Table of Content

30 August 2020, Volume 38 Issue 4

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ORIGINAL ARTICLES

Effect of PD-1 blockade on immune responses in mice infected with Plasmodium berghei

WANG Zuo-ling, PAN Yan-yan, SUN Xiao-dan, CAO Ya-ming

2020, 38(4):  405-411.  doi:10.12140/j.issn.1000-7423.2020.04.001

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Objective To investigate the effect of programmed cell death-1(PD-1) blockade on immune responses to the infection of Plasmodium berghei ANKA (PbA) in mice.Methods BALB/c mice were divided by random number table method into 3 groups: the healthy group, infection group and PD-1 group, 8 mice each. Mice in the infection group and PD-1 group were injected intraperitoneally with 1 × 10⁶ PbA-infected red blood cells, while those in the healthy group did not receive any treatment. On the day of infection and on days 3, 5, and 7 after infection, mice in the PD-1 group were injected intraperitoneally with 200 μg of PD-1 monoclonal antibody, while the infection group was injected with equal dose of PD-1 homotype control monoclonal antibody. The erythrocyte infection rate and mice survival rate were monitored every other day from day 4 after infection. On day 5 after infection, 4 mice in each group were sacrificed. Spleen tissues were collected to prepare spleen cell suspensions. Myeloid dendritic cells (mDCs) and the expression of PD-1 ligand (PD-L1) in spleen cells, as well as the percentages and absolute numbers of bone marrow-derived inhibitory cells (myeloid-derived suppressor cells, MDSCs) and Th1 cells were detected by flow cytometry. IFN-γ, IL-6 and IL-10 levels in spleen cell culture supernatant were determined by ELISA.Results In the infection group, Plasmodium-infected red blood cells began to appear in peripheral blood 5-6 days after infection, and then the infection rate of red blood cells increased rapidly, reaching about 40% on day 16 after infection, but there was no difference between the PD-1 group and the infection group. In the infection group, deaths occurred from day 15 after infection and all died by day 23 after infection. In the PD-1 group, deaths occurred from day 13 and all died by day 18. Flow cytometry showed that the percentage of CD11c⁺CD11b⁺ mDCs in PD-1 group was (2.21 ± 0.10)%, which was significantly lower than that in the infection group [(4.51 ± 0.21)%, P < 0.05]; the percentage of CD4⁺T-bet⁺IFN-γ⁺ Th1 cells [(3.38 ± 0.54)%] was also lower than that in the infection group [(5.85 ± 0.42)%, P < 0.05]. The expression of PD-L1 on mDCs was higher in PD-1 group [(55.6 ± 6.35)%] than that in the infection group [(21.35 ± 4.45)%, P < 0.05]. The percentage of Gr-1⁺CD11b⁺ MDSCs in the PD-1 group [(9.03 ± 0.62)%] was higher than that in the infection group [(3.58 ± 0.16%), P < 0.05]. The levels of IFN-γ, IL-6 and IL-10 in the infection group were (901.69 ± 73.37) pg/ml, (200.94 ± 4.97) pg/ml and (551.95 ± 121.71) pg/ml, respectively, while those in the PD-1 group were (231.17 ± 57.69) pg/ml, (86.1 ± 3.93) pg/ml and (101.72 ± 20.73) pg/ml, respectively.Conclusion PD-1 blockade weakened the protective immune response to PbA infection in mice.

Establishment of BALB/c mouse model of Echinococcus granulosus-induced sensitization and changes of related immune cells

YU Xiao-dong, YALI Ya-sen, WANG Jia-ling, LI Meng, YE Jian-rong

2020, 38(4):  412-416.  doi:10.12140/j.issn.1000-7423.2020.04.002

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Objective To establish a BALB/c mouse model of Echinococcus granulosus-induced sensitization, and explore the changes of related immune cells.Methods Eighteen BALB/c mice were divided into 3 groups (6 mice each): sensitized group, non-sensitized group and control group. Microcapsules of incubated E. granulosus of sheep source were injected intraperitoneally in mice of the sensitized and non-sensitized groups (50 microcapsules/mouse) to establish the mouse model of E. granulosus infection. The control group received the same volume of normal saline. Six months after infection, mice in the sensitized group was sensitized by intraperitoneal injection of hydatid cyst fluid, while the non-sensitized group and the control group were injected with the same volume of normal saline. After sensitization, the symptoms were scored and anal temperature was measured every 5 min. One hour after sensitization, venous blood of the inner canthus was collected, and the spleen was collected to prepare. Single cell suspension. Flow cytometry was performed to evaluate changes of dendritic cells (DCs), regulatory T cells (Tregs), helper T cells 17 (Th17), interleukin-10 (IL-10), transforming growth factor-β1 (TGF-β1), and IL-17A. Data plotting and analysis were made with the Graphad Prism 7.0 software.Results Results of flow cytometry showed that the percentages of DCs in the control, non-sensitized and sensitized groups were (3.2 ± 0.5)%, (0.2 ± 0.1)% and (1.5 ± 0.2)%, respectively, with that in the sensitized group significantly lower than that in the control group (P < 0.01), but higher than that in the non-sensitized group (P < 0.01). The percentages of Treg cells in the control, non-sensitized and sensitized groups were(5.7 ± 2.1)%, (15.9 ± 3.4)% and (7.4 ± 2.6)%, respectively, with that in the sensitized group significantly lower than that in the non-sensitized group (P < 0.05). The percentages of Th17 cells in the control, non-sensitized and sensitized groups were(4.5 ± 0.6)%, (2.8 ± 0.1)% and(8.6 ± 1.6)%, respectively, with that in the sensitized group significantly higher than that in the control and the non-sensitized groups (P < 0.01). The IL-10 concentration in the control, non-sensitized, and sensitized groups were (116.9 ± 15.6) pg/ml, (1 261.2 ± 208.3) pg/ml, and (386.7 ± 126.5) pg/ml, respectively, with that in the sensitized group significantly higher than that in the control group but lower than that in the non-sensitized group (P < 0.05). The TGF-β1 concentration in the control, non-sensitized, and sensitized groups were (36.0 ± 10.2) pg/ml, (225.9 ± 64.3) pg/ml, and (91.7 ± 15.9) pg/ml, respectively, with that in the sensitized group significantly higher than that in the control group but lower than that in the non-sensitized group (P < 0.05). The IL-17A concentration in the control, non-sensitized, and sensitized groups were (57.3 ± 14.1) pg/ml, (15.1 ± 1.6) pg/ml and (168.6 ± 50.6) pg/ml, respectively, with that in the sensitized group significantly higher than that in the control group and the non-sensitized group (P < 0.01).Conclusion The number of Treg cells was increased after E. granulosus infection in BALB/c mice model, enhancing the secretion of IL-10 and TGF-β1, while the numbers of DC and Th17 cells were decreased, which inhibited the production of IL-17A, leading to the allergic reaction.

Sentinel-1A radar remote sensing-based modeling for quick identification of potential risk areas of schistosomiasis transmission after flood

XIA Shang, XUE Jing-bo, GAO Feng-hua, LV Shan, XU Jing, ZHANG Shi-qing, LI Shi-zhu

2020, 38(4):  417-422.  doi:10.12140/j.issn.1000-7423.2020.04.003

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Objective To use the image data of radar remote sensing for extracting water body information to perform rapid and effective identification of schistosomiasis transmission risk areas due to spreading of snails resulted from flooding.Methods Binary map-sets of Sentinel-1A satellite synthetic aperture radar （SAR） image data for Dangtu County of Anhui Province on May 15, 2020 before the flood and on July 16 at flooding peak period, were collected. A bipolar threshold segmentation method was used to estimate the area covered by flood. The data of snail survey in Anhui Province in 2016 were collected to generate a snail spacial distribution database of Dangtu County. The areas with 75% and 25% snail distribution were randomly selected as the training and verifying map-sets. The threshold discrimination method of normalized vegetation index was applied to extract eco-environmental characteristics of snail habitats and to identify schistosomiasis transmission risk areas after a flood.Results Of Dangtu County, the water body surface area before flood was about 228.07 km², and 259.26 km² in the flood peak period, showing an area expansion of about 13.6%. Based on the identified potential spreading areas of snail habitants after flooding were mainly distributed in where adjacent to the previously recorded snail-infested areas including Jiangxin township, Huyang in the west bank of Shijiu Lake, Dalong, Tangnan and Wuxi townships, as well as in the inland fields connecting rivers. The contrast of the snail actual distribution on the verification map-set with the model analysis indicated an accuracy rate of 82%.Conclusion It is feasible to identify schistosomiasis transmission risk areas after flooding using Sentinel-1A satellite SAR image data for extraction of water body information. There is a risk of spread of snail breeding in flooded areas, thus, it is imperative to strengthen surveillance and control that relevant to the target areas.

Evaluation of the efficacy of loop-mediated isothermal amplification in detecting Plasmodium falciparum and other species of Plasmodium

ZHOU Shui-mao, TU Zu-wu, YANG Yan, CHEN Fang, JIA Xi-shuai

2020, 38(4):  423-428.  doi:10.12140/j.issn.1000-7423.2020.04.004

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Objective To detect the DNA of malaria parasites using the loop-mediated isothermal amplification (LAMP) method and evaluate the efficacy of this method.Methods Blood samples on filter papers were collected from confirmed malaria patients returning from endemic areas of other countries during 2013-2018. According to the 18S rRNA sequences of malaria parasites, LAMP primers for Plasmodium falciparum and other species of Plasmodium were designed using the Primer Explorer V5 software. The LAMP method for detecting malaria parasites was established and its sensitivity, specificity, detection limit and amplification efficiency were assessed and compared with the nested-PCR. The effect of calcein indicator on LAMP reaction was tested.Results The LAMP and nested-PCR were performed separately on 96 blood samples, including 47 with P. falciparum and 49 with other species of Plasmodium. Either method found 93 samples as malaria-positive. The LAMP method produced positive results for all the 47 blood samples with P. falciparum, while having a false negative rate of 2.1% among the samples with other Plasmodium spp.. The LAMP method provided negative results for 10 samples with Leishmania, 8 with Schistosomiasis japonicum, and 38 blood samples from healthy participants, highly consistent with the results of nested-PCR (Kappa value, 0.956). The sensitivity of LAMP for P. falciparum, P. vivax, P. ovale and P. malariae was 25, 3, 4, and 2 parasites/μl blood, respectively. Amplification efficiency test showed that the turbity time (Tt) and peak value of rate (Df) of LAMP for the four malaria species were less than 60 min and above 0.14, respectively, of them the amplification efficacy was particularly high for P. falciparum (Tt, 20.4 min; Df, 0.16). In visualized LAMP assay for the four malaria species, using calcein indicator delayed LAMP reaction Tt about 8-22 min, and lower the Df by about 21%-35%.Conclusion The LAMP method is highly sensitive, specific, of low detection limit and has potentials for application on-site in the field and in primary medical settings.

Epidemiological analysis of malaria in Hubei Province from 2015 to 2018

XIA Jing, ZHANG Hua-xun, LIU Si, WU Dong-ni, ZHANG Juan, LIN Wen, SUN Ling-cong, WAN Lun, CAO Mu-min, ZHU Hong

2020, 38(4):  429-435.  doi:10.12140/j.issn.1000-7423.2020.04.005

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Objective To understand the epidemiological characteristics of malaria in Hubei Province from 2015 to 2018, providing basis for adjusting strategies in malaria elimination.Methods Information of malaria cases reported from Hubei Province during 2015-2018 was collected through the Disease Reporting Information System of Chinese Center for Disease Control and Prevention, and the epidemiological characteristics were analyzed using descriptive epidemiological method.Results A total of 494 malaria cases were reported in Hubei Province during 2015-2018, all of them were imported from abroad. There were 120, 151, 96 and 127 malaria cases reported from 2013 to 2018, respectively. All cases were diagnosed by laboratory examination. Of them, 337 were infected with Plasmodium falciparum (68.2%), 65 with P. vivax (13.2%), 75 with P. ovale (15.2%), 14 with P. malariae (2.8%) and 3 with mixed infection (0.6%). The cases were mainly distributed in Wuhan (34.0%, 168/494), Yichang (15.2%, 75/494), Huanggang (7.9%, 39/494), Huangshi (7.1%, 35/494), Xiangyang (6.3%, 31/494) and Shiyan cities (5.7%, 28/494). The peak of disease onset occurred in January to February (26.1%, 129/494) and in May to July (27.7%, 137/494). The disease mainly occurred in age groups of 20-49 years (85.2%, 421/494). The 494 malaria cases comprised 473 males and 21 females, with a male-to-female ratio of 22.5 ∶ 1. Primary diagnosis was mainly made in medical institutions at county-level and higher (324, 65.6%), and 345 (69.8%) cases were confirmed of diagnosis with malaria upon visit first to doctor. Significant difference in the corrective rate of malaria diagnosis was found between different medical units making primary diagnosis (P < 0.05). In addition, 44.3% (219/494) of the cases were diagnosed as malaria on the day visiting doctor; they comprised cases infected by P. falciparum (49.3%, 166/337), P. vivax (41.5%, 27/65), P. ovale (32.0%, 24/75), and P. malariae (1/14), and those with mixed infection (1/3). There was a significant difference in the time from seeing a doctor to definitive diagnosis being made among different types of malaria (P < 0.05). A higher proportion (57.7%, 285/494) of the cases were diagnosed in medical institutions at the county level or higher. In addition, 94.1% (465/494) cases were imported from 30 African countries, with the leading number being Congo-Kinshasa (69, 14.0%) and Nigeria (61, 12.3%).Conclusion During 2015-2018, malaria cases in Hubei Province were all imported cases. Of them, 94.1% were imported from Africa, and 44.3% were diagnosed on the day seeking medical care.

Analysis of imported malaria in Tengchong City, Yunnan Province during 2016-2019

WANG Jia-zhi, FENG Jun, LI Xi-shang, LI Sheng-guo, WANG Xing-juan, YANG Dong-hai, YIN Shou-qin

2020, 38(4):  435-439.  doi:10.12140/j.issn.1000-7423.2020.04.006

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Objective To analyze the epidemiological status of imported malaria in Tengchong City, Yunnan Province during 2016-2019 and provide reference for surveillance of imported malaria after malaria elimination.Methods Information on malaria endemic status, investigation and management of epidemic foci, and case treatment in Tengchong City during 2016-2019 was collected and analyzed by Microsoft Excel 2010.Results A total of 123 malaria cases were reported in Tengchong City during 2016-2019, including 55, 28, 18 and 22 on each year, and all were imported cases, among them most were vivax malaria (95.93%, 118/123), with a small portion of falciparum malaria (4.07%, 5/123). In 2019, no imported falciparum malaria case was reported for the first time. Imported malaria cases were reported in every month, with the highest number of cases reported in May and June, accounting for 40.65% (50/123) of the total. The reported cases comprised 104 males and 19 females, with a male-to-female ratio of 5.47 ∶ 1; the youngest case were at the age 3, while the eldest at age 63, with the most cases occurred in the age group of 31-40 years (39.02%, 48/123). The occupation distribution showed that farmers and migrant workers were in the majority (91.87%, 113/123). The infection source mostly came from Myanmar (86.18%, 106/123), followed by Laos (10.57%, 13/123). The confirmation rate of laboratory diagnosis was 100% (123/123); the definite diagnosis was made in county disease prevention and control institutions (44.71%, 55/123) and county medical institutions (39.84%, 49/123). The median time from onset to diagnosis was 5 days, with the longest time spent being 23 days. Verified by provincial Institute of Parasitic Diseases Prevention and Control, the coincidence rate of diagnosis results with those made by township clinics, county medical settings, and county institute of disease prevention and control were 86.36%, 90.74%, and 98.21%, respectively. The 24 h epidemic reporting rate was 100%, the epidemiological tracing of cases within 3 days was completed by 100% (123/123), and the epidemic site management rate within 7 days was 100% (117/117).Conclusion The imported malaria cases in Tengchong City, Yunnan Province showed a trend of decrease in recent years. The key to control and prevention of imported malaria after malaria elimination includes enhancing the capability in diagnosis and treatment, standardizing the management of infection source, improving the surveillance system for cases and mosquito vectors, and strengthening health education for out-going migrant workers.

Surveillance on soil-transmitted nematode infections in 2018 in Ningxia, China

DUAN Hong-ju, WU Xiang-lin, FU Yi-ren, LI Hai-jun, MA Rong, MA Tian-bo, QI Rong-ting

2020, 38(4):  440-444.  doi:10.12140/j.issn.1000-7423.2020.04.007

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Objective To understand the infection status of human soil-transmitted nematodes in Ningxia, and to provide scientific evidence for prevention and control.Methods The survey was conducted according to the National Surveillance Program and Implementation Guideline for Chlonorchiasis and Soil-transmitted Healminthiasis. A total of 50 surveillance sites were selected from 10 counties (Helan, Haiyuan, Pingluo, Yanchi, Tongxin, Qingtongxia, Jingyuan, Huinong, Hong sibu and Dawukou) using the stratified cluster random sampling method, each site having no less than 200 permanent residents aged above 3 years. Fecal samples were collected from the residents, in which eggs of soil-transmitted nematodes were examinted with the modified Kato-Katz thick smear method. Cellophane anal swab method was used to detect Enterobius vermicularis eggs in children aged 3-9 years. In each survey site, 5 households were randomly selected to collect 30 g of soil sample from around toilet or vegetable gardens. The Ascaris lumbricoides eggs in the soil samples were detected and counted using the saturated sodium nitrate solution floatation method. The correlation between the egg positive rate of A. lumbricoides eggs in soil and the infection rate of A. lumbricoides in population was analyzed by Spearman correlation method.Results Examination for a total of 11 035 people found an overall soil-transmitted nematode infection rate of 1.0% (110/11 350), predominated by A. lumbricoides. The infection rates of A. lumbricoedes and E. vermicularis was 0.8% (95/11 350) and 0.1% (16/11 350), respectively. The infection rate of soil-transmitted nematodes was highest in Pingluo County (3.0%, 32/1 053), and there was statistically significant difference among the survey sites (P < 0.05). The infection rates of soil-transmitted nematode in males and females were 1.0% (55/5 641) and 1.0% (55/5 709), with no significant difference between them (P> 0.05). The infection occurred in all age groups, with the highest infection rate in the age group over 70 years old (2.5%, 18/708). The infection rate in ethnic minority (0.6%, 32/5 092) was lower than that in Han ethnicity (1.3%, 78/6 258) (P < 0.05). Among different occupation groups, farmers had the highest infection rate (1.5%, 99/6 585). The education distribution showed that illiterate or semi-illiterate residents had the highest infection rate (2.2%, 19/850). Notably, There were statistically significant difference in the infection rate among different age groups, ethnicities, occupations and education background (P < 0.05). A total of 275 soil samples were examined, and the result indicated an egg positive rate of A. lumbricoedes eggs of 11.6% (32/275). The A. lumbricoedes egg positive rate in soil samples was positively correlated with the infection rate of A. lumbricoedes in residents.Conclusion The infection rate of soil-transmitted nematode in rural residents of Ningxia is low, and shows an obvious regional difference, with A. lumbricoedes as the main nematode species. The elder, farmers, illiterate or semi-illiterate, and Han ethnic group are the underlined target population for control.

Differential diagnosis of a case of Babesia microti infection previously misdiagnosed as malaria

ZHANG Yan, XU Ai-fang, ZHANG Jia-qi, YAO Li-nong, GU Kai-long, XUE Li-zhi, PAN Ke-nv

2020, 38(4):  445-448.  doi:10.12140/j.issn.1000-7423.2020.04.008

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Objective To perform differential diagnosis of a case of Babesia microti infection earlier misdiagnosed as malaria, and analyze the clinical treatment.Methods Clinical and epidemiological information of the case was collected. Blood sample was collected and examined by microscopy with. Giemsa-stained thick and thin blood smears for observing Babesia morphologically. Peripheral blood sample was also underwent rapid immunological assay for malaria parasite. DNA was extracted from the patient’s blood sample and PCR amplification was performed with genus and species-specific primers of Babesia 18S rRNA gene, and specific primers of Plasmodium falciparum small subunit ribosomal ribonucleic acid (SSU rRNA) gene.Results The patient had recurrent fever for more than 2 months since February 2019, and his blood routine examinations showed progressive decrease of white blood cells, red blood cells, and platelets, with moderate anemia and splenomegaly. Epidemiological investigation showed that the patient had no history of travel out of town. A large number of P. falciparum-like parasites were seen in the thick and thin blood smears of the patient, and and malaria rapid diagnostic assay presented negative result. Using B. microti-specific primers, PCR amplification indicates genus and species-specific positive bands of 400 bp and 1 600 bp length, respectively.Conclusion Combining the clinical information, epidemiological history, etiology and PCR analysis data, the case was diagnosed as B. microti infection.

Investigation of Fasciola spp. infection in Galba pervia and buffaloes in Guangxi

LIANG An-li, NONG Zhen-ni, LU Xiu-hong, SHI Yun-liang, ZHANG Wei-yu

2020, 38(4):  449-453.  doi:10.12140/j.issn.1000-7423.2020.04.009

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Objective To investigate the status of Fasciola spp. infection in the intermediate host Galba pervia and the definitive host buffaloes.Methods From April to October 2018, Galba pervia snails and buffalo feces were collected in six counties(cities) of Guangxi Province, including Hengxian County, Binyang County, Long’an County, Du’an County, Dahua County and Laibin County. The snails underwent compressed smear microscopy to observe worm larvae, and the fecal samples were examined using washing-sedimentation method for eggs. The DNA extracted from the larvae and eggs of Fasciola were processed for ITS2(internal transcribed spacer 2, ITS2) amplification and identification.Results A total of 1 523 snails were collected, showing an average Fasciola infection rate of 0.3% (5/1 523). Fasciola infection was found in the snail samples from four counties of Hengxian, Binyang, Long’an, and Laibin, but not from the Du’an and Dahua counties. A total of 128 buffalo fecal samples were collected, displaying an average Fasciola infection rate of 79.7% (102/128). The buffaloes from all six counties were found Fasciola egg positive in feces, with the Laibin County having the highest infection rate(88.2%, 15/17), and Du’an County the lowest rate (64.0%, 16/25). The sequence length of ITS2 amplification products was about 500 bp. The ITS2 amplification product from larvae in the snails had sequence homology of 98.8%-99.0% to that of F. gigantica (GenBank accession no. KF667375.1); the amplified sequence from fecal eggs of water buffaloes showed 98.4%-99.4% similarity to that of F. gigantica (GenBank accession no. KF667375.1).Conclusion The survey indicates that F. gigantica infections were found in snail Galba pervia and buffaloes in Guangxi, suggesting potential risk of human infection, thus, it is imperative to strengthen prevention and control measures.

Analysis of deltamethrin resistance-related genes based on the transcriptome of Culex pipiens quinquefasciatus

SHEN Rui-xin, WANG Yi-ting, LI Chun-xiao, WU Jia-hong, ZHAO Tong-yan, CHEN Yan

2020, 38(4):  453-463.  doi:10.12140/j.issn.1000-7423.2020.04.010

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Objective To screen for differentially-expressed genes related to deltamethrin resistance by transcriptome analysis of deltamethrin-susceptible and -resistant strains of Culex pipiens quinquefasciatus.Methods Bioassays were performed on deltamethrin-susceptible (SS) strain, Hainan (HN) strain, and deltamethrin-resistant (RR) strain of Cx. pipiens quinquefasciatus. cDNA libraries of each strain were constructed for transcript sequencing. The differentially-expressed genes obtained by differential analysis base on the FPKM value (number of fragments per kilobase of transcript sequence per millions base pairs sequenced) were subjected to GO enrichment analysis and KEGG (kyoto encyclopedia of genes and genomes) functional annotation and enrichment analysis. Genes with significant differences in expression level were screened out and verified by real-time quantitative PCR.Results The resistance levels of the HN and RR strains were 4 828 and 197 241 folds of the SS strain, respectively, both showing high resistance to deltamethrin. A total of 197 079 transcripts were annotated among the transcriptomes of the three Cx. pipiens quinquefasciatus strains. The results of GO enrichment analysis showed enrichment of genes in terms of binding, catalytic activity, cellular process, metabolic process, single organism process, cellular process, metabolic process, cell, cell junction, and organelle. The results of KEGG enrichment analysis showed that among the top 20 items, the RR strain showed enrichment of genes in terms of spliceosome and ribosome pathways, while the HN strain showed significant enrichment of genes in spliceosome, RNA transport, hedgehog signaling pathway, cell cycle, nucleotide excision repair, and DNA replication.Results of differential analysis based on FPKM value showed that there were 5 357 up-regulated and 10 978 down-regulated genes in both the RR and HN strains, compared to the SS strain. The targeting screening for genes related the genes with differential expression in RR and HN strains including cytochrome P450 (P450), glutathione transferase (GST), odorant binding protein (OBP), odorant receptor (OR), opsin gene, ribosomal protein gene, and carbonic anhydrase, in comparison with the SS strain. The annotated transcriptomes of these differential genes in RR and HN strains were found having 100, 17, 13, 4, 16, 191 and 1 up-regulated transcripts, and 253, 48, 43, 4, 15, 504 and 9 down-regulated transcripts, respectively, compared to the SS strain. To verify, twelve up-regulated genes were selected for real-time quantitative PCR, including 2 P450 genes, 1 GST gene, 1 opsin gene, 1 ribosomal protein gene, 1 carbonic anhydrase (CA) gene, 1 nucleic acid endonuclease gene, 2 OBP genes and 3 OR genes. The results showed that in RR and HN strain, the 12 genes were all significantly up-regulated compared to the SS strain, among them the expressions of those in the RR strain were up-regulated by 1.62-80.26 folds, and those in the HN strain up-regulated by 2.01-189.48 folds. The correlation analysis on the 12 targeting genes showed a positive correlation between the results of RNA-seq and the results of real-time quantitative PCR for NH and RR strain, with a correlation coefficient r of 0.802 and 0.710, respectively. It demonstrates that for the 12 genes, the results of real-time quantitative PCR were consistent with the transcriptome sequencing data.Conclusion Based on the high-throughput sequencing results and quantitative PCR verification analysis, some genes including cytochrome P450 genes, glutathione S-transferase genes, visual genes, and olfactory protein genes in Cx. pipiens quinquefasciatus may play certain roles in the deltamethrin resistance.

EXPERT VIEWPOINT

Consideration and recommendations for malaria blood testing during the COVID-19 pandemic

LI Mei, XIA Zhi-gui, YIN Jian-hai, YAN He

2020, 38(4):  464-468.  doi:10.12140/j.issn.1000-7423.2020.04.011

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With the ongoing global spread of coronavirus disease 2019 (COVID-19) epidemic, there is a risk of co-occurrence of malaria and COVID-19 in people returning from malaria-endemic areas abroad. In order to conduct timely, accurate and safe detection of malaria cases, ensuring early finding, diagnosis and treatment of imported malaria, we propose that facing the current pandemic situation, higher level of biosafety protective practice is needed for handling malaria blood samples with potential risk, use of rapid diagnostic test and nuclear acid detection method is the first choice, confirmation of Plasmodium species should be made based on consistency between at least two detection methods, and blood smears should be prepared with special procedures when necessary.

TEACHING RESEARCH

Exploration and practice of micro-video-based“flipped classroom”in laboratory teaching of human parasitology

MA Shu-lan, FENG Meng, CAI Jun-long, FU Yong-feng, MAO Zuo-hua, CHENG Xun-jia

2020, 38(4):  469-472.  doi:10.12140/j.issn.1000-7423.2020.04.012

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In the teaching of laboratory experiment course of human parasitology, we established an online course platform via internet, integrated important knowledge points of the laboratory lessons, produced a total of 23 micro videos on specimen preparation and operational procedures, and uploaded the contents to the platform as online teaching course for students to preview beforehand. Multidimensional evaluation was conducted through the whole teaching course, combining with questionnaire feedback to complehensively appraise the outcome of the reform of teaching course. As the result of applying the micro-video-based “flipped classroom” teaching tactic, the students majoring in preventive medicine and basic medicine remarkably improved their laboratory exam scores, compared with the traditional teaching method. Further analysis on the performance of the students with lower scores in laboratory exam showed that the time of viewing the videos of specimen preparation and the operational demonstration is found to be significantly correlated with the score of online test (P < 0.01). Questionnaire analysis indicates that most students thought of micro-videos being helpful to offline classroom study on specimen study (262/264, 99.24%) and practical operations (264/264, 100%); 81.20%（217/264） students liked the “flipped classroom” study mode; and 95.69% students regarded it acceptable the time they spent for micro-video study occupying their spare time. The micro-video-based flipped classroom can enhance students’ academic performance and practical skills, and welcomed by students too. However, for those students who have the ability to learn more, the enhancements were not significant. This suggests that further analysis on the reason of weak points is needed to perfect the reform with flipped classroom teaching, and bring benefit to more students.

INFORMATION EXCHANGE

Analysis of publication time delay of Chinese Journal of Parasitology and Parasitic Diseases in 2008-2018

YI Feng-yun, ZHANG Zheng-yan, CHEN Qin, YANG Fan, SHENG Hui-feng

2020, 38(4):  473-476.  doi:10.12140/j.issn.1000-7423.2020.04.013

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To analyze the publication time delay of Chinese Journal of Parasitology and Parasitic Diseases from 2008 to 2018 using bibliometrics method, based on measuring, the time from acceptance to publishing of all papers in 66 volumes of the journal over the past 11 years. The results showed that 3 044 manuscripts were received during this period, of which 1 470 were published, and 1 574 were rejected, with a rejection rate of 51.7%. Of the 1 479 published papers, 41 (2.8%) had a publication time delay of ≤ 90 d, 36 (2.4%) had a delay of ≥ 380 d, and 685 (46.6%) papers had a publication delay in the range of 181-280 d. The overall average publication delay was 218.0 d. Original articles, reviews and short reports had a delay of 205.9 d, 209.3 d and 238.8 d, respectively. After the initiation of the “Priority Digital Publishing” service in cooperation with China National Knowledge Infrastructure, the online publication delay in 2017 and 2018 was shortened by 28 d and 26.9 d, respectively, as compared to the time of print publications. The original articles had shortest average publication delay among other types article, and the use of the online submission system further shortened the publication time delay.

REVIEWS

Advances in research on the roles of natural killer T cells in immune responses to parasitic infections

LIU Yi, CAI Yu-chun, CHEN Shao-hong, CHEN Jia-xu

2020, 38(4):  477-481.  doi:10.12140/j.issn.1000-7423.2020.04.014

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Natural killer T(NKT) cells are a type of innate immune cells that express both T cell and NK cell surface markers. The cytokines secreted by NKT cells upon activation possess some properties that affect the adaptive immunity, thus bridging innate and adaptive immunity and playing important roles in anti-infection processes, tumor immunity and autoimmune diseases. NKT cells also play an important role in bridging innate and adaptive immunity during immune responses to parasitic infections. However, little research has been conducted in this field. In this article, the roles of NKT cells in immune responses to Leishmania, Plasmodium, Trypanosoma and Schistosoma infections are reviewed.

The prevalence and impacting factors of Echinococcus infection in canine in Qinghai-Tibet plateau

CUI Xiao-yu, GUAN Ya-yi, WU Wei-ping

2020, 38(4):  482-489.  doi:10.12140/j.issn.1000-7423.2020.04.015

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Echinococcosis is a zoonotic disease caused by the larvae of the genus Echinococcus, which is widely prevalent in Qinghai-Tibet plateau of China. Canine is the major infection source of human echinococcosis, and canine infection with Echinococcus spp. has become a heavy burden in Qinghai-Tibet plateau. In this paper, we review the prevalence and impacting factors of canine infection with Echinococcus spp. in Qinghai-Tibet plateau.

Advances in methods for detecting drug-resistance molecular markers of Plasmodium falciparum

YE Sheng-yu, CHENG Yi-yi, LI Man, ZHOU Hong-ning

2020, 38(4):  490-495.  doi:10.12140/j.issn.1000-7423.2020.04.016

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Malaria is a major tropical disease prevalent in Africa and Southeast Asia, which seriously threatens the health of local residents. The emergence and spread of Plasmodium falciparum resistance to anti-malaria drugs has challenged the realization of global malaria elimination goal. Current monitoring methods for P. falciparum drug resistance mainly include in vivo pharmacodynamic test, in vitro drug sensitivity test, and method of molecular markers of drug-resistance, of which the detection of molecular markers is widely used. This paper reviews research progress in the detection method using molecular markers for drug-resistance of P. falciparum resistance.

Research progress on the anti-tumor effects of Toxoplasma gondii and the underlying mechanisms

ZHANG Fu-qiang, QIAO Jiao-jiao, LI Hao-ran, ZHANG Zhen-chao, LI Xiang-rui, WANG Shuai

2020, 38(4):  496-502.  doi:10.12140/j.issn.1000-7423.2020.04.017

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Toxoplasma gondii is an important opportunistic pathogenic protozoan and is a big threat to human health. However, studies have revealed significant anti-tumor effects of the T. gondii parasite, as well as its culture supernatant or excretory secretory antigen, antigen lysate, and secreted proteins. In the mechanism of the anti-tumor effects, the induction of tumor cell apoptosis, inhibition of tumor tissue neovascularization and enhancement of the function of host immune cells play crucial roles. In this review, we summarize research progress on the anti-tumor effects of T. gondii and the mechanisms in association with the parasite and its related components.

Research advances on factors affecting distribution characteristics of different hosts of Echinococcus spp.

WEI Si-hui, WU Wei-ping

2020, 38(4):  502-507.  doi:10.12140/j.issn.1000-7423.2020.04.018

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Echinococcosis is a parasitic zoonosis caused by hydatid cyst infection, which seriously affects human physical and mental health. The distributions of the definitive and intermediate hosts of Echinococcus spp. is highly related to social, biological and environmental factors. Therefore, it is of great significance in public health to study the factors affecting the distributions of definitive and intermediate hosts of Echinococcus spp., and thus provide basis for formulating control measures. In this paper, the social, biological and environmental factors affecting the distribution characteristics of definitive and intermediate hosts of Echinococcus spp. are reviewed.

Applications of molecular techniques in classification and identification of Leishmania

LIU Jian-xiu, WANG Jun-yun

2020, 38(4):  508-513.  doi:10.12140/j.issn.1000-7423.2020.04.019

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Leishmania species are complex and diverse, and they cause mainly three types of disease: cutaneous leishmaniasis, metastatic mucocutaneous leishmaniasis, and usually-fatal visceral leishmaniasis. The severity of clinical manifestations depends largely on the type of species of Leishmania. Therefore, correct classification and identification of Leishmania are critical for diagnosis and treatment, and for making efficient control strategies. This review introduces the applications of molecular techniques and molecular markers in identification and classification of Leishmania species.

SHORT COMMUNICATIONS

Application of propensity score matching method in the analysis of knowledge, attitude and practice in health education of schistosomiasis control

ZHANG Yu, LU Ding, PU Chen, CHEN Lin, MAO Yong, XU Liang, LIU Yang

2020, 38(4):  513-517.  doi:10.12140/j.issn.1000-7423.2020.04.020

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To explore application of the propensity score matching (PSM) method in knowledge, attitude and practice(KAP) analysis of health education on schistosomiasis control. Baseline questionnaire survey of the schistosomiasis intervention pilot project behavior change communication (BCC) was performed among villagers aged 16 and above in April 2018 in two villages in Xide County, Liangshan Prefecture, Sichuan province (Taoyuan Village of Hongmo Town served as the intervention village and Luonaige Village of Plums township as the control village). The survey results were analyzed using the PSM method to score the matching of age, gender, educational background and knowledge, attitude and practice of the surveyed villages in the two selected villages. Statistical analysis was performed using SPSS 25.0 software. The composition ratio was compared between the groups by chi-square test, and the scores were analyzed by t-test. Person correlation analysis and linear regression analysis were used to analyze the correlations between knowledge, attitude and practice. A total of 619 valid questionnaires were collected during the baseline survey. There were 319 valid questionnaires in the intervention village, including 202 males and 117 females, with the majority villagers at age 40-59 (145, 45.5%) and in illiteracy (129, 40.4%). There were 300 valid questionnaires in the control village, including 159 males and 141 females, with the majority villagers at age 40-59 (139, 46.3%) and having primary school education (168, 56%). The 120 valid questionnaires selected from the intervention village were successfully matched with 102 subjects from the control village by the PSM method, and the number of subjects was close to that of the control villages. There were significant differences in gender, age and educational background between the intervention and the control villages before matching (P < 0.01); however, these differences became insignificant after matching (P > 0.05). The scores of knowledge, attitudes and practices in the intervention village before matching were 6.5 ± 2.0, 3.4 ± 0.9 and 11.7 ± 0.9, respectively, while those in the control village were 8.1 ± 2.9, 3.2 ± 0.7 and 10.0 ± 2.3, respectively, being statistically significant between the scores of two villages (P < 0.05). After matching, the scores of knowledge, attitude and practice in the intervention village were 7.0 ± 1.5, 3.3 ± 0.9 and 11.3 ± 0.9, respectively, and those in the control village were 7.8 ± 2.4, 3.4 ± 0.7 and 11.4 ± 1.4, respectively. There were no significant differences in scores of attitude and practice between the intervention village and the control village after matching (P > 0.05). Although the difference in knowledge score between the intervention and the control villages after matching remained statistically significant(P < 0.01), the difference in the knowledge scores decreased from 1.6 before matching to 0.8 after matching. Results of Person correlation analysis showed that the three variables knowledge, attitude and practice were all positively correlated(r > 0). Regression analysis showed that knowledge had a positive impact on attitude, and practices, while attitudes also positively impacted practices. The knowledge-attitude-practice path has mediating effects. When active intervention is being conducted in schistosomiasis endemic areas based on the KAP approach, proper statistical methods may be integrated to analyze the control results, and thereby to pertinently formulate intervention strategy.

Retrospective epidemiological analysis of 1 917 cases of hepatic echinococcosis diagnosed by ultrasonography in Qinghai Province, China

HOU Yu-hu, MA Shu-mei, FAN Hai-ning, QIAO Zhi-zhong, YANG Hai-fang, LUO Qiao

2020, 38(4):  518-520.  doi:10.12140/j.issn.1000-7423.2020.04.021

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To analyze the 1 917 cases of hepatic echinococcosis diagnosed by ultrasound in Qinghai Province retrospectively, in order to understand the classification and epidemiological characteristics of the disease, providing basis for prevention and control and for evaluations of control effects. Primary information were collected of the 1 917 cases of hepatic echinococcosis diagnosed by abdominal ultrasound scanning during the period from January 2013 to March 2019 in the Qinghai University Affiliated Hospital. The information collected were analyzed by χ ² test with regard to the infection type, gender, age and ethnicity using SPSS 19.0. Among the 1 917 cases, the cases of cystic, alveolar and mixed was 1 041 (54.3%), 867 (45.2%), and 9 cases (0.5%), respectively, with the difference being statistically significant (P < 0.05). Of the 1 917 cases, 914 (47.7%) were males and 1 003 (52.3%) were females (P > 0.05). The numbers of patients in the age groups of 0-19 years, 20-39 years, 40-59 years and ≥ 60 years were 148 (7.7%), 739(38.6%), 735 (38.3%) and 295 (15.4%), respectively, with significant difference (P < 0.05). The numbers of patients of Tibetan, Han, Hui, Mongolian and other ethnicities were 1 564 (81.6%), 256 (14.9%), 66 (3.4%), 19 (1.0%) and 11 (0.6%), respectively, with statistically significant differences (P < 0.05). Among the total, the number of consolidatory cystic echinococcosis(340, 32.7%) and infiltrative elveolar echinococcosis (442, 51.0%) are the highest. The cystic and elveolar echinococcosis are the main type of hepatic echinococcosis in Qinghai Province.

Clinical features of 65 cases of fascioliasis in Yunnan Province

LI Qin-cui, CHEN Feng, GU Wei, YANG Lei

2020, 38(4):  521-523.  doi:10.12140/j.issn.1000-7423.2020.04.022

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Clinical data of fascioliasis patients recorded in 6 prefectures(cities) in Yunnan Province were collected from November 2011 to November 2018. A total of 65 cases were enrolled, including 28 males and 37 females. The majority of them were farmers (64.6%, 42/65), being Han ethnicity (89.2%, 58/65), and coming from Dali District(72.3%, 47/65). All of the 65 cases had eaten raw vegetables, and 6 of them had drunk unboiled gully water. Eighteen cases involving 5 families had family aggregative phenomenon. All the cases visited hospital for suffering fever and abdominal pain. Blood routine tests showed increased eosinophilia; abdominal color ultrasound scanning or CT (and/or) MRI examination suggested varying degrees of organ lesion particularly in the liver; and fecal sample examination revealed a positive rate of Fasciola eggs of 23.1% (15/65). The test for serum antibody against Fasciola found 58 strongly positive and 7 positive, resulting in a positive rate of 100% (65/65). All of the cases showed obvious improvement in symptoms of fever and abdominal pain after treatment with trichlorobendazole, and blood routine tests showed that eosinophils and liver lesions gradually returned to normal.

Clinical analysis on 21 cases of acute intrabiliary rupture of hepatic Echinococcus granulosus cyst

GAO Yu, WU Xiang-wei, ABU Duwaiti, LIU Gui-sheng

2020, 38(4):  524-527.  doi:10.12140/j.issn.1000-7423.2020.04.023

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To retrospectively analyze the therapeutic effect of partial pericystectomy in 21 cases of acute intrabiliary rupture of hepatic Echinococcus granulosus cyst performed from December 2015 to November 2018 in the First Affiliated Hospital of Shihezi University, Xinjiang Uygur Autonomous Region. The 21 patients included 14 males and 7 females; 18 of primary onset and 3 relapsed. All of the cases were admitted as the cases of acute hydatid cyst rupture, and showed jaundice at admission (14 had persistent progressive jaundice and 7 had intermittent jaundice) accompanied by symptoms of shiver, high fever, peritoneal irritation sign, nausea, and vomiting. In 4 patients, when the cyst ruptured into biliary tract. E. granulosus protoscoleces were found being seeded in the abdominal cavity. The operations spent 2.7 h on average, and the average intraoperative blood loss was 75 ml. Duing the operation, all patients were inserted with T-tube for drainage, 11 patients were concurrently placed with abdominal drainage tube, 3 patients with residual cavity drainage tube, and 3 patients with abdominal drainage tube/residual cavity drainage tube. One patient developed postoperative residual cavity infection, and 3 patients developed postoperative bile leakage. No other related complications occurred. During 1-3 years of follow up, no relapse cases were reported. The partial pericystectomy has good therapeutic effect for intrabiliary rupture of hydatid cyst.