ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Diseases caused by arboviruses cause extensive mortality and morbidity throughout the world. Weather directly affects the breeding, abundance, and survival of mosquitoes, the principal vector of many arboviruses. The goal of this study was to test whether climate variables could predict with high levels of accuracy (more than 70%) epidemics of one arbovirus, Ross River virus disease.Methods.Weather data from two regions in southeastern Australia were matched with Ross River virus disease data for the period 1991 to 1999. Our aim was to develop simple models for the probability of the occurrence of an epidemic in an area in a given year.Results.Two predictable epidemic patterns emerged, after either high summer rainfalls or high winter rainfalls. A prerequisite relating to host-virus dynamics was lower than average spring rainfall in the preepidemic year. The sensitivity of the model was 96% for Region 1 and 73% for Region 2.Conclusions.Early warning of weather conditions conducive to outbreaks of Ross River virus disease is possible at the regional level with a high degree of accuracy. Our models may have application as a decision tool for health authorities to use in risk-management planning.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Previous research on air pollution effects has found associations with chronic adverse health effects even at the relatively low levels of ambient particulates currently measured in most urban areas.Methods.We assessed the impact of declines of total suspended particulates and sulfur dioxide in eastern Germany after reunification on the prevalence of nonallergic respiratory disorders in children. In the 1990s, particle mass (total suspended particulates) and sulfur dioxide declined, whereas number concentrations of nucleation-mode particles (10–30 nm) increased. In three study areas, questionnaires for 7,632 children between 5 and 14 years of age were collected in three phases: 1992–1993, 1995–1996, and 1998–1999.Results.Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for a 50-&mgr;g/m3increment in total suspended particulates were 3.0 (CI = 1.7–5.3) for bronchitis, 2.6 (CI = 1.0–6.6) for sinusitis, and 1.9 (CI = 1.2–3.1) for frequent colds. The effect sizes for a 100-&mgr;g/m3increment in sulfur dioxide were similar. The effect estimates for ambient total suspended particulates and sulfur dioxide were stronger among children not exposed to gas stove emissions, visible molds or dampness, cats, or environmental tobacco smoke.Conclusions.The decreasing prevalence of nonallergic respiratory symptoms, along with improvements in ambient particle mass and sulfur dioxide (but not in nucleation-mode particles), indicates the reversibility of adverse health effects in children. This adds further evidence of a causal association between combustion-related air pollutants and childhood respiratory symptoms.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Kuru is a transmissible spongiform encephalopathy that was identified in Papua New Guinea in the late 1950s. Several thousand cases of the disease occurred during a period of several decades. Epidemiologic investigations implicated ritual endocannibalistic funeral feasts as the likely route through which the infectious agent was spread.Methods.We estimated the incubation period distribution of kuru using a back-calculation model and explored the relation among sex, age at infection, and incubation period. Key assumptions in the model were that the number of new kuru infections in a year was proportional to the number of kuru cases dying that year, and that the epidemic arose from a single case of sporadic Creutzfeldt-Jakob Disease occurring around 1900.Results.The mean incubation period of kuru was estimated at between 10.3 and 13.2 years. Point estimates of the 90th percentile ranged from 21.1 to 27.0 years. The incubation period in females was estimated to be shorter than that in males. The shortest incubation periods were estimated in adult women, who may have been exposed to the largest doses of infectious material.Conclusions.Our findings suggest that the relatively young age of cases of variant Creutzfeldt-Jakob disease probably reflects increased levels of exposure in young people, rather than age-dependency in the incubation period.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Oxidative stress plays an important role in the pathophysiology of preeclampsia.Methods.In a case-control study of 109 women with preeclampsia and 259 controls, maternal dietary and plasma vitamin C in relation to preeclampsia risk were assessed. Dietary intake during the periconceptional period and pregnancy was ascertained using a semiquantitative food frequency questionnaire. Logistic regression procedures were used to derive odds ratios (OR) and 95% confidence intervals (CI). Plasma ascorbic acid was determined using automated enzymatic procedures.Results.After adjusting for maternal age, parity, prepregnancy body mass index, and energy intake, women who consumed <85 mg of vitamin C daily (below the recommended dietary allowance), as compared with others, experienced a doubling in preeclampsia risk (OR = 2.1; 95% CI = 1.1–3.9). The OR for extreme quartiles of plasma ascorbic acid (<42.5vs≥ 63.3 &mgr;mol/liter) was 2.3 (95% CI = 1.1–4.6). Compared with women in the highest quartile, those with plasma ascorbic acid <34.6 &mgr;mol/liter (lowest decile) experienced a 3.8-fold increased risk of preeclampsia (95% CI = 1.7–8.8).Conclusions.Our results, if confirmed, would suggest that current public health efforts to increase intake of fruits and vegetables rich in vitamin C and other antioxidants may reduce the risk of preeclampsia.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.Etiologic hypotheses in infantile autism suggest a strong genetic component, as well as possible environmental risks linked to early fetal development. We evaluated the association of maternal, pregnancy, delivery, and infant characteristics and risk of infantile autism.Methods.We conducted a case-control study nested within a population-based cohort (all Swedish children born in 1974–1993). We used prospectively recorded data from the Swedish Birth Register, which were individually linked to the Swedish Inpatient Register. Cases were 408 children (321 boys and 87 girls) discharged with a main diagnosis of infantile autism from any hospital in Sweden before 10 years of age in the period 1987–1994, plus 2,040 matched controls. Conditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).Results.The risk of autism was associated with daily smoking in early pregnancy (OR = 1.4; CI = 1.1–1.8), maternal birth outside Europe and North America (OR = 3.0; CI = 1.7–5.2), cesarean delivery (OR = 1.6; CI = 1.1–2.3), being small for gestational age (SGA; OR = 2.1; CI = 1.1–3.9), a 5-minute Apgar score below 7 (OR = 3.2, CI = 1.2–8.2), and congenital malformations (OR = 1.8, CI = 1.1–3.1). No association was found between autism and head circumference, maternal diabetes, being a twin, or season of birth.Conclusions.Our findings suggest that intrauterine and neonatal factors related to deviant intrauterine growth or fetal distress are important in the pathogenesis of autism.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

When comparing tests for a disease, it is necessary to know whether individuals are diseased or nondiseased. In practice, the confirmatory (gold standard) procedure is often limited to individuals with positive test results, because the confirmatory procedure is not applied to individuals with negative test results. We present a model for estimating the sensitivity and specificity when two tests are compared and the gold standard classification is unavailable (semi-latent) for those individuals with negative results on both tests. The model does not assume independent error rates, and estimates of specificity conditional on a false-positive result for another test are derived. We use a Bayes approach for estimating the distributions of the performance parameters.

ISSN:1044-3983    

出版商:OVID    

年代:2002

数据来源: OVID