail habitats were treated covering 266.97 hm2. Before the implementation of the project from 2003 to 2006, cumulative 47.87 hm2 snail habitats were detected in regions where the project was located, and no snails were found in regions where the project was located from the implementation of the project in 2006 to 2018. However, a few snails were found in the project⁃affected regions in 2017 and 2018. In addition, there were problems found in the later⁃stage maintenance and management of the project. Conclusions　The water⁃saving irrigation projects shows a high efficiency on snail control in hilly regions of Yixing City. The later⁃stage maintenance of the project and monitoring of snails remain to be intensified to enhance the snail control efficiency of the water⁃saving irrigation project.

Surveillance of schistosomiasis in Xiaogan City from 2016 to 2020

CHENG Bin, WU Jing⁃Yi

2021, 33(4):  420. 

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Objective　To analyze the surveillance data of schistosomiasis in Xiaogan City, Hubei Province from 2016 to 2020, so as to provide the scientific evidence for understanding the epidemiological changes of schistosomiasis and evaluating the schistosomiasis control strategy. Methods　A total of 16 surveillance sites were selected in the schistosomiasis endemic foci of Xiaogan City from 2016 to 2020, where Schistosoma japonicum infections in humans, livestock and Oncomelania snails and the schistosomiasis transmission risk were monitored. The schistosomiasis surveillance results were descriptively analyzed. Results　During the period from 2016 to 2020, there was no schistosomiasis emergency epidemic in Xiaogan City. A total of 660 sero⁃positive individuals were identified in Xiaogan City during the 5⁃year period, and the seroprevalence of S. japonicum infections reduced from 2.08% in 2016 to 0.97% in 2020. Higher seroprevalence of S. japonicum infections was detected in men than in women, and in individuals at ages of over 60 years than in those at other age groups; however, no egg⁃positives were detected in humans or livestock. The mean density of living snails was 0.05 to 0.06 snails/0.1 m2 during the 5⁃year period, and the occurrence of frames with snails increased from 2.99% in 2016 to 3.92% in 2020; however, no S. japonicum infection was found in snails. Conclusions　The endemic situation of schistosomiasis remarkably decreases in Xiaogan City during the period from 2016 through 2020. Further improvements of the sensitive and effective schistosomiasis surveillance system are required with an emphasis on the monitoring of the schistosomiasis transmission risk and management of floating populations. 　

Status and control of common food⁃borne parasitic diseases in China: a review

HUANG Ji⁃Lei, WANG Yao, ZHOU Xia

2021, 33(4):  424. 

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Food⁃borne parasitic diseases include meat⁃borne, fish⁃borne, plant⁃borne, water⁃borne, mollusk⁃borne and freshwater crustacean⁃borne parasitic diseases. The review summarizes the current status and control of 6 major food⁃borne parasitic diseases in China, including clonorchiasus, paragonimiasis, Taenia solium taeniasis, toxoplasmosis, trichinellosis and angiostrongyliasis, aiming to increase the understanding of food⁃borne parasitic diseases and provide insights into the development of the control strategy for food⁃borne parasitic diseases. The transmission of food⁃borne parasitic diseases are predominantly associated with diet, and neither eating raw nor semi⁃cooked food is the most effective measure to prevent the development of food⁃borne parasitic diseases.

Progress of researches on novel diagnostic markers for alveolar echinococcosis

CHEN Rui, WANG Zhi⁃Xin, ZHOU Liu⁃Xin, WANG Kai⁃Qiang, XIE Guo⁃Wei, FAN Hai⁃Ning, WANG Hai⁃Jiu

2021, 33(4):  430. 

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Imaging and serological approaches play an important role in the diagnosis and treatment of alveolar echinococcosis; however, they also suffer from some problems during their applications in clinical practices, which urges the identification of potential diagnostic markers. Novel serological, genomics and proteomics diagnostic markers alone or in combination may increase the sensitivity and specificity in early diagnosis of alveolar echinococcosis, which play vital roles in monitoring of disease courses and prognostic evaluation. This review mainly presents the advances in the studies on novel diagnostic markers for alveolar echinococcosis.

Progress of researches on the role of neutrophil extracellular traps in the immune responses against parasites

LI Wen⁃Lin, XU Zhi⁃Wei, LI Shu⁃Ning, SHEN Hai⁃E, WANG Yang, LI Zhi⁃Min, ZHANG Chen⁃Shuo, XING Yang⁃Guang, SHEN Xin

2021, 33(4):  434. 

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Neutrophil extracellular trap (NET) is a type of bead⁃like, fibrous and reticular substances that is actively released by activated inflammatory neutrophils during the stage of infections or inflammatory responses. NET, which is composed of chromatin DNA and multiple intracellular protein components, may wrap pathogens to limit their diffusions. Meanwhile, NET may kill pathogens via a wide range of antibacterial proteins, which is considered as the third antibacterial mechanism of neutrophils, in addition to phagocytosis and degranulation. Recent studies have shown the involvement of NET in the immune response against parasitic infections. This review summarizes the advances of NETs in the immune responses against parasitic infections, so as to provide insights into the elucidation of the pathogenesis and development of therapeutics of parasitic diseases.

Subcutaneous sparganosis: a case report

WU Deng⁃Yan, TANG Da⁃Jun, ZHANG Ying, HE Bai⁃Lin, WANG Yan, TAN Ran⁃Jing

2021, 33(4):  439. 

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This case report presents the diagnosis and treatment of a case with subcutaneous sparganosis.

A local case with alveolar echinococcosis in Nanzhang County, Hubei Province

WANG Dao⁃Hu, ZHANG Juan, WU Kai

2021, 33(4):  442. 

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The diagnosis and treatment of a local case with alveolar echinococcosis was presented. Based on clinical data and epidemiological surveys, this is a rare, local case with alveolar echinococcosis in Nanzhang County, suggesting the possibility of local transmission of echinococcosis. The prevention, control and surveillance of echinococcosis requires to be reinforced in non⁃endemic areas.