Table of Content

30 August 2026, Volume 44 Issue 4

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INVITED REVIEWS

Epidemiology and control of angiostrongyliasis in China during the recent 20 years

HE Anqi, TIAN Xia, LV Shan

2026, 44(4):  461-467.  doi:10.12140/j.issn.1000-7423.2026.04.001

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Since the outbreak of angiostrongyliasis in Beijing in 2006, epidemiological investigations, surveillance and early warning, diagnosis and treatment, and other related studies had been conducted targeting this disease in China. During the past two decades, cluster outbreaks had been successively reported in Beijing Municipality, Guangning County of Guangdong Province, and Dali City of Yunnan Province. Although the overall number of reported angiostrongyliasis cases has declined during the past 20 years, cases continue to be detected in selected areas. In addition, intermediate hosts, such as Pomacea snails, have continued to spread, and the coverage of natural foci has expanded, indicating that angiostrongyliasis transmission risk remains. An angiostrongyliasis control system has been gradually built in China, which combines case surveillance, host surveillance, and risk early warning, and diagnostic criteria, expert consensus, and molecular diagnostic assays have been continuously improved. This article summarizes the epidemiological changes, surveillance and response, diagnosis and treatment, and research advances of angiostrongyliasis in China over the past 20 years, which provide insights into improvements in the disease control strategies.

Progress on the epidemiological characteristics, detection techniques, and control strategies of Cyclospora cayetanensis

HULALAI Hader, ZUO Qingqiu, GULIBANU Aimaier, LI Shizhu, ZHENG Bin, SHEN Yujuan

2026, 44(4):  468-476.  doi:10.12140/j.issn.1000-7423.2026.04.002

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Cyclospora cayetanensis is an emerging foodborne intestinal protozoan parasite that causes cyclosporiasis, a disease primarily characterized by persistent diarrhea. In recent years, it has become a major public health threat worldwide and is a pathogen under surveillance by FoodNet in the United States. The oocysts of C. cayetanensis become infective only after sporulation in the environment and are primarily transmitted via contaminated agricultural products and water sources. No direct human-to-human transmission has been documented to date. Cases of cyclosporiasis have been reported in at least 54 countries globally, with large-scale foodborne outbreaks occurring repeatedly in the United States, Canada, and other regions. The 2026 cyclosporiasis outbreak in the United States was the most severe on record, with 13 895 reported indigenous confirmed cases and over 10 455 suspected cases (as of August 11, 2026). In China, the first case of cyclosporiasis was reported in 1995, and sporadic human infections have been documented across multiple regions with significant geographical variation. However, due to the absence of a national surveillance network, baseline data at the national level remain lacking, and the epidemiological characteristics of the disease in China are still unclear. This article reviews the research progress on the etiological characteristics, clinical manifestations, epidemiology, detection techniques, and surveillance systems of C. cayetanensis, aiming to provide a reference for surveillance, risk assessment and prevention and control strategies for cyclosporiasis.

ORIGINAL ARTICLES

National syndromic surveillance of angiostrongyliasis in China from 2009 to 2025

HAN Qingchi, YANG Limin, ZHU Zelin, ZHANG Yi, CHEN Junhu, GUO Yunhai, LV Shan

2026, 44(4):  477-483.  doi:10.12140/j.issn.1000-7423.2026.04.003

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Objective To investigate the current prevalence of angiostrongyliasis in China, so as to provide insight into angiostrongyliasis control programmes. Methods Data pertaining to human angiostrongyliasis cases and surveillance of intermediate host snails were collected from 12 pilot areas conducting syndromic surveillance for angiostrongyliasis in China from 2009 to 2025. The geographical distribution of angiostrongyliasis cases, prevalence of Angiostrongylus cantonensis infection in snail hosts, and distribution and spread of snail hosts were analyzed. Results A total of 251 angiostrongyliasis cases were reported from the pilot areas from 2009 to 2025, including 88 clinically diagnosed cases and 163 suspected cases. Most cases were reported from Dali Prefecture (63 clinically diagnosed cases and 10 suspected cases) and Kunming City of Yunnan Province (12 clinically diagnosed cases and 8 suspected cases), and Fuzhou City of Fujian Province (11 clinically diagnosed cases and 99 suspected cases), and a few cases were reported from Jinghong City of Yunnan Province (26 suspected cases), and Xiamen City of Fujian Province (one clinically diagnosed case and 15 suspected cases). The number of reported angiostrongyliasis cases showed an overall tendency towards a decline from 2009 to 2025. Surveillance on intermediate host snails identified Pomacea spp. and Lissachatina spp. as predominant intermediate snail hosts, and the overall prevalence rates of A. cantonensis infections were 1.07% (2 647/247 801) in Pomacea spp. and 9.62% (878/9 124) in Lissachatina spp., respectively. A. cantonensis infection was detected in Pomacea spp. each year from 2009 to 2025, with the highest prevalence recorded in 2009 (3.13%, 109/3 480), while A. cantonensis infection was found in Lissachatina spp. in 9 years from 2009 to 2025, with the highest prevalence recorded in 2016 (31.61%, 165/522). The distributions of both Pomacea spp. and Lissachatina spp. showed a tendency towards expansion northwards. Pomacea spp. has already invaded in the southern part of the Qinling-Huaihe Line and colonized in two provinces of Shandong and Henan. Conclusion The overall prevalence of angiostrongyliasis appeared a tendency towards a decline in the pilot areas of China from 2009 to 2025. However, geographical distributions of invasive Pomacea spp. and Lissachatina spp. continue to expand, which increase the risk of angiostrongyliasis transmission.

Blood-brain barrier disruption in rats infected with Angiostrongylus cantonensis

WEI Hang, LIAO Liang, XING Mengdan, LUO Jingtong, SHI Yue, LI Sinuo, LÜ Zhiyue

2026, 44(4):  484-492.  doi:10.12140/j.issn.1000-7423.2026.04.004

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Objective To investigate the characteristics and dynamic patterns of the blood-brain barrier (BBB) disruption in rats infected with Angiostrongylus cantonensis, so as to provide experimental evidence for elucidating the pathogenesis of angiostrongyliasis. Methods A. cantonensis infection was modeled in Sprague-Dawley (SD) rats, which were then divided into an uninfected group and six infection groups corresponding to 7, 14, 21, 28, 35 and 42 days post-infection (dpi), with 10 rats in each group. Brain tissues were collected from rats in each group. The alterations of BBB integrity were detected using Evans blue (EB) extravasation assay in rats at different time points post-infection, and the leakage of albumin was detected using immunofluorescence staining in brain tissues of infected rats. RNA and proteins were extracted from rat brain tissues. The mRNA expression of BBB tight junction proteins claudin-5, occludin, Zonula occludens-1 (ZO-1) and platelet endothelial cell adhesion molecule (CD31) was quantified using real-time fluorescent quantitative reverse transcription PCR (RT-qPCR) assay in rats infected with A. cantonensis, and the expression of claudin-5, occludin and CD31 proteins was determined using Western blotting assay. In addition, the transcriptional levels of BBB disruption-related genes were quantified using RT-qPCR assay in rats infected with A. cantonensis at different time points, including matrix metalloproteinase-2 (mmp2), mmp9, intercellular adhesion molecule-1 (icam-1), vimentin, tumor necrosis factor-α (tnf-α) and interleukin 1β (il-1β). Differences of means between groups were tested for statistical significance with Student’s t-test. Results EB extravasation assay revealed remarkable BBB disruption in rats at 28 dpi with higher amount of EB extravasation [(20.030 ± 5.580) μg/g vs. (1.000 ± 0.327) μg/g; t = -5.896, P < 0.01] and EB fluorescence intensity (2.452 ± 3.14 vs. 0.596 ± 0.485; t = -6.464, P < 0.01] than in uninfected rats. The amount of EB extravasation gradually decreased on 35 dpi (6.568 ± 2.072) and 42 dpi (4.237 ± 2.033)， and the EB fluorescence intensity gradually reduced on 35 dpi (2.843 ± 2.314) and 42 dpi (1.816 ± 0.697), indicating gradual recovery of BBB functions. Immunofluorescence staining demonstrated remarkable albumin extravasation from rat brain tissues into extravascular regions, notably during the period from 28 to 42 dpi. RT-qPCR assay quantified lower relative mRNA levels of occludin and CD31 in infected rats on 21 and 28 dpi (occludin: 0.729 ± 0.087, 0.664 ± 0.162; CD31: 0.700 ± 0.145, 0.584 ± 0.208) than in uninfected rate (occludin: 1.017 ± 0.189; CD31: 1.032 ± 0.296) (occludin: t = -2.834 and -2.999, both P < 0.05; CD31: t = -2.515 and -3.193, both P < 0.05), and the transcriptional expression of occludin and CD31 recovered on 35 dpi (occludin: 0.943 ± 0.139; CD31: 0.815 ± 0.205) and 42 dpi (occludin: 1.139 ± 0.531; CD31: 0.869 ± 0.107). The relative mRNA level of ZO-1 was significantly lower in infected rats on 14 dpi (0.756 ± 0.110) and 21 dpi (0.726 ± 0.109) than in uninfected rats (1.017 ± 0.219) (t = -2.602 and -2.919, both P < 0.05), and gradually increased on 28 dpi (0.824 ± 0.131), 35 dpi (0.928 ± 0.072) and 42 dpi (0.868 ± 0.111). No significant difference was observed in claudin-5 mRNA level between infected and uninfected rats across all time points dpi (t = 1.031, 1.429, 1.906, 0.798, 0.991 and 0.473, all P > 0.05). Western blotting assay determined lower relative occludin protein expression in brain tissues in rats infected with A. cantonensis (1.240 ± 0.176) on 21 dpi than in uninfected rats (0.734 ± 0.159) (t = 3.693, P < 0.05), and the protein expression gradually recovered to normal on 28 (t = 2.679, P > 0.05), 35 (t = 1.155, P > 0.05) and 42 dpi (t = 1.459, P > 0.05). The relative CD31 protein expression was lower in infected rats than in uninfected rats on 28 dpi [(0.693 ± 0.009) vs. (1.118 ± 0.104); t = ‒14.569, P < 0.01], and then recovered on 35 dpi (0.925 ± 0.294) and 42 dpi (1.068 ± 0.052). In addition, the relative mRNA levels of BBB disruption-related genes mmp2, mmp9, icam-1, vimentin, tnf-α, il-1β were all higher in infected rats (2.735 ± 0.560, 3.393 ± 2.066, 4.717 ± 2.037, 17.447 ± 5.129, 1.739 ± 0.572, 7.449 ± 1.905) than in uninfected rats (1.017 ± 0.225, 1.109 ± 0.647, 1.250 ± 0.266, 1.040 ± 0.354, 1.026 ± 0.252, 1.111 ± 0.593) on 28 dpi (t = 5.794, 2.504, 2.686, 6.381, 2.347, 6.648, P < 0.05 or P < 0.01), and exhibited a tendency towards a decline from 35 dpi to 42 dpi, with similar dynamic changes with the pattern of BBB disruption and recovery. Conclusion A. cantonensis infection may induce BBB disruption in rats, which peaks at 28 dpi and then gradually recovers. It is hypot underlying mechanism may be closely related to the reduced expression of tight junction proteins and the upregulation of BBB disruption-related genes such as mmp2 and mmp9.

Genetic differentiation between sexes of and development of a sex identification method for Angiostrongylus cantonensis based on whole-genome sequencing

WANG Kun, CHEN Shenbo, SHEN Haimo, GUO Yunhai, HONG Yang, WU Xiaonen, GAO Mingfei, CHEN Junhu

2026, 44(4):  493-499.  doi:10.12140/j.issn.1000-7423.2026.04.005

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Objective To investigate the genome-wide genetic differentiation between male and female Angiostrongylus cantonensis populations based on whole-genome sequencing, establish a gender inference method for unknown samples, and explore the functional characteristics of potential sex-related genomic regions. Methods A total of 20 adult worms of morphologically identified A. cantonensis were obtained, including 10 males and 10 females. Whole-genome sequencing of adult worms was performed, and single nucleotide polymorphism (SNP) data were subjected to principal component analysis, population structure analysis, nucleotide diversity (π) analysis, and population differentiation index (F_ST) analysis. Candidate X-linked assembly sequences were screened through the difference in sequencing coverage between males and females, and candidate genes in sex-related regions were subjected to functional annotation and gene ontology (GO) enrichment analysis to decipher their potential biological functions. A gender determination threshold was defined by the ratio of the average sequencing depth of X-linked assembly sequences to the average sequencing depth of autosomal regions (X/A). The inference strategy was tested using a training set and a validation set (10 samples each), and the effectiveness was evaluated using machine learning tools. Results Whole-genome analysis revealed no stable gender clustering of male and female worms, with similar overall genetic diversity, consistent changing trends of π values, and similar overall fluctuation range. The average whole-genome F_ST was -0.005 8, and the weighted F_ST was -0.002 7, both approaching to 0. A few windows exhibited significantly increased F_ST values, with multiple extreme high values reaching up to 1.0. Based on coverage analysis screening, 2 631 candidate X-linked assembly sequences with coverage ratios ranging from 0.4 to 0.6 were yielded. The significantly enriched entries in candidate genes involved processes such as chromatin structure regulation, nucleosome assembly, and DNA helicase activity regulation, and the enriched entries shared linker histone H1 family proteins such as H1FOO and H1F0. In the training set, the average X/A ratios of female and male samples were 1.808 ± 0.090 (range, 1.659 to 1.879) and 0.977 ± 0.078 (range, 0.879 to 1.080), with a significant deviation in the distribution intervals, and an X/A coverage ratio of 1.4 was defined as a gender determination indicator. In the validation set, the X/A ratios of female samples were all above the threshold (mean, 1.852 ± 0.047; range, 1.809 to 1.924), while the ratios of male samples were all below the threshold (mean, 1.137 ± 0.073; range, 1.042 to 1.217). Among the 20 samples, the X/A ratio of female samples was higher than that of male samples (t = 18.582, P < 0.01). The classification results using machine learning tools further supported that the X/A coverage ratio had a high stability and accuracy for sex identification. Conclusion Male and female A. cantonensis populations show no remarkable genetic differentiation at a whole-genome level, and the X/A coverage ratio-based approach is stable for sex identification. Chromatin regulation-related genes enriched in candidate sex-related regions suggest their potential involvement in sex-related chromosome structure formation and epigenetic regulation.

Dynamic distribution and DNA load of Angiostrongylus cantonensis in rats

LI Tianmei, JIANG Yingrui, FANG Wen, LI Ting, ZHAO Shenhua, REN Jianhui

2026, 44(4):  500-504.  doi:10.12140/j.issn.1000-7423.2026.04.006

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Objective To investigate the dynamic distribution and changes in DNA load of Angiostrongylus cantonensis in rats, so as to provide experimental evidence for clinical diagnosis and disease control. Methods Fifty-five SD rats were randomly assigned to a control group (n = 10) and an infection group (n = 45). The infection group was subdivided into a low-dose group (20 larvae/rat), a medium-dose group (60 larvae/rat), and a high-dose group (100 larvae/rat), with 15 rats per subgroup. Rats in the infection groups were infected with third-stage larvae of A. cantonensis by oral gavage; the control group received an equal volume of sterile physiological saline by gavage. Cerebrospinal fluid, whole blood, serum, brain tissue, heart, and lung tissue were collected on days 3, 7, 14, 28, and 35 post-infection. Brain, heart, and lung tissues were examined under a dissecting microscope and visible worms were removed. All valid samples were tested for the ITS2 sequence with conventional PCR assay and ITS1 sequence with TaqMan probe-based qPCR assay, and positive PCR amplification products were subjected to bidirectional sequencing, followed by sequence alignment using the BLAST program. The limit of detection was determined by both conventional PCR and qPCR using serially diluted standard plasmids of A. cantonensis (positive standard), and the specificity was assessed using genomic DNA from Trichinella spiralis, Cysticercus cellulosae, Necator americanus, and rats as templates, while repeatability was evaluated across a range of 1.67 × 10⁷ to 1.67 × 10² copies/μL. All statistical analyses were performed using the software SPSS 26.0. Results Visible parasites were detected in 45 rats from the infection groups by dissection microscopy, with a 100% (45/45) percentage of successful infections. A total of 270 samples were collected, including 245 valid samples. Conventional PCR assay yielded no specific bands, with a detection rate of 0 (0/245), while the detection rate of qPCR assay was 67.35% (165/245). The sensitivity of the qPCR assay was 10 copies/μL, and no cross-reactivity was observed with genomic DNA from T. spiralis, C. cellulosae, N. americanus, or rats. The detection rates showed a tendency towards a rise in the low-, medium-, and high-dose infection groups over time (χ² = 11.82, 13.57, 14.84, all P < 0.01), with 7/18, 5/18, and 11/18 on day 3 post-infection, 8/18, 11/18, and 11/18 on day 7 post-infection, 6/13, 7/11, and 13/15 on day 14 post-infection, 11/17, 12/15, and 15/15 on day 28 post-infection and 15/16, 16/18, and 17/17 on day 35 post-infection, while no A. cantonensis DNA was detected in samples from the negative control group at any time point. The highest detection rate of A. cantonensis was seen in brain tissues (88.37%, 38/43) using qPCR assay, followed by in heart (74.42%, 32/43), lung tissue (72.09%, 31/43), cerebrospinal fluid (65.79%, 25/38), serum (52.94%, 18/34), and whole blood (47.73%, 21/44). Three-way analysis of variance (ANOVA) revealed that tissue type (F = 22.110, P < 0.01), dose of infection (F = 3.762, P < 0.05), and time of infection (F = 34.768, P < 0.01) significantly affected DNA load, with a significant interaction between tissue and time (F = 4.295, P < 0.01). DNA signals were predominantly concentrated in brain tissues at early stage of infection (3 to 7 days post-infection), and the DNA load increased rapidly in lung and heart since day 14 post-infection. High levels of DNA load were seen in brain, lung, and heart on days 28 to 35 post-infection, and the DNA load was higher in lung tissues than in brain tissues on day 35 post-infection. Conclusion Residual DNA of A. cantonensis is predominantly distributed in brain and lung tissues of rats and evolves dynamically over the course of infection, with the period from 14 to 35 days post-infection representing the peak of residual DNA load.

Prevalence of Angiostrongylus cantonensis infection in and phylogenetic analysis of Pomacea from Fujian Province

CHEN Yunhong, XIE Xianliang, CHEN Baojian, LIN Yaoying, YU Wenwu, XIE Hanguo

2026, 44(4):  505-511.  doi:10.12140/j.issn.1000-7423.2026.04.007

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Objective To investigate the distribution of Pomacea and the prevalence of Angiostrongylus cantonensis infections in Pomacea in four major river systems of Fujian Province, and to analyze the population genetic polymorphisms and phylogenetic relationships of Pomacea. Methods Pomacea samples were collected from 13 sampling sites across four major river systems in Fujian Province from May to September 2025, including the Min River, Jiulong River, Jin River and Ting River, and A. cantonensis infections in Pomacea were detected using lung microscopy. One individual Pomacea was sampled from each sampling site for extraction of genomic DNA, and mitochondrial cytochrome c oxidase subunit 1 (COⅠ) gene was amplified using PCR assay, followed by sequencing. Sequencing raw reads were assembled using the SeqMan software, and the obtained target sequences were submitted to the NCBI database for sequence homology alignment using the BLAST tool. The base composition and number in DNA sequences and length of DNA sequences were analyzed with the DnaSP software, and the haplotype type and number in COⅠ gene sequences were calculated. Pomacea COⅠ gene sequences were downloaded from the GenBank. The downloaded haplotype sequences of the Pomacea COⅠ gene obtained from this study were aligned using the ClustalW program. After trimming the head and tail redundant sequences, the genetic distance was calculated among different haplotypes using the Kimura 2-parameter model with the MEGA 7.0 software, and phylogenetic trees were built using the neighbor-joining (NJ) method. Results A total of 892 Pomacea snails were collected, among which 690 individuals were randomly selected for the detection of A. cantonensis infections, with an overall prevalence rate of 4.92% (34/690). The prevalence of A. cantonensis infections was 5.62% (25/445) in Pomacea snails from Min River, 5.00% (1/20) from Ting River, 4.00% (6/150) from Jiulong River, and 4.00% (2/50) from Jin River, respectively. PCR assay showed that the Pomacea COⅠ gene was 691 bp in length. Among the obtained 13 sequences, 8 belonged to P. canaliculata and 5 belonged to P. occulta. A total of 76 polymorphic sites were detected in the 13 COⅠ gene fragments, accounting for 11.00% of total sites, and no single variable sites, insertion or deletion sites, base transitions or transversions were identified. The average contents of the four nucleotides T, A, G and C were 40.1%, 23.8%, 19.9% and 16.2%, respectively. Three haplotypes (HAP-1, HAP-2, and HAP-3) were annotated from these 13 sequences, with a haplotype diversity of 0.705 1. HAP-1 was derived from Min River, Jiulong River and Ting River, and HAP-2 was derived from Min River, Jiulong River and Jin River, while HAP-3 was derived from Min River and Jiulong River. HAP-1 showed the closest genetic distance with P. occulta (GenBank accession number: PV793390), and the farthest genetic distance of 0.232 to the outgroup Pila conica (GenBank accession number: EF514948), and HAP-2 and HAP-3 shared the closest genetic distance with P. canaliculata from the Philippines (GenBank accession number: EU528483), and the largest genetic distance with the outgroup P. conica. The genetic differentiation distance ranged from 0.051 to 0.100 among the three haplotypes, and HAP-2 and HAP-3 shared the closest phylogenetic relationship with a genetic distance of 0.051. Phylogenetic analysis showed that HAP-2 was clustered with P. canaliculata from the Philippines into the same clade, HAP-3 formed an independent clade and belonged to the same major evolutionary clade with HAP-2, while HAP-1 was clustered with P. occulta from Shanghai area into the same clade. Conclusion The infection rate of A. cantonensis in apple snails in Fujian Province has decreased significantly compared with previous years. There are two species of Pomacea, including P. canaliculata and P. occulta, distributed in different river systems, and genetic differentiation has occurred within the populations of P. canaliculata.

Spatiotemporal distribution of Pomacea snails in China based on GBIF data and its association with genetic tracing

MAO Qi, YU Qing, LV Xihong, SUN Zhongxing, JIN Yanjun

2026, 44(4):  512-516.  doi:10.12140/j.issn.1000-7423.2026.04.008

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Objective To analyze the spatiotemporal distribution characteristics of Pomacea snail presence records in China in the Global Biodiversity Information Facility (GBIF) platform and their associations with genetic tracing, so as to provide insights into precise monitoring and control of hotspot colonization and risk areas of Pomacea snails. Methods Records of valid Pomacea snail presence in China from 2001 to 2024 were collected from the GBIF platform, and a descriptive statistical was performed using the software SPSS 26.0. In addition, publications regarding genetic tracing of Pomacea snails in China were systematically retrieved during the same study period, and population genetic structure and tracing evidence were extracted from publications to comprehensively examine their correlations. Results A total of 1 785 valid records were screened, covering 17 province-level administrative regions in China. The records were predominantly based on human observations (1 669 records, 93.50%), with a mean coordinate uncertainty of 70.42 m, indicating high spatial accuracy. The latitudes of valid records ranged from 18.298 967°N (Hainan) to 32.078 623°N (Jiangsu) and the longitudes ranged from 100.787 644°E (Yunnan) to 121.924 861°E (Taiwan), exhibiting a distribution pattern of a higher density in the southern region and a lower density in the northern region. Taiwan (1 435 records, 80.39%), Hunan (108 records, 6.05%), and Guangdong (85 records, 4.76%) emerged as the three primary hotspots for records. Temporally, a three-phase progression characteristic of “sporadic development” “slow initial growth” and “explosive growth” was found. From 2001 to 2010, a total of 4 records were documented; from 2011 to 2020, 503 records (an annual average of 50.3) were recorded. The record counts surged to 1 278 during the period between 2021 and 2024 (an annual average of 319.5), peaking in 2024 (386 records), with Taiwan as the primary contributor (364 records, 94.30%). A literature review of nine studies on genetic tracing revealed P. canaliculata as the overwhelmingly dominant Pomacea species in China, with origins traced to Argentina and Brazil in South America. Pomacea snail populations in Taiwan exhibited the most complicated genetic structure, while Pomacea snail populations from the lower reaches of the Yangtze River (Jiangsu and Shanghai) showed high genetic diversity (Hd = 0.627). In addition, some hotspots recorded in GBIF strongly coincided with areas with a high genetic diversity. Conclusion Some hotspots recorded in GBIF are spatially consistent with areas with a high genetic diversity of Pomacea snails. Taiwan serves as the core dispersal origin, while the lower reaches of the Yangtze River exhibit independent invasion events and a sustained northward expansion trend.

Assessment of the risk of cyclosporiasis importation into China

XIA Shang, XUE Jingbo, HAO Yuwan, LI Zhen, TIAN Tian, NI Haobo, SHEN Yujuan, ZHENG Bin, LI Shizhu

2026, 44(4):  517-524.  doi:10.12140/j.issn.1000-7423.2026.04.009

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Objective To systematically assess the risk of cyclosporiasis importation into China during multistage cyclosporiasis outbreaks in the United States in 2026, so as to provide insights into surveillance, early warning, and precision prevention and control of foodborne parasitic diseases. Methods A systematic search was conducted in Chinese and English databases as well as official websites of the United States Centers for Disease Control and Prevention and the United States Food and Drug Administration to collect data pertaining to the prevalence of Cyclospora infections, events of cyclosporiasis outbreaks, epidemiological investigations, and China import requirements for food products. The risk assessment matrix was employed to construct an indicator system for assessment of the risk of cyclosporiasis importation into China, and the likelihood of disease development and severity of consequences were comprehensively evaluated. Results Human Cyclospora infections have been reported across 54 countries in the world, with a pooled global prevalence rate of 3.4%. As of July 13, 2026, a total of 1 645 domestically acquired laboratory-confirmed cases had been reported in the United States. Evidence of human Cyclospora infections has been identified in nine provinces (municipalities) of China, with a pooled detection rate of 0.8% as revealed by PCR assay; however, no routine surveillance system has been established. The Kendall’s coefficients of concordance were 0.725 for likelihood of cyclosporiasis development (P < 0.001) and 0.796 for severity of consequences (P < 0.001), based on two rounds of expert consultations. Weighted scoring indicated that the likelihood of disease development was classified as Level C (possible) and the severity of consequences as Level 2 (minor). A comprehensive analysis with a risk assessment matrix revealed that the overall risk of cyclosporiasis importation into China was moderate. The risk associated with the specific implicated food chain was low, as Mexico-produced head lettuce lacked market access authorization for export to China and no relevant trade records were identified. By contrast, the risk associated with imported fresh produce and products sharing origins, suppliers, or processing links with United States markets was assessed as moderate to high. Conclusion The specific implicated food chain from the current United States outbreak poses a low risk of cyclosporiasis importation into China; however, there is a potential risk for shared-source contamination along global fresh produce supply chains, and China is not non-endemic for this disease. Dynamic surveillance of imported fresh produce and products linked to shared supply chains and improvements in domestic surveillance systems and supply chain traceability capacity are recommended.

Retrospective molecular detection and genetic analysis of Cyclospora cayetanensis in stool samples from children with diarrhea in Ningbo City, Zhejiang Province

LIU Hua, NI Hongxia, ZHU Na, ZHOU Hao, ZUO Qingqiu, CAO Jianping, ZHENG Bin, YIN Jianhai

2026, 44(4):  525-531.  doi:10.12140/j.issn.1000-7423.2026.04.010

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Objective To retrospectively detect the presence of Cyclospora cayetanensis infections in stool samples from children with diarrhea in Ningbo City, Zhejiang Province, and to analyze the genetic and evolutionary characteristics of human-derived C. cayetanensis in China. Methods Stool samples from children with diarrhea in Ningbo City that were maintained in our laboratory were tested for C. cayetanensis 18S rRNA gene using nested PCR assay, and positive PCR amplification products were sequenced bidirectionally. Following sequence alignment and analysis, a phylogenetic tree was created using the neighbor joining method in the MEGA 7 software. In addition, the 18S rRNA gene sequences of human-derived C. cayetanensis isolates in China were retrieved in public databases, including NCBI, and the genetic and evolutionary characteristics of these gene sequences were analyzed. Results A total of 227 stool samples from children with diarrhea were included for retrospective testing, and there were 7 samples (3.08%) tested positive for C. cayetanensis. Sequence alignment and phylogenetic analysis demonstrated that six of these positive samples (GenBank accession no.: PZ748322) shared identical nucleotide sequences and exhibited 100% homology with a human-derived reference sequence (GenBank accession no.: KJ569531) from GenBank, and a novel gene sequence (GenBank accession no.: PZ737096) was identified, which shared 99.6% similarity with the sequence KJ569531. In the phylogenetic tree constructed based on the 18S rRNA gene, the gene sequences of these 7 positive samples were clustered with the sequence KJ569531 into the same clade, indicating a highly close genetic relationship. All C. cayetanensis isolates formed a distinct monophyletic clade, which were remarkably separated from outgroup species including Eimeria spp., Babesia microti, and Cryptosporidium parvum, supporting the monophyly of the genus Cyclospora. A total of 62 human-derived C. cayetanensis 18S rRNA gene sequences from China were integrated and screened, ultimately yielding 25 distinct gene sequences, in which 39 nucleotide polymorphic sites were identified. The overall nucleotide diversity (Pi) of the 25 gene sequences was 0.015, indicating that the average probability of a base difference occurring at any site between two random sequences was 1.5%. In addition, compared to other sequences, the new sequence (GenBank accession no.: PZ737096) obtained from this study showed base substitutions C→T at position 404 and A→C at position 406. Conclusion The prevalence of C. cayetanensis infection is high in stool samples from children with diarrhea in Ningbo City, Zhejiang Province, and the locally prevalent C. cayetanensis isolates exhibit genetic sequence differences from previously reported human-derived parasite isolates in China, which supplements the baseline data on genetic variation of C. cayetanensis in Chinese populations.

Evaluation of the classical nested PCR method for Cyclospora cayetanensis detection

ZHOU Hao, LIU Hua, JIANG Yanyan, SHEN Yujuan, LI Zhen, YIN Jianhai, ZHENG Bin, LI Shizhu

2026, 44(4):  532-537.  doi:10.12140/j.issn.1000-7423.2026.04.011

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Objective To systematically evaluate a classical nested PCR assay targeting the 18S rRNA gene of Cyclospora cayetanensis for the detection of human infections. Methods A nested PCR assay targeting the 18S rRNA gene of C. cayetanensis was performed with optimized reaction conditions. The specificity was evaluated using DNA templates from 8 non-Eimeriidae parasites, including Clonorchis sinensis, Schistosoma japonicum, Echinococcus granulosus, and Cryptosporidium parvum, as well as 4 Eimeriidae coccidia, including Eimeria caprovina, Cystoisospora canis, E. tenella, and E. bovis. The sensitivity was assessed using 10-fold serial dilutions of recombinant plasmids containing the target fragment (10⁴-10⁰ copies/μL). Results The specificity test showed that the positive DNA of C. cayetanensis from human origin yielded a specific amplicon of approximately 500 bp, while no amplification was observed for the 8 non-Eimeriidae parasites or the negative control. However, the 4 Eimeriidae coccidia (E. caprovina, I. canis, E. tenella, and E. bovis) all produced amplicons of approximately 500 bp. Sequencing confirmed that the sequences shared > 99% similarity with reference sequences of both Cyclospora and Eimeria. The sensitivity test showed that the detection limit of the nested PCR for recombinant plasmids was 10¹ copies/μL. Conclusion The assay exhibits high sensitivity for detecting C. cayetanensis in human fecal samples but shows cross-reaction with Eimeriidae coccidia. Given the strict host specificity of these coccidia, which typically do not infect humans, this method is applicable for screening C. cayetanensis in human-derived samples but is not suitable for detection in animal feces, environmental, or food samples, to avoid overestimation of Cyclospora infection levels. Results should be interpreted with caution.

Epidemiological characteristics of echinococcosis in Ningxia from 2005 to 2024

YAN Fang, QI Rongting, MA Tianbo, LIU Xuan, DUAN Hongju, WU Xianglin

2026, 44(4):  538-542.  doi:10.12140/j.issn.1000-7423.2026.04.012

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Objective To analyze the changing trend of echinococcosis in Ningxia from 2005 to 2024 and provide a reference for the comprehensive prevention and control of echinococcosis in Ningxia. Methods The reported cases of echinococcosis in Ningxia from 2005 to 2024 were collected from the China Information System for Disease Control and Prevention, and the population data were obtained from the National Bureau of Statistics website. Descriptive statistical analysis was conducted using SPSS 26.0, and spatial distribution and spatial autocorrelation analysis were performed using ArcGIS 10.8 software. The Moran’s I index was used to evaluate spatial clustering, and a heat map was used to visualize the number of cases among children aged 6-12 years in each county over the years. Results A total of 4 705 cases of echinococcosis were reported in Ningxia from 2005 to 2024, the average annual incidence rate is 3.57 per 100 000. Cases were reported every year, with the highest number of cases in 2009 [accounting for 11.2% （528/4 705）], and a decreasing trend was observed after 2009. Cases were reported every month, but the distribution was uneven, with the highest number of cases in March (515 cases) and the lowest in September (282 cases). The cases were mainly distributed in Guyuan City (29.7%, 1 396/4 705), Zhongwei City (28.3%, 1 332/4 705), and Wuzhong City (24.3%, 1 145/4 705), accounting for 82.3% (3 873/4 705) of the total cases. There was a statistically significant difference in the average annual incidence rate among different cities (χ² = 18 918.778, P < 0.01). The spatial distribution showed that cases were distributed in all counties and districts of Ningxia, with an average annual incidence rate ranging from 0.38 to 9.01 per 100 000. The highest incidence rate was in Haiyuan County in the south (9.01 per 100 000), and the overall pattern was “high in the south and low in the north”. The global autocorrelation Moran’s I = 0.38 (Z = 2.82, P < 0.01), indicating significant clustering. The local autocorrelation analysis found that the high-high clustering area was located in the southern Yuanzhou District, and the low-low clustering area was concentrated in some counties in the north. The hotspots were mainly located in Haiyuan County and Yuanzhou District. The male-to-female ratio of cases was 1:1.15, with an average annual reported incidence rate of 3.17 per 100 000 for males and 3.81 per 100 000 for females. There was a statistically significant difference in the average annual reported incidence rate between different genders (χ² = 39.815, P < 0.01). The cases were mainly concentrated in the age group of 30-69 years, accounting for 73.0%. There was a statistically significant difference in the incidence rate among different age groups (χ² = 3 008.457, P < 0.01). A total of 24 cases among children aged 6-12 years were reported from 2005 to 2024. The majority of the cases were farmers, accounting for 79.5% (3 740/4 705). Conclusion From 2005 to 2024, the number of reported cases of echinococcosis in Ningxia reached a peak in 2009 and has been decreasing year by year since then. The incidence of echinococcosis in Ningxia presented a spatial pattern of higher in the south and lower in the north, with statistically significant spatial aggregation. There were also notable differences in its distribution across gender and age groups, and pediatric cases still persist in the region.

A dual-tube multiplex qPCR system for detection of Plasmodium and Babesia parasites in human blood

LI Mei, XIA Zhigui, ZHOU Hejun, LIU Qin

2026, 44(4):  543-549.  doi:10.12140/j.issn.1000-7423.2026.04.013

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Objective To develop a multiplex real-time quantitative PCR (qPCR) assay for the simultaneous detection of multiple pathogens in a single sample, which can identify Plasmodium and Babesia at the genus level and determine clinically important Plasmodium species. Methods The 18S rDNA sequences of Homo sapiens, 16 18S rDNA sequences of 8 Plasmodium species and 14 18S rDNA sequences of 14 Babesia species were aligned using the bioinformatic tools DNAman 4.0 and BioEdit. The V4 region of Plasmodium 18S rDNA and the corresponding region of Babesia were selected to design universal primers to identify Plasmodium and Babesia, genus-specific probes to distinguish Plasmodium and Babesia, and species-specific probes to differentiate P. falciparum, P. vivax, and P. ovale with software Oligo 6.0. The 18S rDNA gene sequences of 3 mongkey Plasmodium species and 7 Babesia species with 400 to 500 bp in length were artificially synthesized, prepared into plasmids and diluted in a 10-fold gradient for subsequent experiments. Specific primers and species/genus probes were screened using 5 × 10⁵ copies/μL 18S rDNA plasmid as templates. The qPCR system was optimized through assigning degenerate primers and probes and introducing mismatched base into primers. The 18S rDNA plasmids of P. falciparum, P. vivax, B. microti, and B. venatorum with gradient dilution of 5 × 10⁰ to 5 × 10⁸ copies/μL were used as templates, and amplifications were performed in separate tubes using dye-based and probe-based qPCR assays to determine the lowest limit of detection. The standard curve of the system was plotted to calculate the amplification efficiency. The 18S rDNA plasmids of P. malariae, P. ovale (variant subspecies), P. knowlesi, 3 Plasmodium species of monkey, 5 species of Babesia, and genome DNA from 18 clinical samples, including 11 samples diagnosed positive for malaria (4 species), one clinical sample diagnosed positive for B. microti and 6 clinical samples diagnosed negative for malaria was collected to test the application of the system. Results A dual-tube multiplex qPCR system was developed and optimized for detecting multiple pathogens, including 3 universal primers, 3 genus- specific probes, and 5 species-specific probes. The amplification efficiency of the system was 90% to 110%, with the lowest limit of detection ranging from 5 × 10⁰ to 5 × 10¹ copies/μL for the original template concentration and the stable limit of detection of 5 × 10¹ copies/μL and higher. The 10 18S rDNA plasmid samples were tested positive with this system, and the 18S rDNA plasmid of B. bigemina, which had mismatched base with the first base of forward primer at 3′ terminal, was tested negative. The results for testing 12 positive clinical samples and 5 negative samples were consistent with previous diagnosed results, and one malaria-negative clinical sample was tested positive for P. vivax. The accordance rate was 17/18 for detection of clinical samples. Conclusion A dual-tube multiplex qPCR system has been established to detect 18 species of Plasmodium and Babesia, distinguish between Plasmodium and Babesia, and differentiate P. falciparum, P. vivax, and P. ovale, which may be used for pathogen detection of two genera in clinical blood samples.

Epidemiological and clinical characteristics of 174 cases with parasitic infections of the central nervous system in Jiangxi Province

XU Yun, GONG Zhihong, CHEN Xiaowei, XU Hui, ZHOU Feng, LIU Junpu, FU Ziyang, XIONG Yuping, XIE Huiqun, DING Sheng

2026, 44(4):  550-556.  doi:10.12140/j.issn.1000-7423.2026.04.014

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Objective To analyze the clinical characteristics, epidemiological exposure, disease spectrum, diagnosis, treatment and outcomes of individuals with parasitic infections of the central nervous system (CNS) in Jiangxi Province, so as to provide the clinical evidence for early identification of rare diseases. Methods All data pertaining to individuals with parasitic infections of the CNS receiving diagnosis and treatment in Jiangxi Provincial Institute of Parasitic Diseases from 2006 to 2025 were collected, and demographic features, epidemiological history, clinical manifestations, auxiliary examinations, discharge diagnoses, treatment modalities, and outcomes were statistically analyzed. Results A total of 174 cases with CNS parasitic infections were enrolled, including 110 men (63.2%) and 64 women (36.8%), and there were 105 cases (60.3%) at ages between 19~60 years. Farmers (40.8%, 71/174) and students (32.2%, 56/174) were predominant types of occupations, and the three mostly affected cities included Ji’an City (23.0%, 40/174), Yichun City (22.4%, 39/174) and Nanchang City (14.4%, 25/174). The positive rates of anti-Spirometra mansoni antibody, anti-Cysticercus cellulosae antibody, anti-Schistosoma antibody, anti-Paragonimus antibody, anti-Angiostrongylus cantonensis antibody, and anti-Toxoplasma antibody with HIV positivity were 67.2% (117/174), 62.6% (109/174), 8.0% (14/174), 4.6% (8/174), 5.7% (10/174) and 0.6% (1/174), respectively. Of 152 cases receiving immunological tests of cerebrospinal fluid (CSF), the detection of anti-S. mansoni antibody, anti-C. cellulosae antibody, anti-Schistosoma antibody, anti-Paragonimus antibody, and anti-Toxoplasma antibody was 62.5% (95/152), 58.6% (89/152), 9.2% (14/152), 2.9% (5/174), and 0.6% (1/174), respectively. Eosinophilia was observed in 103 cases (59.2%, 103/174). PCR assay was performed among 15 cases, in which Next-generation sequencing of CSF revealed one case with cerebral sparganosis, and parasites captured from surgical craniotomy were identified as S. mansoni among 11 cases, and one case with primary amebic meningoencephalitis, one case with Balamuthia mandrillaris encephalitis, and one case with encephalopathy caused by Babesia. All 174 patients underwent cranial magnetic resonance imaging scans, with an abnormality rate of 100%. A total of 41 cases were confirmed by etiological evidence and pathological examinations. A clear history of epidemiological exposure was present in 89.7% (156/174) of patients, with intake of raw water (32.2%, 56/174) and consumption of raw or undercooked food (28.7%, 50/174) as the two most common exposures. The leading diagnoses included central nervous system sparganosis mansoni （73.6%, 128/174）, cerebral cysticercosis (11.5%, 20/174), and cerebral schistosomiasis (8.0%, 14/174); rare diseases accounted for 6.9% (12/174). Symptoms of the CNS were the predominant clinical manifestation. Seizures or epileptic attacks were the most important initial or primary symptom (89.1%, 155/174), followed by headache and dizziness (36.8%, 64/174), and limb weakness or numbness (32.2%, 56/174). Praziquantel-based deworming was the primary treatment option, and there were 43 cases receiving deworming in combination with surgical resection, with a response rate of 92.0% (160/174). Although rare and uncommon central nervous system parasitic diseases account for a relatively small proportion, cerebral paragonimiasis, A. cantonensis encephalopathy, and cerebral toxoplasmosis could be comprehensively diagnosed by integrating epidemiological history, specific serum antibodies, and brain MRI. Cerebral babesiosis was confirmed by blood smear and PCR, whereas amoebic encephalitis was mainly diagnosed by molecular biological testing of cerebrospinal fluid. Conclusion Cerebral sparganosis mansoni predominated among CNS parasitic infections in Jiangxi Province, followed by cerebral cysticercosis and cerebral schistosomiasis. Clinical diagnosis can be established by combining epidemiological history, clinical manifestations, imaging, serological/ cerebrospinal fluid immunological tests and molecular biological test.

Epidemiological characteristics and influencing factors of severe cases of imported malaria in Shandong Province from 2015 to 2025

MA Yufang, XU Yan, WANG Yongbin, WANG Longjiang, LI Yuejin, BU Cancan, LV Wenxiang, LI Yuanchang, XU He, ZHANG Shengnan, KONG Xiangli

2026, 44(4):  557-564.  doi:10.12140/j.issn.1000-7423.2026.04.015

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Objective To investigate the epidemiological characteristics and influencing factors of imported severe malaria cases in Shandong Province from 2015 to 2025, so as to provide insights into formulation of control strategies targeting the reduction of severe malaria cases. Methods The epidemic status of imported malaria and epidemiological case surveys of malaria cases in Shandong Province from 2015 to 2025 were collected from the Notifiable Disease Report Information Management System and Parasitic Diseases Prevention and Control Information Management System of China Information System for Disease Control and Prevention. The species of malaria parasites, source of acquiring infections, temporal, spatial and population distributions, healthcare seeking behaviors and definitive diagnosis of severe malaria cases were analyzed using a descriptive epidemiological method, and factors affecting the development of severe cases were identified with a logistic regression model. Results A total of 2 004 malaria cases were reported in Shandong Province from 2015 to 2025, including 155 severe cases (7.73%). Among the severe cases, there were 138 cases with falciparum malaria (89.03%), 10 cases with vivax malaria (6.45%), 6 cases with ovale malaria (3.87%), and 1 case with malariae malaria (0.65%), with 96.77% imported from African countries and 3.23% from Asian countries. Severe malaria cases were reported across all cities in Shandong Province except Heze City, with Qingdao City (46 cases, 29.68%), Jinan City (37 cases, 23.87%), and Jining City (16 cases, 10.32%) as the three most highly affected cities. There were 48 severe malaria cases (30.97%) receiving trans-regional medical services within the province. Of severe malaria cases, there were 149 males (96.13%) and 6 females (3.87%), with an average age of 41 years, and labors as the predominant occupation (69.68%, 108/155). The highest number of severe malaria cases was recorded in January (21 cases, 10.34% of monthly cases), while the lowest number was reported in March and April (8 cases each, 5.16% of monthly cases). The median interval from disease onset to initial diagnosis was 2 days among severe malaria cases, and the median interval from initial diagnosis to definitive diagnosis was 1 day. There were 13 cases (8.39%), 62 cases (40.00%), 42 cases (27.10%), 28 cases (18.06%), and 10 cases (6.45) receiving initial diagnoses at provincial, municipal, county, sub-county, and other institutions (disease control and prevention institutions and private doctors), with correct first-diagnosis rates of 12/13, 75.81% (47/62), 45.24% (19/42), 3.57% (1/28), and 3/10, respectively. Multivariate logistic regression analysis identified age group of 50-59 years (OR = 2.076, 95% CI : 1.081 to 3.986), occupation of housework or unemployed (OR = 1.989, 95% CI: 1.134 to 3.490), disease onset out of China (OR = 2.139, 95% CI: 1.287 to 3.555), history of malaria (OR = 0.364, 95% CI: 0.254 to 0.521), interval from initial diagnosis to definitive diagnosis of 3 days and longer (OR = 2.120, 95% CI: 1.252 to 3.591), falciparum malaria (OR = 2.798, 95% CI: 1.633 to 4.792), and cross-regional healthcare-seeking behaviors (OR = 1.741, 95% CI: 1.185 to 2.558) as factors affecting the development of severe malaria. Conclusion The proportion of imported severe malaria cases is high in Shandong Province. Old age, long duration from initial diagnosis to definitive diagnosis, P. falciparum infection, and cross-regional healthcare-seeking behaviors increase the risk of severe malaria.

Morphological identification and phylogenetic analysis of pentastomids in snakes from Guangxi

ZHOU Qing’an, CHEN Zimei, ZHENG Min, BI Jingshan, LI Yiqin, HU Wei, LI Jian

2026, 44(4):  565-571.  doi:10.12140/j.issn.1000-7423.2026.04.016

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Objective To investigate the prevalence of pentastomid infections in snakes from Guangxi and conduct phylogenetic analysis. Methods Snakes that died during rescue and management at the Nanning Municipal Wild Animals and Plants Protection Station between September 2011 and December 2022 were collected and necropsied, and pentastomid adults and nymphs were recovered. Parasite morphology was examined under an optical microscope, and body length, number of abdominal annulations, hook measurements, and male copulatory spicules were recorded, while tegumental ultrastructure was examined by scanning electron microscopy. In addition, the pentastomid 18S ribosomal RNA (18S rRNA) gene was amplified using PCR assay, followed by sequence alignment and phylogenetic analyses. Results A total of 158 snakes were collected, and the detection rate of pentastomids was 15.19% (24/158). A total of 162 pentastomid specimens were recovered, with a mean infection intensity of 6.75 worms per infected snake. Based on morphological characteristics, the specimens were provisionally characterized as Raillietiella, Kiricephalus, and Waddycephalus. Sequencing of pentastomid adults and nymphs revealed that the 18S rRNA gene sequences had valid sequence lengths of 1 776 to 1 796 bp, and were deposited in GenBank under accession numbers KC904945, KC904947, MH194559, and KC904946. These sequences showed 98.62% similarity to Hispania vulturis (GenBank accession No. AY304520), 99.22% similarity to Kiricephalus sp. (GenBank accession No. MZ919326), and 98.50% similarity to Levisunguis subaequalis (GenBank accession No. MN065568), respectively. Phylogenetic analysis revealed that R. orientalis was located within the Raillietiella-related lineage, whereas K. pattoni adults and nymphs and W. radiata were located within the Porocephalus-related lineage. K. pattoni adults and nymphs were clustered into a clade with 99% bootstrap support. The genetic distance between sequences of K. pattoni adults (GenBank accession number: KC904947) and nymphs (GenBank accession number: KC904946) was 0.002 4, with only four nucleotide differences, while the genetic distances between each of these sequences and the reference sequence of Kiricephalus sp. (GenBank accession number: MZ919326) were both 0.007 9. Conclusion Pentastomids were detected in snakes from Guangxi, and the recovered specimens were identified as R. orientalis, K. pattoni, W. radiata, and Waddycephalus sp.

REVIEWS

Host infection spectrum and comprehensive control of Angiostrongylus cantonensis under the framework of One Health

LIU Xiadie, YIN Jiaxiang

2026, 44(4):  572-578.  doi:10.12140/j.issn.1000-7423.2026.04.017

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Angiostrongyliasis is a zoonotic parasitic disease caused by Angiostrongylus cantonensis infection, with snails and rodents as its major reservoir and transmission hosts. With the development of international trade, and tourism and changes of ecological environments, the interaction of human-animal-environment interface is becoming more and more frequent, resulting in a significant increase in the risk of angiostrongyliasis transmission. The One Health concept advocates a systematic response to public health challenges through interdisciplinary and cross-sectoral collaborations. Based on the One Health perspective, this article systematically reviews the life cycle, epidemiological characteristics, clinical diagnosis and treatment of A. cantonensis, and A. cantonensis infections in host animals, analyzes the environmental factors associated with the development and transmission of angiostrongyliasis, and proposes angiostrongyliasis control strategies, with aims to reduce angiostrongyliasis transmission risk and achieve the healthy and coordinated development of humans, animals and environmental ecology.

Advances in the epidemiological studies of angiostrongyliasis in China: ecological models

ZHU Zelin, GUO Yunhai, Qin Zhiqiang, HAO Yuwan, TIAN Tian, CHEN Yijun, XIA Shang, CHEN Muxin, LI Shizhu, ZHOU Xiaonong

2026, 44(4):  579-586.  doi:10.12140/j.issn.1000-7423.2026.04.018

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Angiostrongyliasis is a neglected food-borne zoonotic parasitic disease with a prominent potential threat to public health. Current researches have primarily focused on pathogens and diagnosis of angiostrongyliasis, whereas studies on ecological models are still at initial stages. Based on epidemiological characteristics of angiostrongyliasis, this review describes the applications, strengths, and limitations of four common ecological models in angiostrongyliasis research. Subsequently, transmission dynamics models have been developed for angiostrongyliasis based on system dynamics, and interdisciplinary collaborations are recommended to refine future research, so as to provide insights into precise control of angiostrongyliasis.

Advances in molluscicides against major snail intermediate hosts of Angiostrongylus cantonensis

WANG Weisi, CHEN Ying, SUN Yang, HUANG Shuijin, LUO Yanping, KE Shaoyong, DUAN Liping

2026, 44(4):  587-594.  doi:10.12140/j.issn.1000-7423.2026.04.019

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Angiostrongyliasis is an emerging zoonosis. Its primary intermediate hosts, the apple snails (Pomacea) and giant African land snails (Achatina fulica), have significantly exacerbated the risk of disease transmission through their population expansion. Applying molluscicides to control these intermediate host populations is an effective strategy for interrupting disease transmission. This review systematically summarizes the research progress on molluscicides for controlling these two snail species. It provides a focused overview of the current research landscape, which features chemical molluscicides as the dominant approach, complemented by plant-derived and microbial molluscicides, alongside RNA-based molluscicides in the frontier exploratory stage and attractants employed for behavioral regulation. This review aims to serve as a valuable reference for the development of novel molluscicides and the integrated control of angiostrongyliasis.

Research progress on the application of loop mediated isothermal amplification technology in the detection of foodborne parasites

DONG Yaru, WANG Lei, WU Ziyang, WEI Ziyan, ZHANG Ziyang, WANG Qiuyue

2026, 44(4):  595-599.  doi:10.12140/j.issn.1000-7423.2026.04.020

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Foodborne parasites are an important factor affecting food safety, and the resulting foodborne parasitic diseases have become a serious threat to human health. In order to effectively prevent the infections and transmission of foodborne parasites, and to protect food and public dietary safety, effective tools for detection of foodborne parasitic infection are essential. Currently, detection of foodborne parasites primarily depends on pathogenic methods, which suffer problems of time-consuming and labor-intensive procedures, and high requirement of personnel professionalism and detection sites, resulting in limitations in application scenarios. Loop-mediated isothermal amplification (LAMP) is convenient, highly efficient, and has no excessive dependence on equipment in relative to parasitological techniques, which has been widely used for nucleic acid detection of bacteria, viruses and parasites. This article summarized the principle of LAMP assay and its application in the detection of common foodborne parasites and proposes the development trend of LAMP assay in detection of foodborne parasites.

Roles of immunosuppressive molecules in parasitic protozoan and helminth infections

YANG Yuxuan, WU Binjie, FAN Haining

2026, 44(4):  600-607.  doi:10.12140/j.issn.1000-7423.2026.04.021

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Parasite infection will induce host innate and specific immune responses. Some helminth and protozoan can evade host immune response, resulting in long-term parasitism. Immune checkpoints are widely expressed in various types of immune cells, which can induce immune exhaustion and suppress immune response. In recent years, studies have found that immunosuppressive molecules programmed cell death protein-1 (PD-1), cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), lymphocyte activation gene-3 (LAG-3) and T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3) are widely expressed in hosts infected with helminth and protozoa, playing an important role in regulating host immune function. Exploring the role of immunosuppressive molecules in helminth and protozoan infections is of great reference value for drug development and clinical diagnosis and treatment. Hence, we provide a summary of this review article to summarize the recent research studies on progress of the immunosuppressive molecules and its role in protozoan and helminth infection.

Research progress on deep learning-based detection of parasite microimages and its applications

LIU Qiuchi, LI Song, DONG Liqi, FU Ziyu, WU Xiaoqi, LI Silong, LIU Guihong, JIANG Meihan, ZHANG Hao

2026, 44(4):  608-614.  doi:10.12140/j.issn.1000-7423.2026.04.022

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Parasite identification is a critical task in the medical diagnosis and public health field. The precision of image segmentation directly determines the reliability of detection results. Recently, deep-learning technologies have developed rapidly and shown great potential in medical image analysis. Deep learning-based tools are superior to conventional manual microscopy in terms of efficiency, objectivity and consistency. This review summarizes the applications of deep-learning models in parasite image processing, including Convolutional Neural Network (CNN), Efficient Convolutional Network (EfficientNet), You Only Look Once version 8 (YOLOv8), ested U-Net (U-Net++), and Transformer, describes the structural features, performance metrics and applicable scenarios of these models, and analyzes the problems encountered in current relevant studies.

SHORT COMMUNICATIONS

Investigation on potential risk factors for angiostrongyliasis transmission across Chongming District, Shanghai Municipality

LI Chunyuan, JIN Yanjun, YANG Jiawei, CHENG Gang, HUANG Jiayin, WANG Shuang, YU Qing

2026, 44(4):  615-618.  doi:10.12140/j.issn.1000-7423.2026.04.023

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To investigate the potential risk factors for angiostrongyliasis transmission across Chongming District of Shanghai Municipality, so as to provide insights into monitoring and assessment of angiostrongyliasis transmission risk in this island. A survey was conducted on Pomacea snail distribution across Chongming District of Shanghai Municipality, from April to October 2023, and six high-risk townships with relatively large areas of Pomacea snail-infested habitats south of the Yangtze River in the island were selected for a retrospective survey of angiostrongyliasis cases, survey of paratenic hosts, wild environments and market-sold snails, and field questionnaire surveys among residents. In addition, wild mice were captured with a trapping method at night from a representative township for detection of Angiostrongylus cantonensis infections. There were 15 out of 18 townships detected with Pomacea snails in Chongming District. A total of 60 wild environments were investigated in 6 high-risk townships, with 1 228 Pomacea snails captured. A total of 1 200 Cipangopaludina cathayensis and 12 Bellamya aeruginosa snails were sampled from 18 farmers’ markets and restaurants, with no Pomacea snails or Lissachatina fulica found, and a total of 257 paratenic hosts (freshwater fish, river shrimp, and river crabs) were collected, with no A. cantonensis infections detected. A total of 105 wild mice were captured from Shuangjin Village, Gangxi Township, with no adult A. cantonensis worms identified. A total of 300 questionnaires were allocated in 6 townships, with a 100% recovery rate, and the awareness rate of angiostrongyliasis control knowledge was 22% (66/300), with a relatively high awareness rate among respondents at ages of 20 to 39 years (30.37%, 41/135), urban residents (32.65%, 32/98), and respondents with an educational level of junior college and above (30.56%, 44/144) (χ² = 13.193, 16.624, 11.923, P < 0.05). There were 65.99% (198/300) of respondents with at least one of the five living habits of eating raw snails or snails stewed in soy sauce, eating raw or half-cooked snail meat, eating drunk crabs and/or drunk shrimps and crab paste, drinking filtered water or tap water directly, and contact with Pomacea snails or slugs, with the highest proportion for eating drunk crabs and/or drunk shrimps and crab paste (11.67%, 35/300). In addition, 3.67% (11/300) of respondents had a tendency to purchase or consume Pomacea snails. There is a relatively complete transmission chain for angiostrongy-liasis throughout Chongming District, with potential risks for both imported and local transmission. It is recommended to reinforce the dynamic systemic risk monitoring of the “human-animal-environment” and respond to emergency events.

Analysis of malaria detection results among inbound population at Chengdu Port from 2024 to 2025

LI Mengqiu, LU Siyu, TIAN Lvbo, ZHANG Ningfeng, SHI Ying

2026, 44(4):  619-622.  doi:10.12140/j.issn.1000-7423.2026.04.024

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Malaria surveillance data were collected from individuals entering China via Chengdu Port of Entry from 2024 to 2025, and the temporal, regional and population distributions of malaria were analyzed using a descriptive epidemiological method. A total of 11 144 traveler received malaria tests during the study period from 2024 to 2025, and the overall prevalence of malaria parasite infections was 1.55% (173/11 144). Among the confirmed infections, Plasmodium falciparum accounted for 94.22% (163/173), followed by P. malariae 3.68% (6/173), P. ovale 1.16% (2/173) and P. vivax 1.16% (2/173). The detection of malaria parasites was higher in 2025 (2.86%, 139/4 865) than in 2024 (0.54%, 34/6 279) (χ² = 96.78, P < 0.01). In terms of temporal distribution, the highest number of Plasmodium infections (87 cases, 50.29%) was reported during the period from October to December, followed by between July and September (56 cases, 32.37%). In terms of country of origin, most cases entered China from Ethiopia (87.86%, 152/173), followed by Qatar (5.20%, 9/173). In terms of case identification, most cases (70.52%, 122/173) were detected via on-site medical inspection, followed by high fever alerts (21.39%, 37/173). Of the 173 Plasmodium-positive cases, 166 were male (95.95%) and 7 were female (4.05%), with a male-to-female ratio of 23.71: 1. The majority of infected individuals were aged 31 to 60 years (85.55%, 148/173), with the largest number of cases detected at ages of 31 to 40 years (32.37%, 56/173). In terms of occupation, migrant labors constituted the largest proportion (89.02%, 154/173), followed by business (4.62%, 8/173). Among Plasmodium-positive individuals, 5 cases (14.70%, 5/34) in 2024 and 80 cases (57.55%, 80/139) in 2025 had a previous history of malaria. There were 71 cases (41.04%, 71/173) with fever upon entry. Laboratory screening under the multi-disease prevention strategy revealed 13 cases (7.51%, 13/173) co-infected with malaria and sexually transmitted diseases, and 29 cases (16.76%, 29/173) co-infected with respiratory infectious diseases. Malaria infections present distinct temporal, population and geographical characteristics among individuals entering China via Chengdu Port of Entry, and the risk of malaria infections rose markedly in 2025.

Epidemiological characteristics of 530 patients with scabies in Fuzhou City

JING Yue’e, WANG Lili, CHEN Jun, WENG Liqiang, LONG Qinqin

2026, 44(4):  623-625.  doi:10.12140/j.issn.1000-7423.2026.04.025

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To investigate the epidemiological features of patients with scabies attending the Outpatient Department, Institute of Dermatology, Fuzhou First General Hospital, the medical records of 530 patients with scabies with definitive diagnosis by dermoscopy and meeting the inclusion criteria in the Outpatient Department during the period between January 1, 2024 and December 31, 2025 were retrospectively collected, and the gender and age distributions, lesion sites, and time of definitive diagnosis were analyzed among patients with scabies using a descriptive epidemiological method. Among the 530 patients, there were 284 men and 246 women, with a male-to-female ratio of approximately 1.2: 1, and these patients had ages of 10 months to 95 years, with 12.3% (65/530) aged of 0 to 14 years, 24.9% (132/530) aged of 15 to 34 years, 17.7% (94/530) aged of 35 to 59 years, 12.3% (65/530) aged of 60 to 69 years, 16.6% (88/530) aged of 70 to 79 years, and 16.2% (86/530) aged of 80 to 99 years, respectively. All patients presented with pruritus and signs of scratching, and the most common sites of skin injury were palms and interdigital spaces (90.6%, 480/530), followed by scrotum and penis (3.4%, 18/530), buttocks and perianal region (1.5%, 18/530), chest and abdomen (1.5%, 8/530), lower extremities (0.4%, 2/530), bottom and dorsum of the foot (0.9%, 5/530), forearms (0.8%, 4/530), axillae (0.5%, 3/530), and back (0.4%, 2/530), respectively. Dermoscopy of skin lesions showed tunnel-like structures and brown triangle spots in the end of curved white curves. The number of scabies cases remained relatively stable from January through August, increased remarkably from September to November, and peaked in November. There is a high proportion of individuals at ages of 60 years and older among patients with definitive diagnosis of scabies in the Outpatient Department, Institute of Dermatology, Fuzhou First General Hospital, and the most common sites of skin injury are palms and interdigital spaces. The number of patients with definitive diagnosis of scabies appeared a tendency towards an increase in autumn.

CASE REPORT

A case report of rare hepatic echinococcosis with detection of Rhizopus delemar DNA sequences

WANG Danpu, CHENG Yuli, SUN Lei, ZHANG Hongwei, ZHANG Ke, JIA Zhe, SONG Rui

2026, 44(4):  626-628.  doi:10.12140/j.issn.1000-7423.2026.04.026

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This paper reports a rare case of hepatic echinococcosis with detection of Rhizopus delemar DNA sequences. The patient was a 35-year-old female who was admitted to the hospital due to the detection of a space-occupying lesion in the liver. Serum immunological tests indicated positive results for anti-Echinococcus IgG antibody. Postoperative pathological examination revealed multiple cystic lesions in the liver, which contained grayish-yellow tofu-like necrotic materials. Microscopic observation showed residual shadows of spherical spore-like structures and calcification. Metagenomics Capture on Pathology further identified the pathogen as Echinococcus canadensis and detected Rhizopus delemar DNA sequences. Moreover, genotyping confirmed that the hydatid cyst was of the G7 genotype (porcine strain), which is relatively rare in China. The patient underwent robot-assisted resection of the right posterior lobe and segment S8 of the liver, and received symptomatic treatments including anti-infection and liver-protective therapy postoperatively. The patient recovered completely and was discharged after surgery.

Diagnosis, species identification and origin of acquiring infections of a local case with subcutaneous sparganosis in Yanbian, Jilin

LI Jixu, HUANG Baoquan, JIANG Yi, ZHU Ming, JIANG Huilin, XUE Shujiang

2026, 44(4):  629-633.  doi:10.12140/j.issn.1000-7423.2026.04.027

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A 69-year-old Korean ethnic female farmer from Helong City, Jilin Province, was presented. The patient has a habit of drinking raw water and eating raw cod, and reported a subcutaneous mass in the lower left abdomen for 2 years. She sought medical services at a local hospital due to gradual enlargement of the mass on April 8, 2026. Routine blood testing showed a 0.3% eosinophil percentage and an eosinophil count of 0.03 × 10⁹/L; however, no eggs were detected in stool samples using the modified Kato-Katz thick smear method. A subcutaneous mass, measuring approximately 3.0 cm × 2.0 cm, was palpated in the lower left abdomen during physical examinations, which was smooth in surface, tough in texture, absent for tenderness, good in mobility and clear in boundary, and no redness or swelling was found in local skin. Color ultrasound examinations displayed irregular and slightly strong echoes (measuring approximately 26.7 mm × 14.0 mm × 21.0 mm) in the subcutaneous fat layer of the lower left abdomen, along with low echoes of approximately 5.6 mm × 4.9 mm. A white cord-like tissue with 5.5 cm in length was peeled off from the mass, and the head of the tissue was significantly enlarged, with the maximum diameter of 0.3 cm, which was similar to plerocercoid in morphology. Hematoxylin and eosin (HE) staining of pathological sections showed chronic granulomatous inflammation in subcutaneous tissues. The white cord-like tissue was a parasite worm body, which was visible in the transverse section as a completely solid structure. There were vacuolar and tubular structures with varying sizes in the parenchyma, scattered with lime bodies. Convex and concave transverse folds were seen on the longitudinal section of the worm body, exhibiting pathological characteristics of Spirometra plerocercoid. A target band with approximately 475 bp in length was yielded from amplification of the tapeworm cytochrome c oxidase subunit 1 (cox1) gene. Sequencing and alignment showed the gene sequence had 100% similarity with the cox1 gene sequence of S. mansoni (GenBank accession number: OQ552843), and they were clustered into a clade on the phylogenetic tree. The case was diagnosed with subcutaneous sparganosis caused by infection with S. mansoni larvae, and subcutaneous sparganosis-associated granulomatous nodules were resected. Deworming with albendazole was given post-surgery, and no other abnormalities were found during follow-up.