Table of Content

15 October 2023, Volume 35 Issue 5

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Discovery and distribution of and response to arbovirus in China over the past seven decades

XIA Han, YUAN Zhiming

2023, 35(5):  427-436,450. 

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Arbovirus is a group of virus transmitted by blood⁃sucking arthropod bites, which infects both arthropods and vertebrates. More than 600 arboviruses have been characterized worldwide until now, including 65 highly pathogenic viruses, which pose a high threat to public health. The risk of arbovirus transmission is increasing due to climate change, international trade and urbanization. The review summarizes the discovery and distribution of emerging and reemerging arboviruses and novel arboviruses with potential pathogenic risks, and proposes responses to the arbovirus transmission risk, so as to provide insights into the research and management of arboviruses and arthropod⁃borne infectious diseases in China.

Distribution characteristics of emerging and reemerging Oncomelania hupensis in China from 2015 to 2021

YANG Fan, FENG Ting, HE Junyi, ZHANG Lijuan, XU Jing, CAO Chunli, LI Shizhu

2023, 35(5):  437-443. 

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Objective　To analyze the distribution characteristics of emerging and reemerging Oncomelania hupensis snails after the criteria for transmission control of schistosomiasis were achieved in China, so as to provide insights into assessment of schistosomiasis transmission risk and formulation of snail control strategies during the elimination phase. Methods　O. hupensis survey data in China from 2015 to 2021 were collected from the National Schistosomiasis Pevention and Control Information Management System, and the distribution characteristics of emerging and reemerging O. hupensis snails were descriptively analyzed. Results　Emerging and reemerging O. hupensis snails were identified in China each year from 2015 to 2021, with relatively larger areas with emerging and reemerging O. hupensis snail habitats in 2016 and 2021, and relatively higher numbers of counties (districts) where emerging and reemerging O. hupensis snails were detected in 2016 and 2021. A total of 4 586.30 hm2 of emerging O. hupensis snail habitats were found in 10 schistosomiasis⁃endemic provinces of China (except Fujian and Yunnan Provinces) from 2015 to 2021, with 96.80% in Anhui, Hunan and Hubei provinces, where marshland and lake endemic foci were predominant. A total of 21 023.90 hm2 of reemerging O. hupensis snail habitats were found in 12 schistosomiasis⁃endemic provinces of China from 2015 to 2021, with 97.67% in six provinces of Hubei, Sichuan, Jiangxi, Jiangsu, Yunnan and Anhui, where marshland and lake and hilly endemic regions were predominant. Emerging snail habitats were found in 15.08% of all schistosomiasis⁃endemic counties (districts) in China from 2015 to 2021, and 78.75% of all emerging snail habitats were identified in 11 schistosomiasis⁃endemic counties (districts), with the largest area of emerging snail habitats found in Lixian County, Hunan Province (645.00 hm2). Reemerging snail habitats were found in 47.67% of all schistosomiasis⁃endemic counties (districts) in China from 2015 to 2021, and 43.29% of all reemerging snail habitats were identified in 11 schistosomiasis⁃endemic counties (districts), with the largest area of reemerging snail habitats found in Weishan Li and Hui Autonomous County of Hunan Province (1 579.70 hm2). Conclusions　Emerging and reemerging O. hupensis snails were identified in China each year from 2015 to 2021, with much larger areas of reemerging snail habitats than emerging snail habitats, and larger numbers of schistosomiasis⁃endemic provinces and counties (districts) with reemerging snails were found that those of provinces and counties (districts) with emerging snails. Specific snail control interventions are required tailored to the causes of emerging and reemerging snail habitats. Both emergence and reemergence of O. hupensis snails should be paid attention to in marshland and lake endemic areas, and Guangxi Zhuang Autonomous Region, Shanghai Municipality and Zhejiang Province where schistosomiasis had been eliminated, and reemergence of O. hupensis snails should be given a high priority in hilly areas. In addition, monitoring of O. hupensis snails should be reinforced in snail⁃free areas after flooding.

Spatial distribution characteristics of the prevalence of advanced schistosomiasis and seroprevalence of anti⁃Schistosoma antibody in Hunan Province in 2020

ZHOU Yu, TANG Ling, TONG Yixin, HUANG Junhui, WANG Jiamin, ZHANG Yue, JIANG Honglin, XU Ning, GONG Yanfeng, YIN Jiangfan, JIANG Qingwu, ZHOU Jie, ZHOU Yibiao

2023, 35(5):  444-450. 

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Objective　To investigate the spatial distribution characteristics of the prevalence of advanced schistosomiasis and sero⁃prevalence of anti⁃Schistosoma antibody, and to examine the correlation between the prevalence of advanced schistosomiasis and sero⁃prevalence of anti⁃Schistosoma antibody in Hunan Province in 2020, so as to provide insights into advanced schistosomiais control in the province. Methods　The epidemiological data of schistosomiasis in Hunan Province in 2020 were collected, including number of permanent residents in survey villages, number of advanced schistosomiasis patients, number of residents receiving serological tests and number of residents sero⁃positive for anti⁃Schistosoma antibody, and the prevalence advanced schistosomiasis and sero⁃prevalence of anti⁃Schistosoma antibody were descriptively analyzed. Village⁃based spatial distribution characteristics of prevalence advanced schistosomiasis and sero⁃prevalence of anti⁃Schistosoma antibody were identified in Hunan Province in 2020, and the correlation between the revalence advanced schistosomiasis and sero⁃prevalence of anti⁃Schistosoma antibody was examined using Spearman correlation analysis. Results　The prevalence of advanced schistosomiasis was 0 to 2.72% and the sero⁃prevalence of anti⁃Schistosoma antibody was 0 to 20.25% in 1 153 schistosomiasis⁃endemic villages in Hunan Province in 2020, and spatial clusters were identified in both the prevalence of advanced schistosomiasis was 0 to 2.72% (global Moran’s I = 0.416, P < 0.01) and the sero⁃prevalence of anti⁃Schistosoma antibody (global Moran’s I = 0.711, P < 0.01) in Hunan Province. Local spatial autocorrelation analysis identified 98 schistosomiasis⁃endemic villages with high⁃high clusters of the prevalence of advanced schistosomiasis, 134 endemic villages with high⁃high clusters of the sero⁃prevalence of anti⁃Schistosoma antibody and 36 endemic villages with high⁃high clusters of both the prevalence of advanced schistosomiasis and sero⁃prevalence of anti⁃Schistosoma antibody in Hunan Province. In addition, spearman correlation analysis showed a positive correlation between the prevalence of advanced schistosomiasis and sero⁃prevalence of anti⁃Schistosoma antibody (rs = 0.235, P < 0.05). Conclusions　There were spatial clusters of the prevalence of advanced schistosomiasis and sero⁃prevalence of anti⁃Schistosoma antibody in Hunan Province in 2020, which were predominantly located in areas neighboring the Dongting Lake. These clusters should be given a high priority in the schistosomiasis control programs.

Molluscicidal effect of spraying 5% niclosamide ethanolamine salt granules with drones against Oncomelania hupensis in hilly regions

HE Junyi, ZHANG Yun, BAO Ziping, GUO Suying, CAO Chunli, DU Chunhong, CHA Jianwei, SUN Jiayu, DONG Yi, XU Jing, LI Shizhu, ZHOU Xiaonong

2023, 35(5):  451-457,507. 

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Objective　To establish a snail control approach for spraying chemicals with drones against Oncomelania hupensis in complex snail habitats in hilly regions, and to evaluate its molluscicidal effect. Methods　The protocol for evaluating the activity of spraying chemical molluscicides with drones against O. hupensis snails was formulated based on expert consultation and literature review. In August 2022, a pretest was conducted in a hillside field environment (12 000 m2) north of Dafengji Village, Dacang Township, Weishan County, Yunnan Province, which was assigned into four groups, of no less than 3 000 m2 in each group. In Group A, environmental cleaning was not conducted and 5% niclosamide ethanolamine salt granules were sprayed with drones at a dose of 40 g/m2, and in Group B, environmental cleaning was performed, followed by 5% niclosamide ethanolamine salt granules sprayed with drones at a dose of 40 g/m2, while in Group C, environmental cleaning was not conducted and 5% niclosamide ethanolamine salt granules were sprayed with knapsack sprayers at a dose of 40 g/m2, and in Group D, environmental cleaning was performed, followed by 5% niclosamide ethanolamine salt granules sprayed with knapsack sprayers at a dose of 40 g/m2. Then, each group was equally divided into six sections according to land area, with Section 1 for baseline surveys and sections 1 to 5 for snail surveys after chemical treatment. Snail surveys were conducted prior to chemical treatment and 1, 3, 5, 7 days post⁃treatment, and the mortality and corrected mortality of snails, density of living snails and costs of molluscicidal treatment were calculated in each group. Results　The mortality and corrected mortality of snails were 9.49%, 69.09%, 53.57% and 83.48%, and 68.58%, 68.17%, 52.19% and 82.99% in groups A, B, C and D 14 days post⁃treatment, and the density of living snails reduced by 58.40%, 63.94%, 68.91% and 83.25% 14 days post⁃treatment relative to pre⁃treatment in four groups, respectively. The median concentrations of chemical molluscicides were 37.08, 35.42, 42.50 g/m2 and 56.25 g/m2 in groups A, B, C and D, and the gross costs of chemical treatment were 0.93, 1.50, 0.46 Yuan per m2 and 1.03 Yuan per m2 in groups A, B, C and D, respectively. Conclusions　The molluscicidal effect of spraying 5% niclosamide ethanolamine salt granules with drones against O. hupensis snails is superior to manual chemical treatment without environmental cleaning, and chemical treatment with drones and manual chemical treatment show comparable molluscicidal effects following environmental cleaning in hilly regions. The cost of chemical treatment with drones is slightly higher than manual chemical treatment regardless of environmental cleaning. Spraying 5% niclosamide ethanolamine salt granules with drones is recommended in complex settings with difficulty in environmental cleaning to improve the molluscicidal activity and efficiency against O. hupensis snails.

Preliminary application of recombinase⁃aided amplification in detection of Clonorchis sinensis metacercariae in freshwater fish

CHEN Jianfeng, WANG Zhiqi, HUANG Wenming, WANG Jin, CHEN Lijuan, SUN Yunle, ZHAO Lanmei, ZHAO Yang, QIAN Yin, DUAN Junwei, ZHANG Qiang

2023, 35(5):  458-463. 

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Objective　To evaluate the performance of recombinase⁃aided amplification (RAA) assay in detection of Clonorchis sinensis metacercariae in freshwater fish samples, so as to provide insights into standardization and field application of this assay. Methods　Wild freshwater fish samples were collected in the rivers of administrative villages where C. sinensis⁃infected residents lived in Jiangyan District, Xinghua County and Taixing County of Taizhou City, Jiangsu Province from June to September 2022. Genomic DNA was extracted from six freshwater fish specimens (5 g each) containing 0, 1, 2, 4, 8 and 16 C. sinensis metacercariae for fluorescent RAA assay, and the diagnostic sensitivity was evaluated. Fluorescent RAA assay was performed with genomic DNA from C. sinensis, Metorchis orientalis, Haplorchis pumilio and Centrocestus formosanus metacercariae as templates to evaluate its cross⁃reactions. In addition, the detection of fluorescent RAA assay and direct compression method for C. sinensis metacercariae was compared in field⁃collected freshwater fish samples. Results　Positive amplification was found in freshwater fish specimens containing different numbers of C. sinensis metacercariae, and fluorescent RAA assay was effective to detect one C. sinensis metacercaria in 5 g freshwater fish specimens within 20 min. Fluorescent RAA assay tested negative for DNA from M. orientalis, H. pumilio and C. formosanus metacercariae. Fluorescent RAA assay and direct compression method showed 5.36% (93/1 735) and 2.88% (50/1 735) detections rate for C. sinensis metacercariae in 1 735 field⁃collected freshwater fish samples, with a statistically significant difference seen ([χ2] = 478.150, P < 0.001). There was a significant difference in the detection of C. sinensis metacercariae in different species of freshwater fish by both the direct compression method ([χ2] = 11.20, P < 0.05) and fluorescent RAA assay ([χ2] = 20.26, P < 0.001), and the detection of C. sinensis metacercariae was higher in Pseudorasbora parva than in other fish species by both the direct compression method fluorescent RAA assay (both P values < 0.05). Conclusions　Fluorescent RAA assay has a high sensitivity for detection of C. sinensis metacercariae in freshwater fish samples, and has no cross⁃reactions with M. orientalis, H. pumilio or C. formosanus metacercariae. Fluorescent RAA assay shows a higher accuracy for detection of C. sinensis infections in field⁃collected freshwater fish than the direct compression method.

Burden of hepatitis B⁃associated diseases in China from 1990 to 2030

YAO Lixi, LIN Su, HUANG Jiaofeng, WU Yinlian

2023, 35(5):  464-475,496. 

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Objective　To measure the burden of hepatitis B⁃associated diseases in China from 1990 to 2019, and to predict its changes from 2020 to 2030. Methods　The age⁃standardized prevalence, incidence, mortality and disability⁃adjusted life years (DALY) rate of hepatitis B⁃associated diseases in China from 1990 to 2019 were extracted from the Global Burden of Disease 2019 (GBD 2019) data resources, and the trends in burdens of hepatitis B⁃associated diseases were evaluated from 1990 to 2019 using estimated annual percentage change (EAPC) and annual percent change (APC). In addition, the changes in the burden of hepatitis B⁃associated diseases were predicted in China from 2020 to 2023 using the Bayesian model. Results　The overall incidence of hepatitis B⁃associated diseases reduced from 2 725.98/105 in 1990 to 1 397.31/105 in 2019 in China [estimated annual percentage change (EAPC) = −2.35%, 95% confidential interval (CI): (−2.58%, −2.13%)], with a reduction in the prevalence from 12 239.53/105 in 1990 to 6 566.12/105 in 2019 [EAPC = −2.34%, 95% CI: (−2.54%, −2.14%)], a reduction in the mortality from 24.67/105 in 1990 to 8.07/105 in 2019 [EAPC = −4.92%, 95% CI: (−5.37%, −4.47%)], and a reduction in the DALYs rate from 793.38/105 in 1990 to 247.71/105 in 2019 [(EAPC = −5.15%, 95% CI: (−5.64%, −4.66%)]. The DALYs of hepatitis B⁃associated diseases were mainly attributed to liver cancer, and the DALYs of hepatitis B⁃associated diseases appeared a tendency towards a rise in China from 2012 to 2019 [APC = 1.30%, 95% CI: (0.16%, 2.45%)]. The overall burden of hepatitis B⁃associated diseases was higher in males than in females, and the DALYs rate of hepatitis B⁃associated diseases increased with age, with the greatest DALY rate seen among patients at ages of 50 to 69 years. The overall incidence of hepatitis B⁃associated diseases was projected to be 866.79/105 in China in 2030, with the greatest incidence seen in acute hepatitis B (854.87/105), and the burden of hepatitis B⁃associated diseases was predicted to decline in China from 2020 to 2030; however, the burden of liver disease was projected to appear a tendency towards a rise. Conclusions　The burden of hepatitis B⁃associated diseases appears an overall tendency towards a decline in China from 1990 to 2030; however, the burden of liver cancer appears a tendency towards aggravation. Early diagnosis and treatment of liver cancer should be given a high priority.

Analysis and prediction of burden of viral hepatitis C⁃associated diseases in China from 1990 to 2044

ZHOU Mei, YAO Lixi, WU Yinlian, LIN Su, HUANG Jiaofeng

2023, 35(5):  476-485. 

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Objective　To measure the burden of hepatitis C⁃associated diseases in China from 1990 to 2019, and to predict its changes from 2020 to 2044, so as to provide insights into formulation of the targeted hepatitis C control strategy. Methods 　The total burden due to hepatitis C⁃associated diseases in China from 1990 to 2019 were extracted from the Global Burden of Disease 2019 (GBD 2019) data resources, and the trends in age⁃standardized prevalence, incidence, mortality and disability⁃adjusted life years (DALYs) rate of hepatitis C⁃associated acute hepatitis C (AHC), chronic liver diseases (CLD) and liver cancer in China from 1990 to 2019 were evaluated in China from 1990 to 2019 using estimated annual percentage change (EAPC). In addition, the changes in the burden of hepatitis C⁃associated diseases were predicted in China from 2020 to 2044 using a Bayesian model. Results　The prevalence, incidence, mortality and DALY rate of hepatitis C⁃associated diseases all appeared an overall tendency towards a decline in China from 1990 to 2019 (EAPC = −2.64%, −2.24%, −3.81% and −3.90%, respectively); however, there was a minor rise in the incidence and prevalence of hepatitis C⁃associated diseases from 2015 to 2019. The overall prevalence of hepatitis C⁃associated diseases reduced from 2 152.7/105 in 1990 to 1 254.1/105 in 2019 in China, with a reduction of 41.7%. The overall incidence reduced from 87.9/105 in 1990 to 55.0/105 in 2019 in China, with a reduction of 37.4%, and the highest incidence was seen for AHC, followed by CLD and liver cancer. The overall mortality and DALYs rate of hepatitis C⁃associated diseases was 4.0/105 and 100.8/105 in China from 1990 to 2019, with CLD showing the largest contributions to the gross mortality and DALYs. The mortality and DALY rate of hepatitis C⁃associated diseases were 5.5/105 and 142.4/105 among men in China in 2019, which were both much higher than among women (2.8/105 and 60.3/105, respectively), and the overall prevalence (1 604.9/105), mortality (30.2/105) and DALYs (437.1/105) of hepatitis C⁃associated diseases were all highest among patients at ages of 70 years and older, and the highest incidence was seen among patients at ages of 0 to 9 years (167.3/105). The incidence of hepatitis C⁃associated diseases was predicted to rise in China from 2020 to 2044; however, the DALYs was projected to appear a tendency towards a decline. Conclusions　Although the burden of hepatitis C⁃associated diseases showed a tendency towards a decline in China from 1990 to 2019, the burden remained high, and was predicted to slightly rise from 2020 to 2044. High attention should be paid to screening of hepatitis C among infants and treatment among adults.

Construction of a surveillance and early warning index system for schistosomiasis transmission risk along the middle and lower reaches of the Yangtze River basin

JIANG Sanhong, WANG Liman, SUN Li, LIU Tao, LIU Yuwei, LIU Xiaoli

2023, 35(5):  486-491. 

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Objective　To establish a surveillance and early warning index system for schistosomiasis transmission risk along the middle and lower reaches of the Yangtze River basin, so as to provide insights into creation of a sensitive and highly efficient surveillance and early warning system for schistosomiasis. Methods　National and international publications, documents, laws and regulations pertaining to schistosomiasis control were retrieved with keywords including schistosomiasis, surveillance, early warning and control interventions from 2008 to 2022, and a thematic panel discussion was held to preliminarily construct surveillance and early warning index system for schistosomiasis transmission risk along the middle and lower reaches of the Yangtze River basin. The index system was then comprehensively scored and screened using the Delphi method, and the weight of each index was determined using analytic hierarchy process and the modified proportional allocation method. In addition, the credibility of the Delphi method was evaluated using positive coefficient, authority coefficient, degree of concentration and degree of coordination of experts. Results　Following two rounds of expert consultation, a surveillance and early warning index system for schistosomiasis transmission risk in endemic areas along the middle and lower reaches of the Yangtze River basin was preliminarily constructed, including 3 primary indicators, 9 secondary indicators and 41 tertiary indicators. The normalized weights of primary indicators epidemics, natural and social factors and comprehensive control were 0.639 8, 0.145 6 and 0.214 6, respectively, and among all secondary indicators, snail status (0.321 3) and schistosomiasis prevalence (0.318 5) had the highest combined weights, while social factors had the lowest combined weight (0.030 4). Of all tertiary indicators, human egg⁃positive rate (0.041 9), number of acute schistosomiasis cases (0.041 5), number of stool⁃positive bovine and sheep (0.041 1), and prevalence of Schistosoma japonicum in free⁃ranging livestock (0.041 1) had the highest combined weights. During two rounds of consultation, the positive coefficient of experts was both 100%, and the authority coefficient was both 0.9 and greater, while the coordination coefficients were 0.338 to 0.441 and 0.426 to 0.565 ([χ2] = 22.875 to 216.524, both P values < 0.05). Conclusions　The established surveillance and early warning index system for schistosomiasis transmission risk along the middle and lower reaches of the Yangtze River basin is of great scientific values and authority, which may provide insights into construction of the sensitive and highly efficient surveillance and early warning system for schistosomiasis in the context of low prevalence and low intensity of infection in China.

Prevalence of Echinococcus infections in wild carnivores based on copro⁃DNA tests in Serthar County of Sichuan Province

YANG Liu, YANG Yi, YU Wenjie, WANG Qian, ZHONG Bo, HUA Kaiqiong, LIU Yang, HUANG Yan

2023, 35(5):  492-496. 

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Objective　To investigate the prevalence of Echinococcus infections in wild carnivores in Serthar County, Sichuan Province, so as to provide insights into echinococcosis control in local areas. Methods　Stool samples were collected from wild carnivores in Serthar County, Sichuan Province in May 2021, and the host sources of stool samples and Echinococcus infections were identified using PCR assays. The prevalence of E. multilocularis, E. granulosus and E. shiquicus infections was estimated in different hosts. Results　A total of 583 stool samples were collected from wild carnivores, including 147 stool samples from fox, 154 from wolf, 227 from wild dogs and 11 from lynx. The overall prevalence of E. multilocularis, E. granulosus and E. shiquicus infections was 5.68%, 0.19% and 14.20% in canine stool samples, and no E. granulosus infection was detected in fox stool samples, while the prevalence of E. multilocularis and E. shiquicus infections was 0.68% and 47.62% in fox stool samples ([χ2] = 88.41, P < 0.001). No E. granulosus or E. shiquicus infection was detected in wolf stool samples, and the prevalence of E. multilocularis infection was 10.39% in wolf stool samples. The prevalence of E. multilocularis, E. granulosus and E. shiquicus infections was 5.73%, 0.44% and 2.20% in canine stool samples ([χ2] = 12.13, P < 0.01). In addition, the prevalence of E. multilocularis infections was significantly higher in wolf stool samples than in canine and fox stool samples ([χ2] = 13.23, P < 0.01), and the prevalence of E. shiquicus infections was significantly higher in fox stool samples than in canine and wolf stool samples ([χ2] =187.01, P < 0.001). No Echinococcus infection was identified in 11 lynx stool samples. Conclusions　The prevalence of Echinococcus infections is high in wild canines in Serthar County, Sichuan Province. Wolf, wild dog and fox all participate in the wild life cycle of E. multilocularis in Serthar County, and wolf and wild dogs may play a more important role.

Quality of blood smear examinations for malaria parasites in Chenzhou City after malaria elimination

ZHU Hanwu, HOU Xishuo, YANG Hui

2023, 35(5):  497-500. 

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Objective　To analyze the quality of blood smear examinations for malaria parasites in Chenzhou City, so as to provide insights into sustainable consolidation of malaria elimination achievements. Methods　All positive blood smears from fever patients were irregularly sampled from each county (district) of Chenzhou City from 2018 to 2022 and reexamined, and no less than 3% negative blood smears were reexamined. The preparation, dyeing, cleanliness and microscopic examination results of blood smear were reexamined, and the quality of blood smear reexaminations was assessed using a descriptive statistical method. Results　A total of 13 625 fever patients received blood smear examinations for malaria parasites in Chenzhou City from 2018 to 2022, of which 21 were positive and 13 604 were negative; 687 blood samples were reviewed, and the percentage of negative blood smear reexaminations was 4.90% (666/13 604), with a 63.51% rate of qualified negative blood smears preparation, a 67.87% rate of qualified dyeing and a 76.13% rate of qualified cleanliness, and no missing diagnosis found. There were 21 positive blood smears reexamined, and the proportions of qualified blood smears preparation, dyeing and cleanliness were all 85.71%, with 2 smears mistaking Plasmodium species (9.52%). The percentage of qualified negative blood smears preparation was 51.41% in 2022, which reduced by 31.61% in relative to that (75.17%) in 2019 ([χ2] = 9.033, P < 0.05), and the percentage of qualified negative blood smears dyeing was 60.19% in 2022, which reduced by 28.82% in relative to that (84.56%) in 2019 ([χ2] = 19.498, P < 0.05), while the percentage of qualified negative blood smears cleanliness was 62.96% in 2022, which reduced by 28.93 in relative to that (88.59%) in 2019 ([χ2] = 23.826, P < 0.05). In addition, there were no significant differences in the proportion of qualified negative blood smears preparation ([χ2] = 0.260, P > 0.05) or dyeing ([χ2] = 1.094, P > 0.05) among the three years, while a significant difference was detected in the percentage of qualified negative blood smears cleanliness ([χ2] = 12.175, P < 0.05). Conclusions　No missing diagnosis was seen in blood smear examinations for malaria parasites among fever patients in Chenzhou City after malaria elimination; however, there were reductions in proportions of qualified blood smears preparation, dyeing and cleanliness. Quality control of blood smear examinations is recommended to be reinforced in key regions of Chenzhou City.

Sequence analysis of Paragonimus internal transcribed spacer 2 and cyclooxygenase 1 genes in freshwater crabs in Henan Province

CHEN Weiqi, JIANG Tiantian, DENG Yan, ZHANG Yalan, AI Lin, JI Penghui, WANG Dan

2023, 35(5):  501-507. 

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Objective　To investigate the sequences of internal transcribed spacer 2 (ITS2) and cyclooxygenase 1 (COX1) genes of Paragonimus metacercariae in freshwater crabs in Henan Province, identify the species of Paragonimus and evaluate its genetic relationships with Paragonimus isolates from other provinces in China. Methods　Freshwater crabs were collected from 8 survey sites in Zhengzhou, Luoyang, Pingdingshan, Nanyang and Jiyuan cities of Henan Province from 2016 to 2021, and Paragonimus metacercariae were detected in freshwater crabs. Genomic DNA was extracted from Paragonimus metacercariae, and the ITS2 and COX1 genes were amplified using PCR assay, followed by sequencing of PCR amplification products. The gene sequences were spliced and aligned using the software DNASTAR, and aligned with the sequences of Paragonimus genes in the GenBank. Phylogenetic trees were created using the MEGA6 software with the Neighbor⁃Joining method based on ITS2 and COX1 gene sequences, with Fasciola hepatica as the outgroup. Results　The detection rates of Paragonimus metacercariae were 6.83% (11/161), 50.82% (31/61), 18.52% (5/26), 8.76% (12/137), 14.29% (9/63), 17.76% (19/105), 18.50% (32/173) and 42.71% (41/96) in freshwater crabs from 8 survey sites in Zhengzhou, Luoyang, Pingdingshan, Nanyang and Jiyuan cities of Henan Province, with a mean detection rate of 19.46% (160/822), and a mean infection intensity of 0.57 metacercariae/g. The amplified ITS2 and COX1 gene fragments of Paragonimus were approximately 500 bp and 450 bp in lengths, respectively. The ITS2 gene sequences of Paragonimus metacercariae from 8 survey sites of Henan Province showed the highest homology (99.8% to 100.0%) with the gene sequence of P. skrjabini (GenBank accession number: MW960209.1), and phylogenetic analysis showed that the Paragonimus in this study was clustered into the same clade with P. skrjabini from Sichuan Province (GenBank accession number: AY618747.1), Guangxi Zhuang Autonomous Region (GenBank accession number: AY618729.1) and Hubei Province (GenBank accession number: AY618751.1), and P. miyazaki from Fujian Province (GenBank accession number: AY618741.1) and Japan (GenBank accession number: AB713405.1). The COX1 gene sequences of Paragonimus metacercariae from 8 survey sites of Henan Province showed the highest homology (90.0% to 100.0%) with the gene sequence of P. skrjabini (GenBank accession number: AY618798.1), and phylogenetic analysis showed that the Paragonimus in this study was clustered into the same clade with all P. skrjabini and clustered into the same sub⁃clade with P. skrjabini from Hubei Province (GenBank accession numbers: AY618782.1 and AY618764.1). Conclusions　Paragonimus species from freshwater crabs in Henan Province were all characterized as P. skrjabini, and the ITS2 and COX1 gene sequences had the highest homology to those of P. skrjabini from Hubei Province. The results provide insights into study of Paragonimus in Henan Province and China.

Molecular detection and subtyping of Blastocystis sp. in pigs in Anhui Province

GAO Sichao, WANG Jipu, WU Xinghua, LUO Xinyu, LI Qiaoqiao, CHEN Dongqian, LIU Xinchao, LI Wenchao

2023, 35(5):  508-512. 

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Objective　To investigate the prevalence and subtype distribution of Blastocystis sp. in pigs in Anhui Province. Methods　A total of 500 stool samples were collected from large⁃scale pig farms in Bozhou, Anqing, Chuzhou, Hefei, Fuyang, and Lu’an cities in Anhui Province from October to December 2015. Blastocystis was detected in pig stool samples using a PCR assay based on the small subunit ribosomal RNA (SSU rRNA) gene, and positive samples were subjected to sequencing and sequence analysis. Blastocystis subtypes were characterized in the online PubMLST database, and verified using phylogenetic tree created with the neighbor⁃joining algorithm in the Meta software. Results　The prevalence of Blastocystis infection was 43.2% (216/500) in pigs in 6 cities of Anhui Province, and all pig farms were tested positive for Blastocystis. There was a region⁃specific prevalence rate of Blastocystis (17.2% to 50.0%) ([χ2] = 26.084, P < 0.01), and there was a significant difference in the prevalence of Blastocystis sp. among nursery pigs (39.6%), preweaned pigs (19.1%), and growing pigs (62.3%) ([χ2] = 74.951, P < 0.01). Both online inquiry and phylogenetic analysis revealed ST1, ST3, and ST5 subtypes in pigs, with ST5 as the predominant subtype. Conclusion　The prevalence of Blastocystis sp. is high in pigs in Anhui Province, with three zoonotic subtypes identified, including ST1, ST3, and ST5.

Epidemiological and clinical characteristics of human ocular helaziasis in China from 2011 to 2022 based on bibliometrics

ZHAO Yuhui, PEI Fengting, YANG Naifu, SUN Huayue, GAO Zihui, TIAN Qingmei, LU Xiuzhen

2023, 35(5):  513-516. 

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Objective　To understand the clinical and epidemiological characteristics of human ocular thelaziasis patients in China. Methods　Case reports regarding human ocular thelaziasis cases in China were retrieved in international and national electronic databases, including CNKI, VIP, CBM, Traditional Chinese Medical Literature Analysis and Retrieval System, Wanfang Database, PubMed and Web of Science from 2011 to 2022. Patients’ gender, age, clinical symptoms, treatment, recurrence, site of infections, time of onset, affected eye, affected sites, number of infected Thelazia callipaeda, sex of T. callipaeda and source of infections were extracted for descriptive analyses. Results　A total of 85 eligible publications were included, covering 101 cases of human ocular thelaziasis, including 57 males (56.44%) and 44 females (43.56%) and aged from 3 months to 85 years. The main clinical manifestations included foreign body sensation (56 case⁃times, 22.49%), eye itching (38 case⁃times, 15.26%), abnormal or increased secretions (36 case⁃times, 14.46%), tears (28 case⁃times, 11.24%) and eye redness (28 case⁃times, 11.24%), and conjunctival congestion (50 case⁃times, 41.67%) was the most common clinical sign. The most common main treatment (99/101, 98.02%) was removal of parasites from eyes using ophthalmic forceps, followed by administration with ofloxacin and pranoprofen. In publications presenting thelaziasis recurrence, there were 90 cases without recurrence (97.83%) and 2 cases with recurrence (2.17%). Of all cases, 51.96% were reported in four provinces of Hubei, Shandong, Sichuan, Hebei and Henan, and ocular thelaziasis predominantly occurred in summer (42.19%) and autumn (42.19%). In addition, 56.45% (35/62) had a contact with dogs. Conclusions　The human thelaziasis cases mainly occur in the continental monsoon and subtropical monsoon climate areas such as the Yellow River and the Yangtze River basin, and people of all ages and genders have the disease, with complex clinical symptoms and signs. Personal hygiene is required during the contact with dogs, cats and other animals, and individual protection is required during outdoor activities to prevent thelaziasis.

Effect of information⁃knowledge⁃attitude⁃practice theory⁃based health education on clonorchiasis control among community residents and primary school students in Zhongshan City

HUO Shuting, ZHENG Yingyan, DENG Shaona, HUANG Guoxian

2023, 35(5):  517-521. 

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Objective　To evaluate the effect of information⁃knowledge⁃attitude⁃practice (IKAP) theory⁃based health education interventions on clonorchiasis control among community residents and primary school students in Torch High⁃tech Development Zone of Zhongshan City, so as to provide insights into formulation of clonorchiasis control strategies among different types of populations. Methods　Residents were randomly sampled from two communities and students from two primary schools using a random cluster sampling method in Torch High⁃tech Development Zone, Zhongshan City from 2019 to 2021, and health education pertaining to clonorchiasis control was performed based on the IKAP theory. The changes in the awareness of basic clonorchiasis control knowledge and belief, self⁃reported risk of Clonorchis sinensis infections and dietary behaviors were compared among community residents and primary school students before and after health education interventions. Results　The participants included 146 male and 151 female community residents and 158 male and 153 female primary school students, with no significant difference detected in gender distribution ([χ2] = 0.16, P > 0.05). The mean awareness of basic clonorchiasis control knowledge increased by 44.71% and 43.28% among primary school students and community residents 6 months following health education, and there were significant differences in the awareness of each item of basic clonorchiasis control knowledge before and after health education ([χ2] = 41.53 to 284.44, all P values < 0.05). The proportions of primary school students and community residents thinking very high and high risks of C. sinensis infections increased from 9.35% and 6.71% before health education to 22.15% and 37.75% after health education, but only the difference of the attitudes in community residents achieve statistical significance ([χ2] = 92.18, P < 0.05). The frequency of separation of raw and cooked foods with chopping board and knife significantly increased among community residents and primary school students following health education ([χ2] = 16.04 to 62.65, all P values < 0.05). The frequency of eating raw freshwater fish ([χ2] = 32.85，P < 0.05), fish congee ([χ2] = 7.02，P < 0.05) and fish fillet hot pot ([χ2] = 4.88，P < 0.05) significantly reduced among primary school students following health education, while only the frequency and proportions of eating raw freshwater fish have significantly reduced in community residents ([χ2] = 11.77, P < 0.05). Conclusions　Health education interventions based on the IKAP theory are effective to increase the awareness of clonorchiasis control knowledge and improve dietary behaviors associated with C. sinensis infections among community residents and primary school students in Zhongshan City.

Progress of researches on developmental processes and reproduction mode of Pneumocystis

XUE Ting, DU Weiqin, WANG Jing

2023, 35(5):  522-528. 

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Pneumocystis, an important opportunistic fungal pathogen that parasitizes in multiple mammalian lungs, may cause life⁃threatening Pneumocystis pneumonia (PCP) and even death among immunocompromised individuals. With the rapid development of high⁃throughput sequencing and multi⁃omics technologies, systematic comparative analyses of genome, transcriptome, and whole⁃genome sequencing results demonstrate that Pneumocystis is a type of obligate biotrophic fungi, and requires obtaining nutrition from hosts. In addition, sexual reproduction is an essential process for Pneumocystis survival, production and transmission, and asexual reproduction facilitates Pneumocystis survival, which provides new insights into understanding of the whole developmental process of Pneumocystis in the host lung and inter⁃host transmission of Pneumocystis. This review summarizes the advances in the reproduction mode of Pneumocystis and underlying mechanisms, which provides insights into prevention and treatment of PCP, notably for the prophylaxis against nosocomial transmission of PCP.

Cross⁃species regulation and underlying mechanisms of parasite⁃derived non⁃coding RNAs: a review

DAI Yue, YANG Qingli

2023, 35(5):  529-533. 

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Parasite⁃derived non⁃coding RNAs (ncRNAs) not only contribute to life activities of parasites, and microRNA (miRNA), long non⁃coding RNA (lncRNA), and circular RNA (circRNA) may generate a competitive endogenous RNA (ceRNA) regulatory network with host miRNAs and mRNAs via extracellular vesicles, thereby participating in infection and pathogenic processes. This article presents an overview of characterizing ncRNAs derived from parasites and the cross⁃species regulatory role of parasite⁃derived ncRNAs in host gene expression and its underlying mechanisms.

Progress of researches on molecular mechanisms underlying helminth infection⁃mediated type 1/2 host immune responses

MU Qianqian, ZHOU Biying

2023, 35(5):  534-538. 

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Helminth infections are widespread worldwide, and pose a serious threat to human health and animal husbandry development. Understanding of helminth⁃host interactions is critical to effective control and ultimate eradication of helminthiasis. Following host infections, helminth infections firstly initiate innate immune responses and then mediate adaptive immune responses. Type 1 immune responses are predominant at early stage of helminth infections, which mainly play anti⁃infective actions, and type 2 immune responses are predominant at late stage of infections, which are associated with helminth immune evasion and aggravation of tissue damages. This review summarizes the progress of researches on type 1/2 immune responses⁃associated signaling pathways mediated by helminth infections in hosts.