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Objective To explore the cut?off value of the indirect haemagglutination test(IHA)method for schistosomiasis japonica diagnosis in different endemic areas. Methods Totally 55 nature villages of the lake?type endemic counties,Yugan and Xinzi,in Poyang Lake Region of Jiangxi Province were chosen as the study fields,and all the villagers over 5 years old were parallelly examined by Kato?Katz method+miracidial hatching test and IHA method. The detection data were analyzed by the correlation analysis,and the threshold values of the IHA method in different endemic areas were decided by the receiver operat?ing characteristic(ROC)curve. Results The positive rate of stool examinations of the villagers was correlated with the distribu?tion trend of the antibody level of whole population(r=0.588,P0.05). The antibody level of stool?negative population during the period of 2008 to 2011 detect?ed by IHA method dropped year by year,and the annual difference was statistically significant(F=3.650,P0.05). When the positive rates were5%,the specificity of diagnosis could be improved when 1∶80,1∶20 and 1∶10 were used as the cut?off val? ues of IHA correspondingly. Conclusion The different threshold values for diagnosis of schistosomiasis japonica should be con?sidered while using IHA method to screen out patients in different endemic areas.
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Objective To explore the immune mechanism of negative results of immune tests of schistosomiasis japonica pa?tients. Methods Totally 142 schistosomiasis patients(positive stool examinations)of Poyang Lake region were tested by ELI?SA method,and the ROC curve was applied to determine the high and low response of the patients. The levels of cellular immu?nity and cytokines of high and low responders were compared. Results Totally eight schistosomiasis patients were found as low responders. Besides SWAP?IgA(t= -1.588,P > 0.1),the levels of isotype antibodies were significantly lower in the low re?sponders compared with those in the high responders(t = -14.517 to -2.866,all P 0.05)compared with those in the high responders. The differences of IFN?γ and IL?10 between the high and low responders were both not significant(t= -2.426 to 0.216,all P >0.05). Conclusions There is a significant difference between the high and low responders only in the levels of isotype antibod?ies. One of the reasons of low response in the immune tests is the much lower antibody level after the antigen?antibody compound is completely formulated.
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Objective To design and develop new types of health education materials which are suitable for fishermen and boatmen in endemic areas of marshland and lake regions,and to observe their application effects. Methods A total of 292 adult fishmen and boatmen who lived in Houshan Village,Yugan County,the schistosomiasis endemic area of Poyang Lake Re?gion,were selected randomly and investigated by questionnaires to understand the status of their knowledge,attitudes,practic?es on schistosomiasis control as well as the channels for getting information on schistosomiasis control and the materials that they were willing to accept. Then the information and materials suitable for the target population were developed together by the re?searchers and the volunteers of the villagers through focus group discussions,personal interviews and the Delphi method. Re?sults A series of participatory health education materials of schistosomiasis control targeted to the fishmen and boatmen were developed,including 2 live posters,2 picture puzzles,2 short opusculums and one song about schistosomiasis control. The field application showed that 98.97%,84.38%,78.35% and 80.93% of the participants considered those materials had scientificity, intelligibility,interestingness and practicability,respectively. Conclusion The participatory health education materials of schistosomiasis control is suitable for fishmen and boatmen,which can be used for reference by other endemic areas in marsh?land and lake regions.
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Objective To explore the impact and change regularity of Oncomelania hupensis snails and vegetation in the marshlands of Poyang Lake caused by the impoundment of the Three Gorges Project. Methods By using the methods of stratified systematic sampling and pinpoint navigation,the succession of vegetation was observed and the distribution of O. hupensis snails was investigated in a period of 8 years on 4 typical marshlands in Poyang Lake. The regularity of changes in vegetation and O. hu-pensis snails was analyzed on the marshlands at high,medium and low elevations,respectively. Results After the impoundment of Three Gorges Project,the average flooding days of these 4 marshlands in 2004 and in 2008 were reduced of 74.8 and 65.8 days compared with those in 2002,the year just before the impoundment of the project,respectively. The change of spatial distribution pattern and the succession of dominant species of vegetation on the marshlands of Poyang Lake have taken place since 2005,and several vegetations showed a trend of moving toward the center of the lake. The hygrophilous vegetation has degenerated and gradu-ally been replaced by mesophily meadow in the marshland area above 14 m elevation. Carex,Phalaris arundinacea and Polygo-num appeared in large area and expanded slowly towards the center of the lake on the marshland below 14 m elevation. O. hupensis snails were mostly found under the Carex association. The tendency of decreasing in density of snails and of migration of snail habi-tats towards low terrain was observed. Conclusions The impoundment of Three Gorges Project has had a significant impact on hy-drological regimes,and a new succession of vegetation has taken place in the marshlands of Poyang Lake. O. hupensis snails and the mesophily vegetation show a trend of migrating slowly to the areas of low elevation in the marshlands.
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Objective To explore the relationship between the vegetation and space distribution of Oncomelania snails in Poyang Lake region,so as to get better understanding of the habitats of Oncomelania snails by using remote sensing technology.Methods The marshlands close to schistosomiasis endemic villages in Poyang Lake region were selected,and the traditional methods were used to investigate the situation of vegetation and Oncomelania snails.The longitude and latitude of investigation spots were recorded by GPS,and the field survey data were vectored by using ArcGIS software.The geometric calibration and unsupervised classification were made on TM satellite images of low-flow period of spring by using PCI 9.0.And then,the relationship between space distribution of snail habitats and vegetation was analyzed through superposing the filed data and satellite images.Results The vegetation in marshlands of Poyang Lake region can be differentiated as three types,in which the single dominant vegetation area was mainly breeding place of Oncomelania snails,and wet vegetation type and hybrid weed type were snail seldom breeding areas.Conclusions The distribution roles of vegetation in marshland are closely related to the habitats of snails,presenting a flaky and bandy distribution.The habitats of Oncomelania snails can be quickly understood by remote sensing technology.
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Objectives To explore the correlation between the population characteristics of sero-reactivity with quantitative antibody based-IHA and the transmission parameters,such as epidemic situation,transmission status or infection trend in population.Methods The residents in one endemic administrative village were simultaneously examined by Kato-Katz technique for parasitological stool examination,as well as by immuno-diagnostic technique IHA for detection of IgG antibody against soluble egg antigen for two consecutive years.The results of examination were analyzed and compared on the diagnostic parameters of IHA,the correlation of the changes of positive rates and antibody levels of IHA with the changes of infection trend in population and the distribution of antibody levels between 'the true negative' and 'the true positive'.Results When Kato-Katz technique based on 2 stool samples,each read in 3 thick smears,was used as the reference,the overall sensitivity of IHA was high (from 77.27% to 85.48%) with a relatively poor specificity of lower than 60%,the negative predict value (NPV) was excellent of higher than 94%.The specificity of IHA decreased with the increase of the age in different age-groups of population,showing the highest among the younger less than 15 years old.The distribution trends of positive rates of antibody in different age groups by IHA showed similar to that of egg positive rate detected by Kato-Katz although the positive rates of IHA were higher than these by Kato-Katz,which showed that a higher false positive (from 41.90% to 44.56%) and a certain false negative (from 14.52% to 22.73%)existed in IHA.The positive rate of antibody decreased slowly among the individuals with S.japonicum infection,who received treatment.There was an overlap in the distribution of antibody levels between ' the true negative' and ' the true positive'.Conclusions Under the current schistosomiasis epidemic situation in China,IHA is valuable in the epidemiologic surveys.It should be of further deliberation applying IHA as the screening approaches for identification of target individuals for treatment or determination of the infection rate in community and IHA needs to be combined with the parasitological examination.
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Objective To observe the uhrasenographical characters of liver and spleen of residents and their changes in endearic areas of schistosomiasis japonica in Poyang Lake region.Jiangxi Province and to explore the value of ultrasonography for assessment of the morbidity of the disease.Methods All permanent residents aged above 3 years old were examined by ultrasonography and Kato-Katz method.Results The schistosome positive rates of fecal examinations decreased obviously from 16.29%in 1995 to 8.54%in 2007(P0.05),with the rates of 8.82% and 20.33% in 1995 and 8.54% and 21.34% in 2007,respectively.The abnormal rate of portal vein diameter decreased significantly.from 32.47%in 1995 to 6.50% in 2007.The abnormal rate of liver parenehyma increased remarkably(P<0.01),from 34.85% to 51.83%.The changes of liver parenchyma Grade I showed a bidirectional trend,29.90% of them chased into Grade 0(normal image on ultrasonngraphy),and 34.02% changed into Grade 2 and above.The abnormality of various indices of uhrasonography examinations were related to age,occupation and schistesome infection status.Conclusions Ultrasonography can show the damages of liver and spleen of patients infected with Schistosoma japonicum directly.but it is necessary to study further on the sensitive indices that reflecting early pathological changes and the best combination of the indices for the assessment of schistosomiasis-related morbidity.
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Objective To explore the relationship between vegetation and the distribution of Oncomelania snails inside and outside the embankments of Poyang Lake region. Methods The plantation and Oncomelania snails were surveyed at 4 villages and their related marshlands in Yugan, Nanchang and Jinxian counties by the stratified systematic sampling method. The investigation was targeted to the vegetation species,height,coverage and frequency of plantation and synchronously to the distribution of snails and infection of snails in marshland of high, middle and low altitudes,adjacent beaches as well in cultivated and waste land inside embankment. The relationship between vegetation dominant association and the distribution of snails in those area was analyzed. Results The vegetation inside and outside the embankment were remarkably diverse. Inside the embankment, the species of vegetation varied greatly and distributed randomly,and no snail was found. While outside the embankment,the distribution of vegetation characterized an unregulated annulus or patch. Plant's association types were distinct on marshlands. The snails mainly distributed in areas at 15-17 m altitude,closely related to the species of vegetation. The coverage of dominant plants,Carex cinerascen and Miscanthus sacchariflorus showed a quadratic curve correlation with the density of snails. Conclusions In the Poyang Lake region,plants and snails are impacted by common environmental factors,which then lead to their close association in distribution. It might be attributed to integrated impacts of changes in ecological factors that Oncomelania snails disappear gradually in areas inside embankment after construction of embankment.
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Objective To observe the effect of artemether in the control of prevalence and acute infection of Schistosoma japonicum in humans in high endemic areas. Methods During the transmission season (May-October), the residents in the pilot village took artemether with a 15- day interval to prevent the infection of S. japonicum. Results By the end of the transmission season, the egg positive rate was 0.83% and no acute case occurred in the artemether group, while 15.01% and 3 acute cases were observed in the placebo group. Conclusions Oral administration of artemether at a 15-day interval shows an effective protection from infection of S. japonicum, with a protection rate of 94.47% in residents of a high endemic area and it also shows marked effect to prevent acute schistosomiasis.