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Elimination of the intermediate snail host of Schistosoma is the most effective way to control schistosomiasis and the most important first step is to accurately identify the snail habitats. Due to the substantial resources required for traditional, manual snail-searching in the field, and potential risk of miss-classification of potential snail habitats by remote sensing, more convenient and precise methods are urgently needed. Snail data (N = 15,000) from two types of snail habitats (lake/marshland and hilly areas) in Anhui Province, a typical endemic area for schistosomiasis, were collected together with 36 environmental variables covering the whole province. Twelve different models were built and evaluated with indices, such as area under the curve (AUC), Kappa, percent correctly classified (PCC), sensitivity and specificity. We found the presence-absence models performing better than those based on presence-only. However, those derived from machine-learning, especially the random forest (RF) approach were preferable with all indices above 0.90. Distance to nearest river was found to be the most important variable for the lake/marshlands, while the climatic variables were more important for the hilly endemic areas. The predicted high-risk areas for potential snail habitats of the lake/marshland type exist mainly along the Yangtze River, while those of the hilly type are dispersed in the areas south of the Yangtze River. We provide here the first comprehensive risk profile of potential snail habitats based on precise examinations revealing the true distribution and habitat type, thereby improving efficiency and accuracy of snail control including better allocation of limited health resources., Author summary Schistosomiasis is a parasitic disease caused by parasitic worms of the genus Schistosoma. In China, the sole intermediate snail host is Oncomelania hupensis whose elimination has proved to be the most effective way to interrupt this disease. However, manual snail-searching is labour-intensive, expensive and time-consuming and can lead to inaccurate results. For a better approach, 12 models were employed and compared to characterise the typical snail habitats that vary between the lake/marshlands and the hilly areas. We found that the two types of snail habitats showed notable differences during the modelling process, mainly due to the impact of environmental variables that can form different types of habitats. We further found that habitat characterization contributed to better prediction of areas at risk, and that the precision was high, especially of models based on machine-learning algorithms such as random forest (RF). The highest level of accuracy was achieved by the support vector machine (SVM) approach and artificial neural networks (ANN). Our study provides new insights into accurate prediction of the spatial distribution of potential snail habitats with machine-learning as the preferred approach.

Anhui Province has been one of typical epidemic areas of schistosomiasis in East China as a wide range of large lake and marshland regions provide an ideal environment for growth and reproduction of the intermediate snail host. With the completion of the Yangtze River-Huaihe River Water Transfer Project (YHWTP), launched by the end of 2016, the epidemic areas are expected to expand and controlling schistosomiasis remains a challenge. Based on annual surveillance data at the county level in Anhui for the period 2006-2015, spatial and temporal cluster analyses were conducted to assess the pattern of risk through spatial (Local Moran's I and flexible scan statistic) and space-time scan statistic (Kulldorff). It was found that schistosomiasis sero-prevalence was dramatically reduced and maintained at a low level. Cluster results showed that spatial extent of schistosomiasis contracted, but snail distribution remained geographically stable across the study area. Clusters, both for schistosomiasis and snail presence, were common along the Yangtze River. Considering the effect of the ongoing YHWTP on the potential spread of schistosomiasis, Zongyang County and Anqing, which will be transected by the new water-transfer route, should be given a priority for strengthened surveillance and control. Attention should also be paid to Guichi since it is close to one of the planned inlets of the YHWTP.

Schistosomiasis japonica, caused by Schistosoma japonicum infection, remains a major public health concern in China, and the geographical distribution of this neglected tropical disease is limited to regions where Oncomelania hupensis, the intermediate host of the causative parasite, is detected. The purpose of this study was to monitor the transmission of S. japonicum in potential risk regions of China during the period from 2008 through 2012. To monitor the transmission, 10 fixed surveillance sites and 30 mobile sentinel sites were selected in 10 counties of four provinces, namely Anhui, Jiangsu, Chongqing and Hubei. There were 8, 9, 6, 2 and 3 cases infected with S. japonicum detected in the 30 mobile sentinel sites during the 5-year study period, while 27 subjects were positive for the antibody-based serum test in the 10 fixed sentinel sites; however, no infection was found. In addition, neither local nor imported livestock were found to be infected. No O. hupensis snails were detected in either the fixed surveillance or the mobile sentinel sites; however, the snail host was found to survive and reproduce at Chaohu Lake, inferring the potential of transmission of the disease. It is suggested that the continuous surveillance of schistosomiasis japonica should be carried out in both the endemic foci and potential risk regions of China, and an active, sensitive system to respond the potential risk of transmission seems justified.

To investigate the cognitive levels of people from Chaohu area, Anhui Province about the prevention and control knowledge of schistosomiasis before the water transfer project operation, so as to provide the reference for formulating the health education intervention.A schistosomiasis questionnaire survey was conducted among the students, fishermen, boat people and villagers from Chaohu selected by the random cluster sampling from May to October, 2014.A total of 1 140 questionnaires were issued with the actual recovery of 1 096 copies and 1 032 valid questionnaires. The awareness rate of prevention and control knowledge of schistosomiasis was from 11.72% to 71.71%. The highest awareness rate was in the "know schistosomiasis", however the lowest awareness rate was in the "know the intermediate host of schistosomiasis". Catching fish or shrimp in river or lake was the main way of contacting water in production activities (39.05%), and swimming or playing in river or lake was the main way of contacting water in life activities (63.18%). The prevention and control knowledge of schistosomiasis by teaching was at a rate of 41.47% on average, and the main way was anti-schistosomiasis professionals going to countryside to do health education (49.53%). That the feces directly discharged into water accounted for 91.14% in fishman and boatman.It is necessary for people from Chaohu to carry out various forms of health education of schistosomiasis prevention and control before the water transfer project operation.

To explore the expression levels of T cell immunoglobulin and mucin domain protein 3 (Tim-3) on peripheral blood CD4+ T cells and its correlation with liver function damage parameters in advanced schistosomiasis patients.Totally 28 advanced schistosomiasis patients were selected as study subjects, and 20 chronic schistosomiasis patients and 30 healthy persons were selected as controls. The expression levels of Tim-3 on CD4+ T cell were detected by flow cytometry, and the serum IFN-γ and IL-4 levels were detected by ELISA. Hitachi 7600 biochemical analyzer was used to analyze the liver function parameters (ALT, γ-GT and TBIL).There was a significant difference in Tim-3 expression among the three groups (F = 4.578,P0.05). Tim-3 expression level in advanced schistosomiasis patients was (8.33 ± 2.28)%, which was significantly higher than that of the healthy control group (6.57 ± 1.99)% (t = 3.015, P0.01). The Spearman nonparametric correlation analysis showed that the Tim-3 expression level on CD4+ T cells in advanced schistosomiasis patients was positively correlated with the serum ALT(r, = 0.746, P0.01), γ-GT(r, = 0.656, P0.01) and IL-4(r, = 0.672, P0.01) levels, but negatively correlated with the serum IFN-γ levels (r(s) = -0.404, P0.05).The expression of Tim-3 on peripheral CD4' T cells is increased in advanced schistosomiasis patients, which may regulate the function of CD4' T cells and then be involved in the liver damage process of advanced schistosomiasis.

To explore the expression of T cell immunoglobulin and mucin domain protein 3 (Tim-3) on CD56(+) NK cells in peripheral blood and its correlation with liver fibrosis indicators in patients with advanced schistosomiasis.Tim-3 expression on CD6(+) NK cells from 28 patients with advanced schistosomiasis and 30 healthy controls was determined by flow cytometry. The serum levels of IFN-y and IL-4 were detected by enzyme-linked immunosorbent assay (ELISA). Fibroscan analyzer was used for liver stiffness measurement (LSM) to determine the extent of liver fibrosis. Four serological indicators of liver fibrosis, collagen type III N-peptide (PIIP N-P), Laminin (LN), collagen IV (CIV) and hyaluronic acid (HA) were measured by the Automated Chemiluminescence Immunoassay Analyzer.Flow cytometry analysis showed that Tim-3 expression on CD56(+) NK cells in advanced schistosomiasis patients was (62.3±11.4)%, significantly higher than that (52.1±6.5)% (P0.01). In patients with advanced schistosomiasis and the healthy controls, the levels of PIIIP N-P were (86.5±29.5) ng/mL and (22.0±7.8) ng/mL, LN (49.3±21.5) ng/mL and (20.4±6.3) ng/mL, CIV (67.5±22.3) ng/mL and (22.0±3.9) ng/mL, HA (645.9±483.1) ng/mL and (54.7±27.7) ng/mL, respectively. There were significant differences in all these indicators between the two groups (P0.05). The levels of IFN-y were (93.9?20.1) ng/L and (107.7?24.6) ng/L, and those of IL-4 were (46.6±11.8) ng/L and (28.9±8.9) ng/L respectively in patients with advanced schistosomiasis and the healthy controls, both with significant differences (P0.05). Spearman nonparametric correlation analysis showed that Tim-3 expression on CD56(+) NK cells in patients was positively correlated with the levels of LSM, PIIIP N-P, LN, CIV and IL-4 (r=0.528-0.834, P0.01), but negatively with serum IFN-y (r=-0.501, P0.01). No correlation was found with the HA level (r=0.352, P0.05).The expression of Tim-3 on peripheral CD56(+) NK cells increases in patients with advanced schistosomiasis compared with the healthy controls, and it positively correlates with the levels of LSM, PIIIP N-P, LN, CIV and IL-4, four indicators of liver fibrosis.

Schistosomiasis japonica was endemic in 12 provinces (including municipalities and autonomous regions) in the People's Republic of China (PR China). Despite the tremendous decrease of schistosomiasis incidence after almost 60 years of control, the distribution of snail-breeding sites has not been reduced significantly. In order to verify current transmission risks and identify the potential establishment of new foci of schistosomiasis driven by environmental changes, we conducted surveillance in selected risk areas of three provinces: Jiangsu, Anhui and Shandong from 2008 to 2010 in addition to routine snail surveillance. We investigated populations and possible reservoirs in sentinel sites and report that the total number of new acute cases did not diminish further in spite of ongoing control activities. In Anhui Province the local count compared to the national count was 43% (19/44) in 2008, 33% (25/75) in 2009 and 40% (17/42) in 2010. In all, 31.58 km(2) areas of snail breeding sites were newly detected nationwide through the year 2008-2010, of which the proportion of Anhui was 42% (5.03/11.98) in 2008, 95% (8.39/8.79) in 2009 and 79% (8.52/10.81) in 2010. Sentinel surveillance showed eight, nine and five confirmed cases of acute schistosomiasis in mobile populations (fishermen, migrant workers) in 2008, 2009 and 2010, respectively. All these cases were detected in Chaohu County, which must therefore be deemed an area at risk. We conclude that continuous surveillance with an emphasis on snails must be enhanced in potential risk areas in PR China.

To analyze the impact of large hydraulic projects on schistosomiasis transmission and evaluate the transmission risk in potential endemic areas.During 2008-2010, surveillance on risk factors related to schistosomiasis transmission and risk assessment were carried out in potential endemic sites in counties of Xuyu, Hongze, Jinhu, and Gaoyou in Jiangsu Province, Weishan County in Shangdong, Qianjiang City and Yiling District of Yichang City in Hubei, Juchao District of Chaohu City in Anhui Province, Wanzhou and Kaixian in Chongqing in Three Gorges Dam region or passed by South-to-North Water Diversion Project and Zhangjiagang City in Jiangsu Province located in lower reach of Yangtze River. At least one fixed and three temporary monitoring sites were set in each county (city or district). Local inhabitants aged 6-65 years old were screened by indirect haemagglutination assay (IHA) or ELISA, and the sero-positives were tested by Kato-Katz or miracidium hatching techniques to investigate possible infection in 2008. The endemic status of schistosomiasis in mobile population was surveyed every year during 2008-2010. Infection status in livestocks was surveyed in Juchao, Qianjiang, Gaoyou and Wanzhou Counties in 2008-2010. Oncomelania hupensis distribution was investigated in risky and suspicious areas. Snail spreading investigation was conducted through salvaging floater and snails-inducing by straw curtains in rivers connected with Yangtze River.8 256 local inhabitants were investigated by serological tests with a positive rate of 0.7% (60/8 256). Among the 60 serologically positive subjects, 55 individuals were examined by stool examination but none of them was egg positive. The antibody prevalence rate of migrating population in 2008-2010 was 2.0%, 1.4%, and 1.7%, respectively, with no significant difference (chi2 = 3.57, P0.05). Among the serologically positive subjects, egg-positive cases were found in migrating population in Juchao District each year and one case was found in Jinhu County in 2010. Oncomelania snails were only found in in Jinhu and Gaoyou without infected ones. A lot of aquatic shell-fish and snails were collected in the water floater and straw curtain without Oncomelania snails.Schistosomiasis is not endemic in the original nonendemic areas in Three Gorges Dam region and areas passed by South-to-North Water Diversion Project until now, but potential risk of transmission exists. Long term surveillance scheme on schistosomiasis should be established with varied monitoring factors in different category areas.

This paper presents an analysis of research progress of schistosomiasis in China, demonstrates the research needs of schistosomiasis control, and put forwards the research priority and prospect during the 12th Five-Year Plan period.

To investigate the possibility of spread of snails and transmission of schistosomiasis japonica due to the construction of water transfer project from Yangtze River to Huaihe River.In order to understand the current endemic situation of schistosomiasis in the project area, the distribution of snails was surveyed by routine methods, level of anti-schistosome antibody in human sera was detected by indirect haemagglutination test (IHA), and the prevalence of schistosomiasis in cattle was detected by egg hatching method. The snail survival and reproduction were observed in Chaohu Lake area(experimental area) and a control area for one year.Snail density was high in two starting points, from where the water in Yangtze River will be directed to Huaihe River. In counties of Wuwei and Hexian, through which the project will be built, the positive rate of anti-schistosome antibody in residents was 22.11% (168/760) and 18.59% (37/199), schistosomiasis prevalence in cattle was 2.42% (9/371) and 0.2% (2/997), respectively. Schistosomiasis was also endemic in Juchao District of Chaohu City. Snails respectively from grassland and hilly area were collected and put in Chaohu Lake for breed and newborn snails were found one year later. During the egg-laying season, the survival rate of snails from grassland in 2 experiment areas and a control area was 11.3%-16.7%, 3.0%-20.8% and 4.7%-14.7% respectively (chi2 = 0.093, 0.760, P0.05; chi2 = 0.647, 0, P0.05), and that of snails from hilly area was 24.1%-44.4%, 37.8%-67.3% and 86.3%-93.1% respectively (chi2 = 9.575, 5.302, P0.05; chi2 = 56.863, 36.218, P0.05). There was no significant difference between the experimental area and the control area on the number of eggs in the ovaries of the same type female snails.The one-year observation reveals that the construction of the project might result in spread of snails and transmission of schistosomiasis japonica in the relevant areas.