[Comparison of pathogenicity and gene expression profiles between adult Schistosoma japonicum isolated from hilly and marshland and lake regions of Anhui Province]

OBJECTIVE

To compare the differences in pathogenicity and gene expression profiles between adult Schistosoma japonicum isolated from hilly and marshland and lake regions of Anhui Province, so as to provide the scientific evidence for formulating the precise schistosomiasis control strategy in different endemic foci.

METHODS

C57BL/6 mice were infected with cercariae of S. japonicum isolates from Shitai County (hilly regions) and Susong County (marshland and lake regions) of Anhui Province in 2021, and all mice were sacrificed 44 days post-infection and dissected. The worm burdens, number of S. japonicum eggs deposited in the liver, and the area of egg granulomas in the liver were measured to compare the difference in the pathogenicity between the two isolates. In addition, female and male adult S. japonicum worms were collected and subjected to transcriptome sequencing, and the gene expression profiles were compared between Shitai and Susong isolates of S. japonicum. The differentially expressed genes (DEGs) were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses.

RESULTS

The total worm burdens [(14.50 ± 3.96) worms/mouse vs. (16.10 ± 3.78) worms/mouse; t = 0.877, P = 0.392], number of female and male paired worms [(4.50 ± 0.67) worms/mouse vs. (5.10 ± 1.45) worms/mouse; t = 1.129, P = 0.280], number of unpaired male worms [(5.50 ± 4.01) worms/mouse vs. (5.60 ± 1.69) worms/mouse; t = 0.069, P = 0.946], number of eggs deposited in per gram liver [(12 116.70 ± 6 508.83) eggs vs. (16 696.70 ± 4 571.56) eggs; t = 1.821, P = 0.085], and area of a single egg granuloma in the liver [(74 359.40 ± 11 766.34) µm² vs. (74 836.90 ± 13 086.12) µm²; t = 0.081, P = 0.936] were comparable between Shitai and Susong isolates of S. japonicum. Transcriptome sequencing identified 584 DEGs between adult female worms and 1 598 DEGs between adult male worms of Shitai and Susong isolates of S. japonicum. GO enrichment analysis showed that the DEGs between female adults were predominantly enriched in biological processes of stimulus response, cytotoxicity, multiple cell biological processes, metabolic processes, cellular processes and signaling pathways, cellular components of cell, organelles and cell membranes and molecular functions of binding and catalytic ability, and KEGG enrichment analysis showed that these DEGs were significantly enriched in pathways of vascular endothelial growth factor signaling, glutathione metabolism, arginine and proline metabolism. In addition, the DEGs between male adults were predominantly enriched in biological processes of signaling transduction, multiple cell biological processes, regulation of biological processes, metabolic processes, development processes and stimulus responses, cellular components of extracellular matrix and cell junction and molecular functions of binding and catalytic ability, and these DEGs were significantly enriched in pathways of Wnt signaling, Ras signaling, natural killer cells-mediated cytotoxicity, extracellular matrix-receptor interactions and arginine biosynthesis.

CONCLUSIONS

There is no significant difference in the pathogenicity between S. japonicum isolates from hilly and marshland and lake regions of Anhui Province; however, the gene expression profiles vary significantly between S. japonicum isolates.

[Trends in the prevalence of schistosomiasis in Anhui Province from 2004 to 2020 based on Joinpoint regression analysis]

OBJECTIVE

To investigate the changing trends in the prevalence of schistosomiasis in Anhui Province from 2004 to 2020, so as to provide the evidence for formulating the schistosomiasis elimination strategy in the province.

METHODS

The epidemiological data of schistosomiasis in Anhui Province from 2004 to 2020 were collected, and the trends in the endemic status of schistosomiasis were analyzed using a Joinpoint regression model. The trends in the prevalence of Schistosoma japonicum infections in humans, bovines and Oncomelania hupensis were measured in Anhui Province from 2004 to 2020 using average annual percent change (AAPC), and the correlations among the changing trends in the prevalence of S. japonicum infections in humans, bovines and O. hupensis snail status were evaluated using Pearson correlation analysis.

RESULTS

The prevalence of S.japonicum human infections continued to decline in Anhui Province from 2004 to 2020, with an annual mean decline of 14.8% [AAPC = -14.8%, 95% confidential interval (CI): (-18.9%, -10.5%), P < 0.01]. The prevalence of S. japonicum infections continued to decline in bovines in Anhui Province from 2004 to 2015 [AAPC = -31.3%, 95%CI: (-35.1%, -27.2%), P < 0.01], and was 0 for 5 successive years from 2016 to 2020. During the period from 2004 to 2020, there was an annual mean decline of 0.7% in areas of snail habitats [AAPC = -0.7%, 95%CI: (-1.2%, 0.3%), P < 0.05] and an annual mean decline of 9.2% in the density of living snails [AAPC = -9.2%, 95%CI: (-18.3%, 1.0%), P = 0.08] in Anhui Province from 2004 to 2020, and an annual mean decline of 35.6% was found in the density of S. japonicum-infected snails [AAPC = -35.6%, 95%CI: (-49.2%, -18.3%), P < 0.01] from 2004 to 2012, with no infected snails detected in Anhui Province from 2013 to 2020. There were significant correlations in the prevalence of S. japonicum infections between humans and bovines (r = 0.959, P < 0.01), between the prevalence of S. japonicum human infections and the density of S. japonicum-infected snails (r = 0.823, P < 0.01) and between the prevalence of S. japonicum infections in bovines and the density of S. japonicum-infected snails (r = 0.902, P < 0.01).

CONCLUSIONS

The prevalence of S. japonicum infections appeared a decline in humans, bovines and O. hupensis in Anhui Province from 2004 to 2020, and significant correlations were found among the changing trends in the prevalence of S. japonicum human infections, the prevalence of S. japonicum bovine infections and the density of S. japonicum-infected O. hupensis snails. Because of a minor decline in the area of snail habitats and widespread distribution of O. hupensis, however, there is still a risk of schistosomiasis transmission, and precision control for schistosomiasis remains to be reinforced in Anhui Province.

[Investigation on prevalence of Schistosoma japonicum infections in wild mice in Shitai County, Anhui Province, 2018]

OBJECTIVE

To investigate the prevalence of Schistosoma japonicum infection in wild mice in Shitai County, Anhui Province, so as to provide insights into precise control of the source of S. japonicum infections.

METHODS

Wild mice were captured using the trapping method for three successive nights at snail-infested settings from Jitan Village of Jitan Township, and Shiquan Village and Xibai Village of Dingxiang Township, Shitai County, Anhui Province in June and October, 2018. All trapped wild mice were sacrificed and liver and mesenteric vein specimens were collected for detection of S. japonicum eggs using microscopy, while the fecal samples in mouse intestines were collected for identification of S. japonicum infections using Kato-Katz technique. In addition, the population density of trapped wild mice was estimated and the prevalence of S. japonicum infection was calculated in trapped wild mice.

RESULTS

A total of 376 wild mice were trapped from three villages in Shitai County. The population density of trapped wild mice was 9.1% (376/4 124), and the prevalence of S. japonicum infection was 24.2% (91/376) in trapped wild mice. The highest prevalence of S. japonicum infection was detected in Shiquan Village of Dingxiang Township (30.1%), and the lowest prevalence was seen in Xibai Village of Dingxiang Township; however, there was no significant difference in the prevalence of S. japonicum infection in trapped wild mice among three villages (χ²= 4.111, P > 0.05). In addition, there was no significant difference in the prevalence of S. japonicum infection in wild mice captured between on June (26.8%, 34/127) and October (22.9%, 57/249) (χ² = 0.690, P = 0.406). The trapped wild mice included 6 species, including Rattus norvegicus, Niviventer niviventer, R. losea, Apodemus agrarius, Mus musculus and N. coning, and the two highest prevalence of S. japonicum infection was detected in R. losea (34.9%, 22/63) and R. norvegicus (31.2%, 44/141).

CONCLUSIONS

The prevalence of S. japonicum infections is high in wild mice in Shitai County, and there is a natural focus of schistosomiasis transmission in Shitai County.

[Sharing the WHO guideline on control and elimination of human schistosomiasis to achieve the goal of schistosomiasis elimination in China]

Currently, the national schistosomiasis control program of China is moving from transmission interruption to elimination, and there are multiple challenges during the stage moving towards the progression of schistosomiasis elimination, including a high difficulty in shrinking snail-infested areas, unstable achievements for infectious source control, imperfect surveillance system and a reduction in schistosomiasis control and administration. Based on the core suggestions proposed in the 2022 WHO guideline on control and elimination of human schistosomiasis, recommendations on schistosomiasis surveillance system building, development of novel diagnostics, adjustment of the schistosomiasis control strategy and maintaining and improvements of the schistosomiasis control capability are proposed for the national schistosomiasis control program of China in the new era according to the actual status of schistosomiasis control in China. Formulation of the national schistosomiasis control strategy and goal from One Health perspective, verification of transmission interruption and elimination of schistosomiasis, precision implementation of schistosomiasis control interventions with adaptations to local circumstances, development and application of highly sensitive and specific diagnostics are recommended for elimination of schistosomiasis in China. In addition, the implementation of the 2022 WHO guideline on control and elimination of human schistosomiasis may guide the elimination of schistosomiasis in China.

[Analysis of the new WHO guideline to accelerate the progress towards elimination of schistosomiasis in China]

On February 2022, WHO released the evidence-based guideline on control and elimination of human schistosomiasis, with aims to guide the elimination of schistosomiasis as a public health problem in disease-endemic countries by 2030 and promote the interruption of schistosomiasis transmission across the world. Based on the One Health concept, six evidence-based recommendations were proposed in this guideline. This article aims to analyze the feasibility of key aspects of this guideline in Chinese national schistosomiasis control program and illustrate the significance to guide the future actions for Chinese national schistosomiasis control program. Currently, the One Health concept has been embodied in the Chinese national schistosomiasis control program. Based on this new WHO guideline, the following recommendations are proposed for the national schistosomiasis control program of China: (1) improving the systematic framework building, facilitating the agreement of the cross-sectoral consensus, and building a high-level leadership group; (2) optimizing the current human and livestock treatments in the national schistosomiasis control program of China; (3) developing highly sensitive and specific diagnostics and the framework for verifying elimination of schistosomiasis; (4) accelerating the progress towards elimination of schistosomiasis and other parasitic diseases through integrating the national control programs for other parasitic diseases.

[Contribution to global implementation of WHO guideline on control and elimination of human schistosomiasis by learning successful experiences from the national schistosomiasis control program in China]

Schistosomiasis is a parasitic disease that seriously hinders socioeconomic developments and threatens public health security. To achieve the global elimination of schistosomiasis as a public health problem by 2030, WHO released the guideline on control and elimination of human schistosomiasis on February, 2022, with aims to provide evidence-based recommendations for schistosomiasis morbidity control, elimination of schistosomiasis as a public health problem, and ultimate interruption of schistosomiasis transmission in disease-endemic countries. Following concerted efforts for decades, great achievements have been obtained for schistosomiasis control in China where the disease was historically highly prevalent, and the country is moving towards schistosomiasis elimination. This article reviews the successful experiences from the national schistosmiasis control program in China, and summarizes their contributions to the formulation and implementation of the WHO guideline on control and elimination of human schistosomiasis. With the progress of the "Belt and Road" initiative, the world is looking forward to more China's solutions on schistosomiasis control.

[Association between polygenic risk score and age at onset of gastric cancer]

Objective: To explore the association between polygenic risk score (PRS) and age at onset and early-onset risk of gastric cancer (GC). Methods: Gastric cancer cases from existing genome-wide association study were included, and 112 single nucleotide polymorphisms associated with GC risk were used to derive individual PRS. Analysis of variance and Pearson correlation test was used to depict the relationship between PRS and GC onset age. Cases diagnosed before 50 years old were defined as early-onset gastric cancer. Cox proportional hazard model was used to test the association between PRS and early-onset GC risk with early-onset age as the timescale and low genetic risk (PRS ≤20%) as the reference group. Results: A total of 8 629 cases, including 6 284 males (72.82%) and 2 345 females (27.18%), were included, and the mean age was (60.61±10.80) years old. The PRS was negatively correlated with age of GC onset (r=-0.05, P<0.001). The mean age of gastric cancer cases with low, intermediate, and high genetic risk were (61.68±10.33), (60.53±10.79), (59.80±11.20), respectively. PRS was significantly associated with the risk of early-onset GC in a dose-response manner (intermediate genetic risk: HR=1.19, 95%CI: 1.03-1.39, P=0.022; high genetic risk: HR=1.44, 95%CI: 1.20-1.71, P<0.001). Conclusions: PRS may contribute to the risk of both GC and early-onset GC. PRS can be used as a measurable indicator for risk prediction for occurrence and early-onset of GC.

[Expert consensus on the strategy and measures to interrupt the transmission of schistosomiasis in China]

Since 2015 when the transmission of schistosomiasis was controlled in China, the country has been moving towards elimination of schistosomiasis, with the surveillance-response as the main interventions for schistosomiasis control. During the period of the 13th Five-Year Plan, the transmission of schistosomiasis had been interrupted in four provinces of Sichuan, Jiangsu, Yunnan and Hubei and the prevalence of schistosomiasis has been at the historically lowest level in China. As a consequence, the goal set in The 13th Five-Year National Schistosomiasis Control Program in China is almost achieved. However, there are multiple challenges during the stage moving towards elimination of schistosomiasis in China, including the widespread distribution of intermediate host snails and complicated snail habitats, many types of sources of Schistosoma japonicum infections and difficulty in management of bovines and sheep, unmet requirements for the current schistosomiasis control program with the currently available tools, and vulnerable control achievements. During the 14th Five-Year period, it is crucial to consolidate the schistosomiasis control achievements and gradually solve the above difficulties, and critical to provide the basis for achieving the ultimate goal of elimination of schistosomiasis in China. Based on the past experiences from the national schistosomiasis control program and the challenges for schistosomiasis elimination in China, an expert consensus has been reached pertaining to the objectives, control strategy and measures for The 14th Five-Year National Schistosomiasis Control Program in China, so as to provide insights in to the development of The 14th Five-Year National Schistosomiasis Control Program in China.

Surveillance-based evidence: elimination of schistosomiasis as a public health problem in the Peoples' Republic of China

BACKGROUND

A steady progress on schistosomiasis control in the Peoples' Republic of China (P.R. China) was achieved and broadened into the twelve-year medium and long term national plan (MLNP) which marled the implementation of an integrated control strategy across all endemic areas in P.R. China in 2004. To understand the endemic trends of schistosomiasis to assess the effectiveness of an integrated strategy, we conducted an analysis of schistosomiasis surveillance data spanned from 2005 to 2015.

METHODS

The schistosomiasis sentinel surveillance data from sentinel sites were collected and analyzed from 2005 to 2015. In these sentinel sites, residents aged 6 years or above were screened annually by indirect hemagglutination assay (IHA), while only antibody positives were followed by stool examination either Kato-katz method (KK) and/or hatching technique (HT). Domestic animals raised in sentinel sites were examined by HT for confirming the infection of schistosomes. Snail investigation was conducted each year through systematic sampling method combined with environmental sampling method. The snails collected from field were tested by microscopic dissection method. The infection rates of schistosomes in residents, domestic animals and snails, as well as the indicators reflecting the snails' distribution were calculated and analyzed. ANOVA analysis was used to examine the changes of the number of eggs per gram feces in population and Chi-square test was used to examine any change in proportions among groups.

RESULTS

A total of 148 902 residents from sentinel sites attended this study and 631 676 blood samples were examined by IHA test during the 11 covered years. The annual average antibody positive rates presented a significant decrease trends, from 17.48% (95% CI: 17.20-17.75%) in 2005 to 5.93% (95% CI: 5.71-6.15%) (χ2 = 8890.47, P < 0.001) in 2015. During 2005-2015, the average infection rate of schistosomes in residents declined from 2.07% (95% CI: 1.96-2.17%) to 0.13% (95% CI: 0.09-0.16%), accompanied by significant decrease of infection intensity in population. In 2015, the stool positives were only found in farmers, fishermen and boatmen with infection rate of 0.16% (95% CI: 0.11-0.20%), 0.17% (95% CI: 0-0.50%) respectively. The infection rate of schistosomes in domestic animals dropped from 9.42% (538/5711, 95% CI: 8.66-10.18%) to 0.08% (2/2360, 95% CI: 0-0.20%) from 2005 to 2015. Infections were found in eight species of domestic animals at the beginning of surveillance while only two cattle were infected in 2015. Totally 98 ha of new snail habitats were found, while 94.90% (93/98) distributed in lake and marshland regions. The percentage of frames with snails decreased from 16.96% (56 884/33 5391, 95% CI: 16.83-17.09%) in 2005 to 4.28% (18 121/423 755, 95% CI: 4.22-4.34%) in 2014, with a slightly increase in 2015. Meanwhile, the infection rate of schistosomes in snails was decreased from 0.26% (663/256 531, 95% CI: 0.24-0.28%) to zero during 2005-2015.

CONCLUSIONS

The infection rate of schistosomes declined significantly, providing evidence that the goal of the MLNP was achieved. Elimination of schistosomiasis as a public health problem defined as WHO was also reached in P.R. China nationwide. Surveillance-response system should be improved and strengthened to realize the final goal of schistosomiasis elimination.

Effects of laying breeder hens dietary β-carotene, curcumin, allicin, and sodium butyrate supplementation on the jejunal microbiota and immune response of their offspring chicks

Our long-term goal is to improve chick health and reduce the use of antibiotics in the poultry industry via maternal effects. To link jejunal microbes with chicks' different immune levels and growth performance in our previous research, this study investigated jejunal microbes, jejunal inflammation, and immune responses based on a comparison between different groups. Newly hatched Hy-Line chicks were allotted into 3 groups: a chick control group (cCON), a ciprofloxacin lactate treatment group (Cipro)—the chicks of the cCON and Cipro groups were hatched from laying breeder hens given a basal diet—and a 5-wk β-carotene, curcumin, allicin, and sodium butyrate supplementation group (cCCAB), wherein chicks hatched from laying breeder hens. All groups were fed the same diet for 4 wk; the Cipro group was given ciprofloxacin lactate in drinking water continuously. At the end of the experiment, the results demonstrated that the jejunal microbes of the Cipro group showed significant changes in alpha and beta diversity, and in taxonomy at phylum and genus levels. Statistically, a total of 67 significantly enriched (P < 0.05) taxa were identified between groups by linear discriminant analysis effect size; Firmicutes was significantly enriched (P < 0.05) in the cCCAB group, 65 taxa were significantly enriched (P < 0.05) in the Cipro group, and 32 of the 65 enriched (P < 0.05) taxa were in the Proteobacteria phylum of the Cipro group. Levels of lipopolysaccharide in jejunal content, and nuclear factor kappa-B, and tumor necrosis factor-α in jejunums of the Cipro and cCCAB groups were increased (all P < 0.05) compared to those in the cCON group. There was obvious neutrophil infiltration and upregulated (all P < 0.05) IL-6 mRNA in the Cipro group jejunums compared to the cCON and cCCAB groups. The expression of PSME3 and PSME4 genes was upregulated (all P < 0.05) in the cCCAB group compared to the cCON and Cipro groups. In conclusion, ciprofloxacin lactate administration led to potential hazards in health and growth in chicks via microbial disturbances-induced jejunal inflammation, and laying breeder hens dietary supplementation with β-carotene, curcumin, allicin, and sodium butyrate could enhance jejunal immunity of their offspring via the interaction between host innate immunity selected microbial colonization and microbiota educated adaptive immunity.

[Endemic situation of schistosomiasis in national surveillance sites of Anhui Province from 2015 to 2018]

OBJECTIVE

To analyze the endemic situation of schistosomiasis in national surveillance sites of Anhui Province from 2015 to 2018, so as to provide scientific evidence for schistosomiasis control and prevention in Anhui Province.

METHODS

According to the National Schistosomiasis Surveillance Programme (2014 version), a total of 51 national schistosomiasis surveillance sites were assigned in Anhui Province in 2015, and Schistosoma japonicum infections in humans and livestock and snail distribution were monitored from 2015 to 2018.

RESULTS

A total of 89 638 local residents and 42 609 mobile populations received serological screening of schistosomiasis in 51 national surveillance sites of Anhui Province from 2015 to 2018, and the sero-prevalence of S. japonicum infections was 1.41% to 3.69% in local residents and 0.84% to 2.13% in mobile populations, respectively. There were 5 egg-positive local residents and 1 egg-positive mobile populations detected in 2015, with occupations of farmers and fishermen. There were 6 405 livestock detected for S. japonicum infections, and no egg-positives were identified. Among an area of 12 661 hm² surveyed in the national schistosomiasis surveillance sites of Anhui Province from 2015 to 2018, the areas of snail habitats were 2 461.27 to 2 628.96 hm², andthemeandensityoflivingsnailswas 0.3757 to 0.4330 snails/0.1 m², with no S. japonicum infections identified in snails.

CONCLUSIONS

The endemic situation of schistosomiasis is at a low level in Anhui Province; however, the risk of schistosomiasis transmission remains in local regions of the province. The construction of the surveillance-responsesystemshouldbereinforcedtoconsolidatetheachievementsofschistosomiasis control in Anhui Province.

[Investigation on human hookworm infections in Anhui Province from 2014 to 2015]

OBJECTIVE

To understand the current status and changing tendency of human hookworm infections in Anhui Province.

METHODS

According to the unified national survey scheme, a total of 48 survey sites were sampled from 16 counties (cities) in 4 ecological regions of Anhui Province using a stratified cluster random sampling method from 2014 to 2015. The hookworm eggs were detected in the fecal samples from permanent residents at ages of over one year living in the survey sites using a modified Kato-Katz thick smear method, and the subjects'health knowledge and behaviors were investigated using questionnaire survey.

RESULTS

A total of 12 300 persons were examined in the 48 survey sites from 4 ecological regions of Anhui Province between 2014 and 2015, and 259 subjects were identified with hookworm infections, with a mean prevalence of 2.11%. Among the four ecological regions, the North China Plain had the highest prevalence of human hookworm infections (3.02%) and in all survey sites, Linquan County had the highest prevalence (7.03%). Ancylostoma duodenale was the predominant hookworm species identified (62.16%), and 65.64% had mild infections. The prevalence of human hookworm infections was significantly greater in women than in men (χ² = 4.16, P < 0.05), and showed a tendency towards a rise with ages (χ²_trend = 113.36, P < 0.01). In addition, the prevalence of human hookworm infections varied in occupations (χ² = 159.41, P < 0.01) and education levels (χ² = 34.95, P < 0.01). Questionnaire survey showed low prevalence of human hookworm infections in subjects knowing the question"how hookworm infection occurs"and denying"using fresh stools for fertilization"(χ² = 15.05, P < 0.01; χ² = 4.19, P < 0.05).

CONCLUSIONS

The prevalence of human hookworm infections has greatly decreased in Anhui Province; however, the prevalence remains relatively high in some regions and populations. The North China Plain should be regarded as the key area for hookworm disease prevention and control, and housewives and populations with advanced ages and low educational levels are key targeted populations in Anhui Province.

Spatio-temporal pattern of schistosomiasis in Anhui Province, East China: Potential effect of the Yangtze River - Huaihe River Water Transfer Project

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.

Population identification of Sarcoptes hominis and Sarcoptes canis in China using DNA sequences

There has been no consistent conclusion on whether Sarcoptes mites parasitizing in humans and animals are the same species. To identify Sarcoptes (S.) hominis and S. canis in China, gDNA was extracted from individual mites (five from patients with scabies and five from dogs with mange) for amplification of rDNA ITS2, mtDNA 16S, and cox1 fragment sequences. Then, the sequences obtained were aligned with those from different hosts and geographical locations retrieved from GenBank and sequence analyses were conducted. Phylogenetic trees based on 317-bp mtDNA cox1 showed five distinctive branches (species) of Sarcoptes mites, four for S. hominis (S. hominis Chinese, S. nr. hominis Chinese, S. hominis Australian, and S. hominis Panamanian) and one for S. animal (S. animal). S. animal included mites from nine animal species, with S. canis China, S. canis Australia, and S. canis USA clustering as a subbranch. Further sequence divergence analysis revealed no overlap between intraspecific (≤ 2.6 %) and interspecific (2.6-10.5 %) divergences in 317-bp mtDNA cox1. However, overlap was detected between intra- and interspecific divergences in 311-bp rDNA ITS2 or 275-bp mtDNA 16S when the divergences exceeded 1.0 %, which resulted in failure in identification of Sarcoptes. The results showed that the 317-bp mtDNA cox1 could be used as a DNA barcode for molecular identification of Sarcoptes mites. In addition, geographical isolation was observed between S. hominis Chinese, S. hominis Australian, and S. hominis Panamanian, but not between all S. canis. S. canis and the other S. animal belonged to the same species.

[The evidences for formulation of schistosomiasis control and elimination criteria: results from a large scale of retrospective investigations]

In this study, we summarized the results from the retrospective investigation on endemic situation of schistosomiasis that was implemented in nine provinces (autonomous region), China in 2009, demonstrated the role of these retrospective investigations in accelerating the progress of schistosomiasis control in China, and clarified the great significance of the investigation for summarizing the experiences for the control of schistosomiasis, and analyzing the changing patterns and affecting factors of endemic status of schistosomiasis in China. In addition, these retrospective investigations provide reliable evidence for revising the Criteria of Schistosomiasis Control and Elimination, and for the more accurate and scientific assessment of the effectiveness of schistosomiasis control in China.

HIV and intestinal parasite co-infections among a Chinese population: an immunological profile

BACKGROUND

Parasite infections often result in a switch of the human body's predominant immune reaction from T-helper 1 (Th1)-type to Th2-type. Hence, parasite infections are widely expected to accelerate the progression of human immunodeficiency virus (HIV) infections to acquired immunodeficiency syndrome (AIDS). In the People's Republic of China, both parasitic diseases and AIDS are epidemic in certain rural areas, and co-infections are relatively common. However, no population-based studies have yet investigated the frequency of HIV and parasite co-infections, and its effects on immune responses. We studied (1) the immune status of an HIV-infected population, and (2) the effect of co-infection of HIV and intestinal parasites on selected parameters of the human immune system.

METHODS

A total of 309 HIV-infected individuals were recruited and compared to an age-matched and sex-matched control group of 315 local HIV-negative individuals. Questionnaires were administered to all participants to obtain information on sociodemographic characteristics, sanitation habits, family income, and recent clinical manifestations. Two consecutive stool samples and 10 ml samples of venous blood were also collected from each individual for the diagnosis of parasite infections and quantitative measurements of selected cytokines and CD4+ T-lymphocytes, respectively.

RESULTS

During the study period, 79 HIV-infected individuals were not under highly active antiretroviral therapy (HAART) and were thus included in our analysis; the prevalence of intestinal helminth infections was 6.3% and that of protozoa was 22.8%. The most common protozoan infections were Blastocystis hominis (B. hominis) (13.9%) and Cryptosporidium spp. (10.1%). The prevalence of Cryptosporidium spp. in HIV-infected individuals was significantly higher than that in HIV negative individuals (P < 0.05). Compared to the non-co-infected population, no significant difference was found for any of the measured immunological indicators (P > 0.05). However, the following trends were observed: IFN-γ levels were lower, but the IL-4 level was higher, in the population co-infected with HIV and helminths. In the population co-infected with HIV and B. hominis, the IL-2 level was higher. The population co-infected with HIV and Cryptosporidium spp. had markedly lower CD4+ T-lymphocyte counts.

CONCLUSION

According to the immunologic profile, co-infection with helminths is disadvantageous to HIV-infected individuals. It was associated with a shift in the Th1/Th2 balance in the same direction as that caused by the virus itself, which might indicate an acceleration of the progress from an HIV infection to AIDS. Co-infection with Cryptosporidium spp. was not associated with a significant change in immune factors but co-infection with Cryptosporidium spp. was associated with a reduced level of CD4 + T-lymphocytes, confirming the opportunistic nature of such infections. Co-infection with B. hominis, on the other hand, was associated with an antagonistic shift in the immunological profile compared to an HIV infection.

Value of 3.0 T diffusion-weighted imaging in discriminating thecoma and fibrothecoma from other adnexal solid masses

Background

To investigate the value of diffusion-weighted imaging (DWI) at 3.0 T (3T), and especially the apparent diffusion coefficient (ADC), in discriminating ovarian thecoma from other adnexal solid masses.

Methods

Eighteen thecomas or fibrothecomas, 14 ligamentous leiomyomas, and 24 other ovarian solid tumors underwent prospective DWI magnetic resonance imaging (MRI) in addition to routine MRI on a 3T MRI machine. The baseline characteristics, components, and conventional MRI and DWI-MRI signals for the thecomas were recorded. The ADC values (ADCs) were measured for each group and compared.

Results

The thecomas often appeared as homogeneous isointensity (17/18) on T1-weighted images (T₁WI; 11/18) or T₂WI (11/18) on DWI-MRI, with minor (9/18) or mild (6/18) enhancement. The mean ADC value for thecoma (1.20 ± 0.45 × 10⁻³ mm²/s) was almost equal to that of the other solid ovarian masses (1.26 ± 0.51 × 10⁻³ mm²/s), but lower than that for leiomyoma (1.48 ± 0.42 × 10⁻³ mm²/s), although not significantly so. There was a significant difference (p = 0.043) in the ADCs of the benign ovarian solid masses (1.16 ± 0.47 × 10⁻³ mm²/s) and leiomyomas (1.48 ± 0.42 × 10⁻³ mm²/s).

Conclusions

There is no significant difference in ADC between thecoma and other adnexal solid masses, but the ADCs of thecomas are lower than those of leiomyomas.

[Study on assessing system for endemicity of schistosomiasis]

OBJECTIVE

To establish a scientific, objective and operational assessing system for schistosomiasis endemicity, so as to provide a scientific evidence for revising the current Criteria for Control and Elimination of Schistosomiasis in China (GB 15976-2006).

METHODS

A questionnaire was designed based on reference review and 20 scientists working in the field of schistosomiasis control, research or management were investigated by using the Delphi method. The importance of each index reflecting the endemicity of schistosomiasis was scored by each scientist. The assessing system for endemicity of schistosomiasis was established and the normalized weight and combined weight were calculated.

RESULTS

The assessing system included three indices in the first grade and seven indices in the second grade. Among the indices in the first grade, the normalized weights of infection status of human beings, infection status of livestock, and Oncomelania snail's status were 0.360 2, 0.335 2, and 0.304 6, respectively. Among the indices in the second grade, the prevalence of livestock showed the highest combined weight of 0.335 2 while the infection rate of snails showed the lowest score of 0.093 3.

CONCLUSIONS

The indexes of the assessing system for the endemicity of schistosomiasis established are reasonable, comprehensive, and authoritative, which provide the scientific evidence for revising the currently available Criteria for Control and Elimination of Schistosomiasis in China.

[Role of the new version of the Control and Elimination Criteria for Schistosomiasis in acceleration of the schistosomiasis elimination program in China]

Based on the historical background for revision of the Control and Elimination Criteria for Schistosomiasis for 6 times, and the role of the criteria in promotion of national schistosomiasis control program of China at various stages, the present study demonstrated the necessity of further revision of the control criteria in the current schistosomiasis elimination program. In addition, the background for revision of the novel version of the Control and Elimination Criteria for Schistosomiasis was illustrated based on literature review, retrospective survey, expert argumentation and index improvement.

[Research progress on transmission capacity of reservoir host of Schistosoma japonicum]

This paper reviews the researches related to the reservoir hosts of Schistosoma japonicum, including bovine, sheep, dog, cat and wild mouse. Combined with the implementation of the comprehensive control strategy with an emphasis on infection source control in current, it puts forward several future research directions under the condition that the effects of people and bovine as infection sources weakened gradually, such as revaluation on the actual transmission capacity of non-bovine livestock, for example, sheep, dog, pig and wild mouse, as well as discussion on some transmission threshold values in the infection link of Oncomelania snails.

[Progress of researches on diagnostic antigens of schistosomiasis japonica]

The development of immunodiagnosis makes important contributions to the control of schistosomiasis. The most common way of diagnosis is to detect unknown antibodies through the known antigens, those are divided into soluble antigens, purified antigens and recombinant antigens. The diagnostic antigens which have high-sensitivity and high-specificity, and have the value of early diagnosis become the focus of researches, and are studied by many scholars. This article reviews the progress of the reaearches on diagnostic antigens of schistosomiasis japonica in recent years.

[Survey on Blastocystis hominis infection in HIV positive individuals in Fuyang City, Anhui Province]

OBJECTIVE

To understand the epidemiological characteristics of co-infection of HIV and Blastocystis hominis and its risk factors.

METHODS

A total of 309 people with HIV positive in the development zone of Fuyang City were recruited, and the face to face questionnaires were conducted to collect the information of behavioral characteristics and sociodemographic data of the participants. Meanwhile, the samples of stool and blood were collected to test B. hominis, cytokines and CD4+/CD8+ T-lymphocyte. The influencing factors of co-infection of HIV and Blastocystis hominis were analyzed by the single factor analysis and Logistic regression analysis.

RESULTS

Among the 309 people involved, 302 accepted feces examinations, 286 accepted the questionnaire investigation, and 263 accepted both of them. The infection rate of B. hominis was 17.11%, that of the female was 21.90%, which was significantly higher than that of the male (11.90%) (P < 0.05). The results from the multivariate Logistic regression model showed that good nutrition was significantly associated with the co-infection of HIV and B. hominis (OR = 0.263, 95% CI: 0.073, 0.945).

CONCLUSIONS

The infection rate of B. hominis is high in people with HIV positive, and the nutrition situation of individuals may be one of the important risk factors associated with co-infection.

Co-infection of HIV and intestinal parasites in rural area of China

BACKGROUND

Intestinal parasite infections (IPIs) are among the most significant causes of illness and disease of socially and economically disadvantaged populations in developing countries, including rural areas of the People's Republic of China. With the spread of the human immunodeficiency virus (HIV) among rural Chinese populations, there is ample scope for co-infections and there have been increasing fears about their effects. However, hardly any relevant epidemiological studies have been carried out in the country. The aim of the present survey was to assess the IPI infection status among a representative sample of HIV-positive Chinese in rural Anhui province, and compare the findings with those from a cohort of non-infected individuals.

METHODS

A case control study was carried out in a rural village of Fuyang, Anhui province, China. Stool samples of all participants were examined for the presence of intestinal parasites. Blood examination was performed for the HIV infection detection and anemia test. A questionnaire was administered to all study participants.

RESULTS

A total of 302 HIV positive and 303 HIV negative individuals provided one stool sample for examination. The overall IPI prevalence of intestinal helminth infections among HIV positives was 4.3% (13/302) while it was 5.6% (17/303) among HIV negatives, a non-significant difference. The prevalence of protozoa infections among HIV positives was 23.2% while the rate was 25.8% among HIV negatives. The species-specific prevalences among HIV positives were as follows: 3.6% for hookworm, 0.7% for Trichuris trichiura, zero for Ascaris lumbricoides, 0.3% for Clonorchis sinensis, 1.3% for Giardia intestinalis, 16.2% for Blastocystis hominis, 1.7% for Entamoeba spp. and 8.3% for Cryptosporidium spp.. Cryptosporidium spp. infections were significantly more prevalent among HIV positives (8.3%) compared to the HIV negative group (3.0%; P < 0.05). Among people infected with HIV, Cryptosporidium spp. was significantly more prevalent among males (12.6%) than females (4.4%; P < 0.05). According to multivariate logistic regression, the factors significantly associated with parasite infections of the people who were HIV positive included sex (male: OR = 6.70, 95% CI: 2.030, 22.114), younger age (less than 42 years old: OR = 4.148, 95% CI: 1.348, 12.761), and poor personal hygiene habits (OR = 0.324, 95% CI: 0.105, 0.994).

CONCLUSIONS

HIV positive individuals are more susceptible to co-infections with Cryptosporidium spp. than HIV negative people, particularly younger males with poor personal hygiene habits, indicating a need for targeted hygiene promotion, IPI surveillance and treatment.

[Evaluation on the effect of comprehensive control strategy of schistosomiasis with emphasis on infection source control in Anhui province]

OBJECTIVE

To evaluate the effect of comprehensive control strategy of schistosomiasis with emphasis on infection source control in Anhui province.

METHODS

Forty endemic villages in Guichi district, Chizhou city, Anhui province were selected as national pilot villages in the years from 2006 to 2008, and another 10 provincial pilot villages were respectively selected from 10 highly endemic villages in 7 cities in 2007. The comprehensive infection source control measures, including "replace cattle with machines", "raise livestock in pens", "improve the sanitary toilets", "supply safe water " and so on were carried out among the above pilot villages. At the end of 2008, 13 national pilot villages and 6 provincial pilot villages were selected to investigate the popularity of schistosomiasis, and the effect of the comprehensive control strategy in those villages were compared.

RESULTS

After implementing the comprehensive control strategy, the infectious rate of schistosomiasis in national pilot villages decreased from 4.57% (487/10 659) to 1.76% (147/8370), with the reduction rate at 61.49%, whose difference showed statistical significance (χ(2) = 115.16, P < 0.01); and the density of infected snails decreased from 0.0067/0.1 m(2) to 0.0008/0.1 m(2), the infectious rate of snails decreased from 0.28% to 0.04%, whose reduction rates were 88.06% and 85.71% respectively. While as to the provincial pilot villages, the infectious rate of schistosomiasis decreased from 1.27% (54/4254) to 0.21% (14/6592), with the reduction rate at 83.46%, whose difference showed statistical significance (χ(2) = 94.57, P < 0.01); and the density of infected snails decreased from 0.0025/0.1 m(2) to 0.0003/0.1 m(2), the infection rate of snails decreased from 0.13% to 0.05%, whose reduction rates were 88.00% and 61.54% respectively.

CONCLUSION

The comprehensive control strategy with emphasis on infection source control implemented in marshland and lake regions can effectively control the transmission of schistosomiasis.

[Cross-section study on co-infection of HIV and Cryptosporidium]

OBJECTIVE

To investigate the co-infection status of HIV and Cryptosporidium, and explore the influencing factors associated with the co-infection.

METHODS

A total of 309 people with HIV positive in Fuyang City of Anhui Province were recruited and their fecal and blood samples were collected for examinations of Cryptosporidium spp. infection and the levels of hemoglobin, cytokines and CD4+/CD8+ T-lymphocytes. Meanwhile, the questionnaire survey was conducted.

RESULTS

Among 302 people involved in fecal examinations, the infection rate of Cryptosporidium spp. was 8.28%, and the difference between infection rates of the male (13.49%) and the female (2.92%) was statistically significant (P < 0.05). The multivariate logistic regression model showed that 4 factors were significantly associated with the coinfection of HIV and Cryptosporidium spp, including male (OR = 6.700, 95% CI: 2.030, 22.114), younger than 42 years old (OR = 4.148, 95% CI: 1.348, 12.761), level of IL-2 below 77 pg/ml (OR = 0.226, 95%CI: 0.076, 0.674) and personal hygiene habits (OR = 0.324, 95% CI: 0.105, 0.994).

CONCLUSION

The co-infection rate of Cryptosporidium spp. and HIV is high, the key targets of control are the people who are male, younger than 42 years old, with high level of IL2 and poor personal hygiene habits.

Tools to support policy decisions related to treatment strategies and surveillance of Schistosomiasis japonica towards elimination

Background

Appropriate diagnostics to monitor disease trends and assess the effectiveness and impact of interventions are essential for guiding treatment strategies at different thresholds of schistosomiasis transmission and for certifying elimination. Field validation of these assays is urgently needed before they can be adopted to support policy decisions of the national programme for control and elimination of schistosomiasis in P.R. China. We compared the efficacy and utility of different immunoassays in guiding control strategies and monitoring the endemic status of S. japonicum infections towards elimination.

Methodology/Principal Findings

A cross-sectional survey was conducted in seven villages with different transmission intensities settings to assess the performance and utility of three immunoassays, e.g., an indirect hemagglutination assay (IHA_JX), an enzyme linked immunosorbent assay (ELISA_SZ), and a dot immunogold filtration assay (DIGFA_SH). 6,248 individuals aged 6–65 years old who gave consent and supplied their stool and blood samples were included for data analysis. Results showed that ELISA_SZ performed significantly higher sensitivity (95.45%, 95%CI: 92.94–97.97%) than IHA_JX (87.59%, 95%CI: 83.51–91.49%) and DIGFA_SH (79.55%, 95%CI: 74.68–84.41%), especially in subgroups with very low infection intensity. The specificity of ELISA_SZ, IHA_JX, DIGFA_SH in 6–9 year olds with occasional exposure was nearly 90%. DIGFA_SH performed the highest screening efficacy for patients among three assays with overall positive predicative value of 13.07% (95%CI: 11.42–14.72%). We found a positive correlation of antibody positive rate of IHA_JX with results of stool examination in age strata (r = 0.70, P<0.001). Seropositivity of IHA_JX in children aged 6–9 years old showed an excellent correlation with prevalence of schistosome infection in the seven communities (r = 0.77, P<0.05).

Conclusions/Significance

Studies suggest that ELISA_SZ could be used to guide selective chemotherapy in moderate or low endemic regions. IHA_JX could be used to as a surveillance tool and for certifying elimination of schistosomiasis through monitoring children as a sentinel population.

Immunodiagnostic assays are widely applied in the field to control schistosomiasis in P.R. China as the prevalence and infection intensity of schistosome infections decrease. Field evaluations are urgently needed before they can be adopted to support policy decisions of the national programme for the control and elimination of schistosomiasis in P.R. China. We carried out a large scale cross-sectional survey in field settings with different transmission situations to validate immunodiagnostic tools that can be used to formulate new schistosomiasis elimination strategy in P.R. China. Regarding stool examination as gold reference, the validity and screening efficacy of each immunodiagnostic kit were calculated and compared with each other. The association of the prevalence of schistosomiasis and antibody positive rates determined by immunoassays were analyzed using Pearson's correlation coefficient values. The study indicates that which test to use with the elimination strategy is dependent on the purpose of testing, the endemic status of community and the resources available. And more sensitive methods need to be explored and used to target infected individuals for treatment or to eliminate schistosomiasis.

[Surveillance and forecast of schistosomiasis transmission in Chaohu Lake area in Anhui Province, 2008-2010]

OBJECTIVE

To understand the dynamic changes of the potential prevalent factors of schistosomiasis in Chaohu Lake area so as to provide forecast information on the outbreak of schistosomiasis in the area.

METHODS

From 2008 to 2010, fixed and mobile surveillance sites in potential endemic areas of Juchao District in Chaohu City, which was located in the southeast side of Chaohu Lake, were selected, and the schistosomiasis infection situation of local people, mobile population and livestock were investigated by immunological assays and/or stool examinations. The distribution of Oncomelania snails was surveyed in risk areas and suspicious areas, the spreading patterns of Oncomelania snails were observed in rivers that directly connected with the Yangtze River, and the Oncomelania snails were raised in the cages on the beaches of Chaohu Lake and a control area, and their survival and reproduction capacity was observed.

RESULTS

In 2008, a total of 301 local people were screened by IHA, and there were no positives. From 2008 to 2010, a total of 321, 362 and 306 mobile population were examined by IHA, respectively, and the positive rate of antibody were 3.74%, 4.97% and 2.94%, respectively. The antibody positives were tested by stool examinations, and the positive rates were 66.67%, 50% and 55.56%, respectively. A total of 91 local livestock and 92 livestock from endemic areas were examined respectively by the miracidium hatching method, and there were no positives. A total of 97.8 hm2 risk areas and 193.62 hm2 suspicious areas in the potential endemic area were surveyed respectively, but no Oncomelania snails were found. The investigation results on snail spreading patterns indicated that snails could spread into Chaohu Lake by adsorbing on floating debris. The field study revealed that Oncomelania snails could survive and reproduce in the Lake.

CONCLUSIONS

The imported infectious sources of schistosomiasis have been found in Chaohu Lake area, and the higher possibility of imported Oncomelania snails spreading into the Lake and surviving and reproducing in the lake is predicted. Therefore, effective measures should be taken to decrease the risks of schistosomiasis transmission in the potential endemic area.

Genetic diversity of Schistosoma japonicum miracidia from individual rodent hosts

Schistosoma japonicum is an important parasite in terms of clinical, veterinary and socio-economic impacts, and rodents, a long neglected reservoir for the parasite, have recently been found to act as reservoir hosts in some endemic areas of China. Any difference in the host's biological characteristics and/or associated living habitats among rodents may result in different environments for parasites, possibly resulting in a specific population structure of parasites within hosts. Therefore knowledge of the genetic structure of parasites within individual rodents could improve our understanding of transmission dynamics and hence our ability to develop effective control strategies. In this study, we aimed to describe a host-specific structure for S. japonicum and its potential influencing factors. The results showed a significant genetic differentiation among hosts. Two factors, including sampling seasons and the number of miracidia genotyped per host, showed an effect on the genetic diversity of an infrapopulation through a univariable analysis but not a multivariable analysis. A possible scenario of clustered infection foci and the fact of multiple definitive host species, the latter of which is unique to S. japonicum compared with other schistosomes, were proposed to explain the observed results and practical implications for control strategies are recommended.

Toward sustainable and comprehensive control of schistosomiasis in China: lessons from Sichuan

Triggered by a fascinating publication in the New England Journal of Medicine detailing China's new multi-pronged strategy to control and eventually interrupt the transmission of Schistosoma japonicum, this PLoS Neglected Tropical Diseases Debate critically examines the generalizability and financial costs of the studies presented from the marshlands of the lake region. Edmund Seto from the University of California and colleagues emphasize that the epidemiology and control of schistosomiasis varies according to the social-ecological context. They conjecture that the successful intervention packages piloted in the lake region is not fully fit for the hilly and mountainous environments in Sichuan and Yunnan provinces, and hence call for more flexible, setting-specific, and less expensive control strategies. In response, Xiao-Nong Zhou from the National Institute of Parasitic Diseases at the Chinese Center of Disease Control and Prevention and colleagues explain the steps from designing pilot studies to the articulation and implementation of a new national control strategy through a careful process of scaling-up and adaptations. Finally, the two opponents converge. The need for integrated, intersectoral, and setting-specific control measures is stressed, supported by rigorous surveillance and continuous research. Experiences and lessons from China are important for shaping the schistosomiasis elimination agenda.

[Retrospective investigation on national endemic situation of schistosomiasis. III. Changes of endemic situation in endemic rebounded counties after transmission of schistosomiasis under control or interruption]

OBJECTIVE

To analyze the changes of schistosomiasis endemic situation before and after reaching the criteria of schistosomiasis transmission control or transmission interruption in endemic rebounded areas, so as to offer the information for modifying the criteria of schistosomiasis control and elimination, and consolidating achievements of schistosomiasis control in People's Republic of China.

METHODS

Twelve counties with endemic rebound were selected from seven endemic provinces and investigated with the retrospective research method. The data including the epidemic information and relative materials 10 years before the counties reached the criteria of transmission control and several years later (until 2008 or 2009) were collected. The changes of epidemic situation of these counties before and after the transmission was under control or interrupted, and the factors causing the endemic rebound were analyzed.

RESULTS

Counties consolidated the endemic situations with an average time of 5 +/- 3 years after the transmission control, with endemic rebound normally caused by single factor. The ratio of Oncomelania snail areas to historically accumulative snail areas increased over 10% in hilly endemic regions and lake endemic regions in 7 and 12 years separately, while it was stabilized in a low level in water-network endemic areas. The rebound peak time of infected snail densities was consistent with or later than that of densities of living snails. The prevalence of schistosome infection in humans in lake endemic regions rebounded 2 years after transmission under control. The transmission interruption counties consolidated the endemic situations with an average time of 7 +/- 4 years. The human prevalence of schistosome infection decreased to a very low level after the counties reaching the criteria of transmission interruption. The snail areas increased to over 2% of historically accumulative snail areas 3-6 years after transmission interruption in lake, water-network endemic areas successively, while densities of living snails and infected snails were increased at the same year or 2-3 years later.

CONCLUSIONS

The endemic rebound in regions after the transmission under control or interrupted is caused by biological, natural and social factors and mainly presents as the rebound of snail status. The modification of criteria for schistosomiasis control and elimination should consider the influence of variation of snails, snail areas and density of infected snails on endemic situations in different endemic areas comprehensively. Sensitive and valid surveillance and forewarning system should be established to strengthen the monitoring and consolidating endemic situation in endemic areas after the transmission under control or interrupted.

[Susceptibilities of Oncomelania hupensis snails to Schistosoma japonicum miracidia from different hosts]

OBJECTIVE

To understand the susceptibilities of Oncomelania hupensis snails to Schistosoma japonicum miracidia from different hosts.

METHODS

The Schistosoma japonicum eggs from different hosts, such as rabbits, cattle and mice were collected. These eggs were incubated for miracidia, respectively. Each snail from the same site was exposed to 5 miracidia of Schistosoma japonicum from different hosts. The infected snails were fed in the laboratory for two months. Then all the snails were dissected and observed under the dissecting microscope in order to know the infection rate of snails.

RESULTS

In the experiment group, the infection rates of snails infected with miracidia from rabbits, cattle and mice were 1.42%, 8.67% and 19.87%, respectively, the mortality rates were 29.5%, 13.5% and 24.5%, respectively. However, the infection rates of snails in the control group were 2.63%, 2.02% and 11.66%, respectively, and the mortality rates were 24.0%, 49.5% and 18.5%, respectively.

CONCLUSION

The susceptibilities of Oncomelania snails to Schistosoma japonicum miracidia from 3 kinds of hosts are significantly different.

[Evaluation of mid-term effectiveness of medium-and-long-term programme for prevention and control of schistosomiasis in Anhui Province]

OBJECTIVE

To evaluate the mid-term effectiveness of the medium-and-long-term programme for prevention and control of schistosomiasis in Anhui Province.

METHODS

In the programme, the comprehensive measures were carried out, including the schistosomiasis detection and chemotherapy for residents and livestock, snail control, health education, and infectious source control. The mid-term effectiveness of the programme was observed and evaluated longitudinally.

RESULTS

From 2004 to 2009, 750 798 schistosomiasis patients and 547 069 persons with the history of infested water contacting were treated. The number of positive cattle treated was 8 462 cattle-times and the number of cattle with history of infested water contact treated was 117 023 cattle-times. The area with snails control by molluscicides was 30 532.0 hm2, and the area with snails control by environmental modification was 13 979.5 hm2. The number of persons who received health education was 31.73 million person-times. The infectious source control measures were carried out in 40% of endemic villages with human infection rate being more than 1%. Up to 2009, the infection rates of population and cattle, and the incidence rate of acute schistosomiasis reduced to 0.51%, 1.25% and 0.30/100 000, respectively. During the period of 2004-2009, the areas with snails fluctuated from 29 065.4 to 29 740.3 hm2. The densities of living snails and infected snails both showed a declining trend in general. During these years, the whole province reached the criteria of infection control, 4 counties reached the criteria of transmission control, and 4 counties reached the criteria of transmission interruption.

CONCLUSION

The effect of the comprehensive strategy of schistosomiasis control is remarkable.

[Retrospective investigation on national endemic situation of schistosomiasis. II. Analysis of changes of endemic situation in transmission-controlled counties]

OBJECTIVE

To summarize and analyze the process of the changes of schistosomiasis infection and Oncomelania snails in schistosomiasis transmission-controlled areas to explore the rules of the impact of changes of snail indexes on human infection before and after the stage of transmission control, so as to provide the evidence for editing snail indexes in the schistosomiasis controlled criterion and a more scientific, standardized control assessment and evaluation.

METHODS

Twenty-one schistosomiasis transmission-controlled or transmission-interrupted counties in lake endemic areas and hilly endemic areas in 8 provinces were selected and investigated retrospectively to collect schistosomiasis epidemiological information 10 years before these counties reached the criterion of transmission control and the subsequent years until 2008 or 2009. A " Standard county schistosomiasis epidemic survey data review software" was developed to establish a national epidemic retrospectively database; the trends of changes of snail status, infected snail status and human infection status were analyzed in different years. The trends and rules of the changes of snail areas, emerging snail areas, living snail densities, infected snail densities, snail infection rates and human infection rates were analyzed and compared before and after the counties reached the schistosomiasis transmission-controlled criterion in different types of endemic areas.

RESULTS

Before the transmission control, the human infection rate presented a declining trend in endemic areas. In lake endemic areas, the human infection rate declined to below 5% 4 years before the transmission control; in hilly endemic areas, the human infection rate declined to below 3% 8 years before the transmission control, and the human infection rates of the lake and hilly endemic areas declined to 2.10% and 1.45%, respectively, at the year of transmission control. However, 3 to 4 years after transmission control, the disease began to rebound, especially in lake endemic areas. The snail areas and snail densities declined year by year 10 years before the transmission control in the lake and hilly endemic areas, and the proportion of snail areas occupying the historic snail areas declined the lowest, being 2.75% and 0.55%, respectively, at the year of transmission control. The average densities of living snails kept a low level from 3-4 years before the transmission control to 9-10 years after the transmission control, and then rebounded. The new snail areas appeared 6-7 years after the transmission control and the snail areas and densities of living snails rebounded 9-12 years after the transmission control.

CONCLUSIONS

The snail status can maintain a relatively low level during about 10 years after the transmission control in the lake and hilly schistosomiasis endemic areas, but the schistosomiasis status rebounded 5 years after the transmission control. While the comprehensive measures mainly including infectious source controlled are implemented, the snail surveillance and control should be still strengthened, and it is recommended that "the proportion of snail areas decreased" and "the control of infected snails" would be the indicators of the criterion of schistosomiasis transmission control.

[Efficacy of tribendimdine in treatment of hookworm infection]

OBJECTIVE

To study the efficacy of tribendimdine in the treatment of hookworm infection.

METHODS

Forty-seven cases of hookworm infection detected in a cross-sectional study were selected and randomly divided into two groups, one was experimental group (23 cases) treated with tribendimdine and the other was control group (24 cases) treated with albendazole. The negative conversion rates and the incidence rates of adverse effects in the two groups were observed and compared.

RESULTS

The negative conversion rates and the incidence rates of adverse effects of the two groups were 95.65% and 95.83%, 8.70% and 8.33%, respectively, there were no statistical differences (both P values > 0.05).

CONCLUSION

The efficacy of tribendimdine in the treatment of hookworm infection is similar to albendazole.

[Spatial analysis of distribution of schistosomiasis in Anhui Province]

OBJECTIVE

To study the distribution of schistosomiasis in Anhui Province based on geographic information system (GIS).

METHODS

The survey data of disease and Oncomelania snails in Anhui Province in 2006 were collected, GIS databases were set up, and the inverse distance weighted interpolation method (IDW) based on ArcGIS 9.3 was used to analyze the spatial distribution of schistosomiasis across the province.

RESULTS

The simulated maps of distribution of human prevalence and positive rate of serological tests were imitated by using IDW. The region with heavier infection rates of schistosomiasis was distributed over the region of the Yangtze River in Anhui Province, and the endemic areas were joined into a patch in the upper and middle reaches and distributed in pieces in the lower reaches. While the endemic areas were compared with the distribution of infected snails, the IDW map of positive rate of serological tests was more exactly than that of the human prevalence.

CONCLUSIONS

The IDW method is helpful to show the distribution of schistosomiasis. The positive rate of serological tests is more sensitive to reflect the current endemic situation of schistosomiasis in Anhui Province.

[Effect of project of afforestation for schistosomiasis prevention on snail control in marshland and lake regions]

OBJECTIVE

To evaluate the effect of the project of afforestation for schistosomiasis prevention on Oncomelania hupensis control.

METHODS

The situation of afforestation for schistosomiasis prevention in the field and the snail distribution in marshland regions were surveyed with the systematic sampling method in the spring, 2009. The database of snail distribution was established and the status of afforestation was investigated, and the effect of the project on snail control was evaluated.

RESULTS

The rates of frames with living snails in the environment with plantations and the environment without a plantation were 14.9% and 19.7%, respectively, and there was a significant difference (Chi2 = 2 267, P < 0.01). The rate of frames with living snails in agroforestry model was lower than that in other models except for fishery-husbandry-forestry model. The average densities of living snails in the environment with plantations and the environment without a plantation were 0.552 snails/0.1 m2 and 0. 989 snails/0.1 m2, respectively. The average densities of living snails in the cultivating group and un-cultivating group were 0.354 snails/0.1 m2 and 0.653 snails/0.1 m2, respectively. The rate of frames with living snails and the average density of living snails were the lowest in the environment of long-term afforestation.

CONCLUSIONS

The project of afforestation for schistosomiasis prevention has a good effect on snail control in Anhui Province. Long-term afforestation could stably maintain the effect on snail control.

[Retrospective investigation on national endemic situation of schistosomiasis I analysis of changes of endemic situation in transmission-interrupted counties]

OBJECTIVE

To analyze the changing rules of schistosomiasis endemic situation in the area of transmission that has been interrupted before and after they reach the criteria of transmission interruption, so as to offer the basis of amending to the criteria of schistosomiasis transmission interruption and a more scientific, standardized assessment and evaluation of the effects of schistosomiasis control in the future.

METHODS

Nineteen counties of transmission that has been interrupted in 9 provinces nationwide were selected and investigated with the retrospective research method to collect and record the endemic detailed data 10 years before they reach the criteria of transmission interruption and several years later (ended in 2008 or 2009) and then a database was established. The changing rules of various disease indices in different endemic areas before and after reaching the criteria of transmission interruption were analyzed and compared.

RESULTS

The average time from the transmission control to the transmission interruption was 17 years in the 17 counties. After reaching the criteria of transmission interruption, the infection rates of people turned down to a minimum level in various endemic areas, the infection rates in a few numbers of lake endemic areas and hilly endemic areas increased slightly after the transmission interruption 4-9 years later, but all of them were below 1%. The densities of living Oncomelania snails in lake endemic areas and water-network endemic areas were high and the changes were great each year, and the densities of living snails were much lower in hilly endemic areas than in the above two types of areas and they came to the lowest 4 years before and after the transmission interruption. The infected snails appeared occasionally in lake endemic areas, and they recurred 6 years and 10 years after the transmission interruption in water-network endemic areas and hilly endemic areas, respectively. The continued time without infected snails found before reaching transmission interruption was 2.71 +/- 1.10 years averagely in transmission-interrupted counties with endemic stable, and was 3. 80 +/- 1.43 years in lake endemic areas.

CONCLUSIONS

It is possible to maintain a low level of population schistosome infection, and the endemic rebound is shown as snail rebound after the endemic areas reach the criteria of transmission interruption, The infected snails could be the comprehensive index reflecting the control achievement and the risk of schistosomiasis transmission. So the persistent control of infected snails is the fundament of schistosomiasis transmission interruption. It is suggested that in our current social and economic development and science and technology capacity conditions, the status of no infected snails found continuously for 5 years would be one of the criteria of schistosomiasis transmission interruption.

[Scientific research priority and prospect of schistosomiasis during the 12th five-year plan period in China]

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.

[Control strategy of schistosomiasis and key points in the 12th Five-Year Plan in China]

Based on the objective of long- and mid-term development program for schistosomiasis control in China, the paper presents an analysis of strategy for schistosomiasis control and its function in the 12th Five-Year Plan. Meanwhile, the strategy and key elements of schistosomiasis control for recent years are put forward for different endemic areas.

[Current endemic situation and control strategy of schistosomiasis in lake and marshland regions in China]

This paper reviewed the current endemic features and situation of schistosomiasis in lake and marshland regions in China, and discussed the comprehensive control strategy for schistosomiasis with emphasis on infectious sources control, including its theoretical basis, the reality conditions of implementation and technical composition, and also introduced the effectiveness of the pilot trails and their large-scale application as well as several issues in the implementation. The aim of the review is to accelerate the process of schistosomiasis control in lake and marshland regions and promote the achievement of mid- and long-term goals in national schistosomiasis control program.

Detection of early and single infections of Schistosoma japonicum in the intermediate host snail, Oncomelania hupensis, by PCR and loop-mediated isothermal amplification (LAMP) assay

Polymerase chain reaction (PCR) with the specific primer set amplifying 28S ribosomal DNA (rDNA) of Schistosoma japonicum was able to detect genomic DNA of S. japonicum, but not S. mansoni, at 100 fg. This procedure enabled us to detect the DNA from a single miracidium and a snail infected with one miracidium at just 1 day after infection. We compared these results with those from loop-mediated isothermal amplification (LAMP) targeting 28S rDNA and found similar results. The LAMP could amplify the specific DNA from a group of 100 normal snails mixed with one infected snail A PCR screening of infected snails from endemic regions in Anhui Province revealed schistosomal DNA even in snails found negative by microscopy. PCR and LAMP show promise for monitoring the early infection rate in snails, and they may be useful for predicting the risk of infection in the endemic places.

Transmission of Schistosoma japonicum in marshland and hilly regions of China: parasite population genetic and sibship structure

The transmission dynamics of Schistosoma japonicum remain poorly understood, as over forty species of mammals are suspected of serving as reservoir hosts. However, knowledge of the population genetic structure and of the full-sibship structuring of parasites at two larval stages will be useful in defining and tracking the transmission pattern between intermediate and definitive hosts. S. japonicum larvae were therefore collected in three marshland and three hilly villages in Anhui Province of China across three time points: April and September-October 2006, and April 2007, and then genotyped with six microsatellite markers. Results from the population genetic and sibling relationship analyses of the parasites across two larval stages demonstrated that, within the marshland, parasites from cattle showed higher genetic diversity than from other species; whereas within the hilly region, parasites from dogs and humans displayed higher genetic diversity than those from rodents. Both the extent of gene flow and the estimated proportion of full-sib relationships of parasites between two larval stages indicated that the cercariae identified within intermediate hosts in the marshlands mostly came from cattle, whereas in the hilly areas, they were varied between villages, coming primarily from rodents, dogs or humans. Such results suggest a different transmission process within the hilly region from within the marshlands. Moreover, this is the first time that the sibling relationship analysis was applied to the transmission dynamics for S. japonicum.

Schistosoma japonicum involves two obligatory host stages, with asexual reproduction within a molluscan host and sexual reproduction within a mammalian host. Having over 40 species of mammals suspected of being potential reservoirs complicates the transmission patterns. Understanding the complex transmission patterns is further hampered by the ethical and logistical difficulty in sampling adult worms from mammalian hosts. However, the two free-swimming larval stages, cercariae (released from a mollusc and then infective to a mammal) and miracidia (hatched from eggs passed in a mammal's faeces, and then infective to a mollusc), are available, and elucidating the genetic composition of parasites at theses two stages could provide information of infection processes. Here we sampled cercariae during April 2006, miracidia during September-October 2006, and cercariae during April 2007 in three marshland and three hilly villages in Anhui Province of China, and, using microsatellite markers, analyzed the population genetic structure and, for the first time, the familial relationships of parasites at different stages. We found contrasting population structures of parasites, and host species-associated diversities and transmission patterns of parasites between and within two regions. Moreover, we demonstrate that the successful application of sibship analyses to infection process provides an alternative approach to the dissection of transmission dynamics.

China's new strategy to block Schistosoma japonicum transmission: experiences and impact beyond schistosomiasis

Despite sustained efforts for its control made over the past 50+ years, the re-emergence of schistosomiasis in China was noted around the turn of the new millennium. Consequently, a new integrated strategy was proposed to stop the contamination of schistosome eggs to the environment, which emphasizes health education, access to clean water and adequate sanitation, mechanization of agriculture and fencing of water buffaloes, along with chemotherapy. Validation of this integrated control strategy in four pilot counties in the provinces of Anhui, Hubei, Hunan and Jiangxi revealed significant reductions in the rate of Schistosoma japonicum infection in humans and intermediate host snails. Importantly, this strategy showed an impact on diseases beyond schistosomiasis, signified by concomitant reductions in the prevalence of soil-transmitted helminth infections. In view of China's new integrated strategy for transmission control of schistosomiasis showing an ancillary benefit on other helminthic diseases, we encourage others to investigate the scope and limits of integrated control of neglected tropical diseases.

Parasite genetic differentiation by habitat type and host species: molecular epidemiology of Schistosoma japonicum in hilly and marshland areas of Anhui Province, China

Schistosoma japonicum, a parasite of significant public health importance in parts of China and Southeast Asia, is a true generalist pathogen with over 40 species of mammals suspected as definitive host reservoirs. In order to characterize levels of parasite gene flow across host species and identify the most important zoonotic reservoirs, S. japonicum larvae (miracidia) were sampled from a range of definitive host species in two contrasting habitat types within Anhui Province, China: a low-lying marshland region, and a hilly region, where animal reservoir populations may be predicted to differ substantially. Miracidia samples were genotyped using seven multiplexed microsatellite markers. Hierarchical F-statistics and clustering analyses revealed substantial geographical structuring of S. japonicum populations within Anhui, with strong parasite genetic differentiation between habitat types. Within most villages, there was very little or no parasite genetic differentiation among host species, suggesting frequent S. japonicum gene flow, and thus also transmission, across species. Moreover, the data provide novel molecular evidence that rodents and dogs are potentially very important infection reservoirs in hilly regions, in contrast to bovines in the marshland regions. The parasite genetic differentiation between habitat types might therefore be associated with contrasting host reservoirs. The high levels of parasite gene flow observed across host species in sympatric areas have important implications for S. japonicum control, particularly in hilly regions where control of infection among wild rodent populations could be challenging.

[A case-control study on the risk factors of cerebral schistosomiasis japonica]

OBJECTIVE

To explore the risk factors of cerebral schistosomiasis japonica.

METHODS

A total of 37 confirmed cases, diagnosed during 1999-2004 in Anhui Province, were involved in the study as case group. Three controls for each case were selected from the general population either without schistosomiasis, with chronic schistosomiasis or with acute schistosomiasis. The relevant risk factors on the disease were analyzed.

RESULTS

Four factors with labour intensity, physical, economical and nutritional conditions before illness between case group and normal control group, 7 factors including epilepsy history, hypersensitivity, intensity and times of infection between case group and acute schistosomiasis control group, 10 factors including intensity of infection, times of infection and treatment between case group and chronic schistosomiasis control group, all showed statistical significance (p < 0.05) . Five factors showed statistical significance (p < 0.05) between case group and the 3 control groups.

CONCLUSION

The intensity of schistosome infection and treatment history are the main risk factors for cerebral schistosomiasis, and the physical and psychosocial conditions of the patients show some effect on the disease.

[Schistosomiasis transmission in areas where inhabitants migrated from outside embankment to new settlement]

OBJECTIVE

To observe the impact on the transmission of schistosomiasis in areas where the local inhabitants migrated from outside embankment to new settlements.

METHODS

Two villages (Chenqiao and Qingjie) where the inhabitants had moved out and another 2 villages (Jiangzhou and Xiaohuang) disused for both inhabitants and cultivated land were selected for the investigation. Data on prevalence in human and domestic animals, and Oncomelania snail habitats, were collected.

RESULTS

After moving from outside embankment to new settlements, the density of infested snails in Chenqiao and Qingjie decreased by 79.1% and 45.2% in 2005 compared with that in 2002, and the infection rate of snails decreased by 75.5% and 84.9%, respectively (P < 001). In Jiangzhou and Xiauhuang, the density of infested snails decreased by 100% and 74.9% in 2005 compared with that in 2002, and the infection rate of snails decreased by 100% and 40.0%, respectively (P > 0.05). In villages that only disused for inhabitants, the density and egg-positive rate of feces collected from the wild were higher than the other 2 villages. However, in villages disused for both inhabitants and cultivated land, the density and egg-positive rate of wild feces decreased gradually and no egg-positive feces was found in 2005. The prevalence of schistosomiasis in humans in villages disused only for inhabitants changed slightly from 2002 to 2005, but decreased gradually in villages disused for both inhabitants and cultivated land. Higher prevalence in cattle was found in villages disused only for inhabitants. Number of cattle reduced yearly and no cattle left in villages disused for both inhabitants and cultivated land in 2005.

CONCLUSION

No significant change on the factors of schistosomiasis transmission has been found in villages disused only for inhabitants, but the transmission has been effectively controlled in villages disused for both inhabitants and cultivated land.