[Establishment of a deep learning-based visual model for intelligent recognition of Oncomelania hupensis].

OBJECTIVE: To establish a deep learning-based visual model for intelligent recognition of Oncomelania hupensis, the intermediate host of Schistosoma japonicum, and evaluate the effects of different training strategies for O. hupensis image recognition. METHODS: A total of 2 614 datasets of O. hupensis snails and 4 similar snails were generated through field sampling and internet capture, and were divided into training sets and test sets. An intelligent recognition model was created based on deep learning, and was trained and tested. The precision, sensitivity, specificity, accuracy, F1 score and Youden index were calculated. In addition, the receiver operating characteristic (ROC) curve of the model for snail recognition was plotted to evaluate the effects of "new learning", "transfer learning" and "transfer learning + data enhancement" training strategies on the accuracy of the model for snail recognition. RESULTS: Under the "transfer learning + data enhancement" strategy, the precision, sensitivity, specificity, accuracy, Youden index and F1 score of the model were 90.10%, 91.00%, 97.50%, 96.20%, 88.50% and 90.51% for snail recognition, which were all higher than those under both "new learning" and "transfer learning" strategies. There were significant differences in the sensitivity, specificity and accuracy of the model for snail recognition under "new learning", "transfer learning" and "transfer learning + data enhancement" training strategies (all P values < 0.001). In addition, the area under the ROC curve of the model was highest (0.94) under the "transfer learning + dataenhancement" training strategy. CONCLUSIONS: This is the first visual model for intelligent recognition of O. hupensis based on deep learning, which shows a high accuracy for snail image recognition. The "transfer learning + data enhancement" training strategy is helpful to improve the accuracy of the model for snail recognition.

[Establishment of a nucleic acid dipstick test for detection of Schistosoma japonicum specific gene fragments based on the recombinase-aided isothermal amplification assay].

OBJECTIVE: To develop a rapid test for detection of Schistosoma japonicum specific gene fragments based on the recombinase-aided isothermal amplification assay (RAA) and nucleic acid dipstick test. METHODS: The S. japonicum SjG28 gene fragment was selected as the target gene fragment, and the primers and fluorescent probe were designed and synthesized. Then, a S. japonicum nucleic acid dipstick test was established. The sensitivity of this dipstick test was evaluated by detecting different copies of recombinant plasmids containing the S. japonicum SjG28 gene fragment and different concentrations of genomic DNA from adult worms of S. japonicum, and the specificity of the dipstick test was evaluated by detecting the genomic DNA from Clonorchis sinensis, S. mansoni, Ancylostoma duodenale, S. haematobium, Babesia and Paragonimus westermani. RESULTS: The S. japonicum nucleic acid dipstick test based on the S. japonicum SjG28 gene fragment showed the minimum detectable limit of 10 copies/µL of the recombinant plasmid containing the S. japonicum SjG28 gene fragment and the minimum detectable limit of 1 pg/µL of S. japonicum genomic DNA, and the dipstick assay tested negative for the genomic DNA from C. sinensis, S. mansoni, A. duodenale, S. haematobium, Babesia and P. westermani. CONCLUSIONS: A rapid, simple, and visualized assay is established for detection of S. japonicum specific gene fragments based on RAA and nucleic acid dipstick test.

[Performance of a recombinase - aided amplification assay for detection of Schistosoma japonicum infections in Oncomelania hupensis].

OBJECTIVE: To evaluate the efficiency of a recombinase-aided amplification (RAA) assay for the detection of Schistosoma japonicum infections in Oncomelania hupensis snails. METHODS: A group test was employed. Fifty Oncomelania snails were collected as a detection sample. The detection samples without infected snails were designated as negative specimens, while the detection samples that contained different numbers of infected snails were designated as positive specimens. A total of 10 negative specimens, 10 positive specimens containing 1 infected snail, 20 positive specimens containing 2 infected snails and 10 positive specimens containing 3 infected snails were assigned. Following random grouping, 40 specimens were subject to the florescent RAA assay using a blind method. The miradium shedding method served as a gold standard, and the sensitivity, specificity, Youden's index and coincidence rate of the florescent RAA assay were estimated. In addition, 20 samples consisted of 5 negative specimens and 15 positive specimens with 1, 2 and 3 infected snails respectively were grouped randomly. The same specimens were detected using the crushing method and fluorescent RAA assay with the blind method in a paired-design manner. Then, the test results were compared and analyzed. RESULTS: Florescent RAA assay detected 29 positives in the 30 specimens containing different numbers of infected snails, with a sensitivity of 96.67%, and 8 negatives in the 10 detection specimens without infected snails, with a specificity of 80.00%, showing a Youden's index of 0.77. The coincidence rate was 100% among 10 repeated assays for a detection specimen. In addition, there was no significant difference in the detection of infected snails between the florescent RAA assay and the crushing method (χ2 = 0, P > 0.05), and the actual coincidence rates of the florescent RAA assay and crushing method were 95.00% (19/20) and 90.00% (18/20) with the real results, respectively. CONCLUSION: Fluorescent RAA assay has a favorable efficiency for the detection of S. japonicum infections in Oncomelania snails, which shows a potential in screening of S. japonicum-infected Oncomelania snails.

[Spatio-temporal patterns of Oncomelania hupensis snail habitats in Suzhou, Wuxi and Changzhou cities along the Taihu Lake region].

OBJECTIVE: To investigate the spatio-temporal distribution characteristics of Oncomelania hupensis snail habitats in three cities of Suzhou, Wuxi and Changzhou along the Taihu Lake region, so as to provide technical supports for establishing a sensitive and highly effective surveillance and forecast system for schistosomiasis. METHODS: Snail distribution data were collected from Suzhou, Wuxi and Changzhou cities from 1950 to 2018, and the changing trend for snail habitats were described over years. In addition, the clusters of snail habitats were detected using Kernel density analysis and SaTScan space-time scan analysis. RESULTS: The number of snail habitats appeared a single-peak distribution in Suzhou, Wuxi and Changzhou cities from 1950 to 2018, which peaked in 1970 and then declined rapidly. There were 62.68% of snail habitats eliminated within 10 years after identification, of which 38.24% were eliminated at the year of identification. Kernel density analysis and SaTScan space-time scan analysis revealed that high-density clusters of snail habitats were mainly distributed in Kunshan City, Wuzhong District and Xiangcheng District from 1970 to 1980, and in Yixing City in 1990; since then, the clusters gradually shrank, and overall appeared a move from northeast to west of Taihu Lake. A total of 4 new clusters were detected after 1970, as revealed by space-time scanning of snail habitats. In current snail habitats, emerging snail habitats are mainly identified in Huqiu District (Dongzhu Town), Wuzhong District (Guangfu Town), Taicang City (Shaxi Town) and Jintan District, and re-emerging snail habitats are scattered in 7 districts. CONCLUSIONS: The distribution of snail habitats are spatio-temporal aggregation in Suzhou, Wuxi and Changzhou cities. The monitoring and prediction of emerging and re-emerging snail habitats are the key points in the future.

[Progress of interruption of schistosomiasis transmission in Jiangsu Province].

Schistosomiasis was once heavily endemic in Jiangsu Province. Following the control efforts for several decades, schistosomiasis was almost eradicated in all endemic counties in Jiangsu Province in 1980, and transmission control was achieved in the province in 2011. According to the principle of "implementing the control measures with adaptation to local circumstances and guiding the control programs with classified interventions", an integrated strategy with emphasis on the management of both infectious sources and snails has been recently employed for schitsosomiasis control in Jiangsu Province. In addition, a sensitive and highly effective surveillance system has been built and the application of novel techniques and information construction has been intensified to effectively interrupt the transmission of schistosomiasis in the Province. Transmission interruption of schistosomiasis was achieved in all endemic counties in Jiangsu Province. The paper summarizes the endemic situation of schistosomiasis, progress of schistosomiasis control, and major schistosomiasis control measures implemented during the stage of transmission interruption in Jiangsu Province.

[Endemic situation of schistosomiasis in national surveillance sites of Jiangsu Province from 2011 to 2018].

OBJECTIVE: To analyze and investigate the changing trend of the endemic situation of schistosomiasis in national surveillance sites of Jiangsu Province from 2011 to 2018, so as to provide scientific evidence for formulating strategies for schistosomiasis control. METHODS: From 2011 to 2014, the national schistosomiasis surveillance sites were set in seven schistosomiasis endemic counties (cities, districts) across Jiangsu Province as according to the National Schistosomiasis Surveillance Scheme (2011 version), and from 2015 to 2018, the national surveillance sites were assigned in all 64 counties (cities, districts) endemic for schistosomiasis in Jiangsu Province according to the National Schistosomiasis Surveillance Scheme (2014 version). Schistosoma japonicum infections in local populations, mobile populations and livestock, and snail status were monitored in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and the monitoring data were statistically analyzed. RESULTS: The sero-prevalence of S. japonicum infections was 1.50% to 4.61% among local populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and a higher sero-prevalence was seen in men than in women, with the sero-positives predominantly detected in local populations at ages of over 50 years. The positive rate of stool examinations was 0 to 0.14% among sero-positive local populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no acute case was found in local populations during the study period. The sero-prevalence of S. japonicum infections was 0.46% to 15.97% among mobile populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no egg-positives were identified. A total of 1 453 livestock were tested in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no S. japonicum infections were detected. During the period from 2011 through 2018, snail survey was conducted in an area of 216 million m2 in the national schistosomiasis surveillance sites of Jiangsu Province, and 1 291.01 hm2 snail habitats were identified, with snail densities ranging from 0.01 to 0.47 snails/0.1 m2; however, no S. japonicum infections were identified in snails. CONCLUSIONS: The overall endemic situation of schistosomiasis appears a tendency towards a decline in Jiangsu Province, and S. japonicum infection remains at a low level in both humans and livestock. No S. japonicum infection has been identified in local populations in Jiangsu Province since 2012. In the future, monitoring and management of imported sources of S. japonicum infections should be intensified in Jiangsu Province, and the capability building of passive surveillance of schistosomiasis should be improved in sentinel hospitals in national schistosomiasis surveillance sites of Jiangsu Province. In addition, the examination of schistosomiasis should be strengthened in mobile populations in Jiangsu Province, a sensitive and effective surveillance-response system for schistosomiasis is urgently needed.

[Assessing the efficiency of schistosomiasis control programs in Jiangsu Province from 2005 to 2015 using data envelopment analysis (Malmquist index method)].

OBJECTIVE: To assess the total factor productivity (TFP) of schistosomiasis control programs in Jiangsu Province, so as to provide insights into sustainable schistosomiasis control. METHODS: The data envelopment analysis-Malmquist index method was employed to analyze the human resources and financial investments in schistosomiasis control programs from health sectors in each schistosomiasis-endemic city of Jiangsu Province from 2005 to 2015, and assess the outputs of each schistosomiasis control project. RESULTS: The overall productive efficiency of schistosomiasis control programs in Jiangsu Province showed an increasing tendency, and the mean fluctuation of annual TFP was 2.3%. The comprehensive technical efficiency, including pure efficiency and scale efficiency, appeared a steady increase with minor fluctuations, and the mean fluctuation of annual comprehensive technical efficiency was 3.8%. The growth rate of technical progress fluctuated greatly from 2005 to 2011, and showed a steady increase from 2012 to 2015, which became a major contributor to the growth of TFP. A higher growth rate of TFP was seen in Huai ' an and Changzhou cities, which showed a greater comprehensive technical efficiency, and a large fluctuation was observed in the growth rate of technical progress in Yancheng, Nanjing, Huai ' an and Yangzhou cities. CONCLUSIONS: There is a continuous improvement in the technical level of schistosomiasis control programs in Jiangsu Province, and technical application and supervision and management capacity also show a steady increase. In addition, the application of new techniques and new strategies contributes greatly to TFP growth. In the future, the investment into new techniques and new strategies should be increased to ensure the sustainable schistosomiasis control in Jiangsu Province.

[Application value of a dynamic automatic identification system in Schistosoma japonicum miracidium hatching test].

OBJECTIVE: To evaluate the value of a dynamic automatic identification system in routine miracidium hatching test with nylon gauzes. METHODS: Different quantities of fresh Schistosoma japonicum eggs were added to bovine fecal samples and divided into the low-infection group, medium-infection group and high-infection group, while the bovine feces without S. japonicum eggs served as negative controls. The detection efficiency and accuracy were compared between the identification system and manual detection in different groups. RESULTS: The identification system can automatically identify S. japonicum miracidium. The detection rate and efficiency of S. japonicum miracidium in bovine fecal samples were both higher by using the identification system than by manual detection. Notably in the low-infection group, the identification system had a significantly higher rate of detection of S. japonicum miracidium than manual detection (χ2 = 10.769, P = 0.002). The identification system completed the detection of bovine fecal samples in the field within 1 min. CONCLUSIONS: The dynamic automatic identification system may effectively improve the detection efficiency and accuracy of routine miracidium hatching test with nylon gauzes, and it may replace manual detection to be used in the field schisotsomiasis examinations and related researches.

[Establishment and operation of schistosomiasis diagnostic reference laboratory in Jiangsu Province].

OBJECTIVE: To construct the schistosomiasis diagnostic reference laboratory in Jiangsu Province, and to examine the role and diagnostic efficiency of the reference laboratory. METHODS: A schistosomiasis diagnostic reference laboratory was built in Jiangsu Province according to the requirements of the construction of the national schistosomiasis diagnostic reference laboratory in China. Inter-laboratory comparisons were conducted and the diagnostic capability of grassroots laboratories was evaluated in Jiangsu Province. RESULTS: The organization structure, environmental conditions, administration and quality systems of the schistosomiasis diagnostic reference laboratory in Jiangsu Province all met the requirements for construction of the national schistosomiasis diagnostic reference laboratory in China, and the schistosomiasis diagnostic reference laboratory in Jiangsu Province was issued a certificate of a province-level schistosomiasis diagnostic reference laboratory. During the 6 inter-laboratory comparisons performed by national schistosomiasis diagnostic reference centers of China, the qualitative and quantitative results of each detection item were all in agreement with the reference samples (Kappa = 1), and the diagnostic capability was identified excellent. The results of indirect hemagglutination assay of 426 serum samples from 4 grassroots laboratories were re-examined, and the mean coincidence rate was 94.13% (range, 92.08% to 96.25%) with the grassroots laboratories, with a mean Kappa value of 0.85 (range, 0.83 to 0.86) and a mean missing rate of 10.19% (range, 0 to 17.65%). CONCLUSIONS: The schistosomiasis diagnostic reference laboratory has been successfully established and effectively operated in Jiangsu Province, which plays an active role in improving the capability of schistosomiasis diagnostic equality in the province.