Modulation of in vivo granuloma formation related to regulation of in vitro IFN-gamma and IL-4 expressions in experimental schistosomiasis japonica.
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OBJECTIVE: To find out relationship between the in vitro schistosome egg antigen (SEA) stimulated IFN-gamma and IL-4 mRNA expressions and the in vivo SEA elicited granulomatous responses, the transcriptions of IFN-gamma and IL-4 gene were investigated in the spleen of BALB/c mice infected with Schistosoma japonicum (S. japonicum). METHODS: Spleens were removed at 0, 3, 5, 8, and 10 and 12 weeks after infection and the spleen cells were incubated in the presence of SEA. The extracted RNA was analyzed for IFN-gamma and IL-4 mRNA by reverse transcription PCR (RT-PCR). Newly-formed liver granulomas were measured. RESULTS: The study revealed that no detectable IFN-gamma and IL-4 mRNA RT-PCR products were found in SEA treated spleen cells from uninfected, or 3-week infected mice, whereas IL-4 mRNA was found to be expressed in 5- and 8-week infected mice, and an appreciable enhanced expression of IL-4 mRNA was observed in SEA stimulated spleen cells at 8-week infection than at 5-week infections. However, SEA could not induce IFN-gamma and IL-4 mRNA transcription in 10- and 12-week infected mice, indicating the modulated expression of IFN-gamma and IL-4 mRNA. CONCLUSION: The significant changes of IL-4 mRNA expression in SEA stimulated spleen cells during S. japonicum infection were coincident with SEA elicited granuloma formation and modulation in vivo. (+info)
A baseline study on the importance of bovines for human Schistosoma japonicum infection around Poyang Lake, China.
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We hypothesize that bovine infections are responsible for the persistence of human schistosomiasis transmission in the Yangtze marshlands of China. To test this hypothesis, we are carrying out a comparative intervention among four administrative villages in the Poyang Lake region, Jiangxi Province, two of which are experimental and two are control. The primary design involves treating, at the onset of the study, all the inhabitants in all four villages with praziquantel and all the bovines in two villages (the experimental or intervention villages). Following treatment, rates of reinfection in people of all villages, and in bovines in the experimental villages, will be assessed as will the ongoing prevalence of infection in bovines in the control villages. Before treatment, the prevalence and intensity of infection among humans and bovines was ascertained in the four villages. Our study design and baseline information are presented here, along with a description of the ecology of the study villages. (+info)
Progress in schistosomiasis control in China.
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PURPOSE: To briefly review schistosomiasis situation in the past, progress in the control program and problems to be solved. DATA SOURCES: Data from literature published at home and abroad on the control and research of schistosomiasis in China in biomedical journals and monographs, and a few data from the Office of Endemic Diseases Control, Ministry of Health, are collected. STUDY SELECTION: Information on this topic are screened and the important ones are selected. RESULTS: Schistosomiasis in China was serious. Through hard work for control for half decade, great progress has been achieved after implementation of the control program. Control approaches are introduced. Compared with data in the early 1950s, endemic provinces decreased from 12 to 5, infected persons, from more than 10 million to around 865,000, and the areas of Oncomelania snail habitats, from 14 billion m2 to 3.6 billion m2. Proportion of symptomatic patients among those infected has a significant reduction. The national criteria for control and elimination of schistosomiasis in China are introduced. CONCLUSIONS: The achievements of schistosomiasis control are tremendous but the tasks in China are arduous. Especially after last year's heavy flood, areas of snail habitats are increasing. To consolidate the success and to put the still endemic areas under control are long-term and arduous tasks confronting China. (+info)
Cloning, expression and immunization of the new antigen gene Sj-Ts4 of Schistosoma japonicum.
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In order to explore the molecular mechanism of high immune protection against schistosomes infection in animals infected with Trichinella spiralis, and to provide several cross-protective antigen genes for developing anti-schistosomiasis vaccine, a Schistosoma japonicum adult worm cDNA library was immunoscreened using sera taken from mice infected with Trichinella spiralis. Nine positive clones were obtained after 3 rounds of immunoscreening. Among them, Sj-Ts4 represents a novel gene of S. japonicum, which coding for a novel protein of 210 amino acids. The protein has a deduced molecular mass of 23 kD and isoelectric point of 7.72. Sj-Ts4 was expressed as a glutathione-S-transferase (GST) fusion protein by cloning into the prokaryotic expression vector pGEX-5X-3. The recombinant Sj-Ts4 protein (rSj-Ts4) was purified and could be recognized by sera of mice infected with S.japonicum. Vaccination of several groups of mice with rSj-Ts4 or rSj-Ts4 incorporated into Freund's complete adjuvant induced high titers of specific IgG antibodies. Two vaccination groups all obtained significant reduction in worm burden (31.36%, 36.80%, P<0.01), compared with the control groups. (+info)
A baseline study of importance of bovines for human Schistosoma japonicum infections around Poyang Lake, China: villages studied and snail sampling strategy.
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An epidemiologic survey among four administrative villages around Poyang Lake, in Jiangxi Province, China (two experimental and two controls) is being conducted to determine if bovine infections are responsible for the persistence of human schistosomiasis transmission on Yangtze River marshlands. A previously published paper presented the experimental design and baseline data for humans and bovines. This paper presents basic data for the four villages using remote sensing, and baseline data for snails that includes geographic information systems and remote sensing technology to classify the areas of bovine grazing ranges and habitats suitable for snails. A new method for sampling Oncomelania snails in China is used to determine the distribution, density, and infection rates of snails throughout the grazing ranges from season to season over a four-year period. Hypothetically, treating bovines should reduce infection rates in snails to below the critical number necessary to maintain infections in man and bovines. (+info)
Down-regulation of specific antigen-driven cytokine production in a population with endemic Schistosoma japonicum infection.
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Schistosome antigen-driven cytokine responses and antischistosome antibody levels of residents of a Schistosoma japonicum endemic island in Poyang Lake, Jiangxi Province were studied before and 45 days after treatment with praziquantel. IL-4, IL-5, IL-10 and INF-gamma were all detected in the supernatants of whole-blood cultures after stimulation with schistosome soluble egg antigen (SEA) and soluble worm antigen preparation (SWAP). The percentages of subjects producing detectable amounts of each cytokine assayed were higher in the group who were negative by stool examination at the start of the study than in those who were initially stool positive. After praziquantel treatment the percentages of subjects producing both type I and type II cytokines increased. This suggests that the production of both types of cytokine was down-regulated in the presence of live, egg-laying S. japonicum adult worms but that this was reversible by treatment. In contrast, the antibody studies showed higher levels of SWAP and SEA-specific antibodies (IgE, total IgG, IgG4, IgM) in subjects who were originally stool-positive than in those who were stool-negative. After treatment specific IgE responses were elevated, but total IgG and IgG4 anti-SEA and IgM anti-SWAP antibody levels all fell significantly. (+info)
Disease transmission models for public health decision making: toward an approach for designing intervention strategies for Schistosomiasis japonica.
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Mathematical models of disease transmission processes can serve as platforms for integration of diverse data, including site-specific information, for the purpose of designing strategies for minimizing transmission. A model describing the transmission of schistosomiasis is adapted to incorporate field data typically developed in disease control efforts in the mountainous regions of Sichuan Province in China, with the object of exploring the feasibility of model-based control strategies. The model is studied using computer simulation methods. Mechanistically based models of this sort typically have a large number of parameters that pose challenges in reducing parametric uncertainty to levels that will produce predictions sufficiently precise to discriminate among competing control options. We describe here an approach to parameter estimation that uses a recently developed statistical procedure called Bayesian melding to sequentially reduce parametric uncertainty as field data are accumulated over several seasons. Preliminary results of applying the approach to a historical data set in southwestern Sichuan are promising. Moreover, technologic advances using the global positioning system, remote sensing, and geographic information systems promise cost-effective improvements in the nature and quality of field data. This, in turn, suggests that the utility of the modeling approach will increase over time. (+info)
Achievements of schistosomiasis control in China.
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The control of schistosomiasis has been spectacularly successful in terms of controlling endemicity and severity of the disease during the last 50 years. It can be categorized into two stages. From 1955 through 1980, the transmission-control strategy had been widely and successfully carried out. By the end of 1980, the epidemic of schistosomiasis was successfully circumscribed in certain core regions including areas at the middle and low reaches of the Yangtze River and some mountainous areas in Sichuan and Yunnan provinces, where control of schistosomiasis had been demonstrated to be very difficult to be sustained. Therefore, since 1980, schistosomiasis control in China has been modified to employ a stepwise strategy, based on which morbidity control has been given priorities and if possible transmission control has been pursued. However, since snail-ridden areas remain unchanged so far, reinfections occur frequently. This necessitates a maintenance phase to consolidate the achievements in the control of schistosomiasis. In the mean time, we are challenged with some environmental, social and economical changes in terms of controlling schistosomiasis. Successfully controlling schistosomiasis in China is still a long-term task but will be achieved without doubt along with the economic development and the promotion of living and cultural standard of people. (+info)