Interactive and lag effects of environmental factors on the density of schistosome-transmitting Oncomelania hupensis: A twelve-year monthly repeated survey.

Schistosomiasis is a significant public health threat, and Oncomelania hupensis is the only intermediate host for schistosoma japonicum. We conducted 12-year monthly repeated surveys to explore the interactive and lag effects of environmental factors on snail density and to monitor their long-term and seasonal trends in a bottomland around the Dongting Lake region in China. Relevant environmental data were obtained from multiple sources. A Bayesian kernel machine regression model and a Bayesian temporal model combined with a distributed lag model were constructed to analyze interactive and lag effects of environmental factors on snail density. The results indicated the average annual snail density in the study site exhibited an increasing and then decreasing trend, peaking in 2013. Snail densities were the highest in October and the lowest in January in a year. Normalized Difference Vegetation Index (NDVI) and water level were the most effective predictors of snail density, with potential interactions among temperature, precipitation, and NDVI. The mean minimum temperature in January, water level, precipitation and NDVI were positively correlated with snail density at lags ranging from 1 to 4 months. These findings could serve as references for relevant authorities to monitor the changing trend of snail density and implement control measures, thereby reducing the occurrence of schistosomiasis.

The prevailing infection of Schistosoma japonicum and other zoonotic parasites in bubaline reservoir hosts in the ricefield of lake ecosystem: the case of Lake Mainit, Philippines.

Bovines are important reservoir hosts of schistosomiasis, placing humans and animals in rice fields areas at risk of infection. This study reported the prevailing infection of zoonotic parasites from bovine feces in the rice fields adjacent to Lake Mainit, Philippines. Formalin Ethyl Acetate Sedimentation was performed on 124 bovine fecal samples from rice fields and documented eggs and cysts from seven parasites: Schistosoma japonicum, Fasciola gigantica, Ascaris sp., Strongyloides sp., Balantidium coli, coccidian oocyst and a hookworm species. Among these parasites, F. gigantica harboured the highest infection with a 100% prevalence rate, followed by hookworms (51.61%), B. coli (30.64%) and S. japonicum (12.09%), respectively. The intensity of infection of S. japonicum eggs per gram (MPEG = 4.19) among bovines is categorized as 'light.' Bovine contamination index (BCI) calculations revealed that, on average, infected bovines in rice fields excrete 104 750 S. japonicum eggs daily. However, across all ricefield stations, bovines were heavily infected with fascioliasis with BCI at 162 700 F. gigantica eggs per day. The study reports that apart from the persistent cases of schistosomiasis in the area, bovines in these rice fields are also heavily infected with fascioliasis. The study confirms the critical role of bovines as a reservoir host for continued infection of schistosomiasis, fascioliasis and other diseases in the rice fields of Lake Mainit. Immediate intervention to manage the spread of these diseases in bovines is recommended.

Open-source environmental data as an alternative to snail surveys to assess schistosomiasis risk in areas approaching elimination.

BACKGROUND: Although the presence of intermediate snails is a necessary condition for local schistosomiasis transmission to occur, using them as surveillance targets in areas approaching elimination is challenging because the patchy and dynamic quality of snail host habitats makes collecting and testing snails labor-intensive. Meanwhile, geospatial analyses that rely on remotely sensed data are becoming popular tools for identifying environmental conditions that contribute to pathogen emergence and persistence. METHODS: In this study, we assessed whether open-source environmental data can be used to predict the presence of human Schistosoma japonicum infections among households with a similar or improved degree of accuracy compared to prediction models developed using data from comprehensive snail surveys. To do this, we used infection data collected from rural communities in Southwestern China in 2016 to develop and compare the predictive performance of two Random Forest machine learning models: one built using snail survey data, and one using open-source environmental data. RESULTS: The environmental data models outperformed the snail data models in predicting household S. japonicum infection with an estimated accuracy and Cohen's kappa value of 0.89 and 0.49, respectively, in the environmental model, compared to an accuracy and kappa of 0.86 and 0.37 for the snail model. The Normalized Difference in Water Index (an indicator of surface water presence) within half to one kilometer of the home and the distance from the home to the nearest road were among the top performing predictors in our final model. Homes were more likely to have infected residents if they were further from roads, or nearer to waterways. CONCLUSION: Our results suggest that in low-transmission environments, leveraging open-source environmental data can yield more accurate identification of pockets of human infection than using snail surveys. Furthermore, the variable importance measures from our models point to aspects of the local environment that may indicate increased risk of schistosomiasis. For example, households were more likely to have infected residents if they were further from roads or were surrounded by more surface water, highlighting areas to target in future surveillance and control efforts.

The prevalence of liver abnormalities in humans due to Schistosoma japonicum by ultrasonography in China: a meta-analysis.

BACKGROUND: Schistosoma japonicum was once one of the most severe parasitic diseases in China. After 70 years of national schistosomiasis control programmes, the prevalence and associated morbidity of the infection have been reduced to a much lower level. However, due to the low sensitivity of the current detection approaches, many minor infections in humans could not be identified and ultimately develop chronic injuries with liver abnormalities, a specific 'network' echogenic pattern under ultrasonography. Therefore, as more people take part in physical examinations, we performed this meta-analysis to estimate the overall prevalence of schistosomiasis-associated liver abnormalities in China. METHODS: The publications were searched systematically across five electronic databases. All eligible studies were assessed with quality evaluation forms. Heterogeneity of studies was determined using the I2 and Q tests. A random effects or fixed effects model was employed based on heterogeneity results. The pooled prevalence and its 95% confidence intervals were calculated with the Freeman-Tukey double arcsine transformation. All analyses were conducted using R with the "meta" package. The protocol registration number was CRD42021232982. RESULTS: A total of 19 relevant articles, including 21 studies, were included. The average score of study quality was 6.4 (total score 7), indicating high quality of all included studies. A total of 268, 247 persons were included, and 43, 917 persons were diagnosed with schistosomiasis liver abnormalities by ultrasonography. High degrees of heterogeneity existed among all studies or within subgroups. The overall pooled prevalence was 18.64% (95% CI: 11.88-26.50%). The estimate significantly increased over time and varied among provinces, with the highest in Shanghai and the lowest in Sichuan. The estimate in people aged 60 years or older was significantly higher than that in people of all ages. No significant difference was seen when based on study areas (urban or rural areas) or gender. CONCLUSION: The long-term burden of schistosomiasis in China remains large, as nearly one-fifth of the examined persons were diagnosed with schistosomiasis liver abnormalities. The pooled prevalence was associated with regions or age groups. Such may have a high reference value in the exact calculation of the disease burden and can be helpful for policy makers in prioritizing public health.

Schistosomiasis in the People's Republic of China - down but not out.

Schistosomiasis has been subjected to extensive control efforts in the People's Republic of China (China) which aims to eliminate the disease by 2030. We describe baseline results of a longitudinal cohort study undertaken in the Dongting and Poyang lakes areas of central China designed to determine the prevalence of Schistosoma japonicum in humans, animals (goats and bovines) and Oncomelania snails utilizing molecular diagnostics procedures. Data from the Chinese National Schistosomiasis Control Programme (CNSCP) were compared with the molecular results obtained.Sixteen villages from Hunan and Jiangxi provinces were surveyed; animals were only found in Hunan. The prevalence of schistosomiasis in humans was 1.8% in Jiangxi and 8.0% in Hunan determined by real-time polymerase chain reaction (PCR), while 18.3% of animals were positive by digital droplet PCR. The CNSCP data indicated that all villages harboured S. japonicum-infected individuals, detected serologically by indirect haemagglutination assay (IHA), but very few, if any, of these were subsequently positive by Kato-Katz (KK).Based on the outcome of the IHA and KK results, the CNSCP incorporates targeted human praziquantel chemotherapy but this approach can miss some infections as evidenced by the results reported here. Sensitive molecular diagnostics can play a key role in the elimination of schistosomiasis in China and inform control measures allowing for a more systematic approach to treatment.

Human Mobility Associated With Risk of Schistosoma japonicum Infection in Sichuan, China.

Urbanization increases human mobility in ways that can alter the transmission of classically rural, vector-borne diseases like schistosomiasis. The impact of human mobility on individual-level Schistosoma risk is poorly characterized. Travel outside endemic areas may protect against infection by reducing exposure opportunities, whereas travel to other endemic regions may increase risk. Using detailed monthly travel- and water-contact surveys from 27 rural communities in Sichuan, China, in 2008, we aimed to describe human mobility and to identify mobility-related predictors of S. japonicum infection. Candidate predictors included timing, frequency, distance, duration, and purpose of recent travel as well as water-contact measures. Random forests machine learning was used to detect key predictors of individual infection status. Logistic regression was used to assess the strength and direction of associations. Key mobility-related predictors include frequent travel and travel during July-both associated with decreased probability of infection and less time engaged in risky water-contact behavior, suggesting travel may remove opportunities for schistosome exposure. The importance of July travel and July water contact suggests a high-risk window for cercarial exposure. The frequency and timing of human movement out of endemic areas should be considered when assessing potential drivers of rural infectious diseases.

Spatiotemporal pattern analysis of schistosomiasis based on village level in the transmission control stage in lake and marshland areas in China.

Hubei Province is one of the endemic regions with severe schistosomiasis in China. To eliminate schistosomiasis in lake and marshland regions, this study detected hotspots of schistosomiasis cases both spatially and spatiotemporally on the basis of spatial autocorrelation; clustering and outlier, purely spatial and spatiotemporal cluster analyses at the village level from 2013 to 2017 in Hubei Province. The number of cases confirmed positive by an immunodiagnostic test and etiological diagnosis and advanced schistosomiasis cases dramatically declined during the study period. Significant global spatial autocorrelation of schistosomiasis patients was found at the village level in the whole province in 5 years. Clustering and outlier analysis showed that most HH villages were mainly concentrated along the Yangtze River, especially in Jianghan Plain. Spatial and spatiotemporal cluster analyses showed that significant clusters of the schistosomiasis cases were detected at the village level. In general, space and spatiotemporal clustering of schistosomiasis cases at the village level demonstrated a downward trend from 2013 from 2017 in Hubei Province. High-risk regions included Jianghan Plain along the middle reach of Yangtze River and Yangxin County in the lower reaches of the Yangtze River in Hubei Province. To eliminate schistosomiasis, precise control and management of schistosomiasis cases should be strictly implemented. Moreover, comprehensive prevention and control measures should be continuously strengthened in these regions.

Current Status of Parasite Infections in Indonesia: A Literature Review.

Indonesia and South Korea have become inseparable in various respects since the 2 countries established diplomatic relation in 1973. Indonesia is a tropical region that stretches across the equator, comprised of 5 main islands (Java, Kalimantan, Sumatra, Sulawesi, and Papua) and 4 archipelagoes (Riau, Bangka Belitung, Nusa Tenggara, and Maluku). As most population of Eastern Indonesia (Sulawesi, Papua and Nusa Tenggara & Maluku) live in poor areas, it is expected that there will be many parasites. Nevertheless, little is known about the status of parasites in Indonesia. This study examines the prevalences of malaria and lymphatic filaria, which are prevalent in Indonesia, as well as those of soil-transmitted-helminths (STH). As a result, the Plasmodium falciparum and P. vivax case loads are almost equal. The current prevalence of P. vivax is uniformly low (<5%) in all age groups and annual parasite incidence (API) showed decreasing tendency as 0.84 per 1,000 population in 2016. However, more than 65 million people still live in malaria epidemic regions. Lymphatic filariasis remains an important public health problem and 236 cities were classified as endemic areas in 514 cities/districts in 2017. It is difficult to ascertain the current prevalence rate of STH in Indonesia, although West Sumba and Southwest Sumba in East Nusa Tenggara reported prevalence rate of more than 20%. The study also considers the (sero) prevalences of other parasites identified in Indonesia. This report should be useful not only to parasitologists but also to travelers and people with business in Indonesia.

The ratio of the seroprevalence to the egg-positive prevalence of Schistosoma japonicum in China: a meta-analysis.

BACKGROUND: Schistosomiasis, caused by Schistosoma japonicum, remains one of the most important parasitic diseases, and detection of S. japonicum infections in humans plays a crucial role in control and treatment. However, comparisons between the parasitological and the immunological examinations in the fields of China are lacking. Therefore we performed a meta-analysis to compare the seroprevalence of Schistosoma japonicum, as determined by IHA or ELISA, with coprological prevalence, as determined by Kato-Katz, and estimate the ratio of the serological to the egg-positive prevalence in order to evaluate the potential threat of egg-negative but worm-positive schistosomiasis. METHODS: Studies published up to July 2018 on the parasitological and immunological examinations of schistosomiasis in the fields of China were searched in five databases including CNKI, WanFang, VIP, PubMed and Web of Science. The ratio of the serological to the egg-positive prevalence and its 95%CI for each study were calculated, and then point estimates and their 95%CIs of pooled prevalence ratio were meta-analyzed. Subgroup meta-analyses were also performed according to potential influential factors. RESULTS: A total of 23 articles were included. The prevalence ratio varied from 0.57 to 48.83 for IHA to Kato-Katz and ranged from 0.38 to 13.97 for ELISA to Kato-Katz. The pooled ratio was 4.72 (95%CI: 3.87~ 5.76) for IHA to KK and 4.65 (95%CI: 3.50~ 6.17) for ELISA to KK. Subgroup analyses implied that the ratio of the serological to the egg-positive prevalence may decrease with the endemic levels. The highest prevalence ratio was observed when Kato-Katz was performed with three slides per stool or in hilly and mountainous regions. CONCLUSIONS: The worm-determined prevalence by IHA or ELISA is 4- to 5-fold higher than the egg-determined prevalence by Kato-Katz, which implied Kato-Katz may largely underestimate the prevalence of S. japonicum in China. The degree of underestimation was greater when Kato-Katz with three slides per stool was carried out, especially in low endemic areas or in hilly and mountainous regions. Therefore, more attention should be paid to those egg-negative but worm-positive patients with the aim of final elimination of S. japonicum in China.

Genetic diversity and structure of Schistosoma japonicum within two marshland villages of Anhui, China, prior to schistosome transmission control and elimination.

Schistosomiasis is caused by the genus Schistosoma and affected more than 250 million people worldwide. Schistosoma japonicum was once seriously endemic in China and nearly 60 years of efforts has seen great success in disease control. However, due to its zoonotic nature and complex life cycle, the schistosomiasis transmission control and final elimination would require, besides an intersectoral approach, deep understanding of population genetics of the parasite. We therefore performed a snail survey in two marshland villages of Anhui province of China and collected S. japonicum cercariae from infected snails. By using the recent developed microsatellite panel comprising seven loci, we genotyped the sampled parasites and analyzed the population genetic diversity and structure. The results showed much lower infection prevalence of S. japonicum in snails and low infected snail density in either marshland village. Through population genetic analyses, a considerable genetic diversity of parasites was revealed, whereas a small number of clusters were inferred and the sign of bottleneck effect was detected in each village. For the first time in S. japonicum in two villages, we provided estimates of effective population sizes with two different approaches. The results indicated that the parasite in two villages could eventually be eradicated with the ongoing integral control measures, but with potential risk of reinvasion of immigrant parasites through the Yangtze River. Such would be of great importance in assessment of the effects of ongoing control measures and prediction of the transmission capability for S. japonicum, thus guiding decisions on the choice of further control work.

Long-term effectiveness of the integrated schistosomiasis control strategy with emphasis on infectious source control in China: a 10-year evaluation from 2005 to 2014.

Schistosomiasis is a neglected tropical parasitic disease of great public health significance worldwide. Currently, mass drug administration with praziquantel remains the major strategy for global schistosomiasis control programs. Since 2005, an integrated strategy with emphasis on infectious source control was implemented for the control of schistosomiasis japonica, a major public health concern in China, and pilot studies have demonstrated that such a strategy is effective to reduce the prevalence of Schistosoma japonicum infection in both humans and bovines. However, there is little knowledge on the long-term effectiveness of this integrated strategy for controlling schistosomiasis japonica. The aim of this study was to evaluate the long-term effectiveness of the integrated strategy for schistosomiasis control following the 10-year implementation, based on the data from the national schistosomiasis control program released by the Ministry of Health, People's Republic of China. In 2014, there were 5 counties in which the transmission of schistosomiasis japonica had not been interrupted, which reduced by 95.2% as compared to that in 2005 (105 counties). The number of schistosomiasis patients and acute cases reduced by 85.5 and 99.7% in 2014 (115,614 cases and 2 cases) as compared to that in 2005 (798,762 cases and 564 cases), and the number of bovines and S. japonicum-infected bovines reduced by 47.9 and 98% in 2014 (919,579 bovines and 666 infected bovines) as compared to that in 2005 (1,764,472 bovines and 33,736 infected bovines), respectively. During the 10-year implementation of the integrated strategy, however, there was a minor fluctuation in the area of Oncomelania hupensis snail habitats, and there was only a 5.6% reduction in the area of snail habitats in 2014 relative to in 2005. The results of the current study demonstrate that the 10-year implementation of the integrated strategy with emphasis on infectious source has greatly reduced schistosomiasis-related morbidity in humans and bovines. It is concluded that the new integrated strategy has remarkable long-term effectiveness on the transmission of schistosomiasis japonica in China, which facilitates the shift of the national schistosomiasis control program from transmission control to transmission interruption and elimination. However, such a strategy seems to have little effect on the shrinking of areas of snail habitats.

A cross-sectional survey comparing a free treatment program for advanced schistosomiasis japonica to a general assistance program.

The prevalence and intensity of schistosomiasis has dropped dramatically in China due to an effective integrated control program. However, advanced schistosomiasis is becoming a key challenge on the road to elimination. The aims of this study were to compare the disease condition between advanced cases under the general assistance program (GAP) and free treatment program (FTP) and to determine whether the FTP should be popularized to provide an objective reference for policymakers in China's advanced schistosomiasis control program. One hundred and ninety-four patients with schistosomiasis japonica who were enrolled in the GAP or FTP participated in this study. Little significant difference was observed in the potential confounders, including general characteristics, comorbidities, and lifestyle, indicating a similar effect on the pathology of liver damage caused by schistosome infection. There was no apparent difference in the incidence of common clinical symptoms. Furthermore, no significant difference was observed in the ultrasound findings, implying that the GAP and FTP groups shared a similar degree of liver lesion. With the exception of the abnormal rates of aspartate aminotransferase (AST), alkaline phosphatase (ALP), and hyaluronic acid (HA), the other serological indicators were comparable between the groups. Overall, the FTP is not a better option for controlling advanced schistosomiasis in China. It is important to reveal the precise mechanism underlying the pathogenesis of advanced schistosomiasis so that specific approaches to treating and preventing the development of advanced schistosomiasis can be developed and schistosomiasis can be eliminated in China.

History of schistosomiasis epidemiology, current status, and challenges in China: on the road to schistosomiasis elimination.

Schistosomiasis is a snail-borne disease caused by worms of the genus Schistosoma. Worldwide, human schistosomiasis remains a serious public health problem, threatening ∼800 million people in 78 countries with a loss of 70 million disability-adjusted life years. Schistosoma japonicum is the only human blood fluke that occurs in China. As one of the countries suffering greatly from schistosomiasis, over the past 65 years, China has made great strides in controlling schistosomiasis, blocking the transmission of S. japonicum in five provinces, remarkably reducing transmission intensities in the other seven endemic provinces, and China is currently preparing to move toward the elimination of this disease before 2025. However, while on the road to schistosomiasis elimination, emerging challenges merit attention, including severe advanced cases, increased movements of population and livestock, large-area distribution of intermediate host snails, limitations of new drug developments and no vaccine available, as well as imported schistosomiasis and its potential risk.

Schistosoma japonicum in Samar, the Philippines: infection in dogs and rats as a possible risk factor for human infection.

The role that animals play in the transmission of Schistosoma japonicum to humans in the Philippines remains uncertain and prior studies have not included several species, adjustment for misclassification error and clustering, or used a cohort design. A cohort study of 2468 people providing stool samples at 12 months following praziquantel treatment in 50 villages of Western Samar, the Philippines, was conducted. Stool samples from dogs, cats, rats, and water buffaloes were collected at baseline (2003-2004) and follow-up (2005). Latent-class hierarchical Bayesian log-binomial models adjusting for misclassification errors in diagnostic tests were used. The village-level baseline and follow-up prevalences of cat, dog, and rat S. japonicum infection were associated with the 12-month cumulative incidence of human S. japonicum infection, with similar magnitude and precision of effect, but correlation between infection levels made it difficult to divide their respective effects. The cumulative incidence ratios associated with a 1% increase in the prevalence of infection in dogs at baseline and in rats at follow-up were 1·04 [95% Bayesian credible interval (BCI) 1·02-1·07] and 1·02 (95% BCI 1·01-1·04), respectively, when both species were entered in the model. Dogs appear to play a role in human schistosomiasis infection while rats could be used as schistosomiasis sentinels.

Development and optimization of cocktail-ELISA for a unified surveillance of zoonotic schistosomiasis in multiple host species.

The zoonotic characteristic of the human parasite Schistosoma japonicum infecting a significant number of wild and domestic animals highlights the need to develop a unified surveillance in multiple host species for a strengthened schistosomiasis control. It has been shown in several studies that water buffaloes and dogs are considered important reservoirs in the transmission of the schistosome parasite to humans. Recombinant antigens like thioredoxin peroxidase-1 (SjTPx-1) and tandem repeat proteins (Sj1TR, Sj7TR) have been shown to be good diagnostic antigens individually in humans, water buffaloes, and dogs in previous studies. Mixing these antigens together in a cocktail-ELISA might not only improve their diagnostic potentials but rather produce a multi-host species detection means for zoonotic schistosomiasis. In this study, we aimed to develop and optimize cocktail-ELISA by testing different combinations of these recombinant antigens in humans, water buffaloes, and dogs. As compared with the diagnostic potential calculated for each of the three recombinant antigens used, their combination has presented improved specificities, positive predictive values, and kappa values. Using samples collected from various endemic areas in the Philippines, results showed that the combination of SjTPx-1/Sj7TR/Sj1TR has the highest sensitivity in humans (84.1 %), water buffaloes, and dogs (80 %) and specificity (100 %) in all host species. This study therefore suggests the use of cocktail-ELISA in improving the zoonotic surveillance in schistosomiasis endemic areas.

CD36-related protein in Schistosoma japonicum: candidate mediator of selective cholesteryl ester uptake from high-density lipoprotein for egg maturation.

Familial cholesteryl ester transfer protein (CETP) deficiency is more common in some East Asian populations than elsewhere, suggesting the possibility of a selective advantage of this genetic defect against regional infectious diseases. Historically, infection with the Asian blood fluke Schistosoma japonicum has been endemic in these regions, including Japan. We previously reported that eggs of S. japonicum require cholesteryl ester uptake from normal high-density lipoprotein (HDL) but not from CETP-deficient HDL for their maturation to miracidia, a critical step of the hepatic pathogenesis of schistosomiasis. Herein we show that cholesteryl ester uptake is selective from HDL, and identified CD36-related protein (CD36RP) as a candidate to mediate the reaction. CD36RP was cloned from the adult and the egg developmental stages of S. japonicum, with 1880 bp encoding 506 amino acid residues exhibiting the CD36 domains and two transmembrane regions. Using antibodies against recombinant peptides representing the potential extracellular domains of CD36RP, Western blotting detected a protein with a molecular mass of 82 kDa in the particulate fraction of the adult parasite cells, which was reduced to 62 kDa after N-glycanase treatment. The extracellular domain peptide bound human HDL, as established by immunoblots following nondenaturing gel electrophoresis. Antibodies against the extracellular domain suppressed HDL cholesteryl ester uptake and maturation of the eggs in vitro. CD36RP is a candidate receptor on eggs of S. japonicum that facilitates uptake of HDL cholesteryl ester necessary for egg embryonation and maturation.

Comparison of the miracidium hatching test and modified Kato-Katz method for detecting Schistosoma japonicum in low prevalence areas of China.

The diagnosis of Schistosoma japonicum (Sj) infection in low prevalence areas of the People's Republic of China is challenging due to the sensitivity of the detection methods, leading to an underestimation of the disease burden. We compared the sensitivities of the miracidium hatching test (MHT) with the modified Kato-Katz method (KK) and the combination of the two methods (KK-MHT) to detect Sj infection in low prevalence areas of China. The stool samples of 3,853 residents from 8 villages with a light to moderate prevalence (0-23%) of Sj infection were examined by KK, MHT and KK-MHT. The findings were inconsistent. The KK-MHT conbination gave more positives than either the KK or MHT alone. Using the KK-MHT, we determined the missed rates with the KK (mR(K)) and MHT (mR(H)) to be 30.1% and 10.2%, respectively. At light prevalence sites (infection rate < 10%) the mR(K) was 60.6%, significantly higher than the mR(K) of 22.3% found at moderate prevalence sites (10-23%). However, the mR(H) at the light and moderate prevalence sites were 11.54% and 9.90%, respectively (p > 0.05). The combination KK-MHT had the best sensitivity in low Sj prevalence areas in China and the KK method alone was the least sensitive. Using KK alone as a screening method will result in an underestimation of Sj infection disease burden.

[Risk evaluation of schistosomiasis japonica input to potential endemic areas in Anhui province].

OBJECTIVE: To analyze the impact of water transfer project from the Yangtze River to the Huaihe River on schistosomiasis transmission, and to evaluate the risk of the disease input to the potential endemic area in Anhui Province, namely the Chaohu Lake region. METHODS: From 2008 to 2012, 1 fixed and 3 mobile surveillance sites in the Chaohu Lake area were selected, and the schistosomiasis infection situation of 615 local residents in the fix surveillance site was investigated in autumn of 2008 and 2012, while the schistosomiasis infection situation of 1603 mobile population in the 3 mobile surveillance sites were investigated in autumn of 2008 to 2012. All people were screened by indirect hemagglutination assay (IHA), and the positive ones were then examined by sedimentation method. 303 local livestock and livestock from schistosomiasis endemic areas were examined by stool hatching method in autumn of 2008 to 2012. From 2008 to 2012, the distribution of Oncomelania snails was investigated in risk areas and suspicious areas, and the snail spreading pattern was conducted through salvaging floaters in rivers connected with the Yangtze River. In addition, the Oncomelania snails were raised in the cages on the beaches of the Chaohu Lake, a control area, from 2007 to 2010, and their survival and reproduction capacity was observed. RESULTS: In 2008 and 2012, 301 and 314 local residents were detected by IHA, but there were no positive found. From 2008 to 2012, a total of 1603 mobile population were examined by IHA, and the positive rate of antibody was 3.1% (49/1603); 75 individuals were examined by sedimentation method, and the positive rate was 36.00% (27/75). A total of 303 livestock were examined by stool hatching method, but no one showed positive. A total of 1630 km(2) in risk areas and 3551 km(2) in suspicious areas were surveyed, but there were no Oncomelania snails found. A total of 457.6 kg floating debris were investigated, and 11 Oncomelania snails were found. From 2007 to 2010, the survival rate of Oncomelania snails in two trail areas in the Chaohu Lake and in the control area was 88% (86/98), 51% (45/89), 30% (25/71), 24% (20/84) and 92% (85/92), 54% (50/92), 23% (12/52), 17% (13/79) and 96% (85/89), 52% (44/85), 26% (18/69), 18% (14/76), respectively, there were no statistical significance between the trial areas and the control area (χ1(2) = 3.78, P > 0.01; χ2(2) = 0.27, P > 0.01; χ3(2) = 2.51, P > 0.01; χ4(2) = 1.50, P > 0.01), and filial generation snails were found in each observation area from 2008 to 2010, the number was 156-312. CONCLUSION: The imported infectious sources of schistosomiasis have been found in the Chaohu Lake region, the possibility of imported exogenous Oncomelania snails spreading into the Lake and surviving and reproducing there is high. The risk of schistosomiasis input to the potential endemic area in Anhui Province is predicted to be high.

Changing seroprevalence of schistosomiasis japonica in China from 1982 to 2020: A systematic review and spatial analysis.

BACKGROUND: Schistosomiasis is a global public health issue. In China, while the seroprevalence of Schistosomiasis japonica has currently reduced to a relatively low level, risk of infection still exists in certain areas. However, there has been a lack of comprehensive research on the long-term trends of national seroprevalence, changes across age groups, and characteristics in spatial distribution, which is crucial for effectively targeting interventions and achieving the goal of eliminating schistosomiasis by 2030. Our study aimed to address this gap by analyzing the long-term trends of Schistosomiasis japonica seroprevalence in China from 1982 to 2020 based on the data from diverse sources spanning a period of 39 years. METHODOLOGY: Seroprevalence data were collected from literature databases and national schistosomiasis surveillance system. Meta-analysis was conducted to estimate the seroprevalence. Joinpoint model was used to identify changing trend and inflection point. Inverse distance weighted interpolation was used to determine the spatial distribution of seroprevalence. PRINCIPAL FINDINGS: The seroprevalence decreased from 34.8% in 1982 to 2.4% in 2020 in China. Before 2006, the seroprevalence was higher in the middle age group, and a pattern of increasing with age was observed afterwards. The areas with high seroprevalence existed in Dongting Lake, Poyang Lake, Jianghan Plain, the Anhui branch of the Yangtze River and some localized mountainous regions in Sichuan and Yunnan provinces. CONCLUSIONS/SIGNIFICANCE: There was a significant decline in the seroprevalence of Schistosomiasis japonica from 1982 to 2020 in China. Nevertheless, schistosomiasis has not been eradicated; thus, implementing precise and personalized monitoring measures is crucial for the elimination of schistosomiasis, especially in endemic areas and with a particular focus on the elderly.

Assessment of the influence of levees along Yangtze River on Oncomelania hupensis, the intermediate host of Schistosoma japonicum.

BACKGROUND: Oncomelania hupensis is the exclusive intermediate host of Schistosoma japonicum in China. Snail control is an essential component of schistosomiasis elimination programme. With 70 years of continuous efforts, the range of O. hupensis had reduced significantly, but slowed down in last decades. A large number of levees against flooding were constructed along Yangtze River and its affiliated lakes in the middle and lower reaches, which influenced the hydrology and ecology in the alluvial plains. The purpose of this study was to assess the impact of levees on the distribution of O. hupensis in the middle and lower reaches of the Yangtze River. METHODS: The snail habitats were digitalised by hand-held GPS system. The years for discovery and elimination of snail habitats were extracted from historical records. The accumulated snail-infested range for each habitat was calculated on the basis of annual reports. The current distribution of O. hupensis was determined by systematic and environmental sampling. The geographical distribution of levees was obtained from satellite imagery. To assess the impact of levees, the data pertaining to O. hupensis were divided into two parts: inside and outside the Yangtze River. Joinpoint regression was utilised to divide the study time span and further characterise the regression in each period. The 5-year-period moving averages of eliminated area infested by snails were calculated for the habitats inside and outside Yangtze River. The moving routes of corresponding geographical median centres were simulated in ArcGIS. Hotspot analysis was used to determine the areas with statistical significance clustering of O. hupensis density. RESULTS: Three periods were identified according to Joinpoint regression both inside and outside Yangtze River. The area infested by O. hupensis increased in the first two periods. It decreased rapidly outside Yangtze River year over year after 1970, while that inside the Yangtze River did not change significantly. Furthermore, the latter was significantly higher than the former. It was observed that the present density of O. hupensis inside Yangtze River was lower than outside the Yangtze River. The median centre for eliminated ranges inside Yangtze River wavered between the east (lower reach) and the west (middle reach). In contrast, the median centre for eliminated ranges continuously moved from the east to the west. CONCLUSIONS: Our findings indicated that the levees had a considerable negative impact on the distribution of O. hupensis outside Yangtze River. Some hotspots observed in the irrigation areas need a sluice system at the inlet of branch for snail control. The major distribution of O. hupensis located in Hubei might be caused by severe waterlogging. The intensive surveillance should be implemented there. The biggest two freshwater lakes, the major endemic regions historically, were identified as cold spots. The long-term impact of Three Gorges Dam on the distribution of O. hupensis in the lakes should be monitored and evaluated.