Table of Content

30 April 2025, Volume 43 Issue 2

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EDITORIAL

History of schistosomiasis control in China: From discovery to transmission interruption

XU Jing, WANG Qiang, GUO Suying, ZHANG Lijuan, ZHOU Xiaonong, LI Shizhu

2025, 43(2):  155-161.  doi:10.12140/j.issn.1000-7423.2025.02.001

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The first modern medical description of schistosomiasis had been recorded in China for 120 years. Following decades of efforts, remarkable achievements have been obtained in schistosomiasis control in China, and the criterion of transmission interruption has been achieved in China by the end of 2023, with 78.49% of endemic counties reaching the target for schistosomiasis elimination. Due to climate change, natural disasters, and population mobility there are still multiple challenges to achieve the goal of schistosomiasis elimination and sustainably consolidate the achievements of disease elimination in China. It is recommended to continue to implement the integrated strategy with an emphasis on management of the source of Schistosoma japonicum infections and intensified snail control in key environments, strengthen surveillance, forecasting and risk assessment, innovate science and technology-empowered schistosomiasis control tools, and improve the capability building for high-quality acceleration of the progress towards schistosomiasis elimination in China.

SPECIAL REPORT

Epidemiological characteristics of malaria in China, 2024

ZHANG Li, XIA Zhigui, LI Shizhu

2025, 43(2):  162-166.  doi:10.12140/j.issn.1000-7423.2025.02.002

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The individual malaria case information forms in 31 Provinces/Municipalities/Autonomous Regions (excluding Taiwai, Hong Kong, Macao) and Xinjiang Production and Construction Corps of China in 2024 were collected from “Information System for Infectious Disease Surveillance”. The epidemiological characteristic of malaria cases was analyzed. In 2024, a total of 3 157 malaria cases were reported, which was increased by 26.9% compared to that in 2023 (2 488). Of these cases, 3 155 imported cases and 2 blood transfusion-induced cases were identified. The reported cases included 2 008 falciparum malaria (63.6%, 2 008/3 157), 798 vivax malaria (25.3%, 798/3 157), 274 ovale malaria (8.7%, 274/3 157), 65 malariae malaria (2.1%, 65/3 157) and 12 cases with mixed-infection (0.5%, 12/3 157). The male-to-female ratio was 12.4 ∶1, with the 30-39 age group having the highest number of cases (28.3%, 895/3 157), primarily among overseas laborers (69.2%, 2 183/3 155). Other 30 provinces except the Xizang and the Xinjiang Production and Construction Corps reported malaria cases. The top five provinces by case numbers were Yunnan (564), Guangdong (246), Henan (241), Shandong (232) and Sichuan (220), cumulatively reporting 1 503 cases (47.6%, 1 503/3 157). A total of 112 severe malaria cases (3.5%, 112/3 157) and 15 deaths (0.5%, 15/3 157) were reported. There has been no reported local mosquito-borne malaria cases for eight consecutive years, but risks from imported malaria persist. It is critical to enhance the sensitivity of the surveillance system, ensure timely detection and treatment of cases, reduce the progression of falciparum malaria to severe or death, and prevent secondary transmission caused by vivax malaria.

ORIGINAL ARTICLES

Establishment and preliminary evaluation of a rapid assay for detection of Schistosoma japonicum nucleic acid based on LAMP-CRISPR/Cas12a

LIN Weina, DENG Wangping, YANG Ying, LI Yinlong, QIN Zhiqiang, HONG Yang, FENG Ting, LV Chao, XU Jing

2025, 43(2):  167-174.  doi:10.12140/j.issn.1000-7423.2025.02.003

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Objective To develop a highly sensitive and specific assay for rapid detection of Schistosoma japonicum nucleic acid fragments by means of loop-mediated isothermal amplification (LAMP) combined with the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 12a (CRISPR/Cas12a) system. Methods The Sj28S ribosomal gene fragment was selected as the target sequence, and LAMP primers, single stranded DNA (ssDNA), and CRISPR RNA (crRNA) were designed. The concentrations of each component was determined, and the optimal reaction system and conditions were screened to establish the LAMP-CRISPR/Cas12a assay for rapid fluorescent detection of S. japonicum nucleic acids. The sensitivity was evaluated using different concentrations of S. japonicum genomic DNA (1 ng/μl,100 pg/μl, 10 pg/μl, 1 pg/μl, 100 fg/μl, 10 fg/μl, 1 fg/μl) and recombinant plasmids containing the targeted Sj28S ribosomal gene fragment (10⁶, 10⁵, 10⁴, 10³, 10², 10¹, 10⁰, 10^-1 copies/μl), and the specificity was assessed using genomic DNA from S. japonicum, S. mansoni, Clonorchis sinensis, Fasciola gigantica, Paragonimus westermani, Angiostrongylus cantonensis, Echinococcus multilocularis, Neotricula aperta infected with S. mekongi, and Oncomelania hupensis with and without S. japonicum infections. Mice were infected with 40, 20 and 10 cercariae of S. japonicum, and mouse fecal samples were collected 3 to 6 weeks post-infection and plasma samples were collected 3 days and 1 to 6 weeks post-infection. The efficiency of the LAMP-CRISPR/Cas12a assay was examined for detection of stool and plasma DNA samples from mice infected with S. japonicum with qPCR assay as a parallel control. Results The LAMP-CRISPR/Cas12a assay was established based on crRNA-2, and the optimal final concentrations of ssDNA, crRNA, and Cas12a were 400, 200, and 200 nmol/L, respectively, with pre-amplification duration of 30 minutes. The lowest detection limit of this assay was 10 fg/μl for the genome of adult S. japonicum, and 1 copy/μl for the recombinant plasmids, and the assay had no cross reaction with genomic DNA from S. mansoni, C. sinensis, F. gigantica, P. westermani, A. cantonensis, E. multilocularis, N. aperta infected with S. mekongi, and O. hupensis without S. japonicum infections. The positive rates of LAMP-CRISPR/Cas12a and qPCR assays were 85.42% (41/48) and 51.02% (175/343) for detection of the pooled fecal samples from S. japonicum-infected mice, respectively (χ² = 8.71, P < 0.05), and the LAMP-CRISPR/Cas12a assay detected fecal samples from S. japonicum-infected mice as early as 3 weeks post-infection, which was earlier than qPCR assay that detected fecal samples from infected mice 4 weeks post-infection. The positive rates of LAMP-CRISPR/Cas12a and qPCR assays were 58.3% (28/48) and 27.11% (93/343) for detection of plasma samples from S. japonicum-infected mice, respectively (χ² = 9.77, P < 0.05), and both LAMP-CRISPR/Cas12a and qPCR assays detected circulating Schistosoma DNA in the plasma of S. japonicum-infected mice as early as 3 days post-infection, with positive rates of 53.06% (26/49) and 22.45% (11/49), respectively (χ² = 9.77, P < 0.05). Conclusion A simple, rapid and highly sensitive, and specific LAMP-CRISPR/Cas12a assay has been developed for rapid, early detection of S. japonicum nucleic acids, which is a promising new tool for field diagnosis of schistosomiasis.

Changes of Tsc22d3 expression in NK cell in liver of mice infected with Schistosoma japonicum and the effect on the cytotoxicity of NK cells

XU Fangfang, CHEN Quan, HU Yuan, CAO Jianping

2025, 43(2):  175-180.  doi:10.12140/j.issn.1000-7423.2025.02.004

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Objective To investigate the expression of Tsc22 domain family member 3 (Tsc22d3) expression in natural killer (NK) cell subsets in liver of mice infected with Schistosoma japonicum and its effect on the cytotoxicity of NK cells. Methods Forty-two female C57BL/6 mice were infected with S. japonicum cercariae (20 ± 1 per mouse) by abdominal patch method. Six mice were sacrificed before infection and at the 4th and 6th weeks after infection respectively. NK cells in the liver were enriched by magnetic bead sorting and single-cell sequencing was performed to analyze the expression of Tsc22d3 in NK cells and the activated signaling pathways. The remaining 24 mice were randomly divided into an infection group and a control group, with 12 mice in each group. At the 4th and 6th weeks after infection, 6 mice in each group were anesthetized and non-parenchymal cells in the liver were isolated. The Tsc22d3 expression was detected in mouse hepatic NK cells in the control and infection groups using flow cytometry. Empty plasmid and Tsc22d3 plasmid were transfected into NK92 cells to obtain the empty plasmid control group (NC group) and the Tsc22d3 overexpression NK92 cell group (Tsc22d3⁺NK92 group) by using liposome transfection method. NK92 cells in the Tsc22d3⁺NK92 group and the NC group were stimulated with soluble egg antigen (SEA) for 24 or 48 h, and the expression of interferon-γ (IFN-γ) and perforin 1 (Prf1) was detected in NK cells using flow cytometry and real-time quantitative fluorescence PCR (qPCR) assay. All statistical analyses were performed with the software GraphPad Prism 9, and differences of means between the two groups was tested for statistical significance with t test. Results Single-cell sequencing revealed that compared with uninfected mice (2.41), the expression of Tsc22d3 continued to increase at 4 weeks (3.16) and 6 weeks after infection (3.76), and Tsc22d3 was highly expressed in the C3 subset of NK cells. The pathway of natural killer cell mediated cytotoxicity in the C3 subgroup were significantly activated. Flow cytometry showed that the proportions of Tsc22d3⁺NK92 cells were (0.24 ± 0.01)% and (1.40 ± 0.14)% in mouse hepatic NK cells 4 weeks and 6 weeks post-infection in the infection group, which were both higher than in the control group (0.12% ± 0.02%) (t = 12.110 and 22.010, both P values < 0.01). The proportions of IFN-γ and Prf1 positive cells were (1.66 ± 0.15)% and (53.23 ± 0.81)% in the Tsc22d3⁺NK92 group 24 h post-stimulation with SEA, which higher than in the NC group [(0.88 ± 0.13)% and (29.93 ± 1.85)%, respectively] (t = 6.800 and 20.010, both P values < 0.01), and the relative mRNA expression of IFN-γ and Prf1 was (1.53 ± 0.24) and (1.41 ± 0.04) in the Tsc22d3⁺NK92 group 24 h post-stimulation with SEA, which was higher than in the NC group [(1.00 ± 0.07) and (1.00 ± 0.140), respectively] (t = 3.573 and 4.973, P < 0.05 and 0.01). The relative mRNA expression of IFN-γ and Prf1 was (2.06 ± 0.39) and (1.54 ± 0.26) in the Tsc22d3⁺NK92 group 48 h post-stimulation with SEA, which was higher than in the NC group [(1.06 ± 0.44) and (1.00 ± 0.04), respectively] (t = 2.953 and 3.588, both P values < 0.05). Conclusion Tsc22d3 is highly expressed in the C3 subset of hepatic NK cells during the course of S. japonicum infection, and high Tsc22d3 expression may increase the cytotoxicity of NK cells.

Epidemiological characteristics of schistosomiasis among transient population in Hangzhou City from 2004 to 2023

ZHU Sujuan, HUO Liangliang, WANG Heng, LIU Shuai, TANG Yi, JIN Xingyi, ZHENG Caifang, XU Minjie

2025, 43(2):  181-186.  doi:10.12140/j.issn.1000-7423.2025.02.005

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Objective To analyze schistosomiasis surveillance Results among transient population in Hangzhou City from 2004 to 2023, and to investigate the epidemiological characteristics of schistosomiasis cases. Methods Schistosomiasis surveillance data among transient population in Hangzhou City from 2004 to 2023 were retrieved from the annual schistosomiasis surveillance reports, historical materials compilation and annual summary of schistosomiasis control in Hangzhou Municipal Center for Disease Control and Prevention, and data pertaining to schistosomiasis epidemics were captured from the Notifiable Disease Report Information Management System of Chinese Center for Disease Control and Prevention, epidemiological case investigation forms and investigation reports of confirmed schistosomiasis cases. Schistosomiasis surveillance was performed among transient population from endemic foci by means of active and passive approaches. The number of transient population monitored for schistosomiasis, number of seropositives, number of transient population receiving stool examinations, number of transient population receiving urine tests and number of transient population positive for urine tests, and the gender, age, occupation, place of origin, clinical symptoms and signs, history of exposure to infested water, place of infection, and local work, living and healthcare-seeking behaviors of confirmed schistosomiasis cases were collected. All data were analyzed statistically using the SPSS 26.0 software and R 4.1.0 package, and the temporal, spatial and population distribution, place of infection, and clinical diagnosis and treatment of schistosomiasis patients were analyzed using a descriptive epidemiological method. Results The mean seroprevalence of schistosomiasis was 0.51% (1 188/234 415) among transient population in Hangzhou City from 2004 to 2023, with the highest in 2004 (1.37%, 115/8 366) and the lowest in 2023 (0.01%, 1/8 160), and the seroprevalence of schistosomiasis appeared a tendency towards a decline over years from 2004 to 2023 (Z = ‒4.190, P < 0.05). There were 40 confirmed schistosomiasis cases, and all were imported cases (34 domestically imported cases and 6 overseas imported cases), including 8 case with acute schistosomiasis, 26 cases with chronic schistosomiasis, 3 cases with schistosomiasis haematobia, 2 cases with schistosomiasis intercalate and 1 case with schistosomiasis mansoni. Man was the predominant gender (85.0%, 34/40) and the occupation mainly included students, labors and farmers (65.0%, 26/40). The schistosomiasis patients detected from 2019 to 2023 were all overseas imported, and were concentrated in Lin’an District (3 cases) and Xihu District (2 cases), and the 34 domestically imported cases mainly acquired infections in Jiangxi Province (41.2%, 14/34), Anhui Province (29.4%, 10/34) and Hubei Province (20.6%, 7/34). Of the 6 overseas imported cases, 5 cases were foreign students with African nationality and another case was a labor with Anhui household registration that worked in Africa, and the place of acquiring infections included Equatorial Guinea (2), Guinea (1), Zambia (1), Nigeria (1) and Zimbabwe (1). Acute schistosomiasis japonica was mainly reported during the period between July and September (7/8), and the symptoms mainly included fever (8/8) and eosinophilia (7/8), 35.5% (11/31) of cases were misdiagnosed or missed, accounting for 4/11, 2/11, and 5/11 of the provincial, municipal, and county-level medical institutions, respectively. Conclusion The seroprevalence of schistosomiasis is low among transient population in Hangzhou City, with schistosomiasis cases shifting from domestic importation to overseas importation and location of case reporting shifting from concentrated areas of migrant labors to universities with a concentration of African students. In addition, misdiagnosis or missed diagnosis remains in medical institutions at all levels.

Efficiency evaluation of three assays for detection of Schistosoma japonicum infections in wild mice

TANG Qi, LV Chao, WANG Xi, GUO Suying, XU Xiaojuan, ZHU Hai, LI Yinlong, LIN Weina, ZHOU Xinjie, FENG Ting, XU Jing, QIN Zhiqiang

2025, 43(2):  186-191.  doi:10.12140/j.issn.1000-7423.2025.02.006

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Objective To evaluate the performance of liver homogenate smear microscopy (parasitological detection), real-time quantitative reverse transcription PCR (qPCR) assay and loop-mediated isothermal amplification (LAMP) for detection of Schistosoma japonicum infections in wild rodents, so as to provide an optimal laboratory diagnostic assay for surveillance of S. japonicum infection in wild rodents. Methods A total of 115 wild rodents liver samples (63 samples from Village A and 52 samples from Village B) were collected from Dongzhi County, Anhui Province, and detected by liver homogenate smear microscopy, qPCR assay and LAMP, respectively. The positive rates of the samples were calculated and compared. The consistency between qPCR and LAMP for detection of the liver samples was evaluated with microscopy as a standard, and 70% of liver samples with a low consistency between the parasitological assay and nucleic acid tests were randomly selected for validation with DNA sequencing. Results Liver homogenate smear microscopy detected 54 positive liver samples, with a positive rate of 46.96% (54/115), and the positive rate of liver samples was 46.03% (29/63) in Village A and 48.08% (25/52) in Village B (χ² = 0.001, P > 0.05). qPCR assay tested a 69.57% (80/115) positive rate of liver samples, which was higher than liver homogenate smear microscopy (χ² = 11.175, P < 0.01), and there positive rate was 66.67% (42/63) in Village A and 73.08% (38/52) in Village B (χ² = 0.340, P > 0.05). LAMP tested a 56.52% (65/115) positive rate of liver samples, which was comparable to liver homogenate smear microscopy (χ² = 1.741, P > 0.05), and the positive rate was higher in Village A(71.43%, 45/63) than in Village B (38.46%, 20/52) (χ² = 11.293, P < 0.01). There was a high consistency between qPCR assay and liver homogenate smear microscopy (Kappa value = 0.524 4), and a low consistency between LAMP and liver homogenate smear microscopy (Kappa value = 0.154 5). Among the 24 liver samples from Village A that were negative for liver homogenate smear microscopy but positive for LAMP, 17 samples were randomly selected for DNA sequencing, and 15 of these samples showed a sequence identity of 98% and higher with the 28S ribosomal DNA of S. japonicum (GenBank accession No.: JF721395.1) and were therefore identified as positives. Conclusion Three assays have diverse sensitivities for detection of S. japonicum infections in wild rodents. qPCR assay has the highest positive rate for detection of S. japonicum infections in wild rodents and a high consistency with liver homogenate smear microscopy, while LAMP is convenient to perform but has a low consistency with liver homogenate smear microscopy.

Analysis of the key sites of Plasmodium vivax VIR14 protein interacting with ICAM-1 receptor

YANG Wanxuan, SHEN Haimo, CHEN Shenbo, CHEN Junhu

2025, 43(2):  192-197.  doi:10.12140/j.issn.1000-7423.2025.02.007

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Objective To investigate the binding of Plasmodium vivax VIR14 protein to intercellular cell adhesion molecule-1 (ICAM-1) receptor and identify key binding sites. Methods The recombinant plasmid pET28a-VIR14 was transformed into Escherichia coli BL21 (DE3). The expression levels and purity of VIR14 protein were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. Binding of VIR14 protein or peptides to ICAM-1 was verified using surface plasmon resonance (SPR). Structures of VIR14 and ICAM-1 (28-480 aa) were predicted, and complex modeling scores (pTM and pLDDT) were integrated. Docking analysis was performed using ClusPro 2.0 to evaluate the interactions between top-scoring VIR14 and ICAM-1 models. Docking sites were analyzed using PDBePISA and Pymol 3.0. Amino acid polymorphisms at binding sites were examined using global isolate data. Key interaction sites were analyzed via epitope competition inhibition assays. Results SDS-PAGE confirmed successful expression and purification of VIR14 protein, with a relactive molecular mass (M_r) of 58 000. SPR showed concentration-dependent binding of VIR14 to ICAM-1, with an affinity of 15.16 μmol/L. According to structural predictions from Alphafold2, the optimal model of the VIR14 protein had a pLDDT score of 78.2 and a pTM score of 0.73. In contrast, the optimal model of the ICAM-1 receptor showed a pLDDT score of 93.8 and a pTM score of 0.65. The regions where polar bonds formed between the VIR14 and ICAM-1 proteins were predominantly located in the C-terminal region of the protein, specifically between the 212 and 406 amino acids. Among the two peptides containing the predicted binding sites, only peptide P2 bound to ICAM-1, with an affinity of 48.99 μmol/L. Competitive inhibition experiments indicated that P2 could inhibit the binding of VIR14 protein to ICAM-1. After replacing the side chains of the four key residues (ASP-310, ARG-314, LYS-316, and ASP-318) with alanine, P2 lost its inhibitory function. P2 was highly conserved across 338 P. vivax global isolates. Conclusion The VIR14 protein of P. vivax exhibits tight binding to the ICAM-1 receptor, with four amino acid residues playing essential roles in this interaction. These key sites demonstrate high conservation across P. vivax global isolates.

Effect and mechanism of Csi-miR-125a induced liver fibrosis in the exosomes of Clonorchis sinensis

WU Yinjuan, YI Xueqing, LI Meiyu, XU Anyuan, WU Aoxun, ZHONG Zifeng, LI Xuerong

2025, 43(2):  198-204.  doi:10.12140/j.issn.1000-7423.2025.02.008

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Objective To examine the role of hub miRNAs from Clonorchis sinensis exosomes in hepatic fibrosis, so as to provide new insights into deciphering the mechanisms underlying hepatic fibrosis induced by C. sinensis. Methods Adult worms of C. sinensis was collected from liver specimens of a domestic cat infected with C. sinensis, cultured in vitro, and excretory/secretory products were collected, centrifuged and filtered. Exosomes were extracted and observed under a transmission electron microscope, and their particle size distribution was analyzed. Total RNA was extracted from exosomes, and sequenced, and miRNA was predicted using the miRDeep2 software. The miRNA sequences were aligned with those in the miRBase database, and the expression of each miRNA was quantified and screened. The target genes of selected miRNAs were predicted using the miRanda, miRDB, and PITA software, and the Gene Ontology (GO) and signaling pathways of target genes were subjected to enrichment analyses using the topGO and clusterProfiler software. Hepatic stellate cells (HSCs) were incubated with exosomes at concentrations of 5, 10, and 20 μg/ml for 24 and 48 h, and a blank control group was assigned. HSCs were transfected with a selected miRNA (Csi-miR-125a) at a final concentration of 50 nmol/L for 48 h, and a negative control group was assigned. The proliferation of HSCs was measured using the cell counting kit-8 (CCK-8) assay, and the expression of HSC activation-related protein α-smooth muscle actin (α-SMA) and type Ⅲ collagen, autophagy-related proteins microtubule associated protein 1A/1B light chain 3 (LC3) and p62, and the phosphorylation of the signaling pathway-related extracellular signal regulated kinase (ERK) protein was determined using Western blotting with mouse anti-human β-actin, rabbit anti-human α-SMA, rabbit anti-human type Ⅲ collagen, rabbit an-human LC3, rabbit anti-human p62, rabbit anti-human ERK, and rabbit anti-human p-ERK primary antibodies (1∶1 000 dilution), and the secondary horseradish peroxidase (HRP) conjugated goat anti-mouse or anti-rabbit IgG antibody (1∶1 000 dilution). Results The C. sinensis exosomes appeared a small vesicular shape with a phospholipid bilayer structure, and the main peak particle size was 72 nm (range, 30 to 150 nm). The C. sinensis exosomes contained multiple miRNAs, and Csi-miR-125a, which had the second highest expression and a high similarity to known miRNA sequences, was selected for subsequent experiment. Csi-miR-125a had overlapping of 301 predicted sites of target genes, and these target genes were significantly enriched in cellular components such as cytoplasm, involved in molecular functions of protein binding and ion binding, and biological processes of biological regulation, systematic development, and nervous system development, and significantly enriched in Hedgehog signaling pathways, extracellular matrix- receptor interaction related pathways, and NOD like receptor signaling pathways. The CCK-8 assay measured the highest A₄₅₀ value (1.707) at an exosome concentration of 10 μg/ml for 24 h incubation, and the A₄₅₀ value was higher in the Csi-miR-125a co-culture group (1.122) than in the negative control group (0.492). Western blotting determined that the grayscale values of the α-SMA bands were 0.588 and 0.904 in the negative control group and the Csi-miR-125a group (t = 10.560, P < 0.01), and the grayscale values of type Ⅲ collagen bands were 0.783 and 0.997 in the negative control group and the Csi-miR-125a group (t = 6.483, P < 0.05).The grayscale ratios of LC3 Ⅱ/LC3 Ⅰ bands were 1.093 and 2.215 in the negative control group and the Csi-miR-125a group (t = 5.206, P < 0.05), and the grayscale values of p62 bands were 0.537 and 1.369 in the negative control group and the Csi-miR-125a group (t = 13.100, P < 0.01), while the grayscale ratios of pERK/ERK bands were 0.791 and 1.037 in the negative control group and the Csi-miR-125a group, respectively (t = 5.067, P < 0.05). Conclusion There are diverse miRNAs in C. sinensis exosomes, which are involved in multiple cellular functions and signaling pathways. Csi-miR-125a may contribute to hepatic fibrosis through blocking the autophagic flux of HSCs and activating the ERK signaling pathway to promote HSCs proliferation and activation.

Epidemiological characteristics of soil-transmitted nematode infections in Shaanxi Province from 2016 to 2023

NIAN Yunpeng, LI Shanshan, ZHANG Yi, CAO Lei, LIU Dongli, MA Lin, NING Shaoqi, MA Chao, ZHANG Luqian

2025, 43(2):  205-209.  doi:10.12140/j.issn.1000-7423.2025.02.009

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Objective To investigate the trends in the prevalence of soil-transmitted nematode infections in Shaanxi Province from 2016 to 2023, so as to provide insights into formulation of the soil-transmitted nematodiasis control strategy. Methods According to the requirements of the National Clonorchiasis and Soil-transmitted Nematodiasis Surveillance Program (Trial), surveillance sites were sampled from counties (districts) in Shaanxi Province each year from 2016 to 2023, and each surveillance site was divided into 5 areas according to geographical locations, including eastern, western, southern, northern and central areas. One administrative village was sampled from each area, and at least 200 residents were surveyed in each administrative village, with at least 1 000 residents were surveyed in each surveillance county. Participants’ fecal samples were collected, and the soil-transmitted nematode eggs were detected using the Kato-Katz technique (two slides of one stool sample). The prevalence of soil-transmitted nematode infections was compared with Chi-square test. Results A total of 76 surveillance sites were assigned in Shaanxi Province from 2016 to 2023. The overall prevalence of soil-transmitted nematode infections was 0.13% (115/90 790) among participants, and only Ascaris lumbricoides infection was detected. The prevalence rates of soil-transmitted nematode infections were 0.70% (63/9 040), 0.20% (18/9 073), 0.17% (15/9 013), 0.07% (6/9 076), 0 (0/9 334), 0 (0/9 061), 0.06% (10/17 122) and 0.02% (3/19 071) in Shaanxi Province from 2016 to 2023, respectively (χ² = 161.424, P < 0.01). The highest prevalence of soil-transmitted nematode infections was detected in Tongchuan City (0.27%, 11/4 042) (χ² = 110.412, P < 0.01) and Fenwei basin ecological zone (0.17%, 67/39 105) (χ² = 18.581, P < 0.01). In addition, the highest prevalence of soil-transmitted nematode infections was found among residents at ages of 20 to 29 years (0.21%, 13/6 071), participants with an occupation of preschool children (0.21%, 16/7 758) and participants with an educational level of preschool children (0.21%, 16/7 770), and there were significant differences in the prevalence of soil-transmitted nematode infections among participants in terms of age groups, occupations and educational levels (χ² = 13.245, 11.243, 16.737, all P < 0.05). Conclusion The prevalence of soil-transmitted nematode infections was at a low level in Shaanxi Province from 2016 to 2023, with A. lumbricoides as the predominant parasite species. The prevalence of human soil-transmitted nematode infections varies greatly in different regions and populations.

Effect of Toxoplasma gondii infection during pregnancy on CD73 expression in trophoblasts and decidual immune cells and the association of CD73 expression with adverse pregnancy

JING Tianyu, MOU Rutao, ZHANG Fan, LIU Xianbing, HU Xuemei, ZHANG Haixia, LI Zhidan

2025, 43(2):  210-216.  doi:10.12140/j.issn.1000-7423.2025.02.010

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Objective To investigate the effect of Toxoplasma gondii infection during pregnancy on CD73 expression in trophoblasts and decidual immune cells and to examine the association of CD73 expression with adverse pregnancy. Methods Four healthy decidua and villi tissue specimens in normal abortions at early pregnancy were collected. Decidual mononuclear cells were isolated with Ficoll-Paque lymphocyte separation solutions, and trophoblasts were isolated with the Percoll method. Purified decidual mononuclear cells and trophoblasts were divided into the control and infection groups, with 1 × 10⁷ cells in each group, and cells in the infection group were infected with T. gondii at a ratio of 3∶1 for 24 hours. Then, the CD73 expression was detected on the surface of trophoblasts, decidual natural killer (dNK) cells, decidual macrophage (dMφ) and decidual dendritic cell (dDC) using flow cytometry. Trophoblasts were divided into the control and infection groups, with 1 × 10⁷ cells in each group, and cells in the infection group were infected with T. gondii at a ratio of 1∶1 for 24 hours. Then, total protein was extracted from cells, and the relative CD73 protein expression was determined in trophoblasts using Western blotting post-infection with T. gondii. Sixty wild-type female mice of the C57BL/6J strain and 30 male mice of the C57BL/6J strain, and 60 female CD73^-/- mice and 30 male CD73^-/- mice were randomly caged overnight at a female to male ratio of 2∶1, respectively. Wild-type pregnant mice were randomly divided into the Wild-type control and Wild-type infection groups, and CD73^-/- pregnant mice were randomly divided into the CD73^-/- control and infection groups. Pregnant mice in the two infection groups were intraperitoneally injected with 400 T. gondii tachyzoites on day 8 of pregnancy, and pregnant mice in the two control groups were injected with the same volume of physiological saline. Mouse uterus was dissected on day 14 of pregnancy, and the placentas and fetal mice were observed, with the percentage of fetal abnormality estimated. The CD73 expression was detected in placental tissues using immunohistochemical staining. All statistical analyses were performed using the software GraphPad Prism 9.0, and differences of means were tested for statistical significance with Student’s t test for independent samples. Results Flow cytometry detected that the proportion of CD73-positive trophoblasts in total trophoblasts was (39.25 ± 1.43)% in the control group and was higher than that in the infection group (31.27 ± 2.79)% in the infection group (t = 5.31, P < 0.05). The proportions of CD73-positive cells were (38.17 ± 7.71)%, (25.80 ± 6.85)% and (9.39 ± 0.75)% on the surface of dDCs, dMφ and dNK cells in the control group higher, all were higher than that in the infection group (36.33 ± 7.64)%, (20.58 ± 5.18)% and (7.74 ± 1.08)% in the infection group (t = 4.25, 5.24 and 3.57; P < 0.05). Western blotting determined that the relative CD73 protein expression was 0.79 ± 0.07 in trophoblasts in the control group and 0.38 ± 0.05 in the infection group (t = 24.80, P < 0.01), and immunohistochemical staining showed that wild-type control placental tissue-positive cells were brown in color and expressed centrally on the lateral side of the placenta, especially near blood vessels, wild-type infected group had fewer positive cells were fewer in the wild-type infected group than in the control group, the grayscale value of CD73 expression was 9.79 ± 0.30 in mouse placental tissues in the wild-type infection group and 20.20 ± 4.60 in the wild-type control group (t = 3.89, P < 0.05). The placentas and fetuses of wild-type control and CD73^-/- control groups were well-developed, shiny, and the uterus was round and full, whereas pregnant rats of wild-type infected and CD73^-/- infected groups were obviously ischemic with severe bruising, and the fetuses and placentas were not shaped, and the fetuses were absorbed, and the placentas were underdeveloped. The mouse placenta and fetal body weights were (0.05 ± 0.01) g and (0.07 ± 0.03) g in the wild-type infection group, and (0.07 ± 0.01) g and (0.13 ± 0.08) g in the wild-type control group (t = 3.22 and 5.36, both P < 0.01). The mouse placenta and fetal body weights were (0.07 ± 0.04) g and (0.12 ± 0.01) g in the CD73^-/- control group, which were comparable to those in the wild-type control group (t = 0.62 and 0.13, both P > 0.05), and were (0.03 ± 0.00) g and (0.01 ± 0.00) g in the CD73^-/- infection group, which significantly reduced as compared with those in the wild-type infection group (t = 3.10 and 5.08, both P < 0.01). The proportions of fetal abnormality were 0 in the wild-type control group and CD73^-/- group, (55.73 ± 0.18)% in the wild-type infection group, which was significantly higher than in the wild-type control group (t = 7.79, P < 0.01), and was (76.00 ± 0.20)% in the CD73^-/- infection group, which significantly increased as compared with that in the wild-type infection group (t = 2.44, P < 0.05). Conclusion T. gondii infection at early pregnancy may remarkably down-regulate CD73 expression on the surface of trophoblasts and decidual immune cells (dNK cells, dMφ and dDC) in the maternal-fetal microenvironment, and CD73 down-regulation is strongly associated with adverse pregnancy caused by T. gondii infection.

CRISPR/Cas9-based generation of the bfd2 deficient strain of Toxoplasma gondii and analysis its phenotype

ZHANG Xiaocheng, HU Yuan, PENG Hui, SHEN Yujuan, LIU Hua, CAO Jianping

2025, 43(2):  217-222.  doi:10.12140/j.issn.1000-7423.2025.02.011

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Objective To generate the bradyzoite formation deficiency 2 (bfd2) gene-deficient Toxoplasma gondii ME49 strain based on clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) 9 system, analyze the phenotype of the strain, and investigate the effect of bfd2 on T. gondii differentiation and proliferation. Methods Small guide RNA (sgRNA) for bfd2 was designed using the E-CRISPR tool, and the sgRNA in the pSAG1::CAS9-U6::SgUPRT plasmid was mutated using the Q5 Site-Directed Mutagenesis Kit to generate the pSAG1::CAS9-U6::SgBFD2 plasmid. The pyrimethamine resistance gene and the upstream and downstream sequences of the bfd2 gene were ligated to form donor DNA and cloned into the pUC19 plasmid, and donor DNA was amplified using PCR assay. The pSAG1::CAS9-U6::SgBFD2 plasmid and donor DNA fragments were electroporation co-transfected into tachyzoites of the T. gondii ME49 strain. Following electroporation, the suspension was inoculated into human foreskin fibroblasts (HFFs), and the electroporated parasite strains were subjected to monoclonal selection with 3 μmol/L pyrimethamine. The screened monoclonal parasite strains were inoculated into HFF cells and passaged, and the Δbfd2 knockout efficiency in the strain was checked using PCR assay. The proliferation of the strains was measured in HFF cells using in vitro proliferation assays, and the plaque-forming ability of the strain was tested in HFFs using plaque assays. In addition, the pathological changes in livers of mice infected with the strains were observed using hematoxylin and eosin (HE) staining. All statistical analyses were performed using the software GraphPad Prism 9, and the experimental data was tested for statistical significance using two-tailed non-paired Student t-test and analysis of variance (ANOVA). Results The pSAG1::CAS9-U6::SgBFD2 and donor DNA plasmid were successfully generated. The dihydrofolate reductase (DHFR)-coding sequence was successfully inserted to the target site, and the monoclonal ME49 ∆bfd2 gene knockout strain (ME49 ∆bfd2 strain) was successfully screened as verified by PCR assay. In vitro proliferation assays revealed that the proportions of parasitophorous vacuoles containing more than 16, 16 and 8 and less tachyzoites were (55.33 ± 5.03)%, (27.00 ± 3.00)% and (17.67 ± 4.04)% in HFF cells inoculated with the ME49 strain, and (25.33 ± 4.16)%, (42.67 ± 3.06)% and (32.00 ± 6.93)% in HFF cells inoculated with the ME49 ∆bfd2 strain, and the number of parasitophorous vacuoles containing more than 16 tachyzoites was higher in HFF cells infected with the ME49 strain than in cells infected with the ME49 ∆bfd2 strain (t = 6.337, P < 0.01). Plaque assays showed (13.50 ± 3.11), (119.75 ± 4.86) and (264.25 ± 28.61) plaques in HFFs inoculated with 100, 1 000 and 10 000 tachyzoites of the ME49 strain, and (1.25 ± 0.96), (6.75 ± 0.96) and (22.00 ± 5.72) plaques in HFFs inoculated with 100, 1 000 and 10 000 tachyzoites of the ME49 ∆bfd2 strain (t = 7.415, 57.72, 18.04, all P < 0.01). HE staining showed alleviation of liver inflammation in mice infected with the ME49 ∆bfd2 strain relative to in mice infected with the ME49 strain. Conclusion The BFD2 deficient strain of T. gondii has been successfully generated using the CRISPR/Cas9 system, and BFD2 deficiency inhibits T. gondii differentiation and proliferation and alleviates liver inflammation in mice.

Prokaryotic expression and preliminary functional identification of Echinococcus granulosus calreticulin

PU Na, BO Xinwen, ZHAO Wenqing, CHEN Xuke, ZHANG Yuxia, ZHANG Yanyan, SUN Yan, WANG Zhengrong

2025, 43(2):  223-230.  doi:10.12140/j.issn.1000-7423.2025.02.012

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Objective To express Echinococcus granulosus (Eg) calreticulin (CRT) in prokaryotic cells and preliminarily explore the function of EgCRT. Methods The cDNA of Eg protoscoleces was used as a template to amplify the target gene using PCR assay, which was ligated into the pET-28a (+) vector to construct the recombinant plasmid pET28a-CRT. The recombinant plasmid was transformed into the Escherichia coli BL21 strain. The rEgCRT was identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting, and the physicochemical properties and some biological functions of the EgCRT protein were predicted using online bioinformatics tools. Mice were immunized with rEgCRT to prepare the polyclonal antibody, and the antibody titer and reactogenicity were detected using indirect ELISA and Western blotting, respectively. The distribution of CRT in protoscoleces and adults and the binding of rEgCRT to canine intestinal epithelial cells were analyzed using indirect immunofluorescence. In addition, the relative transcription level of the crt gene at different developmental stages and the effect of rEgCRT (experimental group and PBS as a control group) on apoptosis and pyroptosis of canine intestinal epithelial cells were examined using real-time quantitative reverse transcription PCR (RT-qPCR) assay. Results The molecular formula of the CRT protein was C₂₀₃₃H₃₀₅₁N₅₁₁O₆₅₀S₉, and the EgCRT protein was predicted to contain α-helix (24.05%), irregular coils (60.00%) and extended chain structures (15.95%). EgCRT, along with the CRTs of E. multilocularis and Taenia solium, were clustered into a clade on the phylogenetic tree. The rEgCRT protein was successfully expressed and highly purified, with a relative molecular weight of approximately 50 000. The rEgCRT protein showed a high antigenic specificity, and indirect immunofluorescence assay showed that EgCRT was localized in the epidermis of protoscoleces and adults and some parenchyma tissues. RT-qPCR assay showed higher expression of EgCRT in the adult stage (24.83 ± 0) than in the protoscoleces stage (27.05 ± 0.008) (t = 45.76, P < 0.01), and indirect immunofluorescence assay showed that the canine small intestinal epithelial cells co-cultured with rEgCRT presented green fluorescence aggregation. RT-qPCR assay showed that the relative transcription levels of the Bax gene were (31.63 ± 0.001) and (24.17 ± 0.027) in the experimental group and the control group 24 hours post-culture (t = 7.94, P < 0.01), indicating up-regulated expression, and the relative transcription levels of Bcl-2 were (34.55 ± 0.070) and (19.65 ± 0.042) (t = 15.70, P < 0.01), indicating downregulated expression, while the relative transcription levels of IL-18 were (25.62 ± 0.067) and (20.93 ± 0.014) (t = 5.05, P < 0.01), indicating downregulated expression, and the relative transcription levels of IL-1β were (28.18 ± 0.001) and (28.71 ± 0.020) (t = 0.26, P > 0.05), indicating downregulated expression. Conclusion The rEgCRT protein has a high antigenicity, and EgCRT is expressed in different developmental stages of E. granulosus, and may play an important role in the fixation, colonization, growth or development of E. granulosus. In addition, rEgCRT adheres to canine small intestinal epithelial cells and regulates cell apoptosis and pyroptosis, which may be involved in the process of E. granulosus infections or host immune responses, and has a promise as potential vaccine candidates and drug targets.

Epidemiological characteristics and spatial landscapes of echinococcosis in Xinjiang in 2023

SHI Guangzhong, YIN Zhe, YALIKUN Maimaitiyiming, MAIMAITIJIANG Umar, KAISAIER Tuerxunjiang, CHENG Xia, ZHAO Jiangshan

2025, 43(2):  231-235.  doi:10.12140/j.issn.1000-7423.2025.02.013

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Objective To investigate the epidemiological characteristics and spatial distribution characteristics of echinococcosis in Xinjiang in 2023, so as to provide insights into formulation of the echinococcosis control strategy. Methods All data pertaining to newly reported echinococcosis cases in Xinjiang in 2023 were captured from the National Notifiable Diseases Reporting System. All statistical analyses were performed with the software Microsoft Excel 2016, and the three-dimension (3D) trend map of newly reported echinococcosis cases was plotted with the software ArcGIS 10.8 to analyze the trends in spatial distribution of newly reported echinococcosis cases. The cold and hot spot maps were plotted based on the spatial relationships of individual case data, in order to analyze the cluster pattern of newly reported echinococcosis cases in different geographical locations, and the cold and hot spots of echinococcosis were predicted with the inverse distance interpolation approach in Xinjiang in 2023 based on cold and hot spot analyses, to project potential high-risk areas across Xinjiang in the future. Results Total of 958 newly diagnosed echinococcosis cases were reported in Xinjiang in 2023, and these cases were reported across 14 prefectures (cities) in Xinjiang, with the highest number of reported cases in Ili Prefecture (309 cases, accounting for 32.25% of all cases). There were 506 male cases (52.82%) and 452 female cases (47.18%), and the cases had a mean age of 45.0 (20.0, 56.0) years (range 2 to 99 years), with high proportion at ages of 6 to 11 years (10.54%, 101/958), 12 to 17 years (10.86%, 104/958) and 48 to 53 years (14.41%, 138/958). Farmer and herdsman were the predominant occupation (46.66%, 447/958). Descriptive spatial analysis showed that the average number of newly reported echinococcosis cases was 6.0 (2.0, 13.5) across 96 counties (cities) in Xinjiang, and the number of newly reported echinococcosis cases a tendency towards a rise followed by a reduction from west to east, and a gradual increase from south to north. Spatial autocorrelation analysis revealed a spatial autocorrelation of echinococcosis in Xinjiang in 2023 (Moran’s I = 0.028, Z = 2.584, P < 0.05), indicating a spatial cluster. Cold and hot spot analyses showed high numbers of newly reported echinococcosis cases in northern Xinjiang, where high-value clusters were found in multiple districts (counties), indicating high-spot areas of echinococcosis, while a few newly diagnosed echinococcosis cases were reported in southern Xinjiang, where low-value clusters were predominant, indicating cold-spot areas. Conclusion There is a spatial cluster of echinococcosis in Xinjiang and the number of newly reported echinococcosis cases is overall higher in northern Xinjiang than in southern Xinjiang. The southwestern part of northern Xinjiang is hot-spot areas of echinococcosis, and the number of echinococcosis cases, centered in the southwestern part of northern Xinjiang, and then radiates towards the southeastern part. These areas should be given a high priority for echinococcosis control.

Isolation and identification of Patagifer bilobus

CAO Yu, LI Ye, GAO Zhongyan, JIANG Botao

2025, 43(2):  236-240.  doi:10.12140/j.issn.1000-7423.2025.02.014

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Objective To characterize the trematode species isolated from Grus japonensis in the Heilongjiang Zhalong Nature Reserve, and to analyze the phylogenetic relationships of the trematode using ribosomal internal transcribed spacer (ITS) and 28S DNA sequences as molecular markers. Methods Trematodes were isolated from intestines of naturally deceased G. japonensis in the Heilongjiang Zhalong Nature Reserve and stained with hydrochloric acid-carmine to observe the morphological characteristics of trematodes. DNA was extracted from trematodes, and ITS and 28S sequences were amplified using PCR assay. PCR amplification products were sequenced, followed by sequence analysis, similarity analysis and repetitive sequence analysis. In addition, phylogenetic trees were built using the maximum parsimony method. Results The isolated trematodes had enlarged bodies, and well-developed, distinctly bilobed head collars. The length of the ITS sequence was 1 007 bp, and the lengths of ITS1, 5.8S and ITS2 sequences were 389, 161 and 457 bp, respectively. The G + C content of the ITS sequence was 52.14%. The length of 28S sequence was 983 bp and the G + C content was 56.79%. The ITS2 sequence had 2 forward repeat sequences with 11 bp in length and the 28S sequence had no repeat sequences. The ITS and 28S sequences of isolated trematodes shared 94.39% and 98.27% sequence similarities with those of P. bilobus (GenBank accession numbers: ON141931 and KT956945), and clustered into the same sub-clade with Patagifer species. The isolated trematodes were therefore identified as P. bilobus. Conclusion The trematodes isolated from G. japonensis in the Heilongjiang Zhalong Nature Reserve are P. bilobus.

REVIEWS

Overview of the prevalence of Toxoplasma gondii infection and toxoplasmosis in Africa

ZHANG Ling, LIU Xingzhuo, LV Fangli

2025, 43(2):  241-251.  doi:10.12140/j.issn.1000-7423.2025.02.015

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There have been limited research reports on Toxoplasma gondii infection and toxoplasmosis in Africa until now. Publications pertaining to the prevalence of T. gondii infection among general populations, prevalence of T. gondii infection among pregnant women, prevalence of T. gondii infection and congenital toxoplasmosis among children, prevalence of T. gondii infection among HIV/AIDS patients and tumor patients, genotypes and geographical distributions of T. gondii strains, and risk factors and route of T. gondii infection in Africa from 2015 to 2024, were retrieved in PubMed using the keywords “Toxoplasma gondii”, “toxoplasmosis”, and “Africa”, so as to provide insights into toxoplasmosis research.

Changes in the epidemiological characteristics and control progress of soil-transmitted nematodiasis in Hainan Island

XU Guangda, ZENG Wen, HUANG Xiaomin, LI Yuchun

2025, 43(2):  252-259.  doi:10.12140/j.issn.1000-7423.2025.02.016

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Hainan Island locates in tropical regions of China, and the climatic and natural environmental conditions are feasible for transmission of multiple types of soil-transmitted nematodiases. This review summarizes the changes in the prevalence of soil-transmitted nematode infections, soil-transmitted nematodiasis control measures and the effectiveness of these control measures in Hainan Island during the past 70 years. The prevalence of soil-transmitted nematode human infections decreased from 94.7% in 1991 to 4.1% in 2023 in Hainan Island. Results from three national surveys on human parasitic diseases and provincial disease surveillance programmes showed a higher prevalence rate of soil-transmitted nematode infections in central mountainous regions than in other regions, a higher prevalence rate among women than among men, a higher prevalence rate among children at ages of 5 to 9 years, adolescents at ages of 10 to 14 years and the elderly at ages of 60 to 69 years and 70 years and greater than among resident at other age groups, and a higher prevalence rate among farmers, students and preschool children than among humans with other occupations. There are three stages of soil-transmitted nematodiasis control programmes in Hainan Island, including small-scale mass examinations and treatment, large-scale mass prevention and treatment, and prevention and treatment of high-risk populations, and the major control measures included large-scale surveys on parasitic infections, mass drug administration, improvements in water and sanitation, health education, and pilot construction of demonstration areas. Currently, the prevalence of soil-transmitted nematode infections is low in Hainan Island; however, sustainable control programmes are required to achieve transmission control and interruption of soil-transmitted nematodiasis. Future multiple control efforts are recommended, including expansion of surveillance regions, to achieve precision control of soil-transmitted nematodiasis.

Researches progress on molecular surveillance of artemisinin resistance in Plasmodium falciparum

LI Fei, LIU Yaobao, CAO Jun

2025, 43(2):  260-268.  doi:10.12140/j.issn.1000-7423.2025.02.017

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The widespread deployment of artemisinin-based combination therapies (ACTs) for falciparum malaria has led to emergence of partial resistance to artemisinin and its derivatives, which has become one of the greatest challenge in the global malaria control programme. Recently, great strides have been achieved in unraveling the molecular mechanism underlying the resistance of P. falciparum to artemisinin and identification of molecular markers. The currently identified P. falciparum artemisinin resistance-associated genes include kelch protein 13 (pfk13), ubiquitin carboxyl-terminal hydrolase 1 (pfubp1), AP-2 complex subunit mu (pfap2μ), and coronin (pfcoronin). Molecular surveillance data reveal widespread distribution of P. falciparum artemisinin resistance-associated gene mutations across Southeast Asia, and emergence of artemisinin-resistant P. falciparum strains of independent origin in Africa, South America and Oceania. Advances in high-throughput sequencing and molecular testing provide powerful tools for molecular monitoring of artemisinin resistance in P. falciparum. This review summarizes the advances in molecular surveillance of artemisinin resistance in P. falciparum, aiming to provide insights into surveillance and management of artemisinin-resistant P. falciparum.

Research progress on the mechanism of Clonorchis sinensis miRNAs in the initiation and progression of cholangiocarcinoma

WU Aoxun, ZHONG Zifeng, XU Anyuan, PAN Xiaowen, YI Xueqing, WU Yinjuan, LI Xuerong

2025, 43(2):  269-273.  doi:10.12140/j.issn.1000-7423.2025.02.018

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Clonorchis sinensis is a food-borne parasite. T he adult worms parasitize in the hepatic bile ducts of the host, which could cause pathological changes and induce cholangiocarcinoma. The International Agency for Research on Cancer of the World Health Organization classified C. sinensis as a Class Ⅰ carcinogen in 2009. As a class of endogenous non-coding RNA, micro RNA (miRNA) has a variety of important regulatory roles in cells. MiRNAs secreted by C. sinensis play a relatively important role in the initiation and progression of cholangiocarcinoma. This review summarized the roles of C. sinensis-derived miRNAs in cholangiocarcinoma, aiming to provide novel strategies for preventing and treating cholangiocarcinoma induced by C. sinensis infection.

Giardia lamblia infection in the population and foodborne contamination in China

PENG Xiaoxue, WANG Xu, JIAN Jinhua, SHEN Yujuan

2025, 43(2):  274-281.  doi:10.12140/j.issn.1000-7423.2025.02.019

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Giardia lamblia is a zoonotic parasite worldwide and infection with the genus G. lamblia may cause giardiasis, with diarrhea and abdominal pain as main clinical symptoms. Giardiasis poses a serious threat to health among children and immunocompromised individuals. Because of limited treatment options and no clinically available vaccines, giardiasis has been paid more and more attention across the world. This review summarizes G. lamblia human infections since the first record of giardiasis in 1924 and waterborne and foodborne contaminations in China, so as to provide insights into formulation of the human giardiasis control strategy in China.

SHORT COMMUNICATIONS

Analysis of the infection factors Echinococcus granulosus in dogs in Shangri-La City, Yunnan Province

LI Benfu, XIAO Dan, LU Chunhua, SHI Shuai, YAN Xinliu, ZI Jinrong, PENG Jia, LI Jianxiong, WANG Zhengqing, XU Qian, WU Fangwei, YANG Yaming

2025, 43(2):  281-285.  doi:10.12140/j.issn.1000-7423.2025.02.020

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Data pertaining to previous echinococcosis cases and local cases were collected from the National Notifiable Disease Reporting System and hospitals in Shangri-La City, and Jiantang, Xiaozhongdian and Geza townships with high prevalence of echinococcosis were sampled as study areas. Based on the Results of surveillance on echinococcosis prevalence in dogs in three townships in Shangri-La City from 2019 to 2021, the positive rate of Echinococcus coproantigens was classified into three strata (high, moderate and low) in each administrative village, and one to three natural villages were randomly sampled from each stratum as study sites. In June 2022, a cluster random sampling method was employed, with one dog feces sample collected from each household, and fecal samples randomly collected from wayside ownerless or stray dogs, and more than 200 dogs were investigated in each township. Echinococcus coproantigen was detected in dogs using ELISA, and factors affecting the prevalence of Echinococcus infections were identified in domestic dogs. A total of 1 587 dogs were detected for Echinococcus coproantigens, with a positive rate of 4.03% (64/1 587), and the positive rates of Echinococcus coproantigens were 3.16% (35/1 107) in domestic dogs and 6.04% (29/480) in ownerless or stray dogs, respectively (χ² = 6.265, P < 0.05). The positive rates of Echinococcus coproantigens were 4.60% (41/891), 3.18% (14/440), and 3.52% (9/256) in dogs in Jiantang, Xiaozhongdian, and Geza townships, respectively (χ² = 12.030, P < 0.05). The positive rates of Echinococcus coproantigens were 3.48% in male domestic dogs and 2.68% female domestic dogs (χ² = 1.184, P > 0.05), and the positive rate of Echinococcus coproantigens was 4.11% in dogs at ages of over 10 weeks, with no age-specific positive rate detected (χ² = 2.384, P > 0.05). The positive rates of Echinococcus coproantigens were 5.56% in wolfhound dogs, 36.36% in free-range dogs, 3.39% without deworming during the latest three months, and 17.20% in dogs that had been fed diseased organs, respectively, and there were significant differences in the positive rates of Echinococcus coproantigens in domestic dogs in terms of dog breeds, ranging styles, deworming during the past three months, and feeding with diseased organs (χ² = 15.431, 49.121, 5.291, 65.391, all P < 0.05). Logistic regression analysis showed that dog breeds, ranging styles, deworming during the past three months, and feeding with diseased organs were significantly associated with Echinococcus infections in dogs. The prevalence of Echinococcus infection is relatively high in dogs in Shangri-La City, and an emphasis on intensified management of dogs is recommended for echinococcosis prevention and control.

Epidemiological characteristics of malaria in Dalian City from 2014 to 2023

MAO Licui, WANG Dezheng, YANG Shihong

2025, 43(2):  286-289.  doi:10.12140/j.issn.1000-7423.2025.02.021

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To understand the epidemiological characteristics of malaria in Dalian City, so as to provide insights into prevention of re-establishment of malaria after elimination. Data pertaining to epidemiological individual investigations of reported malaria cases in Dalian City from 2014 to 2023 were retrieved from the National Information System for Infectious Diseases Surveillance and National Information System for Parasitic Diseases Control and Prevention, and the epidemiological features of reported malaria cases were analyzed using descriptive and analytical epidemiological methods. A total of 125 malaria cases were reported in Dalian City from 2014 to 2023, and all were overseas imported cases, including 2 deaths. Among all reported cases, falciparum malaria accounted for 85.6% (107/125), ovale malaria accounted for 10.4% (13/125), quartan malaria accounted for 3.2% (4/125) and vivax malaria accounted for 0.8% (1/125). The annual average number of reported malaria cases was 12.5 in Dalian City from 2014 to 2023, with the highest number of reported cases in 2017 (25 cases). Malaria cases were reported across all months, and the highest number of malaria cases was reported in January (16.0%, 20/125), without seasonal variations. Malaria cases were detected in permanent residents across all counties (districts) in Dalian City, with the highest number of cases seen in Ganjingzi District (18.4%, 23/125), and the reported malaria cases acquired infections from 20 countries in Africa, and the country where the highest number of malaria cases acquired infections was Nigeria (13.6%, 17/125). The male-to-female ratio of reported malaria cases was 10.36 : 1, and the reported cases had a median age of 42 years, with the highest number of reported cases at ages of 30 to 39 years (28.0%, 35/125). Of all reported malaria cases, junior high school was the predominant educational level (39.2%, 49/125), and worker was the predominant occupation (31.2%, 39/125). The median interval from returning to China to disease onset was 7 days and the median duration from disease onset to diagnosis was 4 days among reported malaria cases. Among all reported malaria cases, there were only 6 cases (4.8%) with definitive diagnosis within 1 day from disease onset, and 30 cases (24.0%) with definitive diagnosis exceeding 7 days from disease onset, and there were 110 cases (88.0%) with definitive diagnosis in city-level medical institutions. These findings demonstrate that there are overseas imported malaria cases in Dalian City, with falciparum malaria as the predominant type. It is recommended to reinforce the prevention and control of imported malaria, and increase clinicians’ diagnostic capability and residents’ awareness of malaria, in order to sustainably consolidate malaria elimination achievements.

Prevalence and risk factors of hookworm infections among agricultural planters in Rongchang District, Chongqing Municipality

ZHU Yong, XU Jingru, YAN Shuning, LI Ling, JIANG Yuanya, WANG Lan, LIU Daiqiang

2025, 43(2):  290-295.  doi:10.12140/j.issn.1000-7423.2025.02.022

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In order to investigate the current prevalence and risk factors of hookworm infections among agricultural planters in Rongchang District, Chongqing Municipality, agricultural planters were sampled using a random cluster sampling method from 5 natural villages in eastern, western, southern, northern and central parts of Rongchang District, Chongqing Municipality in 2024, and participants’ socio-demographic characteristics, living environments, agricultural labor style, and hygiene habits were collected through questionnaire surveys. Participants’ stool samples (> 30 g) were collected, and hookworm infection was detected using a Kato-Katz technique (two slides of one stool sample). Soil samples were collected from households with moderate and severe hookworm infections (one soil sample from each outdoor field or vegetable garden and one sample from a shaded area neighboring the toilet) for hookworm larval isolation. The ITS2 gene sequence of Necator americanus and the 5.8S rRNA gene sequence of Ancylostoma duodenale were amplified using multiplex PCR assay, and a phylogenetic tree was created using the neighbor-joining (NJ) method. Differences of prevalence of hookworm infections were compared with Chi-square test and Chi-square test for trend, and the independent risk factors of hookworm infections were identified using a conditional logistic regression model. The prevalence of hookworm infections was 14.9% (84/563) among 563 participants, with a mean infection intensity of 841.4, and the proportions of mild, moderate, and severe infections were 57.1% (48/84), 34.5% (29/84), and 8.3% (7/84), respectively. The participants had no history of examination or treatment for intestinal parasites during the past 5 years, and had no complaints of any hookworm infections-related symptoms or signs. Age of ≥ 60 years (17.7%, 65/367), an education level of illiteracy (27.8%, 10/36), annual family income < 20 000 RMB (20.1%, 59/294), annual growing labor duration of one month and longer (17.7%, 73/412), use of pit toilets (2/10), growing dryland crops (15.7%, 84/534), use of human feces as fertilizers (20.6%, 75/364), frequent/occasional barefoot labors (21.3%, 68/320), frequent/occasional consumption of food falling to the ground without washing (18.6%, 54/291), frequent/occasional drinking of unboiling water (18.2%, 53/291), frequent/occasional not handwashing post-defecation (21.8%, 58/266) resulted in a relatively higher incidence rate of hookworm infections among participants (χ² = 8.022, 8.920, 15.780, 9.476, 9.793, 4.194, 26.213, 23.402, 6.275, 5.145, 18.827, all P < 0.05), and the prevalence of hookworm infections increased with age, reduced educational levels, decreased annual household incomes and poor hygiene of household toilets (χ²_trend = 7.105, 8.836, 8.836, 7.121, all P < 0.05). Conditional logistic regression analysis identified use of human feces as fertilizers [odds ratio (OR) = 4.041, 95% confidence interval (CI): (1.937, 8.429)] and barefoot labor [OR = 2.726, 95% CI: (1.506, 4.935)] as independent risk factors for hookworm infections among agricultural planters. Hookworm larvae were isolated from 60 soil samples, and PCR assay tested positive in 6 samples, which were all characterized as N. americanus. It is recommended to intensify the surveillance and treatment of hookworm infections, implement health education and health behavior interventions among high-risk populations, improve toilet environmental modifications and harmless treatment of night soil in rural areas, and block the transmission routes of hookworm infection, in order to effectively reduce the risk of transmission of hookworm disease.

CASE REPORTS

A case of Trichomonas tenax infection complicated with asymptomatic pulmonary infection

TANG Juan, XU Lu, PANG Jie

2025, 43(2):  295-297.  doi:10.12140/j.issn.1000-7423.2025.02.023

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A 37-year-old male patient with pulmonary infection was admitted to Lianyungang Municipal First People’s Hospital on May 28, 2024, and he had lightly high-density shadows in the lower lobe of the left lung during physical examinations 16 days ago. The case was given anti-infective therapy with cefazoxime and levofloxacin (unknown dosage) for 9 days, and chest CT scans displayed progression of infections in bilateral lungs. Following admission, the patient underwent tracheoscopy and next-generation sequencing (NGS) of alveolar lavage fluids identified 522 Trichomonas tenax sequences. The patient had a medical history of periodontal disease and had ingested food with chopsticks used for undercooked meat within the past 2 months. The patient was diagnosed with T. tenax infection complicated with asymptomatic pulmonary infection based on his medical history and auxiliary diagnoses, and was treated with biapenem (0.3 g, 3 times per day) and metronidazole (0.5 g, 3 times per day) for 9 days. Chest CT scans displayed improvements in pulmonary infections, and the case was discharged from hospital because of absence of any other special abnormalities. Following discharge, the patient continued to administer moxifloxacin (0.1 g per day) and metronidazole (0.5 g, 3 times per day) orally. Outpatient follow-up visits showed no discomfort two weeks following discharge, and chest CT scans displayed a clear left lung and calcification in the right lung, with no other obvious abnormalities found.

Diagnosis and analysis of an imported case with visceral leishmaniasis in Hubei Province

JIA Xishuai, ZHOU Shuimao, LUO Huatang, LIU Cong, YANG Yan, TIAN Junhua, XU Wenxiu

2025, 43(2):  298-300.  doi:10.12140/j.issn.1000-7423.2025.02.024

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A 31-year-old male patient hailing from Xianfeng County, Hubei Province, was presented. He had gone to work in Yangquan, Shanxi Province on July 2022 and returned to Xianfeng on January 2023. The patient developed a fever on February, and received intravenous therapy at a local health center. On April 28, he had a relapse of fever with the highest body temperature of 39.8 ℃. Despite consultations at multiple hospitals, no definite diagnosis was made. On May 6, he was transferred to the Department of Infectious Diseases, Wuhan Jinyintan Hospital. Abdominal ultrasound scans displayed splenomegaly, and microscopic examination of bone marrow smears identified amastigotes, while rk39 immunochromatographic strip test detected positive serum antibodies against Leishmania. Genomic DNA was extracted from blood samples, and PCR assay of internal transcribed spacer 1 (ITS-1) of Leishmania ribosomal DNA amplified a band with approximately 310 bp in length. Sequencing showed a 99% homology between the amplified sequence and the corresponding sequence of L. donovani. The case was definitively diagnosed with visceral leishmaniasis, and given two cycles of treatment with sodium stibogluconate injection (600 mg/d for 6 d each cycle, with a one-week interval between cycles) since May 8. The patients had goo recovery at the three-month follow-up visit post-treatment, with normal routine blood tests and no Leishmania detected on bone marrow smears.

Diagnosis of a case with scabies in a primary healthcare institution

XIONG Ye, HU Chen

2025, 43(2):  301-303.  doi:10.12140/j.issn.1000-7423.2025.02.025

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A 46-year-old male resident living in Shanghai was presented to Department of General Practice, Outpatient Department of Shanghai University of Traditional Chinese Medicine on April 2024, with complaints of itching all over the body for 14 days. He had a history of night medical chaperones in a hospital on March 2024. Skin tunnel staining of skin lesions on the patient’s wrist palmar crease with gentian violet showed “thread-like” staining, and dermatoscopy displayed a typical “jet with contrail sign”, with mites’ mouth and two pairs of forefoot. The case was therefore definitively diagnosed as scabies, and given treatment with 20% sulphur ointment twice a day for successive one month. Then, the itching symptoms disappeared and dermatoscopy did not detect typical skin lesions.

Fasciola hepatica infection complicated by hepatic tuberculosis: a case report

HUANG Lihua, WU Jun, LI Zhengjin, LUO Jiao, GU Wei

2025, 43(2):  304-306.  doi:10.12140/j.issn.1000-7423.2025.02.026

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A 58-year-old male farmer living in Binchuan County, Dali, Yunnan Province, was admitted to the First Affiliated Hospital of Dali University on July 20, 2022, with a complaint of “right upper abdominal pain for more than two days”. Routine blood tests showed elevated eosinophils counts (1.7 × 10⁹/L), erythrocyte sedimentation rate (ESR, > 120 mm/h), and blood chemical tests showed an increase in alanine aminotransferase (58 U/L), aspartate aminotransferase (74 U/L), gamma-glutamyltransferase (66 U/L) and alkaline phosphatase concentrations (257 U/L). Enzyme-linked immunosorbent assay (ELISA) measured strongly positive serum IgM and IgG antibodies against Fasciola hepatica, and the T-SPOT. TB test was tested positive. Abdominal plain plus enhanced computed tomography (CT) scans displayed the suspicion of hepatic malignancy with infectious diseases that failed to be excluded. Liver histopathology revealed tunnel-like necrosis and formation of foreign body granulomas, with F. hepatica infection and tuberculosis that cannot be excluded. Acid-fast staining of the left medial lobe liver specimen was positive, and Mycobacterium tuberculosis complex DNA was detected. Metagenomic next-generation sequencing (mNGS) of liver tissues detected 20 M. tuberculosis sequences and 15 F. hepatica sequences. The patient resided in Binchuan County, Dali Prefecture, Yunnan Province, where fascioliasis is prevalent, and had a habit of consuming raw or undercooked vegetables. Fascioliasis hepatica complicated by hepatic tuberculosis was diagnosed based on the patient’s epidemiological history, symptoms and signs, and auxiliary diagnosis results. Following deworming with triclabendazole at a dose of 15 mg/(kg·d) divided into 3 doses per day for 2 days and antitubercular therapy with rifampicin capsules (0.45 g once daily, adjusted for the patient’s weight of 48 kg), isoniazid tablets (0.3 g once daily), ethambutol tablets (0.75 g once daily) and pyrazinamide tablets (1.5 g once daily) for a week, the patient’s abdominal pain improved and was discharged from hospital. At the 3-month follow-up, liver enzymes returned to normal, and at the 6-month follow-up, the case had normal eosinophil counts, postoperative changes in liver segment 4 and strip-like dense shadows in surgical areas on plain abdominal CT scans, without remarkable progression.

A case of central nervous system and pulmonary infection caused by Angiostrongylus cantonensis

LI Qingyu, JIN Yong, MA Weiqiong, HUANG Zhiyong

2025, 43(2):  307-310.  doi:10.12140/j.issn.1000-7423.2025.02.027

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A 26-year-old male patient, a freelancer hailing from Huizhou, Guangdong Province, started to experience headaches on July 27, 2024, and developed a low-grade fever on July 30. Treatments targeting “cold” and “upper respiratory tract infections” yielded unsatisfactory outcomes. On August 5, he was admitted to Huizhou Central People’s Hospital for hospitalization due to “10 days of headache and 7 days of fever”, and he reported a history of consuming raw fish (grass carp) and raw-pickled food (freshwater shrimp and crabs) over one month prior to disease onset. Physical examination showed horizontal nystagmus when he gazed toward the left with both eyes. A chest computed tomography (CT) scan displayed infectious lesions in bilateral lungs, and a plain cranial CT scan showed no abnormalities, while a cranial magnetic resonance imaging (MRI) scan displayed a few ischemic and degenerative foci in the white matter area of the right frontal lobe. His peripheral blood eosinophil count was elevated (1.677 × 10⁹/L), as was the percentage of eosinophils (16%). However, enzyme-linked immunosorbent assay (ELISA) detected negative serum IgG antibodies against Angiostrongylus cantonensis. Routine cerebrospinal fluid tests showed a cerebrospinal fluid pressure of 240 mmH₂O (1 mmH₂O = 0.0098 kPa), and metagenomic next-generation sequencing (mNGS) of cerebrospinal fluid specimens detected 7 specific sequences of A. cantonensis, with a relative abundance of 8.1%. Mannitol was administered to reduce intracranial pressure for 18 consecutive days since August 6, and albendazole was orally administered at a single dose of 0.4 g by three times a day, for 20 consecutive days since August 9. Dexamethasone sodium phosphate injection was additionally given at a daily dose of 10 mg for 10 consecutive days since August 17, and dexamethasone was discontinued on August 27, when the patient was switched to oral prednisone acetate tablets, with the dose gradually tapered down to discontinuation over the subsequent 23 days in the sequence of 60 mg, 30 mg, 20 mg, 10 mg and 5 mg. His headache was almost relieved on day 9 post-admission, and a follow-up test showed that the peripheral blood eosinophil counts had returned to normal before discharge, the pulmonary lesions had been absorbed to some extent compared with the previous state, the cerebrospinal fluid pressure had decreased, and mNGS of cerebrospinal fluid specimens indicated a gradual increase in the number of specific sequences of A. cantonensis. The patient improved and was discharged on September 4, and a follow-up phone call on October 8 revealed that the patient was free of discomfort.