Table of Content

03 March 2020, Volume 32 Issue 1

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Strategy for the South-South cooperation on schistosomiasis control under the Belt and Road Initiative

ZHOU Xiao-Nong, LI Shi-Zhu

2020, 32(1):  1. 

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Following the concerted efforts for nearly 70 years, great successes have been achieved in the national schistosomiasis control programme in China. Currently, the national schistosomiasis control programme in China is facing the challenges to solve the problems during the “final mile” stage towards schistosomiasis elimination, and contribute Chinese experiences, Chinese strategy and Chinese wisdom to the global schistosomiasis control programmes, so as to facilitate the transformation of the joint efforts in the Belt and Road Initiative to a high?quality development, thereby well supporting the activities on global health security. This paper analyzes the current global status of schistosomiasis and the challenges of the global schistosomiasis control programmes, describes the basis for the cooperation on schistosomiasis control among the countries along the Belt and Road Initiative, illustrates the challenges for translation of Chinese experiences and techniques in schistosomiasis control to other disease?endemic countries, and proposes the patterns and prospects of the South-South cooperation on schistosomiasis control under the Belt and Road Initiative.

Challenges and countermeasures on Chinese malaria elimination programme during the coronavirus disease (COVID-19) outbreak

ZHU Guo-Ding, CAO Jun

2020, 32(1):  7. 

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Since the end of 2019, the coronavirus disease 2019 (COVID-19) has been extensively epidemic in China, which not only seriously threatens the safety and health of Chinese people, but also challenges the management of other infectious diseases. Currently, there are still approximately three thousand malaria cases imported into China every year. If the diagnosis and treatment of malaria cases as well as the investigation and response of the epidemic foci are not carried out timely, it may endanger patients’ lives and cause the possible of secondary transmission, which threatens the achievements of malaria elimination in China. Due to the extensive spread and high transmission ability of the COVID-19, there is a possibility of virus infections among malaria cases during the medical care-seeking behaviors and among healthcare professionals during clinical diagnosis and treatment, sample collection and testing and epidemiological surveys. This paper analyzes the challenges of the COVID-19 for Chinese malaria elimination programme, and proposes the countermeasures in response to the COVID-19 outbreak, so as to provide the reference for healthcare professionals. 　

Spatio-temporal distribution of Oncomelania hupensis snails along the Danyang section of the Beijing-Hangzhou Grand Canal and the Danyang-Jintan-Liyang Canal

IANG Tian-Tian, SHI Liang, LI Wei, ZHANG Jian-Feng, He Jian, WANG Xin-Yao, LIU Lu, FENG Yun, WANG Lin, XIE Yi-Qing, WANG Zhi-Jian, ZHU Tao, JIANG Tao, SUN Jian-Ping, DAI Wei, Xu Da-Cheng, YANG Kun

2020, 32(1):  10. 

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Objective　To explore the spatio?temporal characteristics of Oncomelania hupensis snails along the Danyang section of the Beijing?Hangzhou Grand Canal and the Danyang?Jintan?Liyang Canal, so as to provide scientific evidence for the dynamic assessment of the risk of snail spread in this region. Methods　O. hupensis snail status was collected in the plain regions with waterway networks in the study area from 2012 to 2017. The spatio?temporal variations of snail distribution were investigated along the Danyang section of the Beijing?Hangzhou Grand Canal and the Danyang?Jintan?Liyang Canal using buffer zone analysis, spatial autocorrelation, hotspot analysis and standard deviational ellipse with the geographical information system (GIS) tools. Results　The number of snail habitats showed a tendency towards a rise in the study area from 2012 to 2017, and snail habitats were predominantly distributed in the 1 000 m long buffer zone of the Danyang?Jintan?Liyang Canal, notably along the Jiuqu River at the junction between the Beijing?Hangzhou Grand Canal and the Danyang?Jintan?Liyang Canal. The distribution of snail habitats appeared spatial autocorrelations in 2014, 2016 and 2017, and the hotspot areas were mainly identified at the junction between the Danyang?Jintan?Liyang Canal and the Beijing?Hangzhou Grand Canal. In addition, the overall distribution of snail habitats was located in the northeastern-southwestern part of the study aera, and gradually shifted to the southern and northern parts with the time. Conclusion　The spatial distribution of O. hupensis snails is complex along the Danyang section of the Beijing?Hangzhou Grand Canal and the Danyang?Jintan?Liyang Canal, and there is a risk of snail spread from the upper reaches to the lower reaches, where snail control needs to be intensified.

Diagnostic value of nucleic acid detection in schistosomiasis japonica: a meta-analysis

WANG Sheng-Lin, WANG Li-Ping, WU Ling-Ling, LI Yin-Long, ZHANG Li-Juan, Lü Shan, XU Jing

2020, 32(1):  15. 

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Objective　To quantitatively evaluate the diagnostic value of variable?temperature and isothermal nucleic acid amplification techniques in the detection of schistosomiasis japonica using a meta?analysis. Methods　The publications pertaining to the nucleic acid detection of schistosomiasis japonica were searched in electronic databases, including Chinese National Knowledge Infrastructure (CNKI), Wanfang Data, PubMed and ScienceDirect, and the compilations and proceedings of schistosomiasis were manually searched. In addition, the citations of publications associated with the nucleic acid detection of schistosomiasis japonica were traced using a document tracing method. The retrieved literatures were screened according to the inclusion and exclusion criteria, and data were extracted from the included literatures. The quality of the included literatures was assessed using the software RevMan version 5.3, and a meta?analysis was performed using the software MetaDiSc version 1.4. Results　A total of 19 publications covering 24 groups of studies were enrolled, including 5 Chinese publications and 14 English publications. There were 17 groups of studies reporting the comparison between the variable?temperature nucleic acid amplification technique and the golden standard, and 7 groups of studies showing the comparison between the isothermal nucleic acid amplification technique and the golden standard. Assessment of the literature quality indicated a minor overall bias of the included literatures, and the Deek funnel plot showed a possible publication bias in the documents reports variable?temperature nucleic acid amplification techniques. There was a heterogeneity caused by non?threshold effect among the studies associated with the variable?temperature amplification technique, and the random effects model was therefore used to combine the effects. The pooled sensitivity and specificity of the variable?temperature amplification technique were 0.81 (0.79 to 0.83) and 0.73 (0.71 to 0.74) for the diagnosis of schistosomiasis japonica, and area under the SROC curve was 0.944 3. There was no heterogeneity among the studies associated with the isothermal amplification technique, and the fixed effects model was therefore used to combine the effects. The pooled sensitivity and specificity of the isothermal amplification technique were 0.96 (0.94 to 0.98) and 0.95 (0.94 to 0.97) for the diagnosis of schistosomiasis japonica, and area under the SROC curve was 0.989 9. Conclusion　Both variable?temperature and isothermal nucleic acid amplification techniques have a high efficiency for the diagnosis of schistosomiasis japonica, and the isothermal amplification technique shows a relatively higher accuracy than the variable?temperature amplification technique. 　

Population genetics of invasive Pomacea spp. in Hangzhou City, Zhejiang Province

HUANG Yun,YUE Zhi-Yuan, MAO Guang-Yao, GUO Yun-Hai, ZHANG Yi

2020, 32(1):  23. 

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Objective　To investigate the distribution and identify the genetic genetics of invasive Pomacea species in Xihu District, Hangzhou City, so as to understand the spread tendency of Pomacea species. Methods　The specimens of Pomacea species were collected from five sites in water systems (lakes, rivers and wetlands) and its costal lands in Xihu District, Hangzhou City in 2017 for morphological identification. Total DNA was isolated from the foot tissues of adult snails for amplification of the COI gene, and haplotype diversity and nucleic acid diversity analyses were performed. In addition, a phylogenetic tree was created based on the haplotype captured from GenBank and those from this study to investigate the phylogenetic relationships. Results　Pomacea specimens, which were preliminarily characterized as Pomacea, were found in ponds, rivers and wetlands in Xihu District of Hangzhou City. A total of 16 sequences were captured from the DNA samples of Pomacea specimens, which belonged to 3 haplotypes, including Hap1, Hap2 and Hap3. A high frequency was seen in Hap1 and Hap3, and a low frequency was found in Hap2. The Pomacea specimens collected from the 5 sites in Xihu Districts included P. canaliculata and P. maculate. The Pomacea specimens with a Hap1 had a close genetic relationship with the P. canaliculata from Argentina, Guangdong?Province and Hong Kong Special Administrative Region of China, and the Pomacea specimens with a Hap2 had a close genetic relationship with the P. canaliculata from Argentina, Japan and Guangzhou City of Guangdong?Province, China, while the Pomacea specimens with a Hap2 had a close genetic relationship with the P. maculate from Argentina and Brazil. Conclusion　P. canaliculata and P. maculata are present in Xihu District of Hangzhou City. P. maculata may spread to Xihu District through multiple introductions or water flow.

Complete mitochondrial genomes of Paragonimus westermani in China and phylogenetic analysis of various geographical isolates

GU Meng-Jie, HUANG Wen-Ling, LI You-Song, DONG Hui-Fen, ZHAO Qin-Ping

2020, 32(1):  28. 

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Objective　To compare the complete mitochondrial genome sequences of two phenotypes of Paragonimus westermani isolated from Fujian Province with different sizes of metacercariae, and perform a phylogenetic analysis of various geographical isolates of P. westermani from Asia, so as to identify the possible genetic characteristics associated with the P. westermani phenotypes. Methods　P. westermani metacercariae with different sizes (large metacercariae, 380–420 μm in diameter; small metacercariae, 320–340 μm) isolated from freshwater crabs were used to infect dogs, and the eggs and adult worms of P. westermani were collected from the dog stool samples and lung tissues. Then, the egg size and morphology were compared. In addition, genomic DNA was extracted from the adult worms of the two phenotypes of P. westermani and used for the PCR amplification to yield the complete mitochondrial genome sequence. Sequence structure and phylogenetic analyses were performed based on the complete mitochondrial genome of P. westermani. Results　Following infection with large and small P. westermani metacercariae, the adult worms recovered from the dog lung had a thick body, and had oral and ventral suckers. The ventral sucker was located slightly in front of the midline of the body, and testes, ovary and vitelline gland were seen in the adult worms. Following fixation, the adults appeared oval, with an approximately 1.7∶1 of the length?width ratio. The length and width of the eggs isolated from the fecal samples of dogs infected with large and small P. westermani metacercariae varied significantly, and the large metacercariae produced bigger eggs than the smaller metacercariae. Based on the morphological features of adults and eggs and the ITS2 sequences, both phenotypes were identified as P. westermani. The complete mitochondrial genome sequence analysis of adults showed almost consistent sequences in the protein?coding region of the mitochondrial genome of adult worms derived from large and small metacercariae, with a major variation seen in the former non?coding region. Sliding window analysis revealed the most polymorphic region within the ND4 gene across the mitochondrial genome from various geographical isolates of P. westermani, and phylogenetic analysis showed that both phenotypes were clustered into the Chinese branch of P. westermani, which was close to the Japanese branch and distinct from the South/Southeast Asian branch. Conclusions 　The genetic distance between the phenotypes of P. westermani isolated from Fujian Province is near at a mitochondrial genome level, with no remarkable genetic differentiation seen; however, the mutation and structural changes in the non?coding region may result in the phenotypic variations. In addition, there is a distinct variation of the evolutionary rate in the mitochondrial coding genes, suggesting the selection of appropriate molecular markers during the phylogenic researches.

Phylogenetic analysis of Echinococcus granulosus genotypes based on the GenBank database

WU Shi-Le, ZHU Wen-Jun, FAN De-Yan, SHI Bing-Qiang, AN Yong-De, WANG Chun-Liang, HAN Xiu-Min, GUO Ya-Min

2020, 32(1):  36. 

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Objective　To analyze the sequences of the cytochrome C oxidase subunit I (Cox1) gene of various Echinococcus granulosus genotypes that are currently recorded in the GenBank database, so as to investigate the genetic variation and differentiation of the E. granulosus genotypes across the world. Methods　The sequences of the Cox1 gene of various E. granulosus genotypes that are currently recorded in the GenBank database were collected, and the same sequences of the Cox1 gene identified from a region were excluded. The mutation sites among the Cox1 gene sequences were identified and a phylogenetic tree was created based on the Cox1 gene. Results　Transversion mutation was the predominant type of mutation in the Cox1 gene of E. granulosus. The same Cox1 gene sequence was found in E. granulosus G1, G6 and G7 genotypes isolated from various geographical locations across the world, with the corresponding GenBank accession numbers of KY766891, MH300971 and MH301007, respectively. Phylogenetic analysis revealed that E. granulosus G10 genotype had a remarkable geographical aggregation. Conclusions　E. granulosus G1, G6 and G7 genotypes have primitive Cox1 gene sequences. There is a geographical aggregation of the E. granulosus G10 genotype in the phylogenetic tree, which has a tendency towards reproductive isolation.

Establishment of an evaluation system for the field assessment of the Kato-Katz technique in detection of soil?transmitted nematodiasis

ZHU Hui-Hui, ZHOU Chang-Hai, ZHU Ting-Jun, QIAN Men-Bao, HUANG Ji-Lei, CHEN Ying-Dan

2020, 32(1):  47. 

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Objective　To establish an evaluation system for the field assessment of the Kato?Katz technique in detecting soil?transmitted nematodes, so as to provide insights into the field application of the Kato?Katz technique. Methods　The initial?evaluation indicators were determined through literature search, brainstorming and expert consultation. The evaluation indicators were improved and the weight of each indicator was decided through three rounds of expert consultation by using the Delphi method. In addition, the expert authority coefficient and the coordination coefficient of each indicator were calculated at each round of expert consultations. Results　The recovery rates of the questionnaire were 100.00%, 100.00% and 89.29% at the first to the third round of the expert consultations, respectively, and the expert authority coefficients were all more than 0.85 at each round. The final evaluation system included 4 first?level indicators and 15 second?level indicators. In the first?level indicators, ''detecting effect'' and ''funds investment'' had the mean weighted value of 4.53 and 4.49, which were relatively higher than that of ''person?time investment'' and "operability'' (both 4.34). Among the second?level indicators under each first?level indicator, the four most significant indicators included ''ability of personnel in egg discrimination'', ''cooperation of village cadres and doctors'', ''Person?time on testing'' and ''organizational start?up cost'', with the mean weighted values of 4.74, 4.43, 4.39 and 4.17, respectively. The coordination coefficients were 0.39 to 0.65, 0.28 to 0.58 and 0.45 to 0.65 at the first to the third round of the expert consultations, respectively, and there were significant differences in the coordination coefficients at all three rounds of the consultations (P < 0.05). Conclusion　An evaluation system for the field assessment of the Kato?Katz technique in detecting soil?transmitted nematodes is successfully established, among which ''ability of personnel in egg discrimination'' and ''cooperation of village cadres and doctors'' have the greatest mean weighted values of the significance.

National surveillance on Enterobius vermicularis infections among children at ages of 3 to 9 years in China from 2016 to 2018

HUANG Ji-Lei, ZHANG Mi-Zhen, ZHU Hui-Hui, ZHU Ting-Jun, ZHOU Chang-Hai, QIAN Men-Bao, CHEN Ying-Dan

2020, 32(1):  54. 

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Objective　To understand the epidemic status of Enterobius vermicularis infections among children aged 3 to 9 years in China, so as to provide scientific basis for the formulation of the prevention and control strategies for enterobiasis. Methods　The national surveillance of enterobiasis was performed in 736 national surveillance sites (counties) from 30 provinces (municipalities/autonomous regions) in China from 2016 to 2018. All surveillance sites were classified into parts according to the geographical directions, including the eastern, western, southern, northern and middle parts, and a township was randomly selected from each part. Then, an administrative village was randomly selected from the township, and 200 permanent residents at ages of over 3 years living in the administrative village were randomly selected using the cluster sampling method. A total of 1 000 residents were examined in each surveillance site. E. vermicularis infections were detected among children at ages of 3 to 9 years using the modified Kato?Katz technique and the adhesive cellophane?tape perianal swab method, and the prevalence of infections was calculated and compared. Results　The prevalence of E. vermicularis infections was 2.50%, 2.84% and 2.46% among children at ages of 3 to 9 years in the 736 surveillance sites from 30 provinces (municipalities/autonomous regions) in China from 2016 to 2018, and there was no gender?specific prevalence of E. vermicularis infections (P > 0.05). Enterobiasis was main prevalent in the southern and southwestern part of China (Jiangxi, Guangxi, Guangdong, Sichuan, Fujian, Chongqing and Hainan), with 5.00% prevalence and greater, and the highest prevalence was seen in Jiangxi and Guangxi for successive 3 years. In addition, the prevalence of E. vermicularis infections was higher in children with the Han ethnicity than in those with the minority ethnicity, and a high prevalence was found in children at ages of 4 to 7 years, and a low prevalence seen in children at ages of 3, 8 and 9 years. Conclusions　The prevalences of E. vermicularis infections have not changed much among children at ages of 3 to 9 years in China from 2016 to 2018, and high prevalence is seen in southern and southwestern China, which should be given a high priority.

Screening and bioinformatic analysis of trehalase in Thelazia callipaeda

ZHENG Ming-Hui, YE Chang-Lin, LI Xian-Chun, Wang Li-Jun, SHEN Yu-Juan, XU De-Lin

2020, 32(1):  60. 

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Objective　To characterize the trehalase gene in Thelazia callipaeda through screening the annotated data of the T. callipaeda genome, and to investigate the biological characteristics of the trehalase gene?coding protein. Methods　The trehalase gene was screened from the T. callipaeda genome and subjected to validation by using a PCR assay. The structural features of the coding protein were analyzed with bioinformatics tools, including hydrophobicity, transmembrane region, signal peptides, conserved domains, as well as the secondary and tertiary structures and the antigen epitope. Homology analysis of the amino acid sequences was performed, and the phylogenetic tree was built by the MEGA X software. In addition, the protein?protein interaction network was deduced from the STRING database. Results　The sequence of the trehalase gene with the complete CDS region was obtained from T. callipaeda genome, which had a length of 1 638 bp and encoded 545 amino acids. The encoded protein was predicted to have a molecular weight of 63 478.48 ku and be a secretory protein. The 5′ domain of the encoded protein contained a signal peptide without transmembrane regions, and was predicted to contain 7 antigen epitopes. Based on the protein?protein interaction network of nematodes in the STRING database, the protein?protein interaction network of the trehalase gene of T. callipaeda was deduced, and 27 interactions covering 10 genes were identified. Conclusion　A trehalase gene is successfully identified in T. callipaeda genome and its coding protein receives a bioinformatics analysis, which provides insights into the research on the biological functions of the protein and the screening of vaccine candidates for thelaziasis callipaeda.

Study on insecticide resistance of Culex pipiens pallens in southwest region of Shandong Province

SONG Xiao, CHENG Peng, WANG Hai-Fang, GUO Xiu-Xia，Lü Ye-Yuan, LIU Hong-Mei, LIU Li-Juan, ZHANG Chong-Xing, ZHAO Yu-Qiang, KOU Jing-Xuan, WANG Huai-Wei, GONG Mao-Qing

2020, 32(1):  69. 

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Objective　To explore the sensitivity of Culex pipiens pallens to common chemical insecticides in the southwestern region of Shandong Province, so as to provide a theoretical basis for the development of reasonable and effective mosquito control measures. Methods　The resistance of Cx. pipiens pallens larvae to 5 chemical insecticides, such as cypermethrin, deltamethrin, DDVP, propoxur, and acetofenate were tested by using the WHO biological test method in 2018, and the co?toxicity coefficients after compounding the above?mentioned insecticides were tested by using a drug compounding method. Results　The resistance indexes of Cx. pipiens pallens to cypermethrin, deltamethrin, DDVP, propoxur, and acetofenate in 3 cities were 144.43–557.54, 118.17–445.33, 6.44–19.00, 2.37–8.10, and 0.88–2.98, respectively, and expect the difference between the DDVP resistances of Cx. pipiens pallens in Jining City and Heze City was not statistically significant (P > 0.05), all the other differences were statistically significant (all P < 0.05). The synergistic coefficients of cypermethrin + DDVP, cypermethrin + propoxur, DDVP + acetofenate, and propoxur + acetofenate were 199.58 – 456.95, 190.56 – 292.37, 123.32 – 319.24, and 192.31 – 367.32, respectively. The lower synergism was observed by using the mixture of DDVP + propoxur (synergistic coefficient: 99.87–108.36）. Conclusions　After decades of chemical control, Cx. pipiens pallens in the southwestern region of Shandong Province has produced different degrees of resistance to common chemical insecticides. Therefore, comprehensive control measures should be taken to control mosquito breeding and prevent the development of insecticide resistance. 　

Observation on the distribution of nerve fibers and neural cells morphology in Aspidogaster conchiola

ZHANG Hao, DU Feng-Xia, GUO Jia, ZHAO Dan, ZHANG Feng-Jiao, XU Ya-Ru, WU Xia-Xia, BAI Qing-Yang

2020, 32(1):  73. 

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Objective　To understand the distribution of nerve fibers and the types of neural cells in Aspidogaster conchiola. Methods　Whole worms were subjected to silver staining, histochemical staining and hematoxylin?eosin (HE) staining, and the nervous systems of the worms were observed. Results　There were 3 types of neural cells in the worm head near the cerebral ganglion, including unipolar, bipolar and multipolar neurons, which were divided into 7 types according to the morphology. There was a nerve network on the surface of pharynx and intestinal tract, as well as the reproductive organ, including testis, ovary, lower uterus and penis sac. The nerve network was consisted of circular and longitudinal nerve fibers, and the structure of the nerve network around the mouth was similar to central nerve. Conclusions　The structure of the A.conchiola central nervous system is very complicated, and the neural networks may be associated with the physiologic activity of the worm. Different neural cells may have diverse functions.

Effect of niclosamide on thyroid endocrine system of larval zebrafish

ZHU Bi-Ran, LI Bo

2020, 32(1):  78. 

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Objective　To examine the effect of niclosamide on thyroid endocrine disruption in larval zebrafish. Methods　　　Zebrafish embryos (2 hours post?fertilization) were exposed to niclosamide at concentrations of 0, 5, 10, 20, 40 μg/L and 80 μg/L until 120 hours post?fertilization, and the body weight, hatching rate, malformation rate and survival rate of zebrafish embryos/larvae were measured. In addition, the triiodothyronine (T3) and thyroxin (T4) activities were determined in zebrafish, and the expression of tshβ and ttr genes that were associated with the regulation of thyroid hormones was quantified using a quantitative real?time PCR (qPCR) assay. Results　Following exposure to niclosamide, there was no concentration?dependent hatching rate (F = 0.947, P = 0.924) or body weight of larval zebrafish (F = 1.042, P = 0.409); however, there were concentration?dependent survival rate (F = 9.309, P = 0.005) and malformation rate (F = 14.900, P = 0.001). As compared to controls, exposure to niclosamide at concentrations of 40 μg/L and 80 μg/L resulted in a significant reduction in the survival rate (both P values < 0.05), and a marked rise in the malformation rate of larval zebrafish (both P values < 0.05). In addition, the T4 activity increased (R2 = 0.927, F = 6.858, P = 0.003) and T3 activity decreased (R2 = 0.925, F = 8.212, P = 0.001) in larval zebrafish with the concentration of niclosamide. qPCR assay determined up?regulation of tshβ gene expression (R2 = 0.840, F = 9.032, P = 0.002) and down?regulation of ttr gene expression (R2 = 0.952, F = 9.130, P = 0.002). Conclusion　Niclosamide exposure at environmental related concentrations may cause thyroid endocrine disruption of larval zebrafish.

Surveillance of soil-transmitted nematode infections in Zhenjiang City from 2006 to 2018

LI Sha-Sha, WANG Lin, LI Ai-Hua

2020, 32(1):  83. 

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Objective　To understand the epidemic trend of soil?transmitted nematodiasis in Zhenjiang City from 2006 to 2018, so as to provide evidence for formulating targeted control measures. Methods　The permanent residents at ages of 3 years and greater and the immigrants who had lived in Zhenjiang City for more than one year were selected as the study subjects. Fecal samples were collected, and the soil?transmitted nematode eggs were detected in fecal samples with the modified Kato?Katz technique (three smears from one stool sample), while the children at ages of 12 years and lower were tested for Enterobius vermicularis eggs using the adhesive cellophane?tape perianal swab method. The prevalence and intensity of parasitic infections were estimated in Zhenjiang City each year from 2006 to 2018, and the data pertaining to the deworming for soil?transmitted nematode infections were collected during the study period. Results　A total of 202 880 person?times were subjected to stool examinations in Zhenjiang City from 2006 to 2018, and 946 persons were detected with soil?transmitted nematode infections, with a mean prevalence of 0.47%. The overall prevalence of human soil?transmitted nematode infections appeared a decline tendency (P < 0.01), with a reduction from 1.10% in 2006 to 0.11% in 2018, and there was a region?specific overall prevalence (P < 0.01), with the highest prevalence seen in Runzhou District (1.65%) and the lowest detected in New District (0.04%). The mean prevalence of human Ascaris lumbricoides, hookworm and Trichuris trichiura infections was 0.33%, 0.09% and 0.04% in Zhenjiang City, respectively, and showed a decline tendency year by year from 2006 to 2018 (P < 0.01). Among all infections, mild infections were predominant. During the period from 2006 through 2018, a total of 45 427 children were examined in Zhenjiang City from 2006 to 2018, and 145 children were positive for E. vermicularis infections, with a mean prevalence of 0.32%. The prevalence of E. vermicularis infections decreased from 1.33% in 2006 to 0.22% in 2018 in children, and the overall prevalence appeared a decline tendency (P < 0.01). A single parasite infection was predominant in soil?transmitted nematode infections (97.46%), and mixed infection of two parasites were mainly detected before 2007. A total of 535 089 person?times received deworming in Zhenjiang City from 2006 to 2018, and the rate of adverse events was 0.002%. Conclusions　Currently, the soil?transmitted nematode infection is at a low level in Zhenjiang City, and the overall prevalence of soil?transmitted nematode infections shows a decline tendency year by year. The surveillance and health education of soil?transmitted nematodiasis should be further intensified to consolidate the control achievements.

Investigation on human hookworm infections in Anhui Province from 2014 to 2015

LIU Dao-Hua, GUO Jian-Duo, JIN Wei, ZHU Lei, WANG Tian-Ping

2020, 32(1):  87. 

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Objective　To understand the current status and changing tendency of human hookworm infections in Anhui Province. Methods　According to the unified national survey scheme, a total of 48 survey sites were sampled from 16 counties (cities) in 4 ecological regions of Anhui Province using a stratified cluster random sampling method from 2014 to 2015. The hookworm eggs were detected in the fecal samples from permanent residents at ages of over one year living in the survey sites using a modified Kato?Katz thick smear method, and the subjects’ health knowledge and behaviors were investigated using questionnaire survey. Results　A total of 12 300 persons were examined in the 48 survey sites from 4 ecological regions of Anhui Province between 2014 and 2015, and 259 subjects were identified with hookworm infections, with a mean prevalence of 2.11%. Among the four ecological regions, the North China Plain had the highest prevalence of human hookworm infections (3.02%) and in all survey sites, Linquan County had the highest prevalence (7.03%). Ancylostoma duodenale was the predominant hookworm species identified (62.16%), and 65.64% had mild infections. The prevalence of human hookworm infections was significantly greater in women than in men (χ2 = 4.16, P < 0.05), and showed a tendency towards a rise with ages (χ2trend = 113.36, P < 0.01). In addition, the prevalence of human hookworm infections varied in occupations (χ2 = 159.41, P < 0.01) and education levels (χ2 = 34.95, P < 0.01). Questionnaire survey showed low prevalence of human hookworm infections in subjects knowing the question “how hookworm infection occurs” and denying “using fresh stools for fertilization” (χ2 = 15.05, P < 0.01; χ2 = 4.19, P < 0.05). Conclusions　The prevalence of human hookworm infections has greatly decreased in Anhui Province; however, the prevalence remains relatively high in some regions and populations. The North China Plain should be regarded as the key area for hookworm disease prevention and control, and housewives and populations with advanced ages and low educational levels are key targeted populations in Anhui Province.

Value of contrast-enhanced ultrasonography and acoustic radiation force impulse elastography in identification of boundary range and viability of hepatic alveolar echinococcosis

ZHANG Yu-Ying, MA Qin-Feng, CHEN Xian-Xia, YING Chun-Hua, MA You-Liang, LI Ping, GAO Li, SONG Hai-Hong, YIN Qiu-Ping

2020, 32(1):  91. 

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Objective　To investigate the biologic viability and boundary range of hepatic alveolar echinococcosis (HAE) by the contrast?enhanced ultrasonography (CEUS) and acoustic radiation force impulse elastography (ARFI). Methods　Totally 27 HAE patients confirmed by pathology underwent CEUS and ARFI examinations. Results　Gray scale sonography of HAE showed unclear boundary, inhomogeneous, and middle hyperechoic nodules, and the maximum area was (6.08 ± 4.47) cm2 in 27 lesions. CEUS of HAE showed non?enhancement in three phases and black hole sign. Circumferential enhancement on the periphery of the lesion was synchronized with the liver parenchyma and showed “fast in and slow out”. The maximum area was (8.87 ± 4.83) cm2. The area of ECUS was larger than gray scale sonography in HAE (t = 2.20, P = 0.03). The mean shear wave velocities (SWVs) of the interior, the boundary range, and the surrounding liver tissues of HAE were statistically different by ARFI (F = 84.538, P < 0.001), and the interior had the highest values. Conclusion　CEUS and ARFI examinations can detect the biologic viability and boundary range of migrating zone around HAE, which is valuable for guiding treatment, judging curative effect, and predicting prognosis.

Value of magnetic resonance imaging in assessment of iron deposition among patients with hepatic alveolar echinococcosis: a preliminary evaluation

WANG Li-Yi, BAO Hai-Hua, KANG Ying-Li

2020, 32(1):  94. 

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Objective　To assess the value of MRI combined with serum ferritin analysis in measurement of hepatic iron deposition among patients with hepatic alveolar echinococcosis. Methods　A total of 96 patients with definitive diagnosis of hepatic alveolar echinococcosis and 30 healthy volunteers were enrolled and underwent routine 1.5T MR scanning, and all laboratory examination data were captured. The liver?to?muscle signal intensity ratio, serum ferritin level and liver functions were analyzed. Results　The liver?to?muscle signal intensity ratio was (1.95 ± 0.57) in patients with hepatic alveolar echinococcosis and (2.22 ± 0.28) in healthy volunteers (t = 2.022, P < 0.05), and the liver?to?muscle signal intensity ratio was negatively associated the serum ferritin level in patients with hepatic alveolar echinococcosis (rs = –0.446, P < 0.01). Conclusions　Abnormal iron deposition is detected in the liver of patients with hepatic alveolar echinococcosis, and serum ferritin level may be helpful for the identification of abnormal iron deposition in the liver of patients with hepatic alveolar echinococcosis. The liver?to?muscle signal intensity ratio measured by MRI may be a non?invasive approached used to assess the hepatic iron deposition in patients with hepatic alveolar echinococcosis.

Endemic situation of schistosomiasis in surveillance sites of Tianmen City from 2015 to 2018

ZHANG Wei-Xing, YUAN Yi, TAN Yun-Zhong, SONG Ai-Hua, SHAN Xiao-Wei, YANG Jing

2020, 32(1):  97. 

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Objective　To monitor the change patterns of the endemic situation of schistosomiasis in Tianmen City from 2015 to 2018, so as to provide the evidence for formulating the schistosomiasis control strategy in the city. Methods　A total of 8 schistosomiasis surveillance sites were assigned in Tianmen City from 2015 to 2018, and the endemic situation of schistosomiasis and the related epidemiological factors were monitored. Results　During the period from 2015 to 2018, a total of 15 983 local person?times and 3 629 mobile populations were detected for schistosomiasis using an indirect hemagglutination test (IHA) in Tianmen City, and the sero?prevalence was 0.88% to 1.44% and 0.96% to 2.39%, respectively; however, no egg?positives were identified. A total of 1 245 herd?times were detected, and no egg?positives were found in bovines. In addition, the areas of snail habitats were 116.69 to 117.23 hm2 and the mean densities of living snails were 0.07 to 0.17 snails/0.1 m2 during the study period; however, no infections were identified in snails. Conclusions　The endemic situation of schistosomiasis appears low in Tianmen City; however, the factors related to schistosomiasis transmission remain in the city. The integrated strategy with emphasis on the control of infectious sources should be still intensified to consolidate the schistosomiasis control achievements.

Survey of Anopheles vectors in Nanyang City from 2005 to 2017

WANG Ting-Zhu, ZHANG Wen-Tao, ZHANG Hong-Pu

2020, 32(1):  100. 

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Objective　To investigate the malaria vectors in Nanyang City. Methods　Two townships were selected as malaria vector surveillance sites in Nanyang City from 2005 to 2017, including Mazhenfu Township in Tanghe County and Huaiyuan Township in Tongbai County, and the malaria vectors were investigated using the semi?overnight human baiting trapping method and mosquito trapping in nets. Results　The mean density of Anopheles sinensis was 0.65 to 22.30 mosquitos/(person · hour) in the two surveillance sites in Nanyang City using the human baiting trapping method from 2005 to 2017, and the peak density was detected in June and July. An. Anthropophagus was captured only in Tongbai County during the period between 2008 and 2011, with a mean density of 0.03 to 1.10 mosquitos/(person · hour). The mean density of An. sinensis was 0.08 to 0.24 mosquitos/(net · night) using the mosquito trapping in nets from 2005 to 2011, and the peak density was detected in July and August, while few An. Anthropophagus captured only in Tongbai County, with a mean density of 0.01 to 0.02 mosquitos/(net · night). Conclusion 　There are malaria vectors in Nanyang City, including An. sinensis and An. anthropophagus, and An. sinensis is the dominant mosquito species.

Endemic situation of schistosomiasis in Jiangshan City from 2008 to 2018

LI Xin-Xiang, WANG Ping, LI Bing, WU Qi

2020, 32(1):  103. 

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Objective　To analyze the endemic situation of schistosomiasis in Jiangshan City from 2008 to 2018，so as to provide evidence for formulating the future control strategy. Methods　The data regarding Oncomelania snail survey and control, schistosomiasis examinations and environmental improvements were collected in Jiangshan City from 2008 to 2018. The changes in snail status and morbidity due to Schistosoma japonicum infections were analyzed to assess the effectiveness of comprehensive schistosomiasis control. Results　From 2008 to 2018, a total of 61 220 person?times were examined for S. japonicum infections in Jiangshan City, and the overall seroprevalence of S. japonicum infections was 0.56% (343/61 220); however, no egg?positives were detected. Among 4 231 cattle screened for S. japonicum infections using blood tests in Jiangshan City during the period from 2008 to 2018, 12 were sero?positive, with sero?prevalence of 0.28% (12/4 231), and no egg?positives were identified. There were 422 snail habitats identified in Jiangshan City during the study period, covering an area of 46.915 hm2, and among the 31 686 snails dissected, no S. japonicum infections were detected. An area of 3 625.492 hm2 snail habitats were subjected to repeated snail control and 11 settings were given environmental improvements, covering snail habitats of 17.880 hm2 and historical snail habitats of 204.380 hm2. Conclusions　Following the implementation of environmental improvements?based comprehensive schistosomiasis control, the endemic situation of schistosomiasis is stable in Jiangshan City; however, there is still a risk of snail importation and re?emerging schistosomiasis. Therefore, the monitoring of snails and morbidity due to S. japonicum infections should be intensified in the city.

Current status of pesticides against ticks

YU Ying-Fang, TIAN Li-Guang

2020, 32(1):  106. 

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Ticks can spread a variety of diseases and cause serious damage to animal husbandry. However, the existing insecticide and vaccine control methods have some disadvantages. In this paper, we review the research status of tick pesticides, including the chemical pesticides and non?chemical pesticides (Chinese herbal medicine, nanometer material, virus, fungus and bacterium pesticides), and analyze the disadvantages of the existing researches on pesticides against ticks, in order to provide a theoretical reference for establishing high?efficient and safety tick control methods.

Primary cystic echinococcosis in the left femur: a case report

DU Chao-Nan, SUN Yan-Qiu, ZHENG Feng, YANG Ming-Fei

2020, 32(1):  110. 

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This article reported a case with primary cystic echinococcosis in the left femur.