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Objective To study the epidemiological characteristics of Keshan disease(KD) and its fiend so as to provide evidences for further research,prevention and treatment of the disease in Sichuan province.Methods Based on KD related data from 1990 to 2008,descriptive method was used to analyze the epidemiological characteristics of KD.Results 87 KD cases were identified during the 19 years.All cases were children from the countryside,with majority of them were Yi nationality.Age of the patients ranged from 5 months to 18 years,with majority at 2-6 year-olds.The annual incidence rates Were from 0/100 000 to 1.73/100 000 with 1999 the highest(1.73/100 000).A total number of 310 preclinical or chronic KD cases were identified and the total detection rates were between 0.28% and 2.8%.with 1992 the highest.As for levels of blood selenium during the 19 years:1995 appeared the lowest(0.1345 μg/g),followed by 1990-2000(0.1558 μg/g) but all of them fell in to the level in the KD epidemic areas.Conclusion There were 5 stages in the development trend of KD disease in Sichuan province,with 2 ascending and 3 descending.The differences between any of the two stages were statistically significant.The 3 descending stages all appeared right after the selenium supplement intervention was taken.Our data showed that the program of selenium supplement was closely related to the incidence of KD,suggesting that a long term mechanism of Selenium supplement in the epidemic areas should be taking into account.
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Objective To find out the status of brick-tea type fluorosis in the epidemic areas.Methods Based on "Scheme for Epidemiological Brick-tea Type Fluorosis in Sichuan Province",ten counties were selected in Sichuan brick-tea areas and ten towns were selected in every county,then the epidemicologic survey was performed in children of 8～12 year-old and adults aged above 20 years old.Results 5044 children and 4053 adults were selected from brick-tea areas.The rates of dental fluorosis in children and adults were 55.69%(2809/5044)and 60.41%(4053/6709)respectively.The dental fluorosis was mainly of mild damage.The skeletal fluorosis found in X-ray film was 44.64%(167/1241)and in clinical examination,38.94%(3883/9973).The levels of urine fluoride in children and adults were 1.88 and 2.78 mg/L.The level of urine fluoride was not differenet among children of different age,but in adults it was higher in the elder than the younger.The level of fluoride in urine was related to the severeness of skeletal fluorosis(r=0.74).The detective rates of skeletal fluorosis in agricuIture,pasturing,and agriculture-pasturing areaswere 31.70%(1369/4318),50.04%(1228/2454),and 40.17%(1286/3201),respectively.The X-ray detecting rates of skeletal fluorosis in men and wonlen were 49.57%(229/462)and 41.72%(325/779) respectively(χ2=11.72,P＜0.05).Conclusion The prevalence of brick-tea type fluorosis is very serious in the regions studied.
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Objective To investigate the influential factors and the control measures thereof iodine salt detection with oxidation-reduction titration method so as to improve the detection quality.Methods 122 samples were obtained randomly from four counties(districts)of Sichuan Province to determine iodine ions forms.In center for diseases control and prevention(CDC)laboratories at the provincial and county levels,iodine contents in the samples were determined with oxidation-reduction titration and the results were compared between laboratories.The provineial lahoratory also employed bromine water oxidation for method comparison.Also the volume fractions of chlorine available were determined in sodium hypochlorite storage in open or sealed status and of different storage periods of 1,2,4,7,14,30 and 60 days.Results The iodine transformed from 103- to I-during the shipment and storage;The iodine contents in the 122 salt samples determined by the laboratories at the provincial and county levels were respectively(32.40±8.44),(31.10±8.34)mg/kg with a result discrepancy of 1.33 mg/kg.Of all the absolute discrepancy values,18.8%(23/122)were lower than or equal to 1 mg/kg;23.0%(28/122)were equal to or higher than 3 mg/kg;23.0%(28/122)were lower than or equal to 5 mg/kg;26.2%(32/122)were lower than or equal to 10 mg/kg;9.0%(11/122)were higher than 10 mg/kg.After the botdes were opened and stood for 60 days,the available chlorine content in the sodium hypochlorite decreased by 43.6%and 32.5%respectively in open and sealed status,Iodine contents were respectively(32.60±8.44),(32.50±8.18)mg/kg(n=114)with the oxidationreduction titration method and bromine water oxidation method,and no significant difierence was found between the results of the two methods(t=0.282,P＞0.05).Conclusions Potassium iodate in salt in Sichuan is Dmne to transform into potassium iodide during shipping,so when determining salt iodine with the oxidation-reduction titration method,the content and the amount of chlorine available in the sodium hypochlorite differ a lot and are difficult to control.Therefore.bromine water oxidation titration is recommended.