Publications (5) View all
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Article: Health risks of limited-contact water recreation.
Samuel Dorevitch, Preethi Pratap, Meredith Wroblewski, Daniel O Hryhorczuk, Hong Li, Li C Liu, Peter A Scheff[show abstract] [hide abstract]
ABSTRACT: Wastewater-impacted waters that do not support swimming are often used for boating, canoeing, fishing, kayaking, and rowing. Little is known about the health risks of these limited-contact water recreation activities. We evaluated the incidence of illness, severity of illness, associations between water exposure and illness, and risk of illness attributable to limited-contact water recreation on waters dominated by wastewater effluent and on waters approved for general use recreation (such as swimming). The Chicago Health, Environmental Exposure, and Recreation Study was a prospective cohort study that evaluated five health outcomes among three groups of people: those who engaged in limited-contact water recreation on effluent-dominated waters, those who engaged in limited-contact recreation on general-use waters, and those who engaged in non-water recreation. Data analysis included survival analysis, logistic regression, and estimates of risk for counterfactual exposure scenarios using G-computation. Telephone follow-up data were available for 11,297 participants. With non-water recreation as the reference group, we found that limited-contact water recreation was associated with the development of acute gastrointestinal illness in the first 3 days after water recreation at both effluent-dominated waters [adjusted odds ratio (AOR) 1.46; 95% confidence interval (CI): 1.08, 1.96] and general-use waters (1.50; 95% CI: 1.09, 2.07). For every 1,000 recreators, 13.7 (95% CI: 3.1, 24.9) and 15.1 (95% CI: 2.6, 25.7) cases of gastrointestinal illness were attributable to limited-contact recreation at effluent-dominated waters and general-use waters, respectively. Eye symptoms were associated with use of effluent-dominated waters only (AOR 1.50; 95% CI: 1.10, 2.06). Among water recreators, our results indicate that illness was associated with the amount of water exposure. Limited-contact recreation, both on effluent-dominated waters and on waters designated for general use, was associated with an elevated risk of gastrointestinal illness.Environmental Health Perspectives 02/2012; 120(2):192-7. · 7.04 Impact Factor -
Article: A comparison of rapid and conventional measures of indicator bacteria as predictors of waterborne protozoan pathogen presence and density.
Samuel Dorevitch, Mary Doi, Fu-Chih Hsu, King-Teh Lin, Jennifer D Roberts, Li C Liu, Ross Gladding, Ember Vannoy, Hong Li, Margit Javor, Peter A Scheff[show abstract] [hide abstract]
ABSTRACT: E. coli and enterococci in recreational waters are monitored as indicators of fecal contamination, pathogen presence, and health risk. Quantitative polymerase chain reaction (qPCR) tests for fecal indicator bacteria can provide beach managers with same-day information about water quality, unlike culture methods which provide that information the following day. The abilities of qPCR measurements of indicator bacteria, as compared to culture measurements of indicator bacteria, as predictors of pathogen presence or density in surface waters are not well understood. The purpose of this study was to make such comparisons between water samples collected from Chicago area surface waters, including rivers, inland lakes, Lake Michigan, and the Chicago Area Waterways System, which is dominated by wastewater effluent. A total of 294 twenty-litre samples were collected and analyzed for Giardia and Cryptosporidium. qPCR and membrane filtration methods were used to quantify E. coli and enterococci. Correlation, logistic regression, and zero-inflated Poisson modeling were utilized to evaluate associations between indicators and parasites. qPCR and culture measures of the indicator bacteria were similar in their ability to predict parasite presence and density. Correlations between parasites and indicators were generally stronger at waters not dominated by effluent. Associations between indicator density and Giarida presence were observed more consistently than between indicator density and Cryptosporidium presence. Associations between enterococci and parasites were generally stronger than associations between E. coli and parasites. The use of qPCR monitoring in our setting would generate more timely results without compromising the ability to predict parasite presence or density.Journal of Environmental Monitoring 08/2011; 13(9):2427-35. · 1.99 Impact Factor -
Article: Water ingestion during water recreation.
Samuel Dorevitch, Suraj Panthi, Yue Huang, Hong Li, Angela M Michalek, Preethi Pratap, Meredith Wroblewski, Li Liu, Peter A Scheff, An Li[show abstract] [hide abstract]
ABSTRACT: Quantitative risk assessments have estimated health risks of water recreation. One input to risk assessment models is the rate of water ingestion. One published study estimated rates of water ingestion during swimming, but estimates of water ingestion are not available for common limited contact water recreation activities such as canoeing, fishing, kayaking, motor boating, and rowing. In the summer of 2009 two related studies were conducted to estimate water ingestion during these activities. First, at Chicago area surface waters, survey research methods were utilized to characterize self-reported estimates of water ingestion during canoeing, kayaking, and fishing among 2705 people. Second, at outdoor swimming pools, survey research methods and the analysis of cyanuric acid, a tracer of swimming pool water, were used to characterize water ingestion among 662 people who engaged in a variety of full-contact and limited-contact recreational activities. Data from the swimming study was used to derive translation factors that quantify the volume of self-reported estimates. At surface waters, less than 2% of canoers and kayakers reported swallowing a teaspoon or more and 0.5% reported swallowing a mouthful or more. Swimmers in a pool were about 25-50 times more likely to report swallowing a teaspoon of water compared to those who participate in limited-contact recreational activities on surface waters. Mean and upper confidence estimates of water ingestion during limited-contact recreation on surface waters are about 3-4 mL and 10-15 mL, respectively. These estimates of water ingestion rates may be useful in modeling the health risks of water recreation.Water Research 02/2011; 45(5):2020-8. · 4.86 Impact Factor -
Article: Prevalence and risk factors of fatty liver disease in Chengdu, Southwest China.
Hong Li, You-Juan Wang, Ke Tan, Li Zeng, Li Liu, Feng-Jun Liu, Tao-You Zhou, En-Qiang Chen, Hong Tang[show abstract] [hide abstract]
ABSTRACT: Fatty liver disease (FLD) is increasingly recognized as one of the most common chronic liver diseases in China. This study aimed to investigate the prevalence and risk factors of FLD in Chengdu, Southwest China, and to provide a relevant basis for the prevention and intervention of FLD. Altogether 9094 subjects (4721 men and 4373 women) of over 18 years old who had received a medical checkup in the West China Hospital of Sichuan University between January and December 2007 were evaluated for FLD. FLD was diagnosed by ultrasonography. Body mass index (BMI), height, body weight, blood pressure, fasting plasma glucose (FPG), triglycerides (TG), total cholesterol (TCh), alanine aminotransferase (ALT), hepatitis B surface antigen (HBsAg), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured using routine laboratory methods. The overall prevalence of FLD was 12.5%, which was more than 3-fold higher in males than in females (18.9% vs. 5.7%, X2=359.624, P<0.001). The prevalence increased with age in females and males of less than 50 years. The prevalence of alcoholic, suspected alcoholic, and non-alcoholic FLD was 2.6%, 3.6%, and 6.3%, respectively. Multiple logistic regression analyses showed that 10 factors (male sex, age, BMI, FPG, hypertension, TG, TCh, HDL-C, LDL-C, and ALT abnormalities) were closely related to FLD. In heavy drinkers, obesity increased the risk of FLD by 23.78-fold (95% CI, 10.22-55.33), but heavy drinking was only associated with a 2-fold (95% CI, 1.50-2.66) increased risk in obese subjects. The prevalence of FLD among a health-checkup population in Chengdu, Southwest China was lower than the published for other areas of China. FLD in Chengdu adults was found to be closely associated with sex, age, BMI, and other metabolic syndrome features.Hepatobiliary & pancreatic diseases international: HBPD INT 09/2009; 8(4):377-82. · 1.08 Impact Factor -
Article: [On the detection of HBV cccDNA and its clinical significance: an overview of research advancement].
Hong Li, Hong Tang[show abstract] [hide abstract]
ABSTRACT: Covalently closed circular DNA (cccDNA) is the existing form of the HBV DNA in the nucleus of host cells and also the original template of HBV replication; its long-term presence in the nucleus makes it difficult to be eliminated by current antiviral drugs; and it becomes the key factor of continuous HBV infection and relapse after antiviral suspension. Detection of HBV cccDNA is of great significance for further understanding the life cycle of HBV and providing guidance for antiviral treatment. This article aims to review the detection and its clinical significance to the advancement of researches on hepatitis B virus cccDNA.Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi 07/2009; 26(3):662-6.
