Application Of Mathematical Model For Schistosomiasis Japonicum

Schistosomiasis is an infectious disease that threat human's health severelyaround the world. Currently, there are a series of problems which influence theefficiency and accuracy in practice of prevention, treatment and scientific research ofthe disease. For example, the widely used pathogen diagnosis method underestimatesactual prevalence of infection, how to improve the sensitivity of the pathogendiagnosis method, how to estimate the prevalence of morbidity and forecast theinfection of schistosomiasis.This paper investigated above question using traditional epidemiological andstatistical methods and mathematical models.â… A mathematical model for variations in Schistosoma Japonicum egg count andapplicationObjective: To further describe epidemiologic features and degree ofSchistosomiasis Japonicum in our country; to analyze the main factors influencingegg count variations; to develop, validate and apply stochastic model of variation inegg count.Methods: Typical endemic areas were selected for study egg count variationsand epidemiological features of Schistosoma Japonicum in Jiangxi Province andHunan Province, respectively. On the basis of understanding features of egg counts, amathematical model was developed to estimate a pocket chart of real SchistosomaJaponicum prevalence and evaluate its effectiveness and efficiency.Results: 1. The overall prevalence and intensity of infection markedly decreasedcompared with past data. There were no significant differences across gender, age andoccupation. 2. Prevalence of infection and intensity of population was obviously lower thanactual infection by single Kato-Katz test, which overestimated the intensity of infection. 3.Modified sampling from the head and/or outside surface of the stool increased thesensitivity of Kato-Katz method, especially for low infection population. 4. A negativecorrelation was observed between the variation of CV and the intensity of infection, which is as the increasing of intensity of infection, the variation of CV decreased gradually. 5. A model ofstochastic which correctly interpreted the variation in fecal Schistosoma Japonicumegg count was established by using the empirical data to estimate model parameters.The validation of the model was tested. 6. A pocket chart that estimated the trueprevalence was drawn by applying the model and validated using the date from fieldstudy.Conclusion: 1. Because of the effective and comprehensive control strategiesand the lost of susceptible population in epidemic areas, the prevalence of infectiondeclined obviously than past years and the feature of the disease was changed. 2. Theintensity of infection would be the possible cause of variation in intra-individual egg count. 3. Astochastic model for variations of egg counts was developed and validatedsuccessfully, by which a pocket chart to estimate the true prevalence was drawn andvalidated.â…¡The development and application of mathematical model in estimating theprevalence of morbidity due to Schistosoma JaponicumObjective: To estimate morbidity of Schistosoma Japonicum, and to provideaccurate data to WHO and Health Department of China for re-assessing the severityof the disease and re-allocating limited resources..Methods: Past data from field study reports were collected. Logistic regressionwas used to establish a mathematical model to predict the prevalence and morbidityof the disease.Results: The associations between the prevalence of infection and prevalenceof morbidity (abdominal pain in 24 hours and two weeks, diarrhea in 24 hours andtwo weeks, hepatomegaly>3cm below the anterior axillary, splenomegaly Hackett'sgrade 1 and 2, ascites) was observed, while hepatomegaly was not associated with theprevalence of infection.Conclusion: The model developed was capable to estimate the prevalence ofmorbidity due to Schistosoma Japonicum. â…¢The time series model to forecast the infection of schistosomiasisObjective: To accurately and instantly forecast infection of schistosomiasis inshort term and to provide evidence to government for re-allocating limited medicalresources.Methods: Data of infection of Schistosomiasis Japonicum in Hunan Provincefrom1990 to 2003 was used to set up autoregressive integrated moving average model(ARIMA) to forecast the infection of schistosomiasis.Results: The relative errors of the ARIMA model in forecasting the prevalenceand intensity of infection by gender were 3.8%,11.9%,11.4%,5.0%, respectively. Allthe observed values were located in the 95% confidence interval.Conclusion: ARIMA was an effective model to forecast the infection of schistosomiasis.