1.Factors affecting and identification of key environmental determinants of the Oncomelania hupensis snail density in the Yangtze River Delta based on machine learning models
Yinlong LI ; Qin LI ; Suying GUO ; Shizhen LI ; Lijuan ZHANG ; Chunli CAO ; Jing XU
Chinese Journal of Schistosomiasis Control 2026;38(1):14-19
Objective To identify factors affecting and key environmental factors of the Oncomelania hupensis snail density in the Yangtze River Delta region using machine learning methods. Methods Administrative village-level O. hupensis snail survey data in the Yangtze River Delta (including Shanghai Municipality, Jiangsu Province, Zhejiang Province and Anhui Province) from 2011 to 2021 were retrieved from the Information Management System for Parasitic Disease Control of Chinese Center for Disease Control and Prevention. Environmental factor data were captured from the Google Earth Engine platform, including elevation, slope, terrain, normalized difference vegetation index (NDVI), vegetation type, soil type, total petroleum hydrocarbon (TPH), ammonium nitrogen, inorganic nitrogen, dissolved oxygen, pH of water, chemical oxygen demand (COD) and inorganic phosphorus, and climatic factor data in the study region were retrieved from the Copernicus Climate Data Store, including annual precipitation, aridity index and annual mean temperature (AMT). O. hupensis snail survey data in the Yangtze River Delta region from 2011 to 2021 were randomly divided into a training set (70%) and a test set (30%), and five machine learning models were selected for machine learning model construction and comparative analysis of the O. hupensis snail density using the software R 4.3.0, including random forest (RF), eXtreme gradient boosting (XGBoost), support vector machine (SVM), gradient boosting machine (GBM) and neural network (NN). The XGBoost model was employed to construct a predictive model for the O. hupensis snail density, and the impact of each environmental factor on O. hupensis snail distribution was quantified. The SHapley Additive exPlanations (SHAPs) values were calculated to estimate the average contribution of each variable to the model prediction, and the core environmental factors affecting the O. hupensis snail population density were screened. Results Among the five machine learning models, the XGBoost model exhibited the optimal comprehensive performance, with the coefficient of determination (R2) of 0.855, mean squared error (MSE) of 0.188, root mean squared error (RMSE) of 0.434 and mean absolute error (MAE) of 0.155, respectively. Analysis of factors affecting the O. hupensis snail density with the XGBoost model showed that among the 16 environmental factors, the top four high-impact factors ranked by SHAPs values included annual precipitation, elevation, aridity index and NDVI, with cumulative SHAPs contributions of 75%, which was higher than that of other environmental factors. If NDVI was higher than 0.6, the O. hupensis snail density increased with NDVI and peaked if NDVI was 0.8 (1.60 snails/0.1 m2). The O. hupensis snail density increased with elevation if the elevation ranged from 14 to 40 m, and slowly rose if the annual precipitation ranged from 900 to 1 300 mm, and then increased rapidly to the peak (1.52 snails/0.1 m2) if the annual precipitation ranged from 1 300 to 1 500 mm. In addition, the O. hupensis snail density increased rapidly to the maximum (1.60 snails/0.1 m2) if the aridity index ranged from 0.8 to 1.1, and decreased gradually if the aridity index exceeded 1.1. Conclusions The XGBoost model shows excellent performance in prediction of the O. hupensis snail density and identification of key environmental factors in the Yangtze River Delta region. Annual precipitation, elevation, aridity index and NDVI are key environmental factors affecting the distribution and density of O. hupensis snails in the Yangtze River Delta region.
2.Influencing Factors of Urate Crystal Deposition in Patients with Hyperuricemia and Prediction Model of TCM Syndrome Types-inflammatory Indicators
Jiaqi XU ; Bin AI ; Chao LIN ; Qiaoxuan LIN ; Changning LI ; Jing CAI ; Yan XIAO ; Jiemei GUO ; Youxin SU
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(7):66-73
ObjectiveTo identify potential influencing factors of urate crystal deposition at ankle/foot in patients with hyperuricemia (HUA), and to analyze the predictive value of inflammatory indicators for urate crystal deposition in patients with different traditional Chinese medicine (TCM) syndromes, so as to provide potential reference for clinical risk assessment and individualized TCM intervention. MethodsA retrospective study was carried out with the enrollment of 231 HUA patients from The Third Affiliated People's Hospital of Fujian University of Traditional Chinese Medicine between January 2021 and December 2024. The enrolled patients were further divided into a crystal deposition-positive group (143 cases) and a crystal deposition-negative group (88 cases) according to the results of dual-energy computed tomography (CT). Sociodemographic data, living habits, serum uric acid levels, and inflammatory indicators of the enrolled patients were collcted, and TCM syndrome differentiation was performed. Furthermore, univariate analysis was used to compare inter-group differences in clinical characteristics. MMultivariate Logistic regression was applied to identify the influencing factors of urate crystal deposition. In addition, the receiver operating characteristic (ROC) curves were plotted to evaluate the predictive efficacy of inflammatory indicators for crystal deposition across different TCM syndromes. ResultsThere were statistically significant inter-group differences in the proportion of males, age, body mass index, proportion of mental labor, rate of low water intake, and rate of high-sugar beverage consumption (P<0.05),whereas no significant difference in low exercise intensity was found between the two groups. Furthermore, compared with the negative group, the positive group had higher serum uric acid level, neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR), but lower systemic immune-inflammation index (SIRI) (P<0.05). Regarding the distribution of TCM syndromes, the positive group was dominated by the dampness-heat accumulation syndrome (55/143,38.46%), while the negative group was mainly characterized by the phlegm-turbidity obstruction syndrome (44/88,50.00%). Multivariate Logistic regression analysis revealed that high-sugar beverage consumption, elevated NLR, and elevated PLR were risk factors for urate crystal deposition [odd ratio (OR) = 8.002, 5.377, 1.034, respectively; 95% CI 1.572-40.732, 2.179-13.270, 1.013-1.054,all P<0.05], while SIRI was a protective factor (OR = 0.869, 95% CI 0.778-0.971, P<0.05). In the positive group, patients with the dampness-heat accumulation syndrome exhibited the highest NLR, while the lowest PLR and SIRI, showing statistically significant differences with those of other syndromes (all P<0.05). In addition, ROC curve analysis indicated that for the dampness-heat accumulation syndrome, the combined "NLR + PLR" model had an area under the curve (AUC) of 0.901 (95% CI 0.850-0.951, P<0.01), with a sensitivity of 89.1% and a specificity of 79.5%; for the blood stasis-heat obstruction syndrome, the combined "NLR + PLR" model had an AUC of 0.880 (95% CI 0.825-0.934, P<0.01), with a sensitivity of 100.0% and a specificity of 67.3%; for the liver-kidney Yin-deficiency syndrome, the single PLR model had an AUC of 0.842 (95% CI 0.731-0.952, P<0.01), with a sensitivity of 83.3% and a specificity of 84.0%. ConclusionUrate crystal deposition in HUA patients exhibits intimate associations with high-sugar beverage consumption as well as elevated NLR and PLR levels. Meanwhile, TCM syndrome differentiation has potential correlation with inflammatory characteristics. The inflammatory indicator-based prediction model constructed based on TCM syndromes exhibits good predictive value.
3.Clinical management of patients with hepatitis D
Xu WU ; Jing DOU ; Feng GUO ; HUXIBAIHETI ; Xiaozhong WANG
Journal of Clinical Hepatology 2026;42(2):272-277
Hepatitis D virus (HDV), as a defective virus, relies on the envelope protein of hepatitis B virus (HBV) to complete replication and transmission. Chronic hepatitis B (CHB) patients comorbid with HDV infection may experience significant acceleration of liver disease progression and a significantly higher risk of serious complications such as liver cirrhosis and hepatocellular carcinoma (HCC) compared with the patients with CHB alone, which poses a serious threat to the life and health of patients. At present, the coverage rate of HDV screening needs to be improved, and some patients with HBV/HDV co-infection have not been found in time. Therefore, strengthening the understanding of HDV among clinicians, expanding the scope of HDV screening, identifying patients with infection in a timely manner, and performing standardized antiviral therapy and long-term follow-up management are of great significance for improving the prognosis of patients, reducing disease burden, improving the quality of life of patients, and achieving the global goal of “eliminating viral hepatitis as a public health threat by 2030”.
4.Historical Evolution and Key Information Research on Classic Formula Puji Xiaoduyin
Lianchao ZHU ; Lyuyuan LIANG ; Jing TANG ; Jialei CAO ; Ziming XU ; Huizhen ZHANG ; Zhidan GUO ; Rongze MA ; Zhengshao ZHANG ; Bingqi WEI ; Xiubo DU ; Bingxiang MA
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(10):238-247
Puji Xiaoduyin, a specialized formula for the swollen-head epidemic, was recorded in the Catalogue of Ancient Classical Formula (the Second Batch)-Han Medicine, published in September 2023. It had been inherited and developed by medical experts of successive generations and passed down to this day. This paper sorted out the historical evolution of this formula using bibliometric methods. It also comprehensively analyzed key information on the formula name, historical origin, drug dosage, herb origin, processing methods, decocting methods, function, and clinical applications. Additionally, this paper analyzed the application of this formula in both modern and ancient times. Results showed that the formula was first recorded as "Puji Xiaodu Yinzi" in LI Dongyuan's Proven Formulas written by LI Gao from the Jin dynasty. The medicinal composition and dosage were: Scutellariae Radix and Coptidis Rhizoma (20.65 g each), Ginseng Radix et Rhizoma 12.39 g, Scrophulariae Radix, Citri Reticulatae Pericarpium, and Glycyrrhizae Radix et Rhizoma (8.26 g each), Forsythiae Fructus, Arctii Fructus, Isatidis Radix, and Lasiosphaera Calvatia (4.13 g each), Bombyx Batryticatus and Cimicifugae Rhizoma (2.891 g each), Bupleuri Radix and Platycodonis Radix (8.26 g each). These medicines were grounded to fine powder. One dose, including 20.65 g of the powder, was mixed with 600 mL of water and decocted to 300 mL. After abandoning slag, the medicine should be taken warm frequently. In the formula, Bombyx Batryticatus is stir-fired. With the effect of dispersing wind and clearing heat, removing stagnation and dissipating mass, the formula is specialized in swollen-head epidemic, pestilence, red and swelling head, face, and neck, dry mouth and tongue, as well as other diseases resulting from toxic heat stagnated in the upper jiao. The formula is widely used in treating diseases involving the respiratory, dermal, ophthalmologic, otolaryngologic, and nervous systems. The formula is most frequently used for respiratory diseases, with a wide range of symptoms including parotitis/mumps (66 times), followed by tonsillitis (28 times). In conclusion, the broadly applied formula has accurate efficacy and great development value.
5.Historical Evolution and Key Information Research on Classic Formula Puji Xiaoduyin
Lianchao ZHU ; Lyuyuan LIANG ; Jing TANG ; Jialei CAO ; Ziming XU ; Huizhen ZHANG ; Zhidan GUO ; Rongze MA ; Zhengshao ZHANG ; Bingqi WEI ; Xiubo DU ; Bingxiang MA
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(10):238-247
Puji Xiaoduyin, a specialized formula for the swollen-head epidemic, was recorded in the Catalogue of Ancient Classical Formula (the Second Batch)-Han Medicine, published in September 2023. It had been inherited and developed by medical experts of successive generations and passed down to this day. This paper sorted out the historical evolution of this formula using bibliometric methods. It also comprehensively analyzed key information on the formula name, historical origin, drug dosage, herb origin, processing methods, decocting methods, function, and clinical applications. Additionally, this paper analyzed the application of this formula in both modern and ancient times. Results showed that the formula was first recorded as "Puji Xiaodu Yinzi" in LI Dongyuan's Proven Formulas written by LI Gao from the Jin dynasty. The medicinal composition and dosage were: Scutellariae Radix and Coptidis Rhizoma (20.65 g each), Ginseng Radix et Rhizoma 12.39 g, Scrophulariae Radix, Citri Reticulatae Pericarpium, and Glycyrrhizae Radix et Rhizoma (8.26 g each), Forsythiae Fructus, Arctii Fructus, Isatidis Radix, and Lasiosphaera Calvatia (4.13 g each), Bombyx Batryticatus and Cimicifugae Rhizoma (2.891 g each), Bupleuri Radix and Platycodonis Radix (8.26 g each). These medicines were grounded to fine powder. One dose, including 20.65 g of the powder, was mixed with 600 mL of water and decocted to 300 mL. After abandoning slag, the medicine should be taken warm frequently. In the formula, Bombyx Batryticatus is stir-fired. With the effect of dispersing wind and clearing heat, removing stagnation and dissipating mass, the formula is specialized in swollen-head epidemic, pestilence, red and swelling head, face, and neck, dry mouth and tongue, as well as other diseases resulting from toxic heat stagnated in the upper jiao. The formula is widely used in treating diseases involving the respiratory, dermal, ophthalmologic, otolaryngologic, and nervous systems. The formula is most frequently used for respiratory diseases, with a wide range of symptoms including parotitis/mumps (66 times), followed by tonsillitis (28 times). In conclusion, the broadly applied formula has accurate efficacy and great development value.
6.Neuroelectromagnetic Activities Across Temporal Scales
Zhuo-Qun SHEN ; Xiao-Fei XU ; Yan-Qing WANG ; Jing-Xin LI ; Lan TIAN ; Wei GUO ; Jing-Jing XU
Progress in Biochemistry and Biophysics 2026;53(6):1541-1560
Although global brain science research has progressed rapidly in recent decades, several fundamental questions in neuroscience remain unresolved. In particular, the physical mechanism underlying neural signal transmission remains controversial, and the carriers responsible for neural information storage and retrieval have not yet been fully clarified. These unresolved issues motivate us to re-examine the processes of neural information generation, transmission, integration, storage, and retrieval from multiple perspectives. A key observation is that neural electromagnetic activities are closely associated with time. Their duration, temporal structure, and dynamic evolution play crucial roles in neural information processing. In this work, we analyze neural electromagnetic activities from the perspective of temporal scales (referred to here as the “time course”). By reviewing and integrating findings from previous studies, we examine the characteristic time requirements and dynamic features of neural processes occurring at different stages of information processing. These stages include neural signal generation, signal transmission along axons, synaptic integration, synaptic plasticity, and memory formation and retrieval. Based on this temporal analysis, we outline a framework describing neural electromagnetic activities across a wide range of time scales, spanning from microseconds to minutes, hours, or even longer periods associated with long-term memory, which suggests that neural information processing involves multiple physical processes operating at different time levels. Rapid electromagnetic events may occur on microsecond scales, whereas electrophysiological phenomena such as action potentials typically last on the order of milliseconds. Longer time scales are associated with synaptic plasticity and memory-related processes. From this perspective, we propose that the physical carrier of neural information may be transient electromagnetic pulses with durations on the microsecond scale. In this framework, action potentials can be interpreted as the macroscopic electrophysiological manifestation of underlying electromagnetic processes triggered by ionic currents across neuronal membranes. Rather than being the fundamental neural signal itself, the action potential may represent a measurable membrane-level response associated with the successful activation of these electromagnetic events. Moreover, we discuss a possible mechanism for long-term memory storage. Considering the apparent temporal contradiction between the millisecond-scale excitation of neurons and the long-term persistence of memories, we believe that long-term memory information may be stored within neural network topologies formed by electrical synapse coupling. Such structures, referred to as electrically coupled memory networks (ECMNs), may enable neurons within the same network to respond rapidly and synchronously to stimuli, thereby facilitating efficient memory retrieval. Overall, this study emphasizes the importance of considering the temporal organization of neural electromagnetic activities when interpreting neural signaling mechanisms. It may provide new insights into the physical nature of neural information carriers and the mechanisms of memory storage and retrieval. Furthermore, highlighting the potential role of electromagnetic interactions in neural activity may contribute to the development of new theoretical frameworks and experimental approaches in neuroscience. Such perspectives may also offer valuable references for future research on neural coding, brain function mechanisms, and neuromodulation technologies.
7.Research on safety risk signals of five drugs for Gaucher disease
Cheng YI ; Qiwei HAN ; Jing XU ; Nianfeng GUO ; Mengru BAI
China Pharmacy 2026;37(12):1607-1613
OBJECTIVE To evaluate the characteristics of adverse drug event (ADE) associated with five therapeutic agents for Gaucher disease(imiglucerase, velaglucerase alfa, taliglucerase alfa, eliglustat,and miglustat). METHODS ADE reports related to the above five drugs were retrieved from the FDA Adverse Event Reporting System (FAERS) database from January 2004 to September 2025. The reporting odds ratio (ROR) and proportional reporting ratio (PRR) methods were applied for data mining. system organ class (SOC) and preferred term (PT) from the Medical Dictionary for Regulatory Activities (MedDRA, version 26.0) drug ADE terminology were used for classification and statistical analysis of ADE. RESULTS A total of 4 329, 1 740, 500, 1 329 and 998 ADE reports were retrieved for the aforementioned five drugs, respectively, generating 4 612, 2 605, 776, 1 157 and 2 185 ADE signals. These signals involved 26 SOC, affecting 25, 26, 16, 19, and 19 SOC, respectively. The predominant SOCs were various injuries, poisoning and procedural complications, as well as infections and infestations. The top one PTs of each drug were as follows: bone infarction, zinc deficiency, failure to perform drug monitoring steps, ichthyosis, abnormal nerve conduction examination. New suspected PTs included weight gain and spontaneous abortion for imiglucerase and velaglucerase alfa, weight gain for taliglucerase alfa and eliglustat, and neuropsychiatric manifestations such as dementia and apathy for miglustat. In terms of severe ADEs, other serious medical events were predominant for imiglucerase and taliglucerase alfa; prolonged hospital stays were the main severe ADE for velaglucerase alfa and eliglustat; and death was the leading severe ADE for miglustat. CONCLUSIONS In clinical medication, apart from common ADE,for imiglucerase, clinicians should be alert to bone infarction, weight gain and spontaneous abortion, and strengthen monitoring related to bones, metabolism and pregnancy. For velaglucerase alfa, attention should be paid to zinc deficiency, bone infarction, weight gain and spontaneous abortion, with focused monitoring of nutritional status and pregnancy risks. For taliglucerase alfa, failure to perform drug monitoring steps and weight gain require vigilance, and medication procedures should be standardized along with regular weight monitoring. For eliglustat, clinicians need to watch out for ichthyosis and weight gain and pay close attention to skin conditions. For miglustat, bone infarction, abnormal nerve conduction examination and dementia should be closely monitored, with enhanced surveillance on nervous system function, infections and prognosis of critically ill patients,to ensure patient medication safety.
8.A preliminary investigation on the carriage of Bartonella by rodents at key ports in western Inner Mongolia
Ruo-wen GUO ; Huai-bo WEI ; Peng LUO ; Xia LIU ; Zong-di LIU ; Jing WU ; Jia XU
Acta Parasitologica et Medica Entomologica Sinica 2026;33(2):134-140
Objective This study investigated the diversity of rodent populations and the infection status of Bartonella at three ports along the China-Mongolia border in 2022. Methods Rodents at three Belt and Road ports along the China-Mongolia border, namely Ganqimaodu, Erenhot, and Zhuengadabuqi, were morphologically identified. The Bartonella citrate synthase(gltA)gene was amplified by nested polymerase chain reaction(PCR), and PCR-positive products were sequenced. The resulting sequences were then analyzed for genetic characteristics. Phylogenetic analysis was performed using MEGA 11.0 software using Neighbor-Joining and Maximum-Likelihood method. Results A total of 94 rodents were captured, representing seven species from five families and six genera: Mus musculus, Meriones unguiculatus, Meriones meridianus, Spermophilus dauricus, Allactaga sibirica, Dipus sagitta, and Phodopus roborovskii. Among them, M. unguiculatus was the most abundant species, with 58 rodents, accounting for 61.70% of the total. Overall,11 positive Bartonella pathogen sequences were obtained from the three ports, with a positive detection rate of 11.70%(11/94). The infected rodent species included M. unguiculatus, M. meridianus, and A. sibirica, and two species of Bartonella were detected. Conclusions Rodents at Ganqimaodu, Erenhot, and Zhuengadabuqi ports along the China-Mongolia border were naturally infected with Bartonella. Rodent monitoring and pathogen prevention and control in this area should be strengthened.
9.Progress of schistosomiasis control in the People’s Republic of China in 2025
Junyi HE ; Lijuan ZHANG ; Suying GUO ; Shizhen LI ; Yinlong LI ; Fan YANG ; Chunli CAO ; Jing XU ; Shizhu LI
Chinese Journal of Schistosomiasis Control 2026;38(3):223-231
To understand the progress of, summarize experiences from, and analyze problems in the national schistosomiasis elimination programme, this article presented the national schistosomiasis epidemiology and surveillance in the People’s Republic of China in 2025. By the end of 2025, Shanghai Municipality, Zhejiang Province, Fujian Province, Guangdong Province and Guangxi Zhuang Autonomous Region maintained the achievement of schistosomiasis elimination, and 7 provinces of Jiangsu, Sichuan, Yunnan, Hubei, Hunan, Anhui and Jiangxi remained at the criteria of schistosomiasis transmission interruption. In 2025, there were 450 counties (cities, districts), 3 203 townships and 26 029 villages endemic for schistosomiasis in China, with a total population of 73.598 million in endemic villages. Among the 450 endemic counties (cities, districts), 421 (93.56%) achieved the criteria of schistosomiasis elimination and 29 (6.44%) reached the criteria of transmission interruption. In 2025, a total of 3 630 874 residents received immunological tests for schistosomiasis across endemic areas in China, with 31 588 seropositives identified (seroprevalence, 0.87%), and a total of 154 293 individuals received parasitological examinations, with 5 egg-positives detected. A total of 26 688 advanced schistosomiasis cases were recorded in China by the end of 2025. Of 529 683 bovines raised in schistosomiasis-endemic villages in China in 2025, 101 637 bovines received immunological tests for schistosomiasis, with 183 seropositives detected (seroprevalence, 0.18%), and 165 654 bovines received parasitological examinations, with no egg-positives identified. In 2025, Oncomelania hupensis snail survey was performed covering an area of 667 524.82 hm2 in China, and 176 378.64 hm2 O. hupensis snail habitats were identified, including 123.77 hm2 emerging O. hupensis snail habitats and 953.71 hm2 re-emerging O. hupensis snail habitats. A total of 19 283 schistosomiasis cases received chemotherapy with praziquantel in China in 2025, and 477 450 person-times and 304 279 herd-times received expanded chemotherapy, respectively. In addition, O. hupensis snail control with chemical treatment covered 116 475.10 hm2 snail habitats across China in 2025, with an actual area with chemical control covering 68 510.93 hm2 and an area with environmental improvements covering 1 101.84 hm2. The national schistosomiasis surveillance results indicated that the mean prevalence of Schistosoma japonicum infections was both 0 among humans and bovines in 2025, and no S. japonicum infection was detected in O. hupensis snails. These data showed that the prevalence of schistosomiasis remained low in China in 2025; however, the area of O. hupensis snail habitats stayed high, with an increase in emerging and reemerging O. hupensis snail habitats. It is recommended to improve the surveillance and forecast mechanism for schistosomiasis and precisely implement the O. hupensis snail control programme in high-risk areas.
10.Integrated effects of climate, land use, and their interactive driving mechanisms on the spatiotemporal dynamics of Oncomelania hupensis density: a case study of Yunnan Province
Jiangling XIANG ; Suying GUO ; Qiang WANG ; Lijuan ZHANG ; Jiayu SUN ; Yi DONG ; Jing XU
Chinese Journal of Schistosomiasis Control 2026;38(3):260-267
Objective To examine the impact of climate, land use and their interaction effect on the population density of Oncomelania hupensis. Methods O. hupensis snail surveillance data in Yunnan Province from 2013 to 2022 were obtained from the National Information System for Parasitic Diseases Prevention and Control of Chinese Information System for Disease Control and Prevention, and the density of living snails was calculated in each county-level administrative district. Climate data were obtained from the China Meteorological Forcing Dataset version 2.0, and land use data were captured from the China Land Cover Dataset. The raster climate data and land use data were clipped to the administrative border of Yunnan Province in the R package version 4.5, and the climate data were resampled to a spatial resolution of 30 m × 30 m consistent with the land use data using bilinear interpolation. Annual meteorological indicators were extracted from each county-level schistosomiasis surveillance administrative area in Yunnan Province from 2013 to 2022, including average temperature, maximum temperature, minimum temperature, temperature difference, average precipitation rate, maximum precipitation rate, minimum precipitation rate, downward shortwave radiation flux, downward longwave radiation flux, air pressure, wind speed, specific humidity and relative humidity. Annual land use structure and landscape pattern index in each county-level schistosomiasis surveillance administrative area in Yunnan Province from 2013 to 2022 were extracted and calculated, including the proportion of areas occupied by each type of land use, patch density, largest patch index, landscape separation index, landscape fragmentation index, landscape segmentation index, contagion index, patch cohesion index, edge density, and shape index. Land use entropy index was introduced to represent the degree of habitat fragmentation and ecological niche breadth. The density of living snails and environmental factors were subjected to rank correlation analysis, and variables with no statistically significant correlation (P>0.1) were excluded. Then, a correlation coefficient matrix was constructed, and |rs| of 0.85 and greater was defined as the threshold of high collinearity. For highly correlated variables in each group, indicators with a more biological explanatory power or a better statistical efficiency were retained. A generalized additive model (GAM) was constructed with O. hupensis snail density as a response variable and screened environmental variables as independent variables, and the model performance was evaluated using the variance explained. Results The area occupied by O. hupensis snail habitats was 1 056 to 1 680 hm2 in Yunnan Province from 2013 to 2022, appearing an overall tendency towards a decline; however, the density of living snails appeared a tendency towards a slight rise. Based on the correlation coefficient matrix, 14 core explanatory variables were retained, including farmland, water bodies, bare land, impervious surface, landscape separation index, landscape fragmentation index, edge density, shape index, land use entropy index, downward longwave radiation flux, downward shortwave radiation flux, maximum temperature, minimum precipitation rate and specific humidity. Two types of GAM were constructed, including the main-effects model without interaction terms and the interaction model with interaction terms. The corrected Akaike information criterion (AICc) of the optimal main-effects model was −285.223, and the core variables included bare land, impervious surface, landscape separation index, edge density, shape index, land use entropy index and downward shortwave radiation flux. Following introduction of second-order interaction terms, the AICc value of the optimal interaction model was −345.526, and the significant interaction combinations included: farmland × impervious surface, farmland × landscape separation index, farmland × shape index, farmland × land use entropy index, impervious surface × landscape separation index, impervious surface × edge density, and shape index × downward shortwave radiation flux. The proportion of the main-effects model explaining the variation of O. hupensis snail density was 39.8%, and the explanatory power of GAM increased to 79.0% following introduction of interaction terms. Conclusion Landscape separation index, edge density, shape index and other landscape pattern indicators pose significant impacts on the intensity and direction of changes in O. hupensis snail density in Yunnan Province.


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