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

Towards an integrated vector management approach for sustainable control of schistosomiasis and malaria in Mwea, Kirinyaga County, Kenya: Baseline epidemiological and vector results

Background

Vector control is an important approach in the control of most parasitic and vector-borne diseases including malaria, and schistosomiasis. Distribution of these two infections often overlaps and in such areas it's more economically viable to employ an integrated approach in the control of their vectors which largely shares the same breeding ecosystem. We carried out a baseline epidemiological and vector surveys for malaria and schistosomiasis in Mwea, Kirinyaga County, in preparation for the upscaling of integrated vector management (IVM) for the two diseases.

Methods

This was a repeated cross sectional survey, where mosquito and snails were sampled during dry and wet seasons in three different ecological zones, Kiamaciri, Thiba and Murinduko to identify possible breeding sites. Mosquito larvae were collected using standard dippers, adults using CDC miniature light traps while snail vectors were sampled using standard snail scoops in different breeding habitats. A total of 1200 pupils from 12 primary schools were tested for malaria using rapid diagnostic tests (Malaria Pf/PAN Ag combo). Stool samples were processed using the Kato Katz technique for intestinal schistosomiasis.

Results

The overall prevalence of intestinal schistosomiasis was 9.08 % (95 % CI: 07.00-11.00), with Kiamaciri zone recording the highest prevalence at 19 % (95%CI: 15.00-23.00) and Murinduko zone the least at 0.17 % (95%CI: 0.00-0.01). Majority of the infections were of light intensity 78.9 % (95%CI: 70.04-86.13). There was no positive malaria case detected in this study. Of the 3208 adult mosquitoes sampled during the dry season, 20.6 % (95 % CI: 19.25-22.08) were Anopheles gambiae s.l while 79.4 % (95 % CI: 77.92-80.75) were culicines. During the wet season, 3378 adult mosquitoes were collected, of which 14.7 % (95 % CI: 13.56-15.98) were Anopheles gambiae s.l and 85.3 % (95 % CI: 84.02-86.44) culicines. Overall, 4085 mosquito larvae were collected during the two seasons, of which, 57.3 % and 42.7 % were anopheles and culicine respectively. Majority of the larvae (85.1 % (95%CI: 84.01-86.10) were collected during the wet season, with only 14.9 % (95%CI: 14.10-16.00) being collected during the dry season. A total of 2292 fresh water vector snails were collected with a majority (69.6 % (95%CI: 68.00-71.10) being Biomphalaria pffeiferi responsible for transmission of intestinal schistosomiasis.

Conclusion

This study demonstrates that intestinal schistosomiasis is prevalent in Kiamaciri and Thiba zones, and points to the possibility of active transmission of schistosomiasis in Murinduko zone. Malaria vectors were predominantly observed in all sites despite there being no malaria positive case. Culex quinquefaciatus responsible for the spread of several arboviruses was also observed. The presence of these vectors may lead to future disease outbreaks in the area if concerted control initiatives are not undertaken. The disease vectors shared the same breeding sites and thus its economical and feasible to adopt an integrated vector management approach in control efforts for these disease in the study area.

IgG persistence showed weak clinical aspects in chronic schistosomiasis patients

Schistosomiasis is a chronic parasitic disease, which affects the quality of daily life of patients and imposes a huge burden on society. Hepatic fibrosis in response to continuous insult of eggs to the liver is a significant cause of morbidity and mortality. However, the mechanisms of hepatic fibrosis in schistosomiasis are largely undefined. The purpose of our study is to detect the indicator to hepatic fibrosis in schistosomiasis. A total of 488 patients with chronic schistosomiasis japonica were enrolled in our study. The patients were divided into two groups according to liver ultrasound examination, which could indicate liver fibrosis of schistosomiasis with unique reticular changes. Logistic regression analysis showed that globulin, albumin/globulin, GGT levels and anti-Schistosoma IgG were independently associated with liver fibrosis in patients with schistosomiasis and IgG was the largest association of liver fibrosis (OR  2.039, 95% CI 1.293-3.213). We further compared IgG+ patients with IgG- patients. IgG+ patients (ALT 25 U/L, GGT 31 U/L) slightly higher than IgG- patients (ALT 22 U/L, GGT 26 U/L) in ALT and GGT. However, the fibrosis of liver in IgG+ patients (Grade II(19.7%), Grade III(7.3%)) were more severe than that in IgG- patients(Grade II(12.5%), Grade III(2.9%)) according to the grade of liver ultrasonography. Our results showed anti-Schistosoma IgG was independently associated with liver fibrosis in patients with chronic schistosomiasis japonica and patients with persistent anti-Schistosoma IgG might have more liver fibrosis than negative patients despite no obvious clinical signs or symptoms.

Changing trends, clinicopathological characteristics, surgical treatment patterns, and prognosis of schistosomiasis-associated versus non-schistosomiasis-associated colorectal cancer: a large retrospective cohort study of 31 153 cases in Shanghai, China (2001-2021)

BACKGROUND

With the elimination of schistosomiasis in China, its role in the pathogenesis of colorectal cancer (CRC) has decreased. However, the trends, clinicopathological features, surgical treatment patterns, and prognosis of schistosomiasis-associated CRC (SACRC) versus non-schistosomiasis-associated CRC (NSACRC) in China remain unclear.

MATERIALS AND METHODS

The percentage trend of SACRC in CRC patients in China was analyzed using data retrieved from the Pathology Registry of Changhai Hospital (2001-2021). Clinicopathological characteristics, surgical treatment patterns, and prognosis-related parameters were compared between the two groups. Multivariate Cox regression analyses were performed for disease-free survival (DFS) and overall survival (OS).

RESULTS

A total of 31 153 CRC cases were included, with 823 (2.6%) cases of SACRC and 30 330 (97.4%) cases of NSACRC. The average percentage of SACRC cases has decreased continuously from 3.8 to 1.7% (from 2001 to 2021). Compared with the NSACRC group, the SACRC group had more men, older age at diagnosis, lower BMI, fewer symptoms; higher rates of rectal cancer, comorbidities, KRAS mutation, multiple primary CRC and concomitant polyps; less lymph node metastasis, distant metastasis, vascular invasion, and tumor budding; less preoperative radiotherapy and preoperative chemotherapy; and more positive resection margins and postoperative targeted therapy. There were no significant differences between the two groups regarding laparoscopic surgery, palliative resection, extended radical resection, or ostomy. Moreover, the SACRC group had adverse DFS and similar OS compared with the NSACRC group. In multivariate analyses, schistosomiasis was not an independent predictor of DFS or OS.

CONCLUSION

The percentage of SACRC in CRC (2.6%) in our hospital was very low, and it decreased continuously over the last two decades, indicating that schistosomiasis is no longer an important risk factor for CRC in Shanghai, China. Patients with SACRC have distinct clinicopathological, molecular, and treatment-related features and survival rates similar to those with NSACRC.

The Current Distribution of Oncomelania hupensis Snails in the People's Republic of China Based on a Nationwide Survey

Schistosomiasis is a helminth infection caused by the genus Schistosoma, which is still a threat in tropical and sub-tropical areas. In the China, schistosomiasis caused by Schistosoma japonicum is mainly endemic to the Yangtze River valley. The amphibious snail Oncomelania hupensis (O. hupensis) is the unique intermediate host of S. japonicum; hence, snail control is a crucial approach in the process of schistosomiasis transmission control and elimination. In 2016, a nationwide snail survey was conducted involving all snail habitats recorded since 1950 in all endemic counties of 12 provinces. A total of 53,254 existing snail habitats (ESHs) were identified, presenting three clusters in Sichuan Basin, Dongting Lake, and Poyang Lake. The overall habitat area was 5.24 billion m², of which 3.58 billion m² were inhabited by O. hupensis. The area inhabited by snails (AIS) in Dongting and Poyang Lakes accounted for 76.53% of the population in the country. Three typical landscape types (marshland and lakes, mountains and hills, and plain water networks) existed in endemic areas, and marshland and lakes had a predominant share (3.38 billion m²) of the AIS. Among the 12 endemic provinces, Hunan had a share of nearly 50% of AIS, whereas Guangdong had no ESH. Ditches, dryland, paddy fields, marshland, and ponds are common habitat types of the ESH. Although the AIS of the marshland type accounted for 87.22% of the population in the whole country, ditches were the most common type (35,025 or 65.77%) of habitat. Six categories of vegetation for ESHs were identified. A total of 39,139 habitats were covered with weeds, accounting for 55.26% of the coverage of the area. Multiple vegetation types of snail habitats appeared in the 11 provinces, but one or two of these were mainly dominant. Systematic sampling showed that the presence of living snails was 17.88% among the 13.5 million sampling frames. The occurrence varied significantly by landscape, environment, and vegetation type. The median density of living snails in habitats was 0.50 per frame (0.33 m × 0.33 m), and the highest density was 40.01 per frame. Furthermore, two main clusters with high snail densities and spatial correlations indicated by hotspot analysis were identified: one in Hunan and Hubei, the other in Sichuan. This national survey is the first full-scale census on the distribution of O. hupensis, which is significant, as transmission interruption and elimination are truly becoming the immediate goal of schistosomiasis control in China. The study discerns the detailed geographic distribution of O. hupensis with the hotspots of snail density in China. It is beneficial to understand the status of the snail population in order to finally formulate further national control planning.

Core components, concepts and strategies for parasitic and vector-borne disease elimination with a focus on schistosomiasis: A landscape analysis

Efforts to control and eliminate human schistosomiasis have accelerated over the past decade. In a number of endemic countries and settings, interruption of schistosome transmission has been achieved. In others, Schistosoma infections continue to challenge program managers at different levels, from the complexity of the transmission cycle, over limited treatment options and lack of field-friendly accurate diagnostics, to controversy around adequate intervention strategies. We conducted a landscape analysis on parasitic and vector-borne disease elimination approaches with the aim to identify evidence-based strategies, core components and key concepts for achieving and sustaining schistosomiasis control and for progressing elimination efforts towards interruption of transmission in sub-Saharan Africa. A total of 118 relevant publications were identified from Web of Science, Pubmed and the grey literature and reviewed for their content. In addition, we conducted in-depth interviews with 23 epidemiologists, program managers, policymakers, donors and field researchers. Available evidence emphasizes the need for comprehensive, multipronged and long-term strategies consisting of multiple complementary interventions that must be sustained over time by political commitment and adequate funding in order to reach interruption of transmission. Based on the findings of this landscape analysis, we propose a comprehensive set of intervention strategies for schistosomiasis control and elimination. Before deployment, the proposed interventions will require review, evaluation and validation in the frame of an expert consultation as a step towards adaptation to specific contexts, conditions and settings. Field testing to ensure local relevance and effectiveness is paramount given the diversity of socio-ecological and epidemiological contexts.

This landscape analysis explored successful concepts, approaches and interventions of past and ongoing parasitic and vector-borne disease elimination efforts and programs with regard to relevance for progress in the elimination of human schistosome infections. Schistosomiasis is a disabling, water borne parasitic disease of public health concern with an estimated 250 million people infected worldwide. The long-term morbidity of this neglected tropical disease significantly impacts growth, cognition and socioeconomic development at all ages. Despite increased global efforts to control morbidity and advance elimination, challenges in view of the complex life cycle which involves freshwater sources, intermediate snail hosts and humans, remain. This calls for targeted interventions and concerted programs. According to the evidence from the literature and as proposed by a wide range of key informants, comprehensive, multipronged and long-term strategies supported by strong political commitment and adequate funding are required in order to achieve and sustain the set goals. Based on the findings, we propose here a comprehensive set of intervention strategies for schistosomiasis control and elimination for review and evaluation to inform implementation research needs and elimination program design.

Metabolic profiles of Oncomelania hupensis after molluscicidal treatment: Carbohydrate metabolism targeted and energy deficiency

Oncomelania hupensis is the intermediate host of Schistosoma japonicum, one of the Schistosoma species that can cause human schistosomiasis. Molluscicidal treatment remains the primary means to control snail. Niclosamide is the only molluscicide recommended by the World Health Organization, and it has been used throughout schistosomiasis-endemic areas in China for almost 30 years. In our previous studies on transcriptomics, morphology, and enzymology of snails after molluscicidal treatment, two effective molluscicides were used, 50% wettable powder of niclosamide ethanolamine salt (WPN) and a new molluscicide derived from niclosamide, the salt of quinoid-2', 5-dichloro-4'-nitro-salicylanilide (LDS, simplified for Liu Dai Shui Yang An). Genes involved in cell structure mintenance, inhibition of neurohumoral transmission, and energy metabolism showed significant differential expression after molluscicide treatments. Damages in the structure of liver and muscle cells were accompanied by inhibited activities of enzymes related to carbohydrate metabolism and energy supply. This study was designed to clarify the dynamic metabolic process by metabonomics, together with the previous transcriptomic and enzymological profiles, to identify potential metabolite markers and metabolism pathways that related to the toxic mechanism of the molluscicide. In total, 56 metabolites were identified for O. hupensis, and 75% of these metabolites consisted of amino acids and derivatives, organic acids, and nucleic acid components. The concentration of glucose, maltose, succinate, choline, and alanine changed significantly after molluscicide treatments. These changes in metabolites mainly occurred in the process of carbohydrate metabolism, energy metabolism, and amino acid metabolism, primarily related to glycolysis/gluconeogenesis, oxidative phosphorylation, and transamination by KEGG pathway identification. Most of the identified pathways were also related to those differentially expressed unigenes and observed enzymes from our previous studies. Inhibited aerobic respiration and oxidative phosphorylation, and energy deficiency were implied further to be the leading causes of the final death of snails after molluscicide treatments. The hypothesised mathematical model in this study identified the rational hysteresis to explain the inconsistency of responses of unigenes, enzymes, and metabolites to molluscicide treatments. This study contributes to the comprehensive understanding of the molluscicidal mechanism in the metabolic process and this could assist in improving existing molluscicide formulations or development of new molluscicides.

Geographical survey of the intermediate host of Schistosoma japonicum: Toward precise management of Oncomelania hupensis

Schistosomiasis caused by Schistosoma japonicum is a public health concern in China, and Hubei is one of the most affected provinces. Although the routine surveillance since the mid 1950s has generated substantial data pertaining to the habitats of the intermediate snail host, Oncomelania hupensis, its spatiotemporal distribution is not known. A review of local chronicles on the annual records of schistosomiasis control program was conducted to retrospectively collect information about O. hupensis habitats. The habitats were mapped by a field survey in 2016. We categorized the habitats into five evolutionary types, namely, Type I, current habitat; Types II-IV, historical habitat; and Type V, suspected habitat according to habitat development. The shape of habitats was determined using geographical information systems. A visual database was established and managed on the ArcGIS platform. A total of 43 472 O. hupensis habitats, covering an area of approximately 430 000 hectares, were identified through the study. Over 60% of these habitats have been eliminated. The highest number of O. hupensis habitats was recorded in 1975; however, most of them were preserved until 1995. Our study, for the first time, sheds light on the spatiotemporal distribution of O. hupensis in the most affected province in China. The data will be valuable for policy making and for formulating strategies to eliminate schistosomiasis in Hubei Province.

The genetic variation of different developmental stages of Schistosoma japonicum: do the distribution in snails and pairing preference benefit the transmission?

BACKGROUND

Schistosoma japonicum is a waterborne parasite that causes schistosomiasis in humans and in more than 40 animal species. Schistosoma japonicum shows distinct genetic differentiation among geographical populations and multiple hosts, but the genetic diversity of different developmental stages of S. japonicum from is less studied. Such studies could elucidate ecological mechanisms in disease transmission by analysing feedbacks in individual physiology and population state.

METHODS

After infection using cercariae from a pool of snails shedding together (Method I) and infection using mixed equal numbers of cercariae from individually shed snails (Method II), different developmental stages of S. japonicum were genotyped with microsatellite loci, including 346 cercariae, 701 adult worms and 393 miracidia. Genetic diversity and molecular variation were calculated at different population levels. Kinships (I') among cercariae at intra-snail and inter-snail levels were evaluated. Genetic distance (Dsw) was compared between paired and unpaired worms, and partner changing was investigated through paternity identification for miracidia.

RESULTS

The cercaria clones in individual snails varied from 1 to 8 and the kinship of cercariae within individual snails was significant higher (P < 0.001) than that among different snails after deleting near-identical multi-locus genotypes (niMLGs). The allelic diversity of worms in Method I was lower (P < 0.001) than that in Method II, and allele frequency among mice in Method I was also less consistent. The parents of some miracidia were worms that were not paired when collected. The Dsw between each female of paired and unpaired males was much larger (P < 0.001) than that between the female and male in each pair.

CONCLUSIONS

Most of the infected snails contained multiple miracidia clones. The aggregation of genetically similar S. japonicum miracidia in individual snails and the unbalanced distribution of miracidia among snails suggests a non-uniform genetic distribution of cercariae among snails in the field. This further influenced the genetic structure of adult worms from infections with different cercariae sampling methods. Schistosoma japonicum in mice can change paired partner, preferring to mate with genetically similar worms. These characteristics provide implications for understanding the balance in genetic diversity of S. japonicum related to the transmission of schistosomiasis.

Temporal transcriptome change of Oncomelania hupensis revealed by Schistosoma japonicum invasion

Background

The freshwater snail Oncomelania hupensis is the obligate intermediate host for Schistosoma japonicum in China. Transcriptomic examination of snail–schistosome interactions can provide valuable information of host response at physiological and immune levels.

Methods

To investigate S. japonicum-induced changes in O. hupensis gene expression, we utilized high-throughput sequencing to identify transcripts that were differentially expressed between infected snails and their uninfected controls at two key time-point, Day 7 and Day 30 after challenge. Time-series transcriptomic profiles were analyzed using R package DESeq 2, followed by GO, KEGG and (weighted gene correlation network analysis) WGCNA analysis to elucidate and identify important molecular mechanism, and subsequently understand host–parasite relationship. The identified unigenes was verified by bioinformatics and real-time PCR. Possible adaptation molecular mechanisms of O. hupensis to S. japonicum challenge were proposed.

Results

Transcriptomic analyses of O. hupensis by S. japonicum invasion yielded billion reads including 92,144 annotated transcripts. Over 5000 differentially expressed genes (DEGs) were identified by pairwise comparisons of infected libraries from two time points to uninfected libraries in O. hupensis. In total, 6032 gene ontology terms and 149 KEGG pathways were enriched. After the snails were infected with S. japonicum on Day 7 and Day 30, DEGs were shown to be involved in many key processes associated with biological regulation and innate immunity pathways. Gene expression patterns differed after exposure to S. japonicum. Using WGCNA, 16 modules were identified. Module-trait analysis identified that a module involved in RNA binding, ribosome, translation, mRNA processing, and structural constituent of ribosome were strongly associated with S. japonicum invasion. Many of the genes from enriched KEGG pathways were involved in lysosome, spliceosome and ribosome, indicating that S. japonicum invasion may activate the regulation of ribosomes and immune response to infection in O. hupensis.

Conclusions

Our analysis provided a temporally dynamic gene expression pattern of O. hupensis by S. japonicum invasion. The identification of gene candidates serves as a foundation for future investigations of S. japonicum infection. Additionally, major DEGs expression patterns and putative key regulatory pathways would provide useful information to construct gene regulatory networks between host-parasite crosstalk.

The Stakeholders' Views on Planting Trees to Control Schistosomiasis in China

China has initiated a tree planting program in epidemic regions of schistosomiasis as a part of efforts to eliminate schistosomiasis. More than 518,900 ha of tree plantations have been planted through the program between 2006 and 2015. However, whether the planting program has fulfilled its mission or not is an open question. In this study, we intended to get the answer from the main stakeholders of the planting program through a large-scale survey. Based on interviews with 80 administrators of the planting program and 1440 farmers in 24 counties and districts in four provinces, we found that most stakeholders viewed the planting program positively. Nearly 92% of farmers and all administrators believed that the planting program had reduced snail densities, while 94.3% of farmers and all administrators believed that the program had lowered the incidences of schistosomiasis. In addition, they reported that the impacts on farmers’ living and local environments by the tree planting program were mainly positive. Based on the stakeholders’ responses, we conclude that the tree planting program has been perceived by the main stakeholders as an effective environmental control measure of schistosomiasis. However, certain places and people that may be impacted negatively by the program should be given more attention when implementing the program.

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.

Elimination of Schistosoma japonicum Transmission in China: A Case of Schistosomiasis Control in the Severe Epidemic Area of Anhui Province

Over the several decades, China has been incessantly optimizing control strategies in response to the varying epidemic situations of schistosomiasis. We evaluated continuously the changing prevalence under different control strategies of two villages, Sanlian and Guifan, in China through five phases lasting 37 years. We tested residents, calculated prevalence and discussed change causes. We found the prevalence in Sanlian did not differ significant from that of Guifan (p = 0.18) in 1981, but decreased to 2.66%, much lower than Guifan’s 11.25%, in 1984 (p = 0). Besides, prevalence in Guifan increased to 21.25% in 1987, while in Sanlian it rose to 20.78% until 1989. Those data confirmed that praziquantel combined with snail control could better reduce the prevalence. From 1992 to 1994, the prevalence in the two villages displayed downtrends, which showed the World Bank Loan Project worked. From 1995 to 2004, repeated oscillations with no obvious change trend was seen. Since 2005, the prevalence in both villages has shown a significant downtrend (p < 0.05), which suggests the integrated strategy is effective. We considered the control strategies were implemented suitably in the study area under changing social circumstances. Adjusting the strategy in consideration of social transformations is necessary and vital. The experience may be useful for policy making of other epidemic areas with an analogous situation.

Effectiveness of the new integrated strategy to control the transmission of Schistosoma japonicum in China: a systematic review and meta-analysis

Since 2004, the national schistosomiasis control strategy in China has shifted from the morbidity control strategy (conventional strategy) to an integrated strategy (new strategy). We investigated the effectiveness of the new strategy and compared it against the conventional strategy. We retrieved from electronic databases the literature regarding the new strategy published from 2000 to 2017. The effect of the new or conventional strategy on infection by Schistosoma japonicum of humans and snails (Oncomelania hupensis) was evaluated with pooled log relative risk (logRR). A total of only eight eligible publications were included in the final meta-analysis. The results showed that implementation of the new strategy reduced the infection risk by 3–4 times relative to the conventional strategy. More specifically, the conventional strategy caused a reduction in both human (logRR = 0.56, 95% CI: 0.12–0.99) and snail infections (logRR = 0.34, 95% CI: −0.69–1.37), while the new strategy also significantly reduced both human (logRR = 1.89, 95% CI: 1.33–2.46) and snail infections (logRR = 1.61, 95% CI: 1.06–2.15). In contrast to the conventional strategy, the new strategy appeared more effective to control both human (logRR difference = 1.32, 95% CI: 0.78–1.86) and snail infections (logRR difference = 1.53, 95% CI: 0.76–2.31). Our data demonstrate that the new integrated strategy is highly effective to control the transmission of S. japonicum in China, and this strategy is recommended for schistosomiasis elimination in other affected regions across the world, with adaptation to local conditions.

Dynamics of spatiotemporal distribution of schistosomiasis in Hubei Province, China

Schistosomiasis caused by parasitic flatworms of blood flukes, remains a major public health concern in China. The significant progress in controlling schistosomiasis in China over the past decades has resulted in the remarkable reduction in the prevalence and intensity of Schistosoma japonicum infection to an extremely low level. Therefore, the elimination of schistosomiasis has been promoted by the Chinese national government. Hubei Province is the major endemic area, that is, along the middle and low reaches of the Yangtze River in the lake and marshland regions of southern China. Eliminating the transmission of schistosomiasis in Hubei Province is challenging. The current issue is to determine the distributions and clusters of schistosomiasis transmission. In this study, we assessed the spatial distribution of schistosomiasis and the risk at the county level in Hubei Province from 2011 to 2015 to provide guidance on the elimination of schistosomiasis transmission in lake and marshland regions. Spatial database of human S.japonicum infection from 2011 to 2015 at the county level in the study area was built based on the annual schistosomias is surveillance data. Moran's I, the global spatial autocorrelation statistics, was utilized to describe the spatial autocorrelation of human S. japonicum infection. In addition, purely spatial scan statistics combined with space-time scan statistics were used to determine the epidemic clusters. Infection rates of S. japonicum decreased in each endemic county in Hubei from 2011 to 2015. Human S. japonicum infection rate showed statistical significance by global autocorrelation analysis during the study period (Moran's I > 0, P < 0.01). This result suggested that there were spatial clusters present in the distribution of S. japonicum infection for the five years. Purely spatial analysis of human S. japonicum infection showed one most likely cluster and one secondary cluster from 2011 to 2015, which covered four and one counties, respectively. Spatiotemporal clustering analysis determined one most likely cluster and one secondary cluster both in 2011-2012, which appeared in 4 and 5 counties, respectively. However, the number of clustering foci decreased with time, and no cluster was detected after 2013.The clustering foci were both located at the Jianghan Plain, along the middle reaches of the Yangtze River and its connecting branch Hanbei River. Spatial distribution of human S. japonicum infections did not change temporally at the county level in Hubei Province. A declining trend in spatiotemporal clustering was observed between 2011 and 2015. However, effective control strategies and integrated prevention should be continuously performed, especially at the Jianghan Plain area along the Yangtze and Hanbei River Basin. Multivariate statistical analysis was carried out to investigate the risk of missing examinations, missing treatment, and unstandardized treatment events. The results showed that age, education level and Sanitary latrines are risk factors for missing examinations (b > 0, OR >1), and treatment times in past and feeding cattle in village group are protective factors (b < 0, OR <1). We also found that age and education level are risk factors for missing treatment (b > 0, OR >1). Study of the risk for un-standardized treatment revealed that occupation is risk factors (b > 0, OR >1), though, education level is protective factors (b < 0, OR <1). Therefore, precise prevention and control should be mainly targeted at these special populations.

TLR Specific Immune Responses against Helminth Infections

Despite marked improvement in the quality of lives across the globe, more than 2 million individuals in socioeconomically disadvantaged environments remain infected by helminth (worm) parasites. Owing to the longevity of the worms and paucity of immunologic controls, these parasites survive for long periods within the bloodstream, lymphatics, and gastrointestinal tract resulting in pathologic conditions such as anemia, cirrhosis, and lymphatic filariasis. Despite infection, an asymptomatic state may be maintained by the host immunoregulatory environment, which involves multiple levels of regulatory cells and cytokines; a breakdown of this regulation is observed in pathological disease. The role of TLR expression and function in relation to intracellular parasites has been documented but limited studies are available for multicellular helminth parasites. In this review, we discuss the unique and shared host effector mechanisms elicited by systemic helminth parasites and their derived products, including the role of TLRs and sphingolipids. Understanding and exploiting the interactions between these parasites and the host regulatory network are likely to highlight new strategies to control both infectious and immunological diseases.

Epidemiological features of and changes in incidence of infectious diseases in China in the first decade after the SARS outbreak: an observational trend study

Background

The model of infectious disease prevention and control changed significantly in China after the outbreak in 2003 of severe acute respiratory syndrome (SARS), but trends and epidemiological features of infectious diseases are rarely studied. In this study, we aimed to assess specific incidence and mortality trends of 45 notifiable infectious diseases from 2004 to 2013 in China and to investigate the overall effectiveness of current prevention and control strategies.

Methods

Incidence and mortality data for 45 notifiable infectious diseases were extracted from a WChinese public health science data centre from 2004 to 2013, which covers 31 provinces in mainland China. We estimated the annual percentage change in incidence of each infectious disease using joinpoint regression.

Findings

Between January, 2004, and December, 2013, 54 984 661 cases of 45 infectious diseases were reported (average yearly incidence 417·98 per 100 000). The infectious diseases with the highest yearly incidence were hand, foot, and mouth disease (114·48 per 100 000), hepatitis B (81·57 per 100 000), and tuberculosis (80·33 per 100 000). 132 681 deaths were reported among the 54 984 661 cases (average yearly mortality 1·01 deaths per 100 000; average case fatality 2·4 per 1000). Overall yearly incidence of infectious disease was higher among males than females and was highest among children younger than 10 years. Overall yearly mortality was higher among males than females older than 20 years and highest among individuals older than 80 years. Average yearly incidence rose from 300·54 per 100 000 in 2004 to 483·63 per 100 000 in 2013 (annual percentage change 5·9%); hydatid disease (echinococcosis), hepatitis C, and syphilis showed the fastest growth. The overall increasing trend changed after 2009, and the annual percentage change in incidence of infectious disease in 2009–13 (2·3%) was significantly lower than in 2004–08 (6·2%).

Interpretation

Although the overall incidence of infectious diseases was increasing from 2004, the rate levelled off after 2009. Effective prevention and control strategies are needed for diseases with the highest incidence—including hand, foot, and mouth disease, hepatitis B, and tuberculosis—and those with the fastest rates of increase (including hydatid disease, hepatitis C, and syphilis).

Funding

Chinese Ministry of Science and Technology, National Natural Science Foundation (China).

Interruption of schistosomiasis transmission in mountainous and hilly regions with an integrated strategy: a longitudinal case study in Sichuan, China

Background

Schistosomiasis remains a major public health concern in China. Since 2004, an integrated strategy was developed to control the transmission of Schistosoma japonicum in China. However, the long-term effectiveness of this integrated strategy for the interruption of schistosomiasis transmission remains unknown in the mountainous and hilly regions of China until now. This longitudinal study aims to evaluate the effectiveness of the integrated strategy on transmission interruption of schistosomiasis in Sichuan Province from 2005 through 2014.

Methods

The data regarding replacement of bovines with machines, improved sanitation, access to clean water, construction of public toilets and household latrines, snail control, chemotherapy, and health education were captured from the annual report of the schistosomiasis control programmes in Sichuan Province from 2005 to 2014, and S. japonicum infection in humans, bovines and snails were estimated to evaluate the effectiveness of the integrated strategy.

Results

During the 10-year period from 2005 through 2014, a total of 536 568 machines were used to replace bovines, and 3 284 333 household lavatories and 15 523 public latrines were built. Tap water was supplied to 19 116 344 residents living in the endemic villages. A total of 230 098 hm² snail habitats were given molluscicide treatment, and 357 233 hm² snail habitats received environmental improvements. There were 7 268 138 humans and 840 845 bovines given praziquantel chemotherapy. During the 10-year study period, information, education and communication (IEC) materials were provided to village officers, teachers and schoolchildren. The 10-year implementation of the integrated strategy resulted in a great reduction in S. japonicum infection in humans, bovines and snails. Since 2007, no acute infection was detected, and no schistosomiasis cases or infected bovines were identified since 2012. In addition, the snail habitats reduced by 62.39% in 2014 as compared to that in 2005, and no S. japonicum infection was identified in snails since 2007. By 2014, 88.9% of the endemic counties achieved the transmission interruption of schistosomiasis and transmission control of schistosmiasis was achieved in the whole province in 2008.

Conclusion

The government-directed and multi-department integrated strategy is effective for interrupting the transmission of schistosomiasis in the mountainous and hilly regions of China.

An integrated environmental improvement of marshlands: impact on control and elimination of schistosomiasis in marshland regions along the Yangtze River, China

BACKGROUND

Schistosomiasis is a global snail-transmitted infectious disease of poverty. Transmission control had been achieved in China in 2015 after the control efforts for over 60 years. Currently, the remaining core regions endemic for Schistosoma japonicum are mainly located in the marshland and lake regions along the Yangtze River basin.

METHODS

During the period from 2001 through 2015, an integrated environmental improvement of the marshlands was carried out through the implementation of industrial, agricultural and resources development projects in Yizheng County along the Yangtze River. S. japonicum infection in humans, livestock and snails was estimated by serology, stool examination, hatching technique and microscopy during the 15-year study period to evaluate the effect of the integrated environmental improvement on control and elimination of schistosomiasis.

RESULTS

A 0.05% overall rate of S. japonicum infection was observed in snails during the 15-year study period, and no infected snails were detected since 2012. The overall prevalence of S. japonicum infection was 0.09% in humans during the study period, and no human infection was found since 2012. In addition, only 13 bovines were identified with S. japonicum infection in 2003 during the 15-year study period, and since 2004, no infection was found in livestock.

CONCLUSION

The results of the present study demonstrate that the implementation of industrial, agricultural and water resources development projects, not only alters snail habitats in marshland regions, and promotes local economic development, which appears a win-to-win strategy to block the transmission of S. japonicum and accelerate socio-economic development along the Yangtze River.

A multidisciplinary, integrated approach for the elimination of schistosomiasis: a longitudinal study in a historically hyper-endemic region in the lower reaches of the Yangtze River, China from 2005 to 2014

BACKGROUND

Although great success has been achieved, schistosomiasis remains a major public health concern in China, and the remaining core endemic regions are concentrated along the middle and lower reaches of the Yangtze River. In this longitudinal study, we evaluated the effectiveness of a multidisciplinary, integrated approach for schistosomiasis elimination in a historically hyper-endemic region in the lower reaches of the Yangtze River, China over the 10-year period from 2005 through 2014.

METHODS

A three-step roadmap for schistosomiasis elimination was designed in the study site, and multidisciplinary, integrated interventions were implemented by the health, agriculture, water resources development, land and resources, and forestry sectors from 2005 to 2014, including chemotherapy for infected individuals, health education, management of the source of Schistosoma japonicum infection, and intermediate host snail control. The annual number of schistosomiasis patients, S. japonicum infection in humans, bovines and Oncomelania hupensis snails, and water infectivity were observed to assess the effectiveness of the multidisciplinary, integrated approach for the elimination of schistosomiasis.

RESULTS

There was a tendency towards a gradual decline in both the number of schistosomiasis cases and the prevalence of S. japonicum human infection across the study period from 2005 through 2014. No S. japonicum human infection was detected since 2012, and no acute infection was seen since 2006. During the study period, no infection was found in bovines, and a 0.03% overall infection rate was observed in O. hupensis snails. Since 2009, no infected snails were identified, and the area of both snail habitats and infected snail habitats appeared a reduction over the study period. Following the 3-year multidisciplinary, integrated control, infection control was achieved, and transmission control was achieved after 6-year implementation, with all infected snails and water infectivity eliminated; in addition, the 10-year implementation resulted in interruption of schistosomiasis transmission in the study site in 2014.

CONCLUSIONS

The results of the present 10-year longitudinal study demonstrate that the multidisciplinary, integrated approach is effective for the elimination of schistosomiasis as a public health problem in the lower reaches of the Yangtze River, China.