Table of Content

30 December 2021, Volume 39 Issue 6

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INVITED REVIEWS

Research progress on the expression regulation of var genes in Plasmodium falciparum

SHI Ming-li, XIAO Bo, JIANG Lu-bin

2021, 39(6):  719-724.  doi:10.12140/j.issn.1000-7423.2021.06.001

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Malaria is an infectious disease caused by Plasmodium infection. The erythrocyte membrane surface protein 1 (PfEMP1) encoded by the var gene family is the key virulence factor in the pathogenic process of P. falciparum, which is closely related with the antigen variation and cytoadhesion. The expression of var genes is strictly controlled by time and space. Generally, a single Plasmodium parasite expresses only one var gene in the erythrocytic stage, following a mutually exclusive expression strategy. Based upon current researches, we make a comprehensive summary on var gene expression regulation mechanism to improve the understanding of the pathogenesis of malaria.

Research progress on proteomics in Schistosoma japonicum

HONG Yang, LIN Jiao-jiao

2021, 39(6):  725-730.  doi:10.12140/j.issn.1000-7423.2021.06.002

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Protein is the major exhibiter and executer of gene function. In recent years, the proteomics studies of Schistosoma japonicum has attracted the attention of researchers and made some progress. This paper reviews the research progress in proteomics of S. japonicum to provide information of referential value for elaborating the mechanism of schistosome growth and development as well as screening potential diagnostic antigens, vaccine candidate molecules and new therapeutic drug targets.

ORIGINAL ARTICLES

Achieving malaria elimination in China: analysis on implementation and effectiveness of the surveillance-response system

XIA Zhi-gui, FENG Jun, ZHANG Li, FENG Xin-yu, HUANG Fang, YIN Jian-hai, ZHOU Shui-sen, ZHOU Sheng, YANG Heng-lin, WANG Shan-qing, GAO Qi, TANG Lin-hua, YAN Jun

2021, 39(6):  733-740.  doi:10.12140/j.issn.1000-7423.2021.06.003

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Objective To analyze the implementation and effectiveness of surveillance-response system in eliminating malaria in China, and to provide scientific basis for preventing re-establishment of transmission by imported malaria in the post-elimination phase. Methods The national scheme and activities records in malaria elimination program were systematically collected and sorted, and the data of individual malaria cases and indicators in 2011—2020 from web-based National Information System for Infectious Diseases Surveillance and National Information System for Parasitic Diseases Control and Prevention were analyzed using SPSS 25.0 and GraphPad Prism 8.4.3. Results From 2011 to 2020, a total of 30 278 malaria cases were reported nationwide, 93.96% (28 448 cases) of them were Chinese nationality. The total cases included 1 732(5.72%) indigenous cases reported from 2011 to 2016, 28 173(93.05%) imported cases from abroad, 9(0.03%) induced cases, 5(0.02%) long incubation malariae malaria cases, 4 (0.01%) introduced vivax malaria cases, as well as 355 (1.17%) cases with unreported origin from 2011 to 2013. The cases were mainly falciparum malaria cases (17 960 cases, 59.32%) and mainly reported by Yunnan(5 415 cases, 17.88%), Guangxi (3 193 cases, 10.55%), and Jiangsu(2 797 cases, 9.24%) provinces. The cases were reported year-round, with the majority in May and July (9 689 cases, 32.00%). The imported cases were mainly from Myanmar (4 856 cases, 17.24%), Ghana (2 957 cases, 10.50%), and Nigeria (2 693 cases, 9.56%). The positive rates of blood tests for malaria by passive case detection, proactive case detection and reactive case detection were 0.76‰ (28 452/37 500 291), 0.03‰ (35/1 215 309) and 0.30‰ (32/105 384), respectively. From 2013 to 2020, case reporting rate within 1 day after diagnosis was 100% (23 114/23 114), the rate of epidemiological investigation for individual case within 3 days after reporting was 94.49% (21 840/23 114), the rate of foci investigated and disposed within 7 days was 93.30% (20 294/21 751), and the median time from the illness onset to first diagnosis and from first diagnosis to confirmed diagnosis of the patients were both 1 d (IQR: 0~3 d). Anopheles sinensis was widely distributed and commonly resistant to deltamethrin. In vivo efficacy of dihydro-artemisinin-piperaquine against uncomplicated falciparum malaria and chloroquine and primaquine against vivax malaria was 92.31%(36/39) and 100%(21/21), respectively. Conclusion Establishment of the sensitive and effective surveillance-response system is a vital experience for the success of malaria elimination in China. In the post-elimination phase, surveillance-response should continue to be the key measure, and active cooperation between different sectors and capacity building should be strengthened, to prevent re-establishment of transmission and consolidate the accomplishments of elimination.

Antigenicity and immunogenicity analysis of the recombinant merozoite surface protein 1 N-terminal of Plasmodium ovale

YU Jia-li, LIU Lei, YANG Bo, CHU Rui-lin, SUN Yi-fan, LIU Yao-bao, CHENG Yang

2021, 39(6):  746-752.  doi:10.12140/j.issn.1000-7423.2021.06.004

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Objective This study aims to express the merozoite surface protein 1 N-terminal proteins of Plasmodium ovale curtisi and P. ovale wallikeri, and analyze their antigenicity and immunogenicity, revealing the potential for being as vaccine candidates of P. ovale. Methods The N-terminal of the Pomsp1 gene was amplified from the genomic DNA of P. ovale. The purified N-terminal sequences of Pocmsp1 and Powmsp1 were separately connected to the plasmid pET30a and pET32a and then transfected into DH5α competent cells. After verification with BamHⅠ and XhoⅠ enzyme digestion and DNA sequencing, the gene sequences were transferred into Escherichia coli BL21 (DE3) pLysS. After induction with 0.1 mmol/L IPTG, the expressed proteins were collected, purified, and verified with SDS-PAGE and Western blotting. Fifteen BALB/c mice were randomly assigned into three groups of 5 each: the rPocMSP1 N-terminal protein group, rPowMSP1 N-terminal protein group, and a negative control group. The mice of the three groups were injected intraperitoneally with the recombinant protein of rPocMSP1 N-terminal and rPowMSP1 N-terminal protein (50 μg of recombinant protein emulsified with Freund’s complete adjuvant) respectively, while the control group mice were injected with PBS. On 21d and 42d after primary immunization, the mice were boosted with the corresponding antigens emulsified with Freund’s incomplete adjuvant. Furthermore, on days 0, 7, 28, and 49 after immunization, tail vein blood samples were collected for serum preparation. ELISA and Western blotting were used to determine the serum specific IgG, analyze antibody titer and antibody affinity index, thereby to evaluate the immunogenicity of rPocMSP1 N-terminal and rPowMSP1 N-terminal proteins. Western blotting was used to determine the cross-reaction of the two recombinant proteins, and protein array was used to analyze their antigenicity in the serum of examinees infected with P. ovale. Results PCR demonstrated that the sequence length of PocMSP1 N-terminal and PowMSP1 N-terminal fragment was 1 068 bp, showing concordant with the expected size. Produced by PCR cloning, expression and purification, the concentration of rPocMSP1 N-terminal and rPowMSP1 N-terminal recombinant protein was 0.5 mg/ml and 1.0 mg/ml respectively. SDS-PAGE showed that the relative molecular mass of the purified rPocMSP1 N-terminal and rPowMSP1 N-terminal protein was 46 000 and 59 000, respectively, and Western blotting indicated the recombinant proteins were successfully expressed. The sera of immunized mice could recognize the corresponding antigens. ELISA detected specific IgG antibodies on 7 d after immunization, revealing specific reaction between the purified recombinant proteins and IgG, which was significantly different compared with that in the negative control group (rPocMSP1 N-terminal: t = 5.824, P < 0.01; rPowMSP1 N-terminal: t = 25.98, P < 0.01). On 28 d after immunization, the mean A₄₅₀ values for serum IgG in groups rPocMSP1 N-terminal and rPowMSP1 N-terminal were 1.043 ± 0.390, and 1.923 ± 1.373, and when the IgG levels continued to rise up to 49 d after immunization the mean A₄₅₀ values for serum IgG in rPocMSP1 N-terminal was 1.217 ± 0.365, and rPowMSP1 N-terminal was 2.463 ± 0.983. rPoMSP1 N-terminal protein induced considerable immune response in mice, with the antibody titer of 1 ∶ 640 000 and 1 ∶ 1 280 000, respectively.ELISA revealed that rPocMSP1 N-terminal and rPowMSP1 N-terminal proteins induced IgG antibody with high affinities in immunized mice, showing the affinity 97.11% by rPocMSP1 N-terminal protein, and 75.72% by rPowMSP1 N-terminal protein. Western blotting showed that the serum IgG antibody in mice immunized with rPocMSP1 N-terminal could recognize rPowMSP1 N-terminal antigen, and vice versa, the antibody in mice immunized with rPowMSP1 N-terminal antigen could recognize rPocMSP1 N-terminal antigen, demonstrating the two antigens have cross reaction property. Analysis with protein array showed that tested with rPocMSP1 N-terminal protein using P. ovale, the sensitivity and specificity was 83.33% and 57.14%, respectively; while rPowMSP1 N-terminal protein presented 97.62% of sensitivity and 54.76% of specificity; in comparison with the reaction using the sera from normal persons, the difference was statistically significant(t = 5.896, 10.42, P < 0.01). Conclusion rPoMSP1 N-terminal protein showed good immunogenicity, inducing humoral immune response in mice, and displaying significant antigenisity in reacting with the serum of people infected with P. ovale.

Risk assessment of schistosomiasis transmission along the middle and lower reaches of Yangtze River after flooding in 2020

GUO Su-ying, ZHU Hong-qing, CAO Chun-li, DENG Wang-ping, BAO Zi-ping, JIA Tie-wu, LI Yin-long, LV Chao, QIN Zhi-qiang, ZHANG Li-juan, FENG Ting, YANG Fan, LV Shan, XU Jing, LI Shi-zhu

2021, 39(6):  753-758.  doi:10.12140/j.issn.1000-7423.2021.06.005

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Objective This study aimed to assess the transmission risk of schistosomiasis along the middle and lower reaches of Yangtze River after flooding in 2020. Methods Snail survey and survey for contamination with wild feces in snail breeding environment were conducted in Hunan, Hubei, Jiangxi, Anhui, and Jiangsu Provinces in October, 2020. According to the historical epidemic of schistosomiasis and the flooding record, two counties of each province were selected for this study, including Nanxian, Huarong, Hanchuan, Yangxin, Lushan, Lianxi, Guichi, Zongyang, Luhe, and Hanjiang. Two townships (town) were selected from each county, and then one administrative village was selected from each township (town) for the survey. Using systematic sampling and environmental sampling method, snail survey was performed in two categories of environment in the current flood-affected area, including snail-infested environment bearing frequent human and animal activities in 2017—2019, and in environment of historically snail-free or snail-free over 20 years. All the collected snails were examined for schistosome infection by loop-mediated isothermal amplification (LAMP) method. During collecting snails from environments, wild feces were collected as well and tested by miracidia hatching method (one sample, triple detection). Chi-square test is used to compare the difference of occurrence rate of frames with living snails surveyed using systematic and environmental sampling methods. Results A total of 64 snail breeding environment sites were surveyed, from where 8 904 snails were collected, of them 7 918 were alive. The overall occurrence rate of living snail frames was 11.7% (1 813/15 464), and the rates were 10.5% (679/6 441) using environmental sampling method and 12.6% (1 134/9 023) using systematic sampling method. The difference between the two rates was statistically significantly (χ² = 14.91, P < 0.01). The occurrence rates of living snail frames by systematic sampling in Zongyang and Guichi of Anhui Province were 60.2% (607/1 008) and 28.4% (251/882), respectively, which were both significantly higher than the rates in other counties (P < 0.01). The average density of live snails in Zongyang (2.177/0.1 m²) and Guichi (3.323/0.1 m²) were over ten folds higher than those in other counties. One sample collected from in Guichi was found schistosome positive detected by LAMP method. A total of 100 wild feces samples were collected from 47 snail breeding environment, three of them were found schistosome positive, which belong to cattle, located in two environments in Lushan, Jiangxi and one environment in Guichi, Anhui. A total of 572 snails were collected from 44 sites of historically snail-free environment and the environment of snail-free for over 20 years, and 550 living snails were detected. These snails were found in the potential spreading areas in one environment in Guichi, Anhui, and two environments in Lushan, Jiangxi, with the average occurrence rates of living snail frames by systematic sampling being 21.2% and 4.5% respectively, showing the average densities of living snails being 1.254/0.1 m² and 0.081/0.1 m² respectively. Two samples collected from Lushan, Jiangxi were detected as schistosome positive by LAMP. Conclusion The flooding in 2020 may expand the schistosomiasis transmission areas in middle and lower reaches of Yangtze River, among them the transmission risk in Anhui and Jiangxi Provinces rose, compared to the previous year.

Evaluation of efficacy of visual intelligent recognition model for Oncomelania hupensis based on deep learning technology

SHI Liang, XIONG Chun-rong, LIU Mao-mao, WEI Xiu-shen, ZHANG Jian-feng, WANG Xin-yao, WANG Tao, HANG De-rong, YANG Hai-tao, YANG Kun

2021, 39(6):  764-770.  doi:10.12140/j.issn.1000-7423.2021.06.006

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Objective To investigate the performance of a deep learning-based visual intelligent recognition model for the intermediate host of Schistosoma japonicum, the snail Oncomelania hupensis, and evaluate its efficacy in recognition and classification. Methods According to the distribution pattern of O. hupensis in the topographic type of lake marsh, hill and water network in Jiangsu Province, seven regions including Nanjing, Zhenjiang, Yangzhou, Suzhou, Changzhou, Wuxi and Yancheng were selected as the fields for sample collection from March 2019 to October 2020. From each of the fields, 3 snail breeding environment sites were randomly selected for collection of snail samples and images by smart phone. The image quality and morphologic features of the sampled snails were screened and classified by six experts of schistosomiasis control to establish a standard data set of snail image classification. The data set was compiled into training set and test set (comprised of internal and external test). Three major convolutional neural network models including MobilenetV2, ResNet50 and Inception-ResNet-V2 were used to exercise the model training in the training data set. Taking the standard snail image classification data set as the gold standard, the receiver operating characteristic (ROC) curves was applied to compare the sensitivity, specificity, diagnostic concordance rate (Kappa value), and Yorden index of three model types with the internal test data; comparison was performed between the best-fit recognition model and the findings of snail search staff through the external test set, evaluating the accuracy of models in snail recognition with the internal and external test set. Results Totally, 3 224 images of 4 types of snails similar to O. hupensis were collected: Semisulcospira cancellata, Opeas gracile, Euphaedus, and Tricula. After screening, 2 719 images were included into the standard snail image classification data set, among them 774 were of O. hupensis and 1 945 of 4 being similar to but not O. hupensis. The concordance Kappa value from the snail recognition models of MobilenetV2, ResNet50 and Inception-ResNet-V2 model with the gold standard was 0.78, 0.83 and 0.88 respectively. The sensitivity, specificity, accuracy, Yorden index, and area under the ROC curve (AUC) of the Inception-ResNet-V2 were found highest, being 92.00%, 97.16%, 96.13%, 0.89 and 0.95, respectively. There was no statistically significant difference in the sensitivity and specificity among the three models (χ² = 3.892, 4.948, P > 0.05), while the difference in accuracy was statistically significant (χ² = 8.607, P < 0.05). In the external test, the best-fit model Inception-ResNet-V2 and the findings by staff showed better concordance with the gold standard, having the Kappa values of 0.80 and 0.83, and the AUCs 0.88 and 0.92, respectively, of which the difference was not statistically significant (P > 0.05). Conclusion The deep learning-based visual intelligent recognition model for O. hupensis snailshowed evident accuracy.

Changes of macrophage subsets and polarization in spleen of mice infected with Echinococcus multilocularis

HOU Jiao, WEN Hao, WANG Ming-kun, LI Wen-ding, LI liang, LI Jing, ZHANG Chuan-shan, WANG Hui

2021, 39(6):  771-778.  doi:10.12140/j.issn.1000-7423.2021.06.007

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Objective To investigate the changes of splenic macrophages subsets and their polarization phenotype in mice infected with different numbers of Echinococcus multilocularis protoscoleces. Methods Sixty female C57BL/6 mice were randomly assigned to mild, moderate, and heavy infection groups and control group with 15 mice in each group. The mice in mild, moderate and heavy infection groups were inoculated with 50, 500, and 2 000 protoscoleces via hepatic portal vein puncture, respectively, while the control group was injected with the same volume of saline. At 2, 12, and 24 weeks after infection, the spleens from five mice randomly selected from each group were collected, followed by calculating the spleen coefficients after weighted, and isolating splenic lymphocytes. The proportions and numbers of different macrophages subsets were determined by flow cytometry. The total RNA of splenic lymphocytes was extracted, and the relative level of mRNA transcription of M1 and M2 polarization related genes in splenic macrophages were examined with real-time quantitative PCR. The M1 type polarization related genes were those involving interleukin-1β (IL-1β), interferon-γ (IFN-γ), chemokine (C-X-C motif) ligand 11 (CXCL11), chemokine (C-C motif) receptor 7 (CCR7) and CD86, and the M2 type polarization related genes were involving mannose receptor C-type 1 (MRC1), resistin like alpha (Retnla) and arginase 1 (ARG1). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as an internal reference. SPSS 26.0 software was used for statistical analysis. The comparison between multiple groups at different time points was analyzed by one-way ANOVA, and the pairwise comparative analysis at the same time point was tested by LSD method. Results Two weeks after infection, the spleen weight, spleen coefficient, the number of splenic lymphocytes, the proportion of splenic macrophages, the number of splenic macrophages and Ly-6C^high splenic macrophage subset proportion in heavy infection group were (157.2 ± 22.8) mg,(0.8 ± 0.1)%,(10.3 ± 2.9) × 10⁷, (9.2 ± 6.4)%,(48.9 ± 32.7) × 10⁵ and (75.8 ± 4.6)%, respectively, which were all significantly higher than that in the control group [(75.0 ± 18.3) mg, (0.4 ± 0.1)%, (3.1 ± 1.3) × 10⁷, (4.3 ± 0.7)%, (7.7 ± 4.1) × 10⁵, (52.1 ± 8.4)%], mild infection group [(89.2 ± 7.4) mg, (0.4 ± 0.0)%, (5.4 ± 2.3) × 10⁷, (3.0 ± 0.9)%, (9.3 ± 6.9) × 10⁵, (50.1 ± 8.8)%], and in moderate infection group [(102.6 ± 15.2) mg, (0.5 ± 0.1)%, (7.0 ± 2.1) × 10⁷, (3.5 ± 0.3)%, (13.7 ± 3.9) × 10⁵, (60.3 ± 8.7)%] (F = 22.744, 23.542, 9.318, 3.935, 6.617, 11.197, P < 0.05 or P < 0.01). Ly-6C^low macrophage subset proportion (20.3 ± 4.2)% was significantly milder than that in the control group (39.0 ± 7.1)%, mild infection group (41.2 ± 8.6)% and in moderate infection group (34.2 ± 7.1)%(F = 9.157, P < 0.01). At 12 weeks after infection, the spleen weight, spleen coefficient, the proportion and number of macrophages and the proportion of the Ly-6C^high macrophage subset in the spleen were significantly higher in heavy infection group than that in the control group, mild and moderate infection groups (F = 12.730, 14.173, 20.380, 7.943, 25.838, P < 0.01), the proportion of Ly-6C^low macrophages was significantly lower than that in the control group, mild and moderate infection groups (F = 27.668, P < 0.01). At 24 weeks after infection, the spleen weight, spleen coefficient, the number of lymphocytes, the proportion and number of macrophages in the spleen were also significantly higher in heavy infection group (F = 8.664, 7.318, 13.047, 3.315, 6.007, P < 0.05 or P < 0.01). The proportions of Ly-6C^high and Ly-6C^low macrophages were not significantly different from those of the control group, mild and moderate infection groups (F = 3.177 and 2.709, P > 0.05). With longer time of infection, the proportion of Ly-6C^high macrophages was gradually decreased (F = 30.649, P < 0.01), and the proportion of Ly-6C^low macrophages was gradually increased (F = 32.407, P < 0.01). Real-time quantitative PCR showed that at 24 weeks after infection, the relative level of mRNA transcription of CXCL11 in heavy infection group (28.2 ± 36.3) was higher than that in control group (1.9 ± 2.7) (t = 2.243, P < 0.05), and the relative level of mRNA transcription of CD86 (0.2 ± 0.1) was significantly lower than that in the control group (0.5 ± 0.3) (t = -2.255, P < 0.05). The relative transcription level of mRNA of MRC1, Retnla, and ARG1 (5.2 ± 2.9, 201.8 ± 176.4, 51.2 ± 69.6) were significantly higher than those in control group (1.8 ± 1.5, 0.8 ± 0.8, 1.2 ± 0.8, respectively) (t = 2.313, 3.470 and 2.185, P < 0.05) Conclusion Two weeks after infection, large numbers of Ly-6C positive monocyte derived macrophages were recruited into spleen in the heavy infection group and the Ly-6C^high macrophage subset gradually transformed shifted to the Ly-6C^low subset during infection. At 12 weeks and 24 weeks after infection, the macrophages in the spleen were dominated by the M2 type, inducing immune tolerance, favorable to chronic infection of Echinococcus multilocularis metacestode.

Roles of nuclear factor-κB/myeloid differentiation factor 88 in the liver fibrosis of cystic echinococcosis patients

MA Wen-mei, SANG Wei, AIMAITI Ya-sen, ZUO Li-ke, FU Li, MIAO Na

2021, 39(6):  779-783.  doi:10.12140/j.issn.1000-7423.2021.06.008

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Objective To investigate roles of nuclear factor-κB/myeloid differentiation factor 88 (NF-κB/MyD88) in the liver fibrosis of patients with cystic echinococcosis (CE). Methods Liver samples were collected from the liver lesion tissue surgically resected from CE patients, by taking the tissue proximal to the lesion (0.5 cm to the outer cyst wall) and distant normal tissue (2 cm to outer cyst wall). Pathological changes of liver samples were observed by HE staining. Collagen deposition was observed with Masson staining. Expression of hepatic stellate cell activation marker α-smooth muscle actin (α-SMA), NF-κB p65 and MyD88 in the liver tissues of CE patients was detected by immunohistochemical staining and qRT-PCR analysis. Pearson correlation coefficient method was used to analyze the correlation of the expression level of NF-κB p65 and MyD88 with the positive area of collagen deposition, and expression level of α-SMA. Results Forty liver lesion samples resected from CE patients were collected, among them there were eight CE1, ten CE2, seven CE3, nine CE4 and six CE5. Of the patients receiving surgery, 24 were males and 16 females, aged from 20 to 45 years with the median of (38.2 ± 12.9) year. HE staining showed that inflammatory microenvironment was formed between CE lesion and proximal liver tissue, presenting massive lymphocyte infiltration, accompanied by increase of granulocyte to different degree. Masson staining showed that collagen was mainly deposited in the inflammatory cell band in the tissue proximal to lesion, around portal areas, biliary ducts and blood vessels. The positive area of collagen deposition in proximal-lesion tissue (20.29 ± 3.96)% was higher than that (2.87 ± 1.74)% in distant normal liver tissue (t = 13.640, P < 0.01). Immunohistochemical staining demonstrated that α-SMA, NF-κB p65 and MyD88 positive cells mainly highly expressed in the inflammatory cell band around proximal-lesion tissue, which was (13.47 ± 3.47)%, (7.30 ± 1.40)% and (7.47 ± 1.86)%, respectively. However, their expression in distant normal liver tissue was quite low, which was (3.43 ± 0.56)%, (1.08 ± 0.29)%, (0.36 ± 0.05)%, respectively, showing significant difference of expression in proximal and distant location(t = 5.682, 18.530, 5.087, P < 0.01). qRT-PCR analysis indicated that relative expression amount of α-SMA, NF-κB p65, MyD88 mRNA in proximal-lesion samples was 5.05 ± 0.42, 3.71 ± 0.33, 7.11 ± 0.50, respectively, which was significantly higher than those in the distant normal tissues (1.07 ± 0.01, 1.02 ± 0.03, 1.07 ± 0.02, respectively) (t = 39.750, 34.130, 50.960, P < 0.01). The expression of NF-κB p65 and MyD88 was significantly correlated with the and positive area of collagen deposition and α-SMA expression (r = 0.98, 0.97, 0.98, P < 0.01). Conclusion NF-κB p65/MyD88 expression in the proximal-lesion liver tissue of hepatic CE patients was significantly higher than that in the distant normal liver tissue, which was positively correlated with the degree of liver fibrosis.

Epidemiological analysis of malaria in Hebei Province from 2011 to 2019

FENG Ning-ning, TAO Wei, FENG Tong, ZHEN Su-juan, LI Jun, LIU Hong-bin

2021, 39(6):  786-793.  doi:10.12140/j.issn.1000-7423.2021.06.009

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Objective To investigate the epidemiological characteristics of malaria in Hebei Province from 2011 to 2019, and to provide a scientific basis for the surveillance and control of imported malaria after malaria elimination in the province. Methods The malaria epidemic data and individual case information in Hebei Province from 2011 to 2019 were collected from National Infectious Disease Surveillance Reporting and Management System and Information Management System for the Prevention and Treatment of Parasitic Disease, based on which the characteristics of the malaria epidemic were analyzed with descriptive epidemiological method. The characteristics of the malaria epidemic were analyzed with descriptive epidemiological methods. Results A total of 611 malaria cases were reported in Hebei Province from 2011 to 2019, with no local cases and cases transmitted from other provinces. All reported cases were imported from abroad, and no case of imported secondary malaria was detected. Among these cases, 571 (93.5%, 571/611) were imported from 34 African countries, mainly falciparum malaria (75.0%, 428/571). The top three source countries of imported cases were Angola (104 cases), Nigeria (76 cases), and Equatorial Guinea (60 cases). Six Asian countries contributed 34 cases (5.6%, 34/611), and among these, vivax malaria was the predominant type (70.6%, 24/34). The top three Asian source countries were Pakistan (14 cases), Myanmar (12 cases), and Cambodia (4 cases). In addition, three cases were imported from Oceania and two from South America. The cases were distributed across 129 counties (cities and districts) in 11 districts of the province, of which the highest number of imported cases were reported from the cities of Baoding (160 cases, 26.2%), Shijiazhuang (121 cases, 19.8%), Handan (89 cases, 14.6%) and Hengshui (58 cases, 9.5%), which accounted for 70.0% (428/611) of the total cases in the province. The imported cases were mainly male (598 cases), while only 13 female cases; mostly in the group aged 20-49 years, accounting for 86.1% (526/611); the majority (282 cases, 46.2%) were farmers, followed by migrant workers or workers (163 cases, 26.7%). Five deaths from malaria were reported from 2011 to 2019. During the nine years, 43.9% (268/611), 20.9% (128/611), and 6.5% (40/611) of patients visited three districts of Shijiazhuang, Beijing and Handan for medical care, respectively, which accounted for 71.4% (436/611) of the total cases. Since 2016, there has been a significant increase in malaria cases reported in Dezhou City, Shandong Province, where 84.4% (27/32) of patients were in Gucheng County, Hengshui City. The mean time period from onset to diagnosis was 5.4 days, with a median of 3.4 days. The shortest period was 0 days and the longest 70 days, among them the time period was ≤ 3 days in 307 patients (50.2%), 4-10 days in 232 patients (38.0%), and > 10 days in 72 patients (11.8%). There was a significant difference between years in the rate of confirmed diagnosis within 3 days from onset(χ² = 30.902, P < 0.01), but no significant difference in the rate of confirmed diagnosis within 10 days from onset(P > 0.05). Conclusion All cases of malaria reported in Hebei Province from 2011 to 2019 were imported from abroad, and no imported secondary malaria was reported.

Effect evaluation of innocent sanitary toilets improvement in rural areas of Jiangsu Province during 2016—2020

DING Xin, JIN Xiao-lin, MAO Fan-zhen, ZHANG Qiang, XU Xiang-zhen, DAI Yang, CAO Jun

2021, 39(6):  794-797.  doi:10.12140/j.issn.1000-7423.2021.06.010

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Objective To evaluate the effectivenss of innocent sanitary toilets improvement in rural areas of Jiangsu Province during 2016—2020. Methods Two villages from one county (city, district), which was randomly selected from each of the 13 cities in Jiangsu Province were set as investigating sites. Ten or more households with toilets renovated from 2016 to 2020 were randomly selected from each village for the household site-visit to collect the information of general condition of household toilet reconstruction, the type of septic tank and its effective volume, and the outflow of the fecal fluid of the third compartment. Fecal fluid samples from the first and third compartment were collected to examine the fecal coliform value, five-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), ammonia nitrogen (AN) and parasite eggs. Household questionnaire was conducted to collect the information of residents’ satisfaction with toilet improvement and the way using fecal manure. The overall incidence of intestinal infectious diseases during 2016—2020 was retrieved from the data reported by local township health clinics. Furthermore, the economic expenditures caused by intestinal infectious diseases were also collected in the year of 2015 and 2020 in each investigated village. Paired t test was used for the difference comparison of fecal coliform value, COD, BOD5 and AN between the first and third tank compartments. Results Totally 367 households from 26 administrative villages were investigated. The main type of septic tank were constructed with brick and prefabricated cement parts, each type of which accounted for 42.7% (157/367) and 24.5% (90/367), respectively. The septic tanks with effective volume reaching 1.5 m³ accounted for 93.0% (279/300). The fecal fluid from the tank-third compartment was mostly used as field fertilizer (212/290). The coliform values of fecal fluid in first and third compartment were (119.8 ± 33.4) and (42.0 ± 18.5) coliform/ml, with significant difference between the compartments (t = 6.534, P < 0.01). The concentrations of BOD5, COD and AN in the fecal fluid in the tank-first compartment were (354.7 ± 124.8), (1 021.8 ± 352.5) and (119.2 ± 64.3) mg/L, while those in the tank-third compartment were (138.6 ± 62.4), (531.1 ± 229.6) and (96.3 ± 42.7) mg/L, repectively, with significant differences between the first and the third tank compartment (t = 5.042, 9.631, 2.455, P < 0.01). No human parasite eggs were detected from all fecal fluid samples. From 2016 to 2020, the incidence of overall intestinal infectious diseases in the community (towns) that the surveyed village affiliated to was reduced from 24.6/100 000 in 2016 to 4.3/100 000 in 2020. A total of 305 household questionnaires were performed and the awareness rate of toilet related knowledge, the positive support to toilet renovation and the satisfaction rate in this aspect reached to 95.1% (290/305), 100% (303/303), and 96.7% (291/301), respectively. The publicity materials were accessible in 88.5% (270/305) residents’s home, and 96.1% (293/305) residents knew that the fecal fluid in tank-third compartment were used as fertilizer. In 2020, the intestinal infectious diseases cost the surveyed village 81 000 Yuan, which decreased by 53.9% compared with 176 000 yuan in 2015. Conclusion During 2016 to 2020, the accomplishment of household toilet harmless-renovation reached to the defined standard of feces harmless sanitary management in rural areas of Jiangsu Province, which could be conducive to control the transmission of infectious diseases via night soil-mouth route, including intestinal parasitic diseases, as well as to improve sanitary conditions and protect people’s health.

Surveillance on soil-transmitted nematode infections in population in Guangxi Zhuang Autonomous Region during 2016—2020

WAN Xiao-ling, LV Guo-li, JIANG Zhi-hua, OU Fang-qi, WEI Hai-yan, TANG Wen-qian, LIN Yuan, ZHANG Wei-wei, HUANG Keng-ling, SHI Yun-liang, LIU Duo, LIU Jian, MENG Jun, YANG Yi-chao

2021, 39(6):  800-806.  doi:10.12140/j.issn.1000-7423.2021.06.011

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Objective To understand and analyze the epidemic status and development trends of soil-transmitted nematodiasis in Guangxi Zhuang Autonomous Region (Guangxi), to provide scientific basis for formulating the disease control strategy, and evaluating the control effect. Methods In 2016—2020, Guangxi was assigned to high-, medium- and low-GDP regions, from which 39 counties (cities, districts) were selected as surveillance sites. Each county under surveillance was divided into 5 regions according to geographic location, i.e., east, west, south, north, and central. From each region, one townships was randomly selected, and an administrative village was selected from the township for the surveillance. In the sampled village, no less than 200 permanent residents aged > 3 years were cluster sampled for examination. Fecal samples were collected from the villagers, and soil-transmitted nematode eggs were detected with the modified Kato-Katz thick smear method. The eggs of Enterobius vermicularis were examined in children aged 3-9 years with the adhesive tape method. Chi-square test and Chi-square trend test were used to analyze and compare the infection status of soil-transmitted nematodes in different areas, gender, age groups, nationalities, education levels and occupations. Results In the 39 surveillance sites, the production modes was mainly agriculture, and the drinking water was mostly tap water and well water. From 2016 to 2020, the coverage rates of sanitary toilets was 77.39% (36 403/47 040), 94.19% (47 120/50 026), 94.47% (55 499/58 750), 86.72% (68 913/79 467), and 94.99% (56 188/59 154), respectively, which differed significantly (χ² = 12 813.53, P < 0.05). A total of 66 355 people were examined, and the infection rates of soil-transmitted nematodes were 4.20% (533/12 699), 2.98% (312/10 458), 2.21% (276/12 485), 1.75% (285/16 329) and 1.54% (222/14 384) in 2016—2020, respectively, showing significant difference between years (χ² = 260.67, P < 0.05), and a decreasing trend year by year (χ² = 316.05, P < 0.05). The rates in the high-, medium- and low-GDP areas were 1.11% (244/22 049), 2.65% (722/27 273) and 3.89% (662/17 033) respectively, and differed significantly between the areas (χ² = 317.57, P < 0.05). The hookworm infection rate in females was 2.68% (900/33 548), which was higher than that in males (1.40%, 458/32 807) (χ² = 136.98, P < 0.05). The Trichuris trichura infection rate in males and females were 0.29% (95/32 807) and 0.32% (108/33 548), respectively; the Ascaris lumbricoides infection rates in males and females were 0.11% (37/32 807) and 0.13% (43/33 548), respectively; and the E. vermicularis infection rates in boys and girls were 11.69% (274/2 343) and 12.17% (257/2 112), respectively. There was no significant differences in the infection rate between genders (χ² = 0.569, 0.326, 0.24; P > 0.05). Among the different age groups, the infection rate of hookworm was highest in the group aged > 80 years, at 4.93% (69/1 399); the rate of A. lumbricoides was highest in the group aged 3-9 years, at 0.28% (31/11 183); and the rate of T. trichura was highest in the group aged 70-79 years, at 0.62% (31/4 961). The infection rate of hookworm was the highest in the Zhuang minority population at 2.77% (870/31 352); and the rates of A. lumbricoides and T. trichura were highest in other minorities, both at 0.60% (18/2 976). The infection rates of hookworm and T. trichura were highest in the illiterate group, at 5.36% (195/3 635) and 0.61% (22/3 635) respectively. The A. lumbricoides infection rate was highest in preschool children, at 0.35% (20/5 674). The infection rate of hookworm was highest in farmers, at 2.80% (1 285/45 943); that for A. lumbricoides in live-scattered children, at 0.71%(10/1 399); and that of T. trichura in institutional personnel, at 0.45% (5/1 105). The infection rate of E. vermicularis in children aged 3-9 years was 8.45% (24/284), 17.99% (86/478), 15.66% (155/990), 11.48% (182/1 586) and 7.52% (84/1 117) in 2016—2020, respectively, which differed significantly (χ² = 54.10, P < 0.05), and showed an increasing trend and then a decreasing trend with time (χ² = 21.07, P < 0.05). Conclusion The infection rate of soil-transmitted nematodes in Guangxi decreased year by year, and displayed low prevalence. However, the E. vermicularis infection rate in children maintained at a considerable high level. Therefore, it is imperative to strengthen comprehensive prevention and control measures in children.

Blastocystis sp. infection in dairy cattle in Yunnan Province and its gene subtype analysis

PU Li-hua, ZHANG Xing-ze, GUAN Shao-jun, CHENG Wen-jie, ZOU Feng-cai, MAO Hua-ming, YANG Jian-fa

2021, 39(6):  809-815.  doi:10.12140/j.issn.1000-7423.2021.06.012

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Objective To understand the prevalence of Blastocystis sp. in dairy cattle and its gene subtype in partial areas of Yunnan Province, thereby to provide information support for the prevention and control of the protozoan infection. Methods Fecal samples were collected from Holstein cows and dairy buffalos in Kunming, Dali, and Baoshan City from June 2019 to August 2020. DNA was extracted from the fecal samples, and the small subunit (SSU) rRNA of Blastocystis sp. was amplified by nested PCR and sequenced. The sequence alignment was performed with BLAST on NCBI database. Phylogenetic trees was constructed using neighbor-joining method of MEGA 6.0. SPSS 20.0 and SAS 9.1 software were used to analyze the infection rates of dairy cattle in different regions, seasons, farming patterns, breeds, genders and growth stages, and those factors with significant difference were further analysised by binary logistic regression. Results A total of 841 fecal samples were collected, of which 65 were SSU rRNA positive with the amplified fragment being 1 100 bp in length. The overall infection rate of Blastocystis sp. in dairy cattle was 7.7% (65/841, 95%CI: 5.92%-9.53%). The infection rates were 12.9% (32/248, 95%CI: 8.73%-17.08%), 8.1% (19/236, 95%CI: 4.58%-11.52%) and 3.9% (14/357, 95%CI: 1.91%~5.94%) in Kunming, Baoshan and Dali, with significant differences between places(χ² = 16.601, P < 0.01); the infection rate in summer, autumn and winter was 9.4% (56/599, 95%CI: 7.86%-37.30%), 8.3% (8/96, 95%CI: 2.80%-13.86%) and 0.7% (1/146, 95%CI: 0-2.02%), respectively, showing significant differences seasonally (χ² = 12.411, P < 0.05); the infection rate in captive farming and field farming was 8.3% (58/702, 95%CI: 6.23%-10.30%) and 5.0% (7/139, 95%CI: 1.40%-8.67%), respectively, with no significant difference (χ² = 1.693, P > 0.05); the infection rate among Holstein cows and dairy buffalos was 8.4% (41/490, 95%CI: 5.92%-10.82%) and 6.8% (24/351, 95%CI: 4.20%-9.48%), respectively, showing no significant difference (χ² = 0.671, P > 0.05); the rate in bull and cow was 11.1% (10/90, 95%CI: 4.62%-17.60%) and 7.3% (55/751, 95%CI: 5.46%-9.19%), repectively, presenting no significant difference (χ² = 1.617, P > 0.05); the rate in different growth stages of pre-weaned calves, post-weaned calves, juvenile cattle and adult cattle was 2/18 (95%CI: 0-25.63%), 26.2% (11/42, 95%CI: 12.89%-39.49%), 15.1% (11/73, 95%CI: 6.86%-23.28%) and 5.8% (41/708, 95%CI: 4.07%-7.51%), respectively, showing significant differences between growing stages(χ² = 29.604, P < 0.01). Binary logistic regression analysis showed that season (P < 0.05) and growth stage (P < 0.01) were independent influencing factor for Blastocystis sp. infection in dairy cattle. The sequence alignment found that the SSU rRNA sequence from one fecal sample was 96.3% homologous to reference sequence GenBank KX618192 (ST3 subtype), thirty-five samples were 97.3%-99.7% homologous to the reference sequences MH104059, KC148207 and MH358363 (ST10 subtype), twenty-three samples were 98.7%-100% homologous to the reference sequence MT453998 and MT453999 (ST12 subtype) and six samples were 98.7%-100% homologous to the reference sequence MH358361, MH358362, KC148205 and KC148206 (ST14 subtype). Phylogenetic tree analysis showed that the SSU rRNA sequences of Blastocystis sp. were clustered at to ST3, ST10, ST12 and ST14 subtype clade, respectively, having the constituent ratio of the subtypes being 1.5% (1/65), 53.9% (35/65), 35.4% (23/65) and 9.2% (6/65), respectively. Conclusion Blastocystis sp. infection are found in dairy cattle in Yunnan Province, and its ST3 and ST12 subtypes may have zoonotic transmission risk, thus, it is imperative to strengthen the control and prevention of the pathogen in the province.

Morphological characteristics and molecular identification of Heterakis sp. peacock origin

LIU Lu-yao, YANG Cong-shan, ZHANG Xiang, CHENG Rong-rong, HONG Yu-hang, WU Cheng-long, SUN Meng, CHEN Mu-xin, AI Lin, XU Qian-ming

2021, 39(6):  816-820.  doi:10.12140/j.issn.1000-7423.2021.06.013

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Objective To analyze taxonomic characteristics of Heterakis sp. from peacocks collected from Hefei Wildlife Zoo using morphological and molecular identification methods. Methods The worms were isolated from the cecum of peacocks and were indentified according to the morphological characteristics. The genomic DNA of the worms was extracted, then 28S rRNA D2-D3 gene and second internal transcribed spacer (ITS2) were amplified by PCR, and sequenced, the homology were analyzed by BLAST tool in GenBank, the phylogenetic tree was constructed by using the neighbour-joining method. Results A total of 48 nematodes were isolated. Male worm was 5.34-7.38 mm in length, while female 7.30-10.28 mm, which was about 2-5 mm longer than male. The copulatory spines in male was 80.00-322.73 μm in length, the pubic valve in female located near the caudal end of the worm. Both males and females contain three lamellae on the head, with a short oral cavity and a esophagus with cylindrical anterior and expanded posterior esophageal bulb. The male contains two unequal copulatory spines at the caudal end, while the female has a thin and smooth caudal tip. The egg is oval-shaped and gray-brown in color, covered by two layers of egg shell, which is fairly thick and smooth-surfaced, containing a single embryonic cell inside. PCR results showed that the 28S rRNA D2-D3 and ITS-2 amplification products were 750 bp and 1 053 bp in length respectively. BLAST showed that the 28S rRNA D2-D3 sequence was 84.59% homologous to S. calotis (GenBank Acession No. LC133189.1, LC133188.1) and 84.46% to H. gallinae (GenBank Acession No. LC185992.1, LC185989.1, LC186015.1, LC186006.1); the ITS-2 sequences was 85.29% homologous to H. beramporia (GenBank Acession No. KU529974, LC592732, LC592731), 80.32% to H. gallinarum (GenBank Acession No. LC59279, LC5928003, LC592805, LC592797) and 79.85% to H. indica (GenBank Acession No. LC592808, LC592809, LC592809). Based on the 28S rRNA D2-D3 gene phylogenetic tree, the Heterakis isolated in this study was genetically closer to S. calotis and the H. gallinae, but not on the same branch; based on the ITS-2 gene phylogenetic tree, it was genetically closer to the H. beramporia, H. gallinarum and H. indica, but not on the same branch. Conclusion The Heterakis worm isolated from peacock is morphologically highly consistent with the reported finding, thus, is preliminarily cassified as the Heterakis sp., but the phylogenetic trees based on the marker 28S rRNA D2-D3 and ITS-2 present certain variance with the reported.

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Exploring the value of remote imaging and multi-disciplinary team in diagnosis and treatment of hepatic echinococcosis in Qinghai Province

CHANG Yi-xue, BAO Hai-hua, LI Wei-xia, XIONG Dao-bin, WEN Sheng-bao

2021, 39(6):  821-825.  doi:10.12140/j.issn.1000-7423.2021.06.014

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To explore the value of remote imaging combined with multi-disciplinary treatment (MDT) in the diagnosis and treatment of hepatic echinococcosis in Qinghai Province, retrospective analysis was performed of 100 hepatic echinococcosis patients being anticipating surgery, of them the clinical images and information were transferred from primary hospital to Xikang group consultation platform of the imaging center in Qinghai University Affiliated Hospital from April 2019 to February 2020. The clinical and imaging data were collected to analyze the classification and staging of hepatic echinococcosis, and the changes of diagnosis and treatment plan after MDT. The analysis showed that after remote imaging and MDT, of the 100 hepatic echinococcosis cases, one case of mixed echinococcosis was referred to superior hospital for surgical treatment; of 44 hepatic cystic echinococcosis patients, 34 were treated by surgery in local hospitals, 6 were referred to superior hospitals for surgical treatment, and 4 were treated with medication; of 55 hepatic alveolar echinococcosis cases, 30 patients received surgery locally, 10 patients were referred to the upper hospital for surgery, and 15 patients received drug treatment. After remote imaging consultation, the cyst classification at initial screening, and the scheme of diagnosis and treatment were adjusted for 48 cases. It was demonstrated that the remote imaging and MDT has great potential in improving the diagnosis and treatment of hepatic echinococcosis in primary hospitals in pastoral areas of Qinghai Province, providing basis for the successful development of localized surgery and zero-clearance of surgical echinococcosis cases in Qinghai area, and saving the medical resources and costs as well.

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Research progress on the interaction between host cell autophagy and apicomplexa protozoa infection

LU Fei, ZHUO Xun-hui, LU Shao-hong

2021, 39(6):  826-831.  doi:10.12140/j.issn.1000-7423.2021.06.015

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Autophagy is a conserved lysosome-depenendant degradation system widely present in eukaryotes, and intracellular substances are transported to lysosomes for degradation through this mechanism, which plays an important role in cell survival under stress conditions of starvation and hypoxia. In addition, cells can also eliminate foreign pathogens such as parasites and viruses through the clearance action of autophagy. Apicomplexa protozoa are obligatory intracellular parasites, often zoonotic pathogens, posing considerable threats to social development and public health. In recent years, researches on the interaction between autophagy and apicomplexa protozoa mainly focused on Toxoplasma gondii and Plasmodium. In this paper, we reviewed the progress of research on the interaction between autophagy and important Apicomplexa protozoa infection.

Advances in research of structure, function and regulatory mechanism of Toxoplasma gondii conoid

ZHANG Xiao-han, FENG Ying, CHEN Ran, SANG Xiao-yu, YANG Na

2021, 39(6):  832-835.  doi:10.12140/j.issn.1000-7423.2021.06.016

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The apical complex is the typical structure of phylum Apicomplexa which consists secretory organelles and cytoskeletal elements, of which a marked feature is the conoid formed by tubulin fibers. Toxoplasma gondii has a relatively intact conoid, thus, it provides a successful model for analyzing the structure, composition and function of conoid. The stability and relevant activities of conoid are closely related to gliding motility and microneme secretion in of Toxoplasma, and are critical for host cell invasion. In this paper, the structure stability, protein function and regulatory mechanism of conoid are reviewed.

Research and application progress of sero-surveillance methods in malaria control and elimination

CUI Yan-wen, HUANG Fang, YIN Jian-hai, XIA Zhi-gui

2021, 39(6):  836-841.  doi:10.12140/j.issn.1000-7423.2021.06.017

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Accurate surveillance data is essential for malaria control, elimination and prevention of transmission re-establishment in the post-elimination phase. In recent years, highly sensitive sero-surveillance methods have been developed and optimized, particularly the magnetic bead-based multiplex immunoassay and protein microarray technique, which make it possible to assess the risk of malaria exposure in low-transmission areas, analyze exposure-related factors and spatial heterogeneity. This article reviews the research and application progress of sero-surveillance methods in malaria control and elimination, providing more suitable methodological tools for malaria surveillance in the elimination and post-elimination phase.

Progress in genotyping of Pneumocystis jirovecii

XUE Ting, DU Wei-qin

2021, 39(6):  842-847.  doi:10.12140/j.issn.1000-7423.2021.06.018

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Pneumocystis jirovecii, an opportunistic pathogenic fungus, may cause severe pneumocystis pneumonia (PCP), especially in immunodeficient patients. Pneumocystis was initially classified as a protozoan, named P. carinii. However, it was phylogenetically reclassified as an atypical fungal pathogen at late 1980s, which was confirmed with genetic sequence analyses, using molecular biology techniques. Due to lack of in vitro culture method, it has been difficult to clearly understand the patho-biological and epidemiological characteristics of Pneumocystis. With the wide application of molecular biology techniques, genotyping method for Pneumocystis has been extensively developed in recent years, however, no international standardization and global consensus on the genotyping scheme has been reached, hindering the investigation of epidemiology, population structure, source of infection, transmission characteristics of the clinical isolate of P. jirovecii, and in turn impeding the studies on the pathogenesis and control strategy of PCP. This review summarizes the progress in research on the genotyping approaches for P. jirovecii, in commemorating the 20th anniversary of its renaming.

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Investigation on the prevalence of Clonorchis sinensis infection in human population of Heilongjiang Province, 2015

TANG Lei, YUAN Shuang, YIN Shi-hui, GE Tao, GE Jing-xue, XING Zhi-feng

2021, 39(6):  741-745.  doi:10.12140/j.issn.1000-7423.2021.06.019

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To understand the current status of Clonorchis sinensis infection in the population of Heilongjiang Province, the survey sites were selected from 104 rural areas and 15 urban areas in the Province in April—June 2015, using stratified cluster random sampling method, in accordance to the guideline of the National Survey, Program for Key Human Parasitic Diseases. The rural areas were divided into four ecoregions: Changbai Mountain-Qianshan Mountains, the Eastern Northeast Plain, Sanjiang Plain, and Xiaoxing’an Mountain coniferous and broad-leaved mixed forest. The number of people surveyed at each survey site was no less than 250. The modified Kato thick smear method was used to examine the participants’ fecal samples (two slide-reading/sample) for C. sinensis eggs and counted. Of the 30 280 examinees, 747 were found infected, with an infection rate of 2.47%. The infection rate in rural and urban areas was 2.77% (734/26 456) and 0.34% (13/3 824) respectively, with the difference being statistically significant (χ² = 82.295, P < 0.05). Most of the infected showed mild infection (82.33%, 615/747). The infection rate was 3.05% (462/15 171) in males and 1.89% (285/15 109) in females, showing significant difference between the sexes (χ² = 42.261, P < 0.05). The highest infection rate was seen in the age group of 30-39 years (3.32%, 147/4 430), revealing significant difference between the age groups (χ² = 122.182, P < 0.05). The highest infection rate was found in farmers (animal husbandry and fishery) (3.16%, 692/21 914), with the difference between occupation groups being statistically significant (χ² = 164.846, P < 0.05). The infection rate differed significantly among the participants with different levels of education (χ² = 124.596, P < 0.05) and was highest in the group with junior high school education (3.46%, 499/14 425). The rate was significantly different between different ethnic groups (χ² = 8.395, P < 0.05), with the Han group having the highest infection rate (2.51%, 739/29 487). In rural areas, most of the infected people showed mild infection intensity (82.56%, 606/734). The infection rate was 3.39% (454/13 378) in males and 2.14 (280/13 078) in females, thus differing significantly between the sexes (χ² = 38.468, P < 0.05). The infection rate differed significantly with age (χ² = 111.315, P < 0.05) and was highest in the 30-39 year age group (3.78%, 145/3 841). Significant difference in infection rate was found also in occupation distribution (χ² = 103.863, P < 0.05), with the highest seen in the group of servants and enterprise-institution employees (5.05%, 10/198). The infection rate differed significantly in education distribution (χ² = 127.308, P < 0.05), and was highest in the group at the education level of junior high school (3.88%, 496/12 792). It also differed significantly between different ethnic groups (χ² = 8.903, P < 0.05), and was highest in the Han group (2.82%, 726/25 734). The Sanjiang Plain ecoregion showed the highest infection rate (8.75%, 575/6 574), and the rate differed significantly between ecoregions (χ² = 1 177.510, P < 0.05). In urban areas, the majority of the infected had mild infection (9/13). The infection rate in males was 0.45% (8/1 793) and that in females was 0.25% (5/2 031). The highest infection rate was detected in the age group 50-59 years (0.79%, 5/636), and among different occupations, the group of servants and enterprise-institution employees had the highest infection rate (0.97%, 4/411). In the education distribution, the illiterate group showed the highest infection rate (1.14%, 2/176). C. sinensis infection was only detected in Han ethnicity, with an infection rate of 0.35% (13/3 753). The C. sinensis infection found in Heilongjiang Province was largely mild, and the highest infection rate was seen in the Sanjiang Plain ecoregion, thus, it is imperative to actively explore feasible control strategies and measures appropriate to the actual situations in different regions in Heilongjiang Province.

Investigation on common infection of diarrhea-causing parasitic protozoa in Shanghai during 2015—2019

WANG Zhen-yu, ZHANG Yao-guang, MA Xiao-jiang, JIANG Li, HE Yan-yan, ZHU Qian, PAN Hao

2021, 39(6):  759-763.  doi:10.12140/j.issn.1000-7423.2021.06.020

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To understand common infection status of diarrhea-causing parasitic protozoa in residents of Shanghai Municipality, a survey was carried out through selecting 1-2 general hospitals from five districts, including Changning, Hongkou, Minhang, Jiading and Pudong New District, as surveillance sites in 2015—2019. Fecal samples were collected from diarrhea patients (defecation for more than three times within 24 h, with abnormal feces appearance), who visited the surveillance site hospital, based on the principle of sampling from both urban and the suburb districts. Using the methods of direct smear with saline, iodine staining, acid-fast staining and coproantigen immuno-chromatography, the fecal samples were examined for Entamoeba histolytica, Giardia lamblia and Cryptosporidium, and analyzing the infection status. The results showed that a total of 6 984 fecal samples were collected from diarrhea patients and examined etiologically, of them 9 were found positive, with an overall infection rate of 0.13% (9/6 984) in 2015—2019. Among the positives, 4 were infected with E. histolytica, 2 were G. lamblia and 3 were Cryptosporidium. The positive rates in each year were 0.08% (1/1 207), 0.40% (5/1 254), 0.13% (2/1 506), 0 (0/1 509) and 0.07% (1/1 508), respectively. Among the 6 984 patients with diarrhea, the age group of 30-40 years (1 370) had 4 cases of protozoa infection; of 3 345 males, 4 were found protozoa positive, while from 3 639 females, 5 were positive; there were 2, 2, 2, 3 positive cases were detected in districts of Changning, Hongkou, Minhang, and Jiading, whereas no positive cases were detected in Pudong New District. Protozoan coproantigen fast test strip detected 31 positives, with an overall positive rate of 0.44% (31/6 984), which was significantly different from the findings by pathogen examination (χ² = 12.13,P < 0.01). The positive rate of parasitic protozoa was found at a considerably low level, maintaining at low prevalence and in scattering distribution in Shanghai. Therefore, it is urged to carry on health education, and to strengthen continuous and effective surveillance; applying combined approaches of etiology, immunology, and molecular biology for improving the detection rate.

Investigation on the prevalence of human parasitic infections in the ecoregion of southern part of Yunnan-Guangxi-Guangdong neighboring area, Yunnan Province in 2015

CAI Xuan, YANG Ya-ming, LI Ben-fu, YAN Xin-liu, PENG Jia, ZI Jin-rong, WU Fang-wei

2021, 39(6):  848-852.  doi:10.12140/j.issn.1000-7423.2021.06.021

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According to the guidelines of the Scheme and Implementation Guideline of Nationwide Survey on Human Major Parasitic Diseases in China, five survey sites were selected from 3 counties (city) in the ecological region of southern part of Yunnan-Guangxi-Guangdong (Y-Gx-Gd) neighboring area in Yunnan Province in 2015 using the stratified cluster random sampling method. At least 250 local residents at ages of over 3 years were surveyed in each survey site. Intestinal helminth eggs were examined using the modified Kato-Katz thick-smear method (two slide-reading/sample); hookworm species was identified using the tube filter paper culture technique; Enterobius vermicularis eggs were examined using additional the transparent adhesive tape method for children at ages of 3 to 6 years; and trophozoites or cysts of intestinal protozoa were detected using direct smear method with physiological saline-iodine. All data were processed using the statistical software SPSS version 17.0. A total of 1 278 residents in the five survey sites were examined, among them 350 were found positive of intestinal parasites infection, with an overall infection rate of 27.4%. Totally, 10 parasite species were identified, including 5 species of helminths and protozoa, respectively. Of the 350 positives, 302 were infected with soil-transmitted nematodes (infection rate 23.6%), 64 infected with protozoa (infection rate 5.0%) and 5 infected with Taenia (infection rate 0.4%). The difference of infection rate between different parasite species was statistically significant (χ² = 464.56, P < 0.01). The infection rate of intestinal parasite was 26.5% (165/622) in men and 28.2% (185/656) in women, showing no significant difference between genders (χ² = 0.450, P > 0.05). There was no significant difference of infection rate between intestinal parasite, soil-transmitted nematode, and intestinal protozoa in different genders (χ² = 0.450, 0.510, 0.001, P > 0.05). The distribution of ethnicity, education levels and age groups in infection rate of intestinal parasite indicated that the highest was seen in the residents of Miao ethnicity (45.3%, 115/254), illiterate (33.2%, 92/277) and the age group of 6—69 years (42.4%, 56/132). Difference in infection rate of intestinal parasite and soil-transmitted nematode between different ethnicities, education levels and age groups was statistically significant (χ² = 72.75 and 78.01, 15.74 and 18.60, 50.74 and 55.57, P < 0.01), but not significant in intestinal protozoa infection (χ² = 5.54, 1.93 and 12.78, P > 0.05). Soil-transmitted nematode infection in the residents was largely mild, as such that the mild infection of Ascaris, Trichuris and hookworm accounted for 66.7% (42/63), 98.3% (58/59) and 96.8% (212/219), respectively. Intestinal parasite infection was detected in all three counties, with the highest infection rate of soil-transmitted nematode found in Hekou County (32.0%, 160/516) (χ² = 32.38, P < 0.05). The infection rate of soil-transmitted nematode was 5.7% (29/505) in Malipo County, 4.7% (24/516) in Hekou County and 4.3% (11/257) in Yingjiang County, with no significant difference between the three counties surveyed (χ² = 0.997, P > 0.05). The survey indicates that the infection rates of intestinal parasite and hook worm remain considerably high, while the infection rate of intestinal protozoa is low in the ecoregion of the southern part of Y-Gx-Gd neighboring area of Yunnan Province.