Nora Chen

Bio: Nora Chen is an academic researcher from Connecticut Agricultural Experiment Station. The author has contributed to research in topics: Outbreak & Waterborne diseases. The author has an hindex of 1, co-authored 1 publications receiving 792 citations.

Surveillance for waterborne-disease outbreaks associated with recreational water--United States, 2001-2002.

Abstract: Problem/condition Since 1971, CDC, the U.S. Environmental Protection Agency, and the Council of State and Territorial Epidemiologists have maintained a collaborative surveillance system for collecting and periodically reporting data related to occurrences and causes of waterborne-disease outbreaks (WBDOs). This surveillance system is the primary source of data concerning the scope and effects of waterborne disease outbreaks on persons in the United States. Reporting period covered This summary includes data on WBDOs associated with drinking water that occurred during January 2001-December 2002 and on three previously unreported outbreaks that occurred during 2000. Description of system Public health departments in the states, territories, localities, and the Freely Associated States are primarily responsible for detecting and investigating WBDOs and voluntarily reporting them to CDC on a standard form. The surveillance system includes data for outbreaks associated with both drinking water and recreational water; only outbreaks associated with drinking water are reported in this summary. Results During 2001-2002, a total of 31 WBDOs associated with drinking water were reported by 19 states. These 31 outbreaks caused illness among an estimated 1,020 persons and were linked to seven deaths. The microbe or chemical that caused the outbreak was identified for 24 (77.4%) of the 31 outbreaks. Of the 24 identified outbreaks, 19 (79.2%) were associated with pathogens, and five (20.8%) were associated with acute chemical poisonings. Five outbreaks were caused by norovirus, five by parasites, and three by non-Legionella bacteria. All seven outbreaks involving acute gastrointestinal illness of unknown etiology were suspected of having an infectious cause. For the first time, this MMWR Surveillance Summary includes drinking water-associated outbreaks of Legionnaires disease (LD); six outbreaks of LD occurred during 2001-2002. Of the 25 non-Legionella associated outbreaks, 23 (92.0%) were reported in systems that used groundwater sources; nine (39.1%) of these 23 groundwater outbreaks were associated with private noncommunity wells that were not regulated by EPA. Interpretation The number of drinking water-associated outbreaks decreased from 39 during 1999-2000 to 31 during 2001-2002. Two (8.0%) outbreaks associated with surface water occurred during 2001-2002; neither was associated with consumption of untreated water. The number of outbreaks associated with groundwater sources decreased from 28 during 1999-2000 to 23 during 2001-2002; however, the proportion of such outbreaks increased from 73.7% to 92.0%. The number of outbreaks associated with untreated groundwater decreased from 17 (44.7%) during 1999-2000 to 10 (40.0%) during 2001-2002. Outbreaks associated with private, unregulated wells remained relatively stable, although more outbreaks involving private, treated wells were reported during 2001-2002. Because the only groundwater systems that are required to disinfect their water supplies are public systems under the influence of surface water, these findings support EPA's development of a groundwater rule that specifies when corrective action (including disinfection) is required. Public health action CDC and EPA use surveillance data 1) to identify the types of water systems, their deficiencies, and the etiologic agents associated with outbreaks and 2) to evaluate the adequacy of technologies for providing safe drinking water. Surveillance data are used also to establish research priorities, which can lead to improved water-quality regulations. CDC and EPA recently completed epidemiologic studies that assess the level of waterborne illness attributable to municipal drinking water in nonoutbreak conditions. The decrease in outbreaks in surface water systems is attributable primarily to implementation of provisions of EPA rules enacted since the late 1980s. Rules under development by EPA are expected to protect the public further from microbial contaminants while addressing risk tradeoffs of disinfection byproducts in drinking water.

Impact of hemorrhage on trauma outcome: an overview of epidemiology, clinical presentations, and therapeutic considerations.

Abstract: The world-wide impact of traumatic injury and associated hemorrhage on human health and well-being cannot be overstated. Twelve percent of the global disease burden is the result of violence or accidental injury. Hemorrhage is responsible for 30 to 40% of trauma mortality, and of these deaths, 33 to 56% occur during the prehospital period. Among those who reach care, early mortality is caused by continued hemorrhage, coagulopathy, and incomplete resuscitation. The techniques of early care, including blood transfusion, may underlie late mortality and long-term morbidity. While the volume of blood lost cannot be measured, physiologic and chemical measures and the number of units of blood given are readily recorded and analyzed. Improvements in early hemorrhage control and resuscitation and the prevention and aggressive treatment of coagulopathy appear to have the greatest potential to improve outcomes in severely injured trauma patients.

Risk and Rationality in Adolescent Decision Making: Implications for Theory, Practice, and Public Policy

Abstract: Crime, smoking, drug use, alcoholism, reckless driving, and many other unhealthy patterns of behavior that play out over a lifetime often debut during adolescence. Avoiding risks or buying time can set a different lifetime pattern. Changing unhealthy behaviors in adolescence would have a broad impact on society, reducing the burdens of disease, injury, human suffering, and associated economic costs. Any program designed to prevent or change such risky behaviors should be founded on a clear idea of what is normative (what behaviors, ideally, should the program foster?), descriptive (how are adolescents making decisions in the absence of the program?), and prescriptive (which practices can realistically move adolescent decisions closer to the normative ideal?). Normatively, decision processes should be evaluated for coherence (is the thinking process nonsensical, illogical, or self-contradictory?) and correspondence (are the outcomes of the decisions positive?). Behaviors that promote positive physical and mental health outcomes in modern society can be at odds with those selected for by evolution (e.g., early procreation). Healthy behaviors may also conflict with a decision maker's goals. Adolescents' goals are more likely to maximize immediate pleasure, and strict decision analysis implies that many kinds of unhealthy behavior, such as drinking and drug use, could be deemed rational. However, based on data showing developmental changes in goals, it is important for policy to promote positive long-term outcomes rather than adolescents' short-term goals. Developmental data also suggest that greater risk aversion is generally adaptive, and that decision processes that support this aversion are more advanced than those that support risk taking. A key question is whether adolescents are developmentally competent to make decisions about risks. In principle, barring temptations with high rewards and individual differences that reduce self-control (i.e., under ideal conditions), adolescents are capable of rational decision making to achieve their goals. In practice, much depends on the particular situation in which a decision is made. In the heat of passion, in the presence of peers, on the spur of the moment, in unfamiliar situations, when trading off risks and benefits favors bad long-term outcomes, and when behavioral inhibition is required for good outcomes, adolescents are likely to reason more poorly than adults do. Brain maturation in adolescence is incomplete. Impulsivity, sensation seeking, thrill seeking, depression, and other individual differences also contribute to risk taking that resists standard risk-reduction interventions, although some conditions such as depression can be effectively treated with other approaches. Major explanatory models of risky decision making can be roughly divided into (a) those, including health-belief models and the theory of planned behavior, that adhere to a "rational" behavioral decision-making framework that stresses deliberate, quantitative trading off of risks and benefits; and (b) those that emphasize nondeliberative reaction to the perceived gists or prototypes in the immediate decision environment. (A gist is a fuzzy mental representation of the general meaning of information or experience; a prototype is a mental representation of a standard or typical example of a category.) Although perceived risks and especially benefits predict behavioral intentions and risk-taking behavior, behavioral willingness is an even better predictor of susceptibility to risk taking-and has unique explanatory power-because adolescents are willing to do riskier things than they either intend or expect to do. Dual-process models, such as the prototype/willingness model and fuzzy-trace theory, identify two divergent paths to risk taking: a reasoned and a reactive route. Such models explain apparent contradictions in the literature, including different causes of risk taking for different individuals. Interventions to reduce risk taking must take into account the different causes of such behavior if they are to be effective. Longitudinal and experimental research are needed to disentangle opposing causal processes-particularly, those that produce positive versus negative relations between risk perceptions and behaviors. Counterintuitive findings that must be accommodated by any adequate theory of risk taking include the following: (a) Despite conventional wisdom, adolescents do not perceive themselves to be invulnerable, and perceived vulnerability declines with increasing age; (b) although the object of many interventions is to enhance the accuracy of risk perceptions, adolescents typically overestimate important risks, such as HIV and lung cancer; (c) despite increasing competence in reasoning, some biases in judgment and decision making grow with age, producing more "irrational" violations of coherence among adults than among adolescents and younger children. The latter occurs because of a known developmental increase in gist processing with age. One implication of these findings is that traditional interventions stressing accurate risk perceptions are apt to be ineffective or backfire because young people already feel vulnerable and overestimate their risk. In addition, research shows that experience is not a good teacher for children and younger adolescents, because they tend to learn little from negative outcomes (favoring the use of effective deterrents, such as monitoring and supervision), although learning from experience improves considerably with age. Experience in the absence of negative consequences may increase feelings of invulnerability and thus explain the decrease in risk perceptions from early to late adolescence, as exploration increases. Finally, novel interventions that discourage deliberate weighing of risks and benefits by adolescents may ultimately prove more effective and enduring. Mature adults apparently resist taking risks not out of any conscious deliberation or choice, but because they intuitively grasp the gists of risky situations, retrieve appropriate risk-avoidant values, and never proceed down the slippery slope of actually contemplating tradeoffs between risks and benefits.

The effects of physical activity and physical fitness on children's achievement and cognitive outcomes: a meta-analysis.

Abstract: It is common knowledge that physical activity leads to numerous health and psychological benefits. However, the relationship between children's physical activity and academic achievement has been debated in the literature. Some studies have found strong, positive relationships between physical activity and cognitive outcomes, while other studies have reported small, negative associations. This study was a comprehensive, quantitative synthesis of the literature, using a total of 59 studies from 1947 to 2009 for analysis. Results indicated a significant and positive effect of physical activity on children's achievement and cognitive outcomes, with aerobic exercise having the greatest effect. A number of moderator variables were also found to play a significant role in this relationship. Findings are discussed in light of improving children's academic performance and changing school-based policy.

Causes of Outbreaks Associated with Drinking Water in the United States from 1971 to 2006

Abstract: Summary: Since 1971, the CDC, EPA, and Council of State and Territorial Epidemiologists (CSTE) have maintained the collaborative national Waterborne Disease and Outbreak Surveillance System (WBDOSS) to document waterborne disease outbreaks (WBDOs) reported by local, state, and territorial health departments. WBDOs were recently reclassified to better characterize water system deficiencies and risk factors; data were analyzed for trends in outbreak occurrence, etiologies, and deficiencies during 1971 to 2006. A total of 833 WBDOs, 577,991 cases of illness, and 106 deaths were reported during 1971 to 2006. Trends of public health significance include (i) a decrease in the number of reported outbreaks over time and in the annual proportion of outbreaks reported in public water systems, (ii) an increase in the annual proportion of outbreaks reported in individual water systems and in the proportion of outbreaks associated with premise plumbing deficiencies in public water systems, (iii) no change in the annual proportion of outbreaks associated with distribution system deficiencies or the use of untreated and improperly treated groundwater in public water systems, and (iv) the increasing importance of Legionella since its inclusion in WBDOSS in 2001. Data from WBDOSS have helped inform public health and regulatory responses. Additional resources for waterborne disease surveillance and outbreak detection are essential to improve our ability to monitor, detect, and prevent waterborne disease in the United States.