Table of Content

25 April 2022, Volume 34 Issue 2

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Harder maintained than achieved: Challenges of maintaining malaria-free in China

ZHU Guo⁃ding, GAO Qi, CAO Jun

2022, 34(2):  109. 

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On June 2021, China was certified malaria-free by WHO. However, the global number and death of malaria cases have recently increased, and the malaria vectors will continue to inhabit in China, resulting in a high difficulty in consolidation of malaria elimination achievements. Hereby, we analyze the current challenges and propose the future priority of the national malaria control program in China, in order to provide insights into prevention of re⁃establishment of imported malaria in the country.

Surveillance and response: The core intervention for malaria control during the post-elimination phase in China

ZHOU Sheng

2022, 34(2):  112. 

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China was certified malaria⁃free by the WHO on June, 2021. Nevertheless, there are thousands of overseas imported malaria cases annually in China, and there are deaths of imported malaria cases reported every year in the country. In addition, there are secondary cases of imported malaria, and malaria vectors remain in regions where malaria were formerly endemic, resulting in a high risk of local transmission of imported malaria in eliminated regions in China. This article analyzes the risk of malaria control and the challenges of malaria surveillance and response during the post⁃elimination stage in China, and proposes some suggestions for future priorities.

Challenges of maintaining malaria elimination in China: Cross⁃border malaria

ZHANG Shu⁃hao, LI Jia⁃yin, ZHANG Jun

2022, 34(2):  115. 

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China was certificated malaria⁃free by WHO in 2021 and has continued to maintain malaria elimination. However, there are still huge challenges in malaria control in the border regions between Yunnan Province, China and Myanmar due to lack of geographic barriers and frequent cross⁃border travel. Hereby, we review the direction contributions of the Global Fund Malaria Program implemented by Health Poverty Action (HPA), an international non⁃governmental organization (NGO), to malaria elimination in China, and analyze the challenges of malaria control caused by external environmental factors, such as COVID⁃19, in regions where the Global Fund Malaria Program is implemented. In addition, some suggestions are proposed for cross⁃border collaboration on malaria control.

Sustainable and precise Anopheles control to maintain malaria elimination in China

LIU Qi⁃yong

2022, 34(2):  117. 

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Malaria caused a heavy disease, economic and social burdens in China. Following 70⁃year concerted efforts, China has been awarded a malaria⁃free certification by the WHO on June 2021. This paper summarizes the control strategies of Anopheles vectors from malaria control to post⁃elimination stages in China, emphasizes the risk of imported malaria cases caused re⁃transmission and the challenges of Anopheles control after malaria elimination in China. Sustainable and precise vector control is still required in China during the post⁃elimination stage to consolidate malaria elimination achievements in the country. In addition, China’s innovative vector control strategies, technologies and experiences will contribute to global malaria control and elimination programs.

Sustainable development roadmap of Chinese antimalarial products

HUANG Yang⁃mu, XU Ming

2022, 34(2):  120. 

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As the first country that has been certified malaria⁃free in the WHO Western Pacific Region for more than 3 decades, China should share its successful experiences of malaria control and provide globally recognized anti⁃malaria products by making full uses of its advantages in provision and production capacity of artemisinin raw materials, to fill the gaps of international demands for mosquito nets, rapid diagnostic reagents and antimalarial compounds. Increasing the investment of research and development of antimalarial products, building overseas bases for artemisinin raw material production, establishing international regulatory authority and promoting the local production of antimalarial products are needed to further promote the  internationalization  of Chinese antimalarial products, so as to achieve the equity and accessibility of Chinese antimalarial products in high⁃burden regions for malaria. 　

Epidemiological trends for human schistosomiasis prevalence in Hubei Province from 2004 to 2018 based on Joinpoint regression analysis

XIAO Ying, ZHONG Chen⁃hui, WEI Feng⁃hua, DAI Ling⁃feng, YANG Jun⁃jing, CHEN Yan⁃yan

2022, 34(2):  122. 

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Objective　To analyze the trends of human schistosomiasis prevalence in Hubei Province from 2004 to 2018, so as to provide the evidence for formulating the schistosomiasis elimination strategy in the province. Methods　All data pertaining to human schistosomiasis prevalence in Hubei Province were collected from 2004 to 2018, and the trends for changes in seroprevalence, egg⁃positive rate and prevalence of human Schistosoma japonicum infection were analyzed using a Joinpoint regression model. Results 　Both of the numbers of residents seropositive and egg⁃positive for S. japonicum infections appeared a tendency towards a decline in Hubei Province from 2004 to 2018, and the prevalence of human S. japonicum infections reduced from 6.85% in 2004 to 0 in 2018. Joinpoint regression analysis showed that the prevalence of human S. japonicum infections appeared an overall tendency towards a reduction in Hubei Province from 2004 to 2018 [average annual percent change （AAPC） = -24.1%, P < 0.01], and the trends for the reduction were both significant during the period from 2004 to 2006 [annual percent change （APC） = -35.1%, P < 0.01] and from 2006 to 2018 （APC = -22.1%, P < 0.01）. The prevalence of human S. japonicum infections appeared a tendency towards a decline in islet （AAPC = -25.1%, P < 0.01）, inner embankment （AAPC = -26.4%, P < 0.01） and hilly subtypes of schistosomiasis⁃endemic areas （AAPC = -32.5%, P < 0.01） of Hubei Province from 2004 to 2018, and the prevalence all appeared a tendency towards a decline during the infection control stage （from 2004 to 2008）, the transmission control stage （from 2009 to 2013） and the transmission interruption stage （from 2014 to 2018） （AAPC = -28.0%, -24.4% and -63.8%, all P values < 0.01）. The seroprevalence of human S. japonicum infections appeared an overall tendency towards a decline in Hubei Province from 2004 to 2018 （AAPC = -14.5%, P < 0.01）, and the trends for the reduction were both significant during the period from 2004 to 2012 （APC = -8.4%, P < 0.01） and from 2012 to 2018 （APC = -22.1%, P < 0.01）. In addition, the egg⁃positive rate of human S. japonicum infections appeared an overall tendency towards a decline in Hubei Province from 2004 to 2018 （AAPC = -30.6%, P < 0.05）, and the trend for the reduction was significant during the period from 2007 to 2014 （APC = -15.5%, P < 0.01）. Conclusions　The prevalence of human schistosomiasis appeared a tendency towards a decline in Hubei Province from 2004 to 2018, and the islet and inner embankment subtypes of endemic areas are a high priority for schistosomiasis control during the stage moving towards elimination in Hubei Province.

Whole transcriptome analysis and critical gene regulatory network analysis during Schistosoma japonicum infection and praziquantel treatment in mice

QU Lei, MA Song⁃cui, XU Li⁃li, JIANG Xin⁃ze, SUN Xue⁃wei, DONG Zhou⁃yan, WU Yu⁃long

2022, 34(2):  128. 

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Objective　To investigate long non⁃coding RNA (lncRNA)⁃microRNA (miRNA)⁃messenger RNA (mRNA) interactions and identify the critical gene regulatory network during Schistosoma japonicum infections and praziquantel treatment using whole transcriptome sequencing. Methods　A total of 110 male C57BL/6 mice were randomly divided into the control group, the infection group and the treatment group. Mice in the infection treatment and the control group were infected with S. japonicum cercariae via the abdomen, and liver specimens were sampled from 10 mice 3, 6, 8 weeks post⁃infection. Praziquantel treatment was given to mice in the treatment group 8 weeks post⁃infection, and liver specimens were sampled from 10 mice 2, 4, 6, 8, 10 weeks post⁃treatment. Total RNA was isolated from mouse liver specimens, and the transcriptome library was constructed for high⁃throughput whole transcriptome sequencing. The significant differentially expressed genes were subjected to functional annotations, Gene Ontology (GO) terms enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Correlation analysis of liver specimens was performed using R Corrplot and Himsc functions, and the lncRNA⁃miRNA⁃mRNA interaction network analysis was performed using R MixOmics and Himsc functions. Results　There were 1 176 differentially expressed miRNAs, 5 270 differentially expressed mRNAs, and 2 682 differentially expressed lncRNAs between the infection group and the control group, 1 279 differentially expressed miRNAs, 7 differentially expressed mRNAs, and 69 differentially expressed lncRNAs between the treatment group and the infection group, and 1 210 differentially expressed miRNAs, 4 456 differentially expressed mRNAs, and 2 016 differentially expressed lncRNAs between the treatment group and the control group. Correlation analysis showed a higher correlation of gene expression between the treatment group and the control group. Principal component analysis showed obvious separate clustering between the infection group and the treatment group. The differentially expressed genes with significant relevance were significantly enriched in 24 GO terms, including arachidonic acid metabolic process, xenobiotic catabolic process, unsaturated fatty acid metabolic process, xenobiotic metabolic process, long⁃chain fatty acid metabolic process, and 8 KEGG metabolic pathways, including cholesterol metabolism, tyrosine metabolism, linoleic acid metabolism, retinol metabolism, and steroid hormone biometabolism. Conclusions　There were 23 mRNAs including Cyp2b9 and 14 lncRNAs including Rmrpr in the core position of the gene regulatory network, which may play a critical role in S. japonicum infections and praziquantel treatment, and 9 miRNAs including miR⁃8105 may serve as potential molecular markers for diagnosis of S. japonicum infections.

Activity of aromatic pyrrole⁃based compounds against of Schistosoma japonicum cercariae and acute toxicity to fish

XING Yun⁃tian, YAO Jia⁃kai, QU Guo⁃li, ZHANG Su⁃yang, DAI Jian⁃rong, FENG Bo⁃nian

2022, 34(2):  141. 

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Objective　To test the activity of aromatic pyrrole⁃based compounds against cercariae of Schistosoma japonicum and test their acute toxicity to fish. Methods　A series of aromatic pyrrole⁃based compounds were synthesized using 4⁃benzyl⁃5⁃(trifluoromethyl)⁃1H⁃pyrrole⁃3⁃nitrile as the lead compound. The synthesized compounds were prepared into solutions at concentrations of 10.00, 1.00, 0.10, 0.01 mg/L, and the activity of these solutions against S. japonicum cercariae was tested in 30 min, while 0.10 mg/L and 0.01 mg/L niclosamide solutions served as a positive control and dechlorinated water with 1% dimethyl sulfoxide (DMSO) was used as a negative control, with 10 to 30 cercariae of S. japonicum in each group. In addition, the compounds were prepared into solutions at concentrations of 0.50, 0.25, 0.12, 0.06, 0.03 mg/L, and their toxicity to zebrafish was tested in 72 h, while 0.15 mg/L and 0.30 mg/L niclosamide solutions served as a positive control and dechlorinated water with 1% DMSO was used as a negative control, with 10 zebrafishes in each group. Results　A total of 7 aromatic pyrrole⁃based compounds were successfully synthesized. Treatment with compounds 102, 104 and 106 at a concentration of 0.01 mg/L for 30 min killed all S. japonicum cercariae, and compounds 105 and 107 showed no activity against cercariae. No death of cercariae was found in the blankcontrol group, while treatment with 0.10 mg/L niclosamide for 10 min caused a 100% mortality rate of S. japonicum cercariae and 0.01 mg/L niclosamide failed to kill S. japonicum cercariae. No zebrafish death was found 72 h post⁃treatment with compounds 101, 104 and 105 at a concentration of 0.03 mg/L, and exposure to compounds 102, 103 and 106 at a concentration of 0.03 mg/L for 12 h resulted in a 100% mortality rate of zebrafish. No zebrafish death occurred 72 h post⁃treatment with 0.50 mg/L Compound 104, and no zebrafish death was found in the blank control group, while treatment with 0.30 mg/L niclosamide for 24 h resulted in a 100% mortality rate of zebrafish. Conclusions　Compound 104 achieves a 100% mortality rate against S. japonicum cercariae at a concentration of 0.01 mg/L for 30 min, and causes no death of zebrafish at a concentration of 0.50 mg/L for 72 h, which may serve as a cercaricide candidate.

Effects of Toxoplasma gondii infection on mouse and human uterine natural killer cells

ZHANG Rong, SHAO Tian⁃ye, SHAO Chen⁃lu, QIU Jing⁃fan, WANG Yong

2022, 34(2):  149. 

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Objective　To examine the effects of Toxoplasma gondii infection on the proportion, quantity, differentiation and function of mouse and human uterine natural killer cells (uNK cells), so as to explore the role of uNK cells in abortion of early pregnancy caused by T. gondii infection. Methods　Pregnant mice were injected intraperitoneally with T. gondii tachyzoites on day 6.5 of pregnancy, and the abortion mouse model caused by T. gondii infections was constructed. Mouse uterine lymphocytes were isolated on day 9.5 of pregnancy. Human uterine lymphocytes were isolated from fresh human decidual specimens after abortion in normal early pregnancy and co⁃cultured with tachyzoites of the T. gondii RH strain for 48 h at T. gondii/uterine lymphocytes ratios of 0.5∶1, 1∶1 and 2∶1. The phenotypes of mouse uNK cells (CD122, NK1.1, DX5) and human uNK cells (CD3, CD56, CD11b, CD27) and the expression of intracellular cytokines interferon⁃γ (IFN⁃γ) and tumor necrosis factor⁃α (TNF⁃ α) were detected by flow cytometry. Mouse and human uNK cells were sorted by magnetic beads, and the cytotoxicity of uNK cells was tested using the lactate dehydrogenase (LDH) release assay at effector/target cell ratios of 1∶1, 5∶1, 10∶1 and 20∶1 with mouse or human uNK cells as effector cells and mouse YAC⁃1 cells or human K562 cells as target cells. Results　On day 9.5 of pregnancy， the mouse abortion rate was significantly higher in the infected group than that in the control group (83.02% vs. 3.51%; [χ2] = 71.359, P < 0.001). Significantly lower absolute number of uNK cells [(4 547 ± 1 610) cells/mouse vs. (8 978 ± 3 339) cells/mouse; U = 2.000， P < 0.05], lower NK1.1 expression on uNK cell surface [(74.53 ± 8.37)% vs. (93.00 ± 1.11)%; U = 0.000, P < 0.05], higher proportion of NK1.1⁃DX5⁃ cells [(20.10 ± 8.03)% vs. (5.04 ± 0.68)%; U = 0.000, P < 0.05], lower proportion of NK1.1+DX5+ cells [(21.70 ± 12.48)% vs. (45.75 ± 2.26)%; U = 0.000, P < 0.05] and higher IFN⁃γ expression [(16.74 ± 1.36)% vs. (8.13 ± 1.90)%; U = 0.000, P < 0.05] were detected in the infected group than in the control group, while no significant difference was seen in TNF⁃α expression between the two groups [(67.98 ± 9.20)% vs. (52.93 ± 10.42)%; U = 2.000, P > 0.05]. The mouse uNK cells showed a strong cytotoxicity in the infected group, and the cytotoxicity gradually increased with the effector/target cell ratio. The cytotoxicity of uNK cells against YAC⁃1 cells was 2.30%, 4.32%, 8.12% and 12.65% in the infected group and 1.21%, 1.63%, 2.51% and 3.22% in the control group at effector/target cell ratios of 1∶1, 5∶1, 10∶1 and 20∶1, respectively. Following co⁃culture of human uterine lymphocytes and tachyzoites of the T. gondii RH strain for 48 h, the proportion [TOX 2∶1 group vs. control group: (6.61 ± 1.75)% vs. (17.48 ± 4.81)%; F = 7.307, P < 0.01], and absolute number of human uNK cells in uterine lymphocytes of human uNK cells in uterine lymphocytes [TOX 2∶1 group vs. control group: (12 104 ± 5 726) cells/well vs. (65 285 ± 21 810) cells/well; H = 11.540, P < 0.01] were significantly lower in the infected group than in the control group. A lower proportion of CD56brightCD16⁃ NK cells [TOX 2∶1 group vs. control group: (25.25 ± 5.90)% vs. (36.03 ± 4.51)%; F = 3.213, P > 0.05] and higher proportion of CD56dimCD16+ NK cells [TOX 2∶1 group vs. control group: (11.15 ± 2.15)% vs. (7.09 ± 2.24)%; F = 2.992, P > 0.05] were detected in uNK cells in the infected group than in the control group, and the ratio of CD56brightCD16⁃ cells/CD56dimCD16+ cells was significantly lower in the infected group than in the control group [TOX 2∶1 group vs. control group: (2.37 ± 0.92) vs. (5.58 ± 2.39); H = 8.228, P < 0.05]. In addition， the proportion of CD11b+CD27⁃ cells in human uNK cells was significantly higher in the infected group than in the control group [TOX 2∶1 group vs. control group: (30.28 ± 6.91)% vs. (17.48 ± 4.67)%; H = 6.556, P < 0.05]， while no significant differences were found between the two groups in terms of IFN⁃γ [TOX 2∶1 group vs. control group: (14.13 ± 1.28)% vs. (15.19 ± 1.64)%; F = 1.639, P > 0.05] or TNF⁃α expression [TOX 2∶1 group vs. control group: (54.76 ± 10.02)% vs. (50.33 ± 3.67)%; F = 0.415, P > 0.05]. Human uNK cells presented a strong cytotoxicity in the infected group, and the cytotoxicity gradually increased with the effector/target cell ratio. The cytotoxicity of human uNK cells against K562 cells was 11.90%, 28.11%, 49.91% and 73.35% in the infected group and 12.21%, 21.63%, 33.51% and 48.22% in the control group at effector/target cell ratios of 1∶1, 5∶1,10∶1 and 20∶1, respectively. Conclusions　T. gondii infection presents diverse effects on the differentiation and secretion ability of mouse and human uNK cells. However, T. gondii infection causes a reduction in the absolute number and enhances the cytotoxicity of both mouse and human uNK cells.

Effect of Echinococcus granulosus hydatid cyst fluid protein on allergic rhinitis induced by ovalbumin in mice

GAO Hong⁃yu, WAN Chen, SUN Fa⁃di, WANG Shu⁃ying, CHU Liang, YUAN Yuan, WANG Pu, YU Xue⁃qin, LIU Wei⁃yue, DONG Huai⁃fu, YANG Xiao⁃di

2022, 34(2):  158. 

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Objective　To investigate the protective effect of Echinococcus granulosus hydatid cyst fluid protein (HCFP) on ovalbumin (OVA)⁃induced allergic rhinitis (AR) in mice. Methods　Twenty⁃four BALB/c mice at ages of 8 to 10 weeks, each weighing approximately 20 g, were randomly divided into four groups, including groups A (blank control group), B (blank intervention group), C (AR model group) and D (AR+HCFP intervention group), with 6 mice in each group. On days 0, 2, 4, 6, 8, 10 and 12, mice in groups A, B, C and D were injected with 200 μL sterile phosphate buffered saline (PBS), 200 μL sterile PBS containing 20 μg HCFP, 200 μL sterile PBS containing 50 μg OVA and 5 mg Al(OH)3 gel, and 200 μL sterile PBS containing 50 μg OVA, 5 mg Al(OH)3 gel and 20 μg HCFP, respectively. On days 14 to 20, mice in groups A, B, C and D were administered with 40 μL sterile PBS, 40 μL sterile PBS containing 20 μg HCFP, 40 μL sterile PBS containing 2 mg OVA and 40 μL sterile PBS containing 2 mg OVA and 20 μL HCFP by nasal drop, respectively. Mouse behavioral changes were observed and behavioral scores were estimated. The serum levels of interferon⁃γ (IFN⁃γ), interleukin⁃4 (IL⁃4), IL⁃5, IL⁃10, transforming growth factor⁃β (TGF⁃β) and OVA⁃specific IgE antibody (OVA⁃sIgE) were measured using enzyme⁃linked immunosorbent assay (ELISA), and the pathological changes of mouse nasal mucosa were observed by hematoxylin and eosin (HE) staining. Results　The mean behavioral score was significantly greater in Group C (6.83 ± 0.50) than in groups A (1.17 ± 0.52) and B (1.33 ± 0.52) (P < 0.05), while a lower mean behavioral score was estimated in Group D (3.50 ± 0.50) than in Group C (P < 0.05). There were significant differences among the groups in terms of serum IFN⁃γ (F = 4.08, P < 0.05), IL⁃4 (F = 275.90, P < 0.05), IL⁃5 (F = 96.82, P < 0.05), IL⁃10 (F = 77.67, P < 0.05), TGF⁃β (F = 9.98, P < 0.05) and OVA⁃sIgE levels (F = 44.69, P < 0.05). The serum IFN⁃γ level was significantly lower in Group C than in groups A, B and C (P < 0.05), and the serum levels of IL⁃4, IL⁃5 and OVA⁃sIgE were significantly higher in Group C than in groups A, B and C (P < 0.05), while the serum IL⁃10 and TGF⁃β levels were significantly greater in Group D than in Group C (P < 0.05). Microscopy showed apparent loss of nasal mucosa cilia, increased number and enlargement of goblet cells, interstitial edema and submucous vascular dilation in Group C, while the pathological changes of nasal mucosa were alleviated in Group D relative to Group C. Conclusion　E. granulosus HCFP has a protective activity against OVA⁃induced allergic rhinitis in mice.

Construction of a risk assessment indicator system for re-establishment of imported malaria

LAN Zi⁃yao, LI Yang, HUANG Yu⁃ting, SHI Wei⁃fang, SHE Dan⁃ya, JIANG Zhi, LIU Lei

2022, 34(2):  163. 

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Objective　To create a risk assessment indicator system for re⁃establishment of imported malaria. Methods　The risk assessment indicator system for re⁃establishment of imported malaria was preliminarily constructed through literature review and thematic discussions. A total of 26 malaria control experts were selected to carry out a two⁃round Delphi consultation of the indicator system. The active coefficient, authority coefficient and coordination coefficient of the experts and the coefficient of variation on each indicator were calculated for indicator screening and the weight of each indicator was calculated. The reliability of the indicator system was evaluated using Cronbach’s coefficient α, and the content validity of the indicator system was evaluated using the authority coefficient of the expert, while the structural validity of the indicator system was evaluated using Kaiser⁃Meyer⁃Olkin (KMO) test and factor analysis. Results　Two rounds of Delphi expert consultations were completed by 23 malaria control experts, and a risk assessment indicator system for re⁃establishment of imported malaria was constructed, including 3 primary indicators, 7 secondary indicators, and 21 tertiary indicators. The active coefficient (100.00% vs. 88.46%; P < 0.01) and coordination coefficient of the expert (0.372 vs. 0.286; P < 0.01) were significantly greater in the second round of the Delphi expert consultation than in the first round. After the second round of the Delphi expert consultation, the authority coefficient of the experts ranged from 0.757 to 0.930 on each indicator, and the coefficients of variation were 0.098 to 0.136, 0.112 to 0.276 and 0.139 to 0.335 for the primary, secondary and tertiary indicators, respectively. The overall Cronbach’s coefficient α of the indicator system was 0.941, and there were significant differences in the KMO values for primary (KMO value = 0.523; [χ2] = 18.192, P < 0.05), secondary (KMO value = 0.694, [χ2] = 51.499, P < 0.01) and tertiary indicators (KMO value = 0.519; [χ2] = 477.638, P < 0.01), while the cumulative contribution rate of six principal components in the tertiary indicators was 84.23%. The normalized weights of three primary indicators of the source of infection, transmission condition and control capability were 0.337, 0.333 and 0.329, and the three secondary indicators with the greatest normalized weights included the number of imported cases and malaria parasite species (0.160), introduction of imported cases in China and medical care seeking (0.152), vector species and density (0.152), while the five tertiary indicators with the greatest normalized weights included the malaria parasite species of imported cases (0.065), vector populations (0.064), and the time interval from onset to medical care seeking (0.059), number of imported cases (0.056), and the time interval from medical care seeking to definitive diagnosis (0.055). Conclusion　A risk assessment indicator system for re⁃establishment of imported malaria is successfully created, which provides insights into the assessment of the risk of re⁃establishment of imported malaria and management of key high⁃risk factors in malaria⁃eliminated areas.

Time to initial diagnosis of imported malaria and its influencing factors in Jiangsu Province

LU Guang⁃yu, CAO Yuan⁃yuan, WANG Wei⁃ming, YANG Meng⁃meng, LIU Yao⁃bao, ZHANG Yu⁃ying, CHEN Qi, LU Yan, ZHOU Hua⁃yun, ZHU Guo⁃ding, CAO Jun

2022, 34(2):  172. 

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Objective　To investigate the health⁃seeking behaviors of imported malaria cases after returning to China, and to investigate the factors affecting the time to initial diagnosis, so as to provide the scientific evidence for early identification of imported malaria cases and prevention of severe cases development and secondary transmission. Methods　The individual demographic features, and the disease onset and the time to initial diagnosis of imported malaria cases in Jiangsu Province in 2019 were captured from the National Notifiable Disease Report System and the Information Management System for Parasitic Disease Control in China. The characteristics of health⁃seeking behaviors and epidemiological features of imported malaria cases were descriptively analyzed, and the factors affecting the time to initial diagnosis of imported malaria cases after returning to China were identified using multivariate logistic regression analysis. Results　A total of 244 imported malaria cases were reported in Jiangsu Province in 2019, and the time to initial diagnosis of the cases were 1-12 days, with mean time of (1.53 ± 1.65) days, with median time of one day. The highest number of malaria cases seeking healthcare services were found on the day of developing primary symptoms (76 cases, 31.1%), followed by on the second day (68 cases, 27.9%), on the third day (46 cases, 18.9%), and 54 cases (22.1%) received initial diagnosis 3 days following presence of primary symptoms, including 3 cases with initial diagnosis at more than one week. High proportions of imported malaria cases with a delay in the time to initial diagnosis were seen in migrant workers who returned to China in January (14 cases, 5.7%) and December (13 cases, 5.3%) and those aged between 41 and 50 years (32 cases, 13.1%). Multivariate logistic regression analysis showed relative short time to initial diagnosis among imported malaria cases returning to China on March [odds ratio (OR) = 0.16, P = 0.03, 95% confidence interval (CI): (0.03, 0.85)] and those with a history of overseas malaria parasite infections [OR = 0.36, P = 0.001, 95% CI: (0.19, 0.67)]. Conclusions　Timely health⁃seeking behaviors should be improved among imported malaria cases in Jiangsu Province, patients with a history of overseas malaria infections require faster health⁃seeking activities.

Scanning electron microscopic observation of the external morphology of Dermatophagoides farinae at different developmental stages

ZHAN Xiao⁃dong, YAO Run, WANG Mei⁃qing, JIANG Feng, GUO Wei, TANG Fei⁃fan, WANG Lan, LI Chao⁃pin

2022, 34(2):  179. 

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Objective　To investigate the morphological characteristics of Dermatophagoides farinae at different developmental stages. Methods　The cultured D. farinae was isolated, and the external morphological features of mites at various developmental stages were observed using scanning electron microscopy (SEM), including egg, larva, nymph and adult stages. Results　 The D. farinae egg appeared a long oval shape, and the larval mites had three pairs of legs. The nymph had four pairs of legs and underdeveloped genital pores containing genital setae and anal setae, and adult mites appeared long and oval in shape, with decorative patterns on epidermis, and had four pairs of legs. In male adult mites, remarkable thickening of the leg I and thicker and longer leg III than the leg IV were seen, and ventral genital regions were found between the basal segments of legs III and IV; the anus was surrounded by a circular peri⁃anal ring, with a pair of anal suckers and anal setae within the ring. In the female adult mites, slender legs III and IV with an equal length were seen, and a “λ⁃shape” genital hole was observed on the ventral surface, with a crescent⁃like genital plate in the anterior part, and the anus appeared a longitudinal slit. Conclusion　An SEM observation of the external morphology of D. farinae provides understandings of the morphological characteristics of D. farinae, which is of great significance for the classification and identification.

Molecular epidemiological investigation on Theileria in yellow cattle from Xiangxi Autonomous Prefecture of Hunan Province

LI Hui, HOU Qiang⁃hong, TANG Guo⁃xiang, WU Yang⁃xiang, ZHANG Da⁃jun, ZHAO Jun⁃long, SONG Jin⁃qiu

2022, 34(2):  183. 

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bjective　To investigate the prevalence and genetic variation of Theileria in yellow cattle in Xiangxi Autonomous Prefecture of Hunan Province. Methods　A total of 184 blood specimens were collected from Fenghuang, Huanyuan and Baojing counties of Xiangxi Autonomous Prefecture during the period from August 2018 through August 2019, and were detect using PCR assay with the specific 18S ribosomal rRNA (18S rRNA) gene targeting Theileria. The gene sequences of positive specimens were aligned with the sequences recorded in GenBank, and a phylogenetic tree was created with Plasmodium ovale 18S rRNA as an outgroup. Results　A total of 143 blood samples were positive for Theileria, with a mean detection rate of 77.7%. Theileria was prevalent in the blood samples from yellow cattle in all three counties, with detection rates of 85.0% in Fenghuang County, 88.3% in Huayuan County and 61.0% in Baojing County, respectively. There was no significant difference in the detection rate of Theileria between Xiangxi yellow cattle and normal yellow cattle (77.2% vs. 79.5%; [χ2] = 0.08, P > 0.05), while the detection of Theileria was significantly lower in the housed yellow cattle than in free⁃range cattle (68.9% vs. 89.7%; [χ2] = 22.36, P < 0.01). A total of 18 PCR positive samples were randomly selected for sequencing and analysis, and all samples showed more than 99.0% homology with T. luwenshuni isolates. Phylogenetic analysis showed that the 18 positive samples were clustered into the same branch with T. luwenshuni, but were far away from other isolates. Conclusions　The prevalence of Theileria is high in yellow cattle from Xiangxi Autonomous Prefecture of Hunan Province, and T. luwenshuni may be the dominant parasite species.

Reconstruction of teaching mode of Human Parasitology among rural order⁃oriented medical students in the context of curriculum ideology and politics

CAO De⁃ping, JIANG Li⁃ping, CHEN Gen, LI Da⁃yu, MO Gang, PENG Xiao⁃hong

2022, 34(2):  187. 

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To set the cultivation goal with adaptation to rural order⁃oriented medical students, the teaching mode of Human Parasitology was reformed in the context of curriculum ideological and political education. The new teaching mode not only enables students to harvest medical knowledge during the school education stage, but also plays a guiding role in cultivation of humanistic qualities and professional spirit, which provides a basis for cultivating general practitioners serving for grassroots healthcare.

Epidemic status of imported malaria before and after malaria elimination in Jiaozuo City of Henan Province

RAN Wei⁃xia, LI Tang⁃yun, ZHANG Zhong⁃cao, MA Qian, XU Xiao⁃li

2022, 34(2):  191. 

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Objective　To analyze and compare the epidemiological characteristics of imported malaria in Jiaozuo City before and after malaria elimination, so as to provide insights into the malaria surveillance during the post⁃elimination stage and prevention of re⁃establishment of imported malaria. Methods　Data pertaining to the epidemic situation and individual investigation of malaria in Jiaozuo City before (from 2010 to 2016) and after malaria elimination (from 2017 to November, 2020) were captured from the National Notifiable Disease Reporting System and the Information System for Parasitic Diseases Control and Prevention of Chinese Center for Disease Control and Prevention and were analyzed statistically. Results　A total of 74 imported malaria cases were reported in Jiaozuo City from 2010 to 2021. Imported cases were predominantly Plasmodium falciparum malaria cases in Jiaozuo City before and after malaria elimination, and there was no significant difference in the proportion of malaria parasite species ([χ2] = 0.234, P > 0.05). The imported malaria cases was predominantly reported in Wuzhi County, and was identified in overseas male farmers and businessmen at ages of 20 to 59 years, while the greatest number of imported malaria cases was reported in June and December before and after malaria elimination. The imported malaria cases predominantly acquired malaria parasite infections in sub⁃Saharan African countries; however, the proportion of imported malaria cases returning from Southeast Asian counties increased after malaria elimination than before malaria elimination ([χ2] = 5.989, P < 0.05). The longest duration from onset to definitive diagnosis of malaria reduced from 27 days before malaria elimination to 18 days after malaria elimination, and the median duration reduced from 3 days to 2 days, while the proportion of definitive diagnosis of malaria increased from 60.47% before malaria elimination to 83.87% after malaria elimination ([χ2] = 4.724, P < 0.05). In addition, the proportion of malaria cases definitively diagnosed and reported by medical institutions increased after malaria elimination than before malaria elimination ([χ2] = 5.406, P < 0.05). Conclusions　The imported malaria patients were predominantly P. falciparum malaria cases in Jiaozuo City during 2010 to 2021, and the patient’s medical care⁃seeking awareness and medical staff’s diagnosis and treatment ability have improved after malaria elimination. It is necessary to strengthen and improve malaria surveillance and response system and prevent the re⁃establishment of overseas imported malaria.

Progress of researches on infection with two species of Echinococcus causing human diseases in animal hosts and influencing factors

LI Chun⁃yang, GUAN Ya⁃yi, WU Wei⁃ping, XUE Chui⁃zhao

2022, 34(2):  194. 

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Echinococcosis is a serious zoonotic parasitic disease caused by infections with larval Echinococcus. The life cycle of Echinococcus involves a variety of animal hosts, including hoofed animals and rodents as intermediate hosts and carnivores as definitive hosts. The transmission of human echinococcosis is closely associated with the life cycle of E. granulosus and E. multilocularis among animal hosts in nature. This review summarizes the recent advances in the prevalence and influencing factors of E. granulosus and E. multilocularis infections in animal hosts, so as to provide insights into precision control of echinococcosis.

Epidemic process and influencing factors of hemorrhagic fever with renal syndrome: a review

WANG Na, YIN Jia⁃xiang

2022, 34(2):  200. 

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Hemorrhagic fever with renal syndrome (HFRS) is a category B infectious disease caused by hantaviruses that cause acute kidney injury and has a high mortality rate, and HFRS control has been given a high priority in China. It has been found that hantavirus types are closely associated with selective host transformation and regional adaption, and continue to evolve in the form of gene recombination. The severity of HFRS varies in hantavirus types. In addition, global environmental changes and alteration of host animal behaviors accelerate Hantavirus genome variations, and large⁃scale land reclamation and infrastructure building increases the likelihood of human contacts with hosts and disease⁃transmitting vectors, thereby increasing the risk of HFRS development. This review summarizes the main characteristics and influencing factors pertaining to the epidemic process of HFRS, so as to provide insights into effective prevention and control of this infectious disease.

Role of the ES-62 protein derived from Acanthocheilonema viteae in regulation of immune dysregulation diseases: a review

HU Qi, XING Jing⁃yu, WU Pei, HUANG Ting⁃ting, YANG Xiao⁃di

2022, 34(2):  204. 

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ES⁃62 is a phosphorylcholine⁃containing, 62 kDa glycoprotein derived from the excretory⁃secretory product of Acanthocheilonema viteae, which is effective for the prevention and treatment of immune dysregulation diseases through triggering activation of immune cells, such as dendritic cells, mononuclear macrophages and regulatory B cells and mediating immune responses. Recently, the role of the ES⁃62 protein in the management of allergic, autoimmune and metabolic diseases has been paid much attention. This review summarizes the regulatory role of the ES⁃62 protein in immune dysregulation diseases and the underlying mechanisms, so as to provide insights into future experimental studies.

Enterobius vermicularis infection in Guiyang City, Guizhou Province: a case report

LU Li⁃Dan, SHE Dan⁃Ya, LIN Guang⁃Chu, GUO Hua

2022, 34(2):  212. 

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The report presents a case with  Enterobius vermicularis infections  in Guiyang City, Guizhou Province, aiming to strengthen the attention to parasitic infections.

Cystic echinococcosis of the waist and hip: a case report

CHEN Rui, WANG Zhi⁃xin, ZHOU Liu⁃xin, CHEN Xiao⁃bin, HAN Jun⁃wei, FAN Hai⁃ning, WANG Hai⁃jiu

2022, 34(2):  214. 

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A patient with cystic echinococcosis was presented with primary lesions in the waist and hip. The case was misdiagnosed as subcutaneous abscess at initial diagnosis, and then definitively diagnosed as echinococcosis by means of imaging examinations and anti⁃Echinococcus antibody test. This case was reported with aims to improve the awareness of cystic echinococcosis among clinical physicians to avoid and reduce the misdiagnosis and missing diagnosis.