Table of Content

10 February 2021, Volume 33 Issue 1

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Key points and research priorities of schistosomiasis control in China during the 14th Five-Year Plan Period

XU Jing, HU Wei, YANG Kun, Lü Shan, LI Shi-Zhu, ZHOU Xiao-Nong

2021, 33(1):  1. 

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Schistosomiasis was once endemic in 12 provinces (municipalities, autonomous regions) along and south of the Yangtze River basin, which seriously damages human health and hinders socioeconomic developments in China. Following the concerted efforts for 70 years, remarkable achievements have been gained in the national schistosomiasis control program of China. However, there are still multiple challenges for elimination of schistosomiasis in the country. This paper describes the current status of schistosomiasis and the challenges during the progress towards the elimination of schistosomiasis, and proposes the goals, key points and research priorities of schistosomiasis control in China during the 14th Five?Year Plan Period.

Challenges and countermeasures in prevention of re?establishment of imported malaria in China

ZHU Guo-Ding, GAO Qi, CAO Jun

2021, 33(1):  7. 

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Malaria was one for the most serious communicable diseases in China. Following the concerted efforts for decades, remarkable achievements have been gained for malaria control in China. Since the national malaria elimination programme was initiated in China in 2010, local malaria transmission was rapidly interrupted, with zero indigenous malaria case reported for the first time in the country in 2017, and the country will undergo the certification of malaria elimination by WHO. Currently, however, malaria remains hyper?endemic across the world. In China, there are more than 2 000 overseas imported malaria cases each year, and prevention of re?establishment of imported malaria will become the major task in future malaria control activities. Hereby, we analyze the main challenges in the prevention of re?establishment of imported malaria in China, and propose the corresponding countermeasures, so as to provide insights into the consolidation of malaria elimination achievements.

Expert consensus on the strategy and measures to interrupt the transmission of schistosomiasis in China

2021, 33(1):  10. 

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Since 2015 when the transmission of schistosomiasis was controlled in China, the country has been moving towards elimination of schistosomiasis, with the surveillance?response as the main interventions for schistosomiasis control. During the period of the 13th Five?Year Plan, the transmission of schistosomiasis had been interrupted in four provinces of Sichuan, Jiangsu, Yunnan and Hubei and the prevalence of schistosomiasis has been at the historically lowest level in China. As a consequence, the goal set in The 13th Five?Year National Schistosomiasis Control Program in China is almost achieved. However, there are multiple challenges during the stage moving towards elimination of schistosomiasis in China, including the widespread distribution of intermediate host snails and complicated snail habitats, many types of sources of Schistosoma japonicum infections and difficulty in management of bovines and sheep, unmet requirements for the current schistosomiasis control program with the currently available tools, and vulnerable control achievements. During the 14th Five?Year period, it is crucial to consolidate the schistosomiasis control achievements and gradually solve the above difficulties, and critical to provide the basis for achieving the ultimate goal of elimination of schistosomiasis in China. Based on the past experiences from the national schistosomiasis control program and the challenges for schistosomiasis elimination in China, an expert consensus has been reached pertaining to the objectives, control strategy and measures for The 14th Five?Year National Schistosomiasis Control Program in China, so as to provide insights into the development of The 14th Five?Year National Schistosomiasis Control Program in China.

Spatial and temporal characteristics of reported schistosomiasis cases in China based on a Bayesian interrupted time?series model

WEN Chu-Chun, ZHAO Ting-Ting, HU Wei-Hua, CAO Wen-Rui, LAI Ying-Si

2021, 33(1):  15. 

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Objective　To investigate the spatial?temporal characteristics of reported schistosomiasis cases in China from 2004 to 2017, so as to provide insights into the development of different schistosomiasis control strategies at various stages. Methods　The monthly data of reported schistosomiasis cases at a provincial level of China from 2004 to 2017 were collected from the Public Health Science Data Center, and the spatial?temporal distribution of reported schistosomiasis cases was preliminarily identified using a descriptive statistical method. According to the goals at different stages proposed by the National Mid? and Long?term Program for Schistosomiasis Prevention and Control in China (2004—2015), a Bayesian interrupted time?series model was established to analyze the provincial reported incidence, time trend and seasonal variations of schistosomiasis in China at different stages. Results　The reported schistosomiasis cases were mainly concentrated in 5 provinces of Anhui, Jiangsu, Jiangxi, Hubei and Hunan and 2 provinces of Sichuan and Yunnan in China from 2004 to 2017, and the number of reported cases in endemic areas decreased gradually. The incidence of reported schistosomiasis cases predominantly peaked during the period from May to September in the marshland and lake regions, while no regular seasonality was seen in hilly regions. Bayesian interrupted time?series analysis showed the peak incidence of reported schistosomiasis cases in 4 provinces of Anhui, Hubei, Hunan and Jiangxi between May and September and in Jiangsu Province from July to November; however, no regular seasonal cycle was identified in hilly regions. The number of reported schistosomiasis cases showed a tendency towards an increase in 2 provinces of Hubei and Hunan from 2008 to 2014, with a minor peak during the period between March and April, and since 2015, the seasonality was not remarkable any longer in 3 provinces of Anhui, Jiangsu and Jiangxi with a decline in the incidence of reported schistosomiasis cases, while the seasonality remained in Hubei Province. Conclusions　The spatial?temporal characteristics of schistosomiasis in China, notably seasonality, vary at different control stages. Bayesian interrupted time?series model is effective to identify the spatial?temporal changes of schistosomiasis, and the schistosomiasis control strategy may be adjusted according to the spatial?temporal changes to improve the schistosomiasis control efficiency.

Association between serum vitamin D level and immune imbalance in advanced schistosomiasis patients with liver fibrosis

ZHOU Li-Yun, ZHANG Li-Fang, WU Yi-Ming, HAN Shuang-Yin

2021, 33(1):  22. 

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Objective　To examine the relationship between serum vitamin D level and immune imbalance in advanced schistosomiasis patients with liver fibrosis. Methods　A total of 120 advanced schistosomiasis patients with liver fibrosis that were admitted to the Department of Schistosomiasis of The First Hospital of Jiaxing City from May 2016 to September 2018 were recruited as the observation group, and 50 healthy volunteers randomly sampled from the hospital during the same period served as the control group. The serum IgG antibody, IgA antibody, C3 complement, C4 complement, CD4+ cell proportion, CD8+ cell proportion, 25?hydroxyvitamin D [25(OH)D] levels were compared between the two groups. Liver fibrosis was classified into grade I, II and III according to the classification criteria of liver fibrosis by ultrasonography, and the serum IgG antibody, IgA antibody, C3 complement, C4 complement, CD4+ proportion, CD8+ proportion, 25(OH)D levels were compared among patients with grade I, II and III liver fibrosis. In addition, all patients were classified into the sufficient group, the insufficient group and the deficient group according to the serum vitamin D level, and the serum IgG antibody, IgA antibody, C3 complement, C4 complement, CD4+ proportion, CD8+ proportion, 25(OH)D levels were compared among these three groups. Moreover, the associations of the serum vitamin D level with these immune indicators were examined. Results　The 120 advanced schistosomiasis patients with liver fibrosis included 58 men and 62 women, and had a mean age of (72.00 ± 3.00) years. There were 32 cases with grade I liver fibrosis, 46 cases with grade II liver fibrosis, and 42 cases with grade III liver fibrosis. There were no significant differences between the observation group and the control group in terms of serum D?dimer, total cholesterol (TC), triglyceride (TG), C3 complement or C4 complement levels (t = 2.467, 0.322, 0.790, -2.432 and -2.630, all P values > 0.05); however, there were significant differences seen in alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood calcium, blood phosphorus, IgG antibody, IgA antibody, CD4+ proportion, CD8+ proportion, and 25(OH)D levels (t = 5.130, 6.382, -1.341, 2.361, 8.708, 11.783, -2.995, -6.543 and -3.022, all P values < 0.05). In addition, there were significant differences in AST, ALT, blood phosphorus, IgA antibody, C3 complement, CD8+ cell proportion and 25(OH)D levels among patients with grades I, II and III liver fibrosis (F = 19.704, 16.254, 62.669, 49.347, 5.430, 5.434 and 5.783, all P values < 0.05). There were significant differences in ALT, blood phosphorus, IgA antibody, CD8+ cell proportion and 25(OH)D levels between patients with grades I and III liver fibrosis (all P values < 0.05), and significant differences were seen between patients with grades II and III liver fibrosis in terms of blood phosphorus, IgA antibody and CD8+ cell proportion (all P values < 0.05), while there was a significant difference in the CD8+ cell proportion between patients with grades I and II liver fibrosis (P < 0.05). Moreover, there were significant differences among the sufficient, insufficient and deficient groups in terms of IgG antibody, IgA antibody, C3 complement, CD4+ cell proportion and CD8+ cell proportion (F = 13.303, 59.623, 8.698, 9.969 and 12.805, all P values < 0.05), and there was a significant difference in the CD8+ cell proportion between the insufficient and deficient groups (P < 0.05). Pearson correlation analysis revealed that serum 25(OH)D level were negatively associated with IgG and IgA antibody levels (r = -0.754 and -0.773, both P values < 0.05), and positively associated with C3 complement, CD4+ cell proportion and CD8+ cell proportion in advanced schistosomiasis patients with liver fibrosis (r = 0.827, 0.850 and 0.830, all P values < 0.05). Conclusions　Immune imbalance occurs in advanced schistosomiasis patients with liver fibrosis, and serum vitamin D level may correlate with immune imbalance in advanced schistosomiasis patients with liver fibrosis.

Study on the mechanisms of the intestinal tight?junction destruction caused by Blastocystis hominis infection in rats

LU Yun-Yu, PEI Pei, ZHANG Li-Lin, XUE Sa, HAN Xue, BI Xiang-Lian, ZHAO Hong-Ying, LIU Deng-Yu, FU Xiao-Yin

2021, 33(1):  28. 

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Objective　To explore the mechanism of the intestinal barrier damage caused by Blastocystis hominis infections in rats. Methods　Thirty SD rats were randomly divided into the control group, and the 1?, 3?, 6? and 9?week?infection groups, of 6 rats in each group. Rats in each infection group were orally infected with B. hominis trophozoites at a density of 2 × 108 parasites per rat, and the control group was given an equal volume of phosphate buffered saline solution. The 7?hour urine samples were collected 1, 3, 6 and 9 weeks post?infection for the measurement of the intestinal permeability. Then, rats were sacrificed using the cervical dislocation method, and the cecum specimens were collected for the detection of the intestinal epithelial cell permeability. The expression of tight junction?related Occludin and Claudin?1 genes and apoptosis?related Bcl?2 and Bax genes was quantified in cecum epithelial cells using the real?time fluorescent quantitative PCR (qPCR) assay, and cell apoptosis was detected in the rat cecum using the TdT?mediated dUTP nick?end labeling (TUNEL) assay. Results　The median urinary lactolose to mannitol ratios were 0.29, 0.72, 0.44, 0.46 and 0.38 in the control group, and the 1?, 3?, 6? and 9?week?infection groups, respectively, and the difference was statistically significant (H = 12.09, P < 0.05). B. hominis invasion and epithelial injury were observed in intestinal epithelial cells of rats infected with B. hominis, and transmission electron microscopy displayed the destruction of tight junctions between intestinal epithelial cells. The relative expression of Occludin, Claudin?1, Bcl?2 and Bax genes was 1.04, 0.62, 0.71, 0.68 and 0.96; 1.03, 0.61, 0.63, 0.76 and 0.86; 1.08, 0.70, 0.75, 0.74 and 1.03; and 1.00, 1.57, 1.33, 1.35 and 1.10 in the control group and the 1?, 3?, 6? and 9?week?infection groups, respectively, and all differences were statistically significant (F = 2.86, 2.85, 3.37 and 4.45, all P values < 0.05). The median number of positive staining cells were 1.00, 13.00, 9.00, 3.50 and 1.00 in rat cecum specimens in the control group, and the 1?, 3?, 6? and 9?week?infection groups, respectively, and the difference was statistically significant (H = 22.95，P < 0.01). Conclusion　B. hominis infection may cause an increase in the rat intestinal permeability through triggering the apoptosis of intestinal epithelial cells to destroy the tight junction between intestinal epithelial cells, thereby destroying the intestinal barrier function.

Genetic diversity of Sparganum isolates from snakes in Hunan Province based on mitochondrial nad4 and nad5 genes

GONG Teng-Fang, HE Jun-Lin, TAN Lei, XIE Li-Xing, LIU Wei

2021, 33(1):  35. 

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Objective　To investigate the genetic diversity and phylogenetic relationship of Sparganum isolates from snakes in Hunan Province. Methods　The partial mitochondrial NADH dehydrogenase subunit 4 (pnad4) and NADH dehydrogenase subunit 5 (pnad5) genes were amplified using a PCR assay in 7 Sparganum isolates from snakes in Hunan Province and the amplification product was sequenced. The homology and genetic evolution were investigated using the software DNAMAN 7.0, MegAlign, DnaSP 5.0 and MEGA 5.0. Results　The pnad4 and pnad5 gene sequences were approximately 578 bp and 484 bp in length in the 7 Sparganum isolates from Hunan Province, and the percentages of genetic variations were 0 to 2.8% and 0 to 0.8%, respectively. There were 4 haplotypes detected in both the pnad4 and pnad5 genes, with global haplotype diversities of 0.810 ± 0.016 and 0.905 ± 0.011, nucleotide diversities of 0.006 ± 0.005 and 0.004 ± 0.003, and mean nucleotide variations of 3.960 and 1.905, respectively. Phylogenetic analysis showed that all 7 Sparganum isolates from snakes in Hunan Province were clustered into the same branch with Spirometra erinaceieuropaei isolates from different regions/hosts in the world, which belonged to S. erinaceieuropaei, which were close to Diphyllobothrium latum and far from other tapeworms. Conclusions　There is a low genetic variation in snake?derived S. erinaceieuropaei isolates from Hunan Province, and both pnad4 and pnad5 genes may be potential molecular genetic markers for identification of S. erinaceieuropaei.

Spatial distribution of canine echinococcosis in Inner Mongolia Autonomous Region from 2012 to 2018

WANG Yu-Ying, HAO Hui-Xia, SONG Jian, GUO Wei-Dong, JIANG Xiao-Feng

2021, 33(1):  40. 

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Objective　To investigate the distribution and changing trend of canine echinococcosis in Inner Mongolia Autonomous Region, so as to provide the scientific evidence for prevention and control of canine echinococcosis in high?risk areas of Inner Mongolia Autonomous Region. Methods　All data pertaining to Echinococcus infections in canine feces and sampling survey of human echinococcosis were collected from the echinococcosis?endemic foci of Inner Mongolia Autonomous Region from 2012 to 2018, and the prevalence of Echinococcus infections was investigated in dogs and humans. In addition, the spatial distribution characteristics and clusters of canine echinococcoses were identified. Results A total of 164 139 canine fecal samples were detected in the echinococcosis?endemic foci of Inner Mongolia Autonomous Region from 2012 to 2018, and there were 2 136 fecal samples positive for Echinococcus coproantigens. The positive rates of Echinococcus coproantigens were 0.54% to 1.73% in dogs from 2012 to 2018, with a tendency towards a decline seen in the prevalence of Echinococcus infections in dogs ([χ2] = 108.83, P < 0.01), and there was a significant difference in the positive rate of Echinococcus coproantigens in dogs among years ([χ2] = 155.27, P < 0.01). Three?dimensional trend analysis showed that canine echinococcosis was mainly concentrated in east of central Inner Mongolia Autonomous Region, and a high prevalence was detected in New Barag Right Banner and Sonid Right Banner. The global spatial distribution of canine echinococcosis appeared a random pattern in Inner Mongolia Autonomous Region from 2012 to 2018 (Moran’s I > 0, P > 0.05), and there were “high?high” and “high?low” clusters of canine echinococcosis in local areas. The prevalence of human echinococcosis was 0.08%, and there was a significant difference in the prevalence among regions ([χ2] = 147.61, P < 0.01), with a high prevalence seen in West Ujimqin Banner, Jarud Banner and New Barag Right Banner. In addition, the prevalence of human echinococcosis correlated positively with the Echinococcus coproantigen?positive rate in dogs (r = 0.52, P < 0.01). Conclusions　The prevalence of Echinococcus infections shows an overall tendency towards a decline in dogs in Inner Mongolia Autonomous Region from 2012 to 2018, with a high prevalence found in New Barag Right Banner and Sonid Right Banner. Human echinococcosis is concentrated in clusters of canine echinococcosis, where health education and targeted control interventions requires to be intensified.

Epidemiological profiles of echinococcosis cases reported in the National Notifiable Disease Report System in non?endemic areas of China from 2004 to 2016

YU Qing, HAN Shuai, XUE Jing-Bo, XIA Shang

2021, 33(1):  48. 

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Objective　To investigate the epidemiological profiles of echinococcosis cases reported in non?endemic areas of China in the National Notifiable Disease Report System from 2004 to 2016, so as to provide insights into the development of effective surveillance and response measures. Methods　The data pertaining to the echinococcosis cases reported in the National Notifiable Disease Report System in 22 non?endemic provinces of China from 2004 to 2016 were collected, and the epidemiological profiles of the reported echinococcosis cases were descriptively analyzed. Results　A total of 462 echinococcosis cases were reported in the 22 non?endemic provinces of China from 2004 to 2016, and the number of reported cases increased with time ([χ2] = 4.516, P = 0.034). During the 13?year period from 2004 to 2016, the highest number of echinococcosis cases was reported in central and eastern China (56.49%), followed by in northern and northeastern China (30.30%), and the highest number of echinococcosis cases was reported in Henan Province (99 cases). Among the 462 echinococcosis cases reported, there were 234 men and 228 women, and the mean age was (41.42 ± 16.03) years (range, 4 to 86 years), with the highest number of echinococcosis cases reported at ages of 20 to 50 years (63.20%). The highest proportion of occupations was farmers and herdsmen (36.15%), and the greatest source was from echinococcosis?endemic provinces (50.43%); in addition, 97.40% of the echinococcosis cases were reported by hospitals. Conclusions　Echinococcosis cases were reported in all 22 non?endemic provinces of China in the National Notifiable Disease Report System from 2004 to 2016, and the number of reported cases appeared an overall tendency for sporadicity and local increase with time. Screening of echinococcosis is recommended among famers and herdsmen at ages of 20 to 50 years from endemic regions by medical institutions in non?endemic regions for timely identification and treatment of echinococcosis cases.

Effects of persistent Echinococcus multilocularis infections on hepatic fibrosis in mice

GAO Hai-Jun, PANG Hua-Sheng, SUN Xu-Dong, ZHANG Ting, JING Tao, WANG Xiao-Ling, MO Xiao-Jin, HU Wei

2021, 33(1):  54. 

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Objective　 To investigate the effects of persistent Echinococcus multilocularis infections hepatic fibrosis in mice, so as to provide insights into the understanding of liver fibrogenesis induced by E. multilocularis infections and the treatment of alveolar echinococcosis. Methods　Hepatic stellate HSC?T6 and LX?2 cells were exposed to the sera (25, 50 and 100 μL) from Meriones unguiculatus infected with E. multilocularis, and E. multilocularis , germinal layer cells (GCs) and protoscoleces (PSCs) for 48 hours, respectively. The cell proliferation was measured using a CCK?8 assay, and the levels of collagen 1 (Col1) and a?smooth muscle actin (α?SMA) were measured in the culture supernatant of HSC?T6 cells using ELISA. In addition, the serum and liver samples were collected 1, 2, 4, 6, 8 months post?infection with E. multilocularis, respectively. The serum Col1 and α?SMA concentrations were measured using enzyme?linked immunosorbent assay (ELISA), and the deposition of collagen fibers was examined in mice livers using Sirius red staining. Results　The sera of E. multilocularis?infected gerbils promoted the proliferation of HSC?T6 and LX?2 cells in vitro, and there were significant differences seen in the proliferative rate of HSC?T6 (FHSC?T6 = 126.50, P < 0.05) and LX?2 cells (FLX?2 = 201.50, P < 0.05) among different serum groups, with the highest proliferative rate of HSC?T6 (573.36% ± 206.34%) and LX?2 cells (940.38% ± 61.65%) found following exposure to 100 μL mouse sera. Exposure to serum from E. multilocularis?infected gerbils resulted in an increase in the Col1 and α?SMA levels in the culture supernatant of HSC?T6 cells, with the greatest Col1 (20.99 ng/mL ± 2.01 ng/mL) and α?SMA levels (305.52 pg/mL ± 16.67 pg/mL) measured following exposure to 100 μL sera. The metacestodes (142.65% ± 9.17% and 189.99% ± 7.75%), GCs (118.55% ± 8.96% and 122.54% ± 0.21%) and PSCs of E. multilocularis (156.34% ± 17.45% and 160.59% ± 31.41%) all promoted the proliferation of HSC?T6 and LX?2 cells in vitro, and there were significant differences in the proliferative rates of HSC?T6 (FHSC?T6 = 11.24, P < 0.05) and LX?2 cells among groups (FLX?2 = 47.72, P < 0.05). Exposure to E. multilocularis resulted in an increase in Col1 and α?SMA levels in the culture supernatant of HSC?T6 cells, and the highest Col1 (4.43 ng/mL ± 2.23 ng/mL) and α?SMA levels (285.20 pg/mL ± 90.67 pg/mL) were detected following treatment with E. multilocularis metacestodes. In addition, a persistent increase was seen in the deposition of collagen fibers in mice livers 1 to 8 months post?infection with E. multilocularis, with the greatest Col1 level (280.26 ng/mL ± 23.04 ng/mL) seen 6 months post?infection and the highest α?SMA level (33.68 ng/mL ± 4.45 ng/mL) detected 8 months post?infection, respectively. Conclusions　Persistent E. multilocularis infections promote hepatic stellate cell proliferation, induce an increase in mouse serum Col1 and α?SMA levels, and cause elevated deposition of collagen fibers in mice livers. The infective stage of E. multilocularis is a critical period for inducing hepatic fibrosis of alveolar echinococcosis.

Epidemiological characteristics of malaria in Henan Province from 1950 to 2019

GUO Wan-Shen, ZHAO Dong-Yang, ZHANG Hong-Wei, LU De-Ling, LIU Ying, QIAN Dan, YANG Cheng-Yun, GUAN Zhou, ZHAO Yu-Ling, ZHOU Rui-Min, LI Su-Hua, WANG Hao, DENG Yan, CHEN Wei-Qi, ZHANG Ya-Lan

2021, 33(1):  62. 

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Objective　To analyze the epidemiological characteristics of malaria in Henan Province from 1950 to 2019, so as to provide the scientific evidence for consolidating malaria elimination achievements in the province. Methods　The epidemiological situation of malaria and demographic data in Henan Province from 1950 to 2019 were collected, and the statistical analyses were performed using a descriptive epidemiological method. The spatial temporal distribution of malaria cases was identified using the software ArcGIS version 10.3. Results　During the period from 1950 through 2019, the progress of malaria elimination was divided into 4 stages in Henan Province, including the baseline?survey and key?control stage, morbidity?control and incidence?reduction stage, basic?eradication and achievement?consolidation stage and elimination stage. The spatial distribution of malaria cases shifted from south of the Huai River and the plain regions between the Yellow River and Taihang Mountain to the Huang?Huai?Hai Plain and Nanyang Basin, then was concentrated in eastern part of southern Huai River where Anopheles anthropophagus was distributed, and finally was gradually under control following malaria outbreak in Eastern Henan Plain. In addition, the species of Plasmodium changed from P. vivax, P. falciparum and P. malariae co?endemics to a single P. vivax infection, and the current co?endemics of 5 invasive malaria parasites, and the malaria vectors shifted from co?existence of Anopheles sinensis and An. anthropophagus to An. sinensis alone. Conclusions　There has been a large change in the epidemiological characteristics of malaria in Henan Province from 1950 to 2019. Although malaria has been eliminated in Henan Province, the consolidation of the malaria elimination achievements remain a great challenge due to overseas imported malaria.

DNA barcoding of 4 species of cheyletid mites based on COI and 18S rRNA gene sequences

ZHAN Yu-Juan, ZHANG Lan-Xiang, SUN Meng-Tao, LI Xin-Mei, WANG Yan, LI Meng-Zhu, TAO Dong-Dong, SUN En-Tao

2021, 33(1):  66. 

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Objective　To analyze the sequences of mitochondrial cytochrome C oxidase subunit I gene (COI) and 18S ribosomal RNA gene (18S rRNA), so as to identify the feasible DNA barcodes for 4 species of cheyletid mites and improve the DNA barcoding database for cheyletid mites. Methods　Cheyletid mite samples were collected from small?scale flour mills in Fuyang, Wuhu and Tongling cities of Anhui Province from May 2018 to July 2019, extracted and morphologically identified. Then, genomic DNA was extracted from a single cheyletid mite, and the COI and 18S rRNA gene sequences were obtained by PCR amplification, cloning and sequencing. The obtained sequences were aligned using the BLAST software. Multiple sequence alignment was done using the software ClustalX version 1.83 using the known gene sequences from cheyletid mites. The genetic distance was calculated using the software MEGA X, and the phylogenetic tree was created using the maximum likelihood method. Results　The DNA barcoding results of Cheyletus malaccensis, C. carnifex and Cheletomorpha lepidopterorum were consistent with the morphological identification, while no sequences pertaining to Eucheyletia reticulate were retrieved in the GenBank database. The proportions of A + T were 69.6% and 55.1% in the COI and 18S rRNA sequences of 4 cheyletid mites species, respectively, and the numbers of base substitutions were 137 and 46, respectively. There were 154 to 321 and 58 to 99 inter?species variation loci in the COI and 18S rRNA gene sequences of 4 cheyletid mites species, respectively, and the intra?species genetic distance was all 0.020 or less in the COI and 18S rRNA gene sequences of 4 cheyletid mites species, with inter?species genetic distance of 0.235 to 0.583 and 0.078 to 0.114, respectively. Phylogenetic analysis based on COI and 18S rRNA genes showed that all four species of cheyletid mites were clustered into a branch with a 100% supportive rate, which was consistent with the morphological identification. Conclusion　Mitochondrial COI gene is superior to 18S rRNA gene as DNA barcodes for 4 species of cheyletid mites, which is more suitable to be used to investigate the phylogenetic relationship of at genus and species levels.

Investigation on seroprevalence of Toxoplasma gondii infections among neonates in Fujian Province

WU Zhi-Hui, ZHUO Bi-Min, QIU Hua-Hong, MA Mei, CHEN Hui-Yu, ZHONG Hui

2021, 33(1):  71. 

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Objective　To investigate the seroprevalence of Toxoplasma gondii infections among neonates in Fujian Province, so as to provide insights into the development of interventions for the prevention and control of congenital toxoplasmosis. Methods　A total of 1 045 neonates delivered in Fujian Province from 2017 to 2018 were recruited, including 387 preterm infants and 658 full?term infants. Umbilical cord blood was sampled from all neonates, and the seroprevalence of anti?T. gondii IgG antibody was detected and compared between preterm and full?term infants. In addition, elbow venous blood samples were collected from neonates’ mothers, and the seroprevalence of anti?T. gondii IgG antibody was detected and compared between preterm and full?term infants’ mothers. Results　The overall seroprevalence of anti?T. gondii IgG antibody was 9.38% among the 1 045 neonates in Fujian Province. The seroprevalence of anti?T. gondii IgG antibody was 18.35% in the 387 preterm infants, and there was no significant difference in the seroprevalence of anti?T. gondii IgG antibody between male and female infants (17.69% vs. 18.75%, [χ2] = 0.07, P > 0.05). The seroprevalence of anti?T. gondii IgG antibody was 4.10% in the 658 full?term infants, and there was no significant difference in the seroprevalence of anti?T. gondii IgG antibody between male and female infants (4.14% vs. 4.08%, [χ2] = 0, P > 0.05). In addition, the overall seroprevalence of anti?T. gondii IgG antibody was 15.02% in all neonates’ mothers, and the seroprevalence was significantly greater in preterm infants’ mothers than in full?term infant’s mothers (20.93% vs. 11.55%, [χ2] = 16.79, P < 0.01). Conclusions　The seroprevalence of T. gondii infections is significantly higher in preterm infants and their mothers than in full?term infants and their mothers. Prenatal detection of T. gondii infections and health education pertaining to toxoplasmosis prevention and control knowledge are required to be strengthened to effectively reduce the incidence of congenital toxoplasmosis.

A preliminary study on the mixed teaching of human parasitology based on MOOC resources and the experimental teaching digital platform

YAN Rong, WANG Ling-Jun, LIU Liu, LI Xiao-Fei, ZHOU Bi-Ying, JIANG Nan, LIU Hui

2021, 33(1):  74. 

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The mixed teaching model combines the advantages of traditional teaching and network teaching in the “Internet +”era, which has become one of the important trends in the higher education teaching development. In order to follow this development trend, the human parasitology teaching team makes a reasonable use of modern information techniques, actively promotes the construction and application of online resources, and conducts mixed online and offline teaching based on MOOC resources and the experimental teaching digital platform. This mixed teaching model has shown a positive impact on both teaching and learning among teachers and students; however, students’ personalized independent and deep learning remains unsatisfactory. It is suggested that the online course resources construction, teaching design and digital literacy remain to be increased, so as to create a high?level, innovative and challenging online?offline mixed “golden course”.

Surveillance of Oncomelania hupensis distribution and water levels in Gaoyou sections of the eastern route project of the South?to?North Water Diversion Project following operation of the project

ZHU Yu-Fang, GAO Jin-Bin, WAN Zhong, HE Yong, GUO Kai-Zhong, ZUO Yin-Ping, HUANG Yi-Xin

2021, 33(1):  79. 

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Objective　To understand the distribution of Oncomelania hupensis snails and changes of water levels in Gaoyou sections of the Li Canal following the operation of the eastern route project of the South-to-North Water Diversion Project. Methods　The Oncomelania snails were monitored in the river banks and water bodies of Gaoyou sections of the Li Canal by means of systematic sampling combined with environmental sampling as well as collection of the floaters from 2014 to 2019, and the water levels were collected in Gaoyou sections of the Li Canal at the typical hydrological year before the operation of the eastern route project of the South-to-North Water Diversion Project and during the period between 2016 and 2019. Results　A total area of 235.42 hm2 were investigated and a total of 75.8 kg floaters were collected in Gaoyou sections of the Li Canal from 2014 to 2019; however, no snails were found. The water level in Gaoyou sections of the Li Canal was predominantly high in the flood season and low in the dry season before the operation of the eastern route project of the South-to-North Water Diversion Project, and the water level was elevated in the dry season and relatively low in the flood season after the operation of the project. Conclusion　Following the operation of the eastern route project of the South-to-North Water Diversion Project, the original river bank that is characterized by “land in winter and water in summer” has changed in Gaoyou sections of the Li Canal, which is not favorable for snail breeding.

Status of chronic filariasis: a cross?sectional study in Jiangxi Province, 2018

LEI Lei, GONG Yan-Feng, LI Zhi-Hong, ZHENG Jian-Gang

2021, 33(1):  81. 

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Objective　To understand the status of chronic filariasis patients in Jiangxi Province in 2018, so as to provide insights into the follow?up care of the patients. Methods　In 2018, a case follow?up study was conducted in all registered patients with chronic filariasis in previously endemic areas of Jiangxi Province, and a clue investigation was done for identifying the missing patients. In addition, the data of caring sites for chronic filarisis patients were collected and analyzed in the province. Results　A total of 802 chronic filariasis patients were identified in 56 counties (districts) of Jiangxi Province in 2018. The patients had a male/female ratio of 1∶1, and 85.41% had ages of over 70 years. There were 58.60%, 93.89%, 17.21% and 3.62% of chronic filariasis patients with lymphangitis, lymphedema/elephantiasis, chyluria and hydrocele, respectively. A total of 273 caring sites were assigned in 56 counties (districts) of Jiangxi Province, and 306 caring activities were carried out in 2018. Conclusion　The number of chronic filariasis patients has significantly decreased in Jiangxi Province; however, the care remains to be intensified for chronic filariasis patients.

Progress of researches on global prevalence of Blastocystis hominis human infections and its subtypes

ZHANG Fu-Qiang, WANG Pei, FENG Xia, MI Qiu-Min, MEI Xue-Fang, ZHANG Zhen-Chao, LI Xiang-Rui, WANG Shuai

2021, 33(1):  84. 

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Blastocystis hominis is a parasite that parasitizes in the intestines of humans and animals, and is closely related to a variety of gastrointestinal diseases such as abdominal pain and diarrhea. B. hominis is distributed worldwide, and the prevalence of B. hominis infections and dominant subgenotypes vary in countries and in regions from the same country. This paper reviews the global prevalence of B. hominis human infections, its subtypes and geographical distribution, so as to provide insights into the understanding of the global epidemiology of B. hominis and the management of B. hominis infections.

Progress of researches on Blastocystis infections in humans and animals in China

NING Chao-Qun, AI Lin, HU Zhu-Hua, CHEN Jun-Hu, TIAN Li-Guang

2021, 33(1):  95. 

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Blastocystis is a unicellular, anaerobic, intestinal protozoan that infects humans and a variety of animals, which is widely prevalent across the world. Blastocystis infections have been detected in healthy populations, children, students, outpatients and inpatients, as well as diarrhea patients in China. High prevalence of Blastocystis infections has been reported in immunocompromised patients, and relatively high prevalence was seen in individuals living in Guangxi and Yunnan regions. Based on the small subunit ribosomal RNA (SSU rRNA) gene sequence, a total of 17 subtypes (ST1 to ST17) of Blastocystis have been characterized until now, among which ST1 to ST9 and ST12 infect humans and animals, and ST10 to ST17 only infect animals. In China, ST1 to ST3 are predominant human Blastocystis subtypes, and ST1/ST3, ST1/ST2 and ST2/ST3 mixed infections have been also identified. This review mainly describes the epidemiology and genotypes of Blastocystis in humans and animals in China. 　

Progress of research on animal models of Blastocystis hominis infections

FENG Xia, ZHANG Fu-Qiang, XU Fu-Yang, MEI Xue-Fang, ZHANG Zhen-Chao, LI Xiang-Rui, WANG Shuai

2021, 33(1):  102. 

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Blastocystis hominis is a common parasitic protozoa in human and animal intestines; however, its pathogenicity remains controversial. Construction of animal models is of great significance to investigate the pathogenicity, pathogenic mechanisms and drug screening of B. hominis. Experimental animals, mode of infections, parasite strains and host immune status are important factors affecting the successful modeling of B. hominis infections in animals. Hereby, we review the progress of researches on animal models of B. hominis infections, and summarize the influencing factors and application of animal models of B. hominis infections, in order to provides insights into the selection of animals models of B. hominis infections.