Increasing prevalence and influencing factors of childhood asthma: a cross-sectional study in Shanghai, China.

BACKGROUND: Asthma has been a global problem, especially in children. We aim to evaluate the contemporary prevalence and influencing factors of asthma among children aged 3-7 years in Shanghai, China. METHODS: A random sample of preschool children was included in this study. The International Study of Asthma and Allergies in Childhood questionnaire was adopted to assess the childhood asthma. Multivariable logistic regression models were used to evaluate the associations between independent variables and childhood asthma. RESULTS: Of 6389 preschool children who were invited to take part in this study, 6163 (response rate: 96.5%) completed the questionnaire and were included in the analysis. The overall prevalence of asthma was 14.6% which increased more than six folds from 2.1% in 1990. Being male, younger age, preterm delivery, being born in spring or autumn, being delivered by elective cesarean section without indication, miscarriage, high socioeconomic status, having allergy history, and exposure to passive smoking, latex paint, and dust were potential risk factors for childhood asthma. Spending more time outdoors (> 30 min/day), having indoor plants, and cleaning rooms more frequently were potential protective factors. CONCLUSIONS: The prevalence of childhood asthma in Shanghai has increased dramatically during the past three decades. The findings about risk and protective factors of childhood asthma could be used to develop appropriate strategies to prevent and control childhood asthma in Shanghai and in other similar metropolitan cities.

Trace element profiles in pregnant women's sera and umbilical cord sera and influencing factors: Repeated measurements.

In utero exposure to toxic heavy metals and deficient or excessive essential trace elements during pregnancy may have adverse effects on pregnant women and their offsprings, which are of great concern. The objective of the present study was to characterize serum concentrations of multiple trace elements at multiple time points during pregnancy in Chinese women. Three thousand four hundred and sixteen pregnant women in total were included from MABC (Ma'anshan Birth Cohort) study. Fasting sera in the morning and questionnaires were obtained at three separate follow-up visits. Nineteen trace elements from serum samples were analyzed, including aluminum (Al), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), barium (Ba), thallium (Tl), lead (Pb), calcium (Ca), magnesium (Mg), mercury (Hg) and molybdenum (Mo). The total detection rates for most elements were 100% rather than Ni (99.98%), As (99.97%), Cd (99.6%), Ba (99.9%), Pb (99.8%), Hg (99.8%). The concentration distributions of 19 elements varied vastly. Median concentrations for all trace elements ranged from 38.5 ng/L to 102.9 mg/L. The moderate interclass correlation coefficients (ICCs) were observed for Co, Cu, Se and Hg, ranging from 0.40 to 0.62; the lower ICCs, ranging from 0.13 to 0.32 were for Fe, Zn, Cd, Ba, Tl, Mg and Mo. The intraclass correlation effects were not observed for the remaining elements, such as Al, V, Cr, Mn, Ni, As and Pb. The concentrations of each element between three time points were significantly different; significant differences were also found between any two time points except for Ni, Cd and Mo. Many factors could affect the levels of trace elements, and a very important factor of them was season. Consequently, a single measurement of elements in sera seems not enough to describe exposure levels throughout pregnancy; additionally, season affected exposure levels of trace elements with moderate ICCs showed certain regularity. Future analyses should take sampling seasons into consideration carefully.

Association between maternal and umbilical cord serum cobalt concentration during pregnancy and the risk of preterm birth: The Ma'anshan birth cohort (MABC) study.

Cobalt is an essential trace element and has been suggested to be involved in oxidative stress and inflammatory responses. However, researches have paid little attention to the association between serum cobalt levels during pregnancy and the risk of preterm birth (PTB, <37 week of gestation). The purpose of this study was to determine the association between maternal and umbilical cord serum cobalt concentrations and the risk of PTB. A total of 2951, 3080, and 2698 serum samples were obtained from pregnant women in the first, the second trimester, and the umbilical cord blood, respectively. The tertile levels of ln-transformed cobalt were defined as low, medium and high levels for cobalt respectively. In our study, the rate of PTB (<37 weeks of gestation) was elevated in subjects with low cobalt levels in the first trimester of pregnancy (adjusted OR 1.61, 95% CI: 1.01, 2.58) and the second trimester of pregnancy (adjusted OR 1.62, 95% CI: 1.03, 2.54). The adjusted OR for PTB was 2.46 (95% CI: 1.34, 4.53) among subjects with low cobalt levels and 2.22 (95% CI: 1.19, 4.15) among subjects with medium cobalt levels in the umbilical cord serum. Our findings demonstrated that the lower levels in maternal and umbilical cord serum cobalt were associated with the increased the risk of PTB.

Current Recommended Vitamin D Prenatal Supplementation and Fetal Growth: Results From the China-Anhui Birth Cohort Study.

Context: Maternal vitamin D insufficiency has been associated with fetal growth restriction. However, the effect of maternal vitamin D supplementation on fetal growth has not been confirmed. Objective: To assess the effect of maternal vitamin D supplementation recommended by the Institute of Medicine (IOM) during pregnancy on the neonatal vitamin D status and the risk of small for gestational age (SGA). Design and Participants: As part of the China-Anhui Birth Cohort study, maternal sociodemographic characteristics, food intake, lifestyle, information on vitamin D supplementation, and birth outcomes were prospectively collected. For participants, 600 IU/d of vitamin D3 was routinely advised to take during pregnancy. Cord blood levels of 25-hydroxyvitamin D [25(OH)D], calcium, and phosphorus were measured in 1491 neonates who were divided into three groups based on the duration of maternal vitamin D supplementation during pregnancy. Results: Mean cord blood concentrations of 25(OH)D were 3.5 nmol/L higher [95% confidence interval (CI), 0.8, 6.2] in neonates (median, 37.9 nmol/L) whose mother took vitamin D supplementation for >2 months during pregnancy compared with those (median, 34.3 nmol/L) whose mother did not take any supplement. These significant differences on cord blood concentrations of 25(OH)D occurred regardless of the season of birth. The adjusted risk of SGA in pregnant women with vitamin D supplementation for >2 months was significantly decreased than that in women without any vitamin D supplementation (11.8% vs 6.9%; adjusted odds ratio = 0.53; 95% CI, 0.32, 0.87). Conclusions: The findings from China suggest that maternal vitamin D supplementation recommended by the IOM results in a slight but significantly higher fetal level of 25(OH)D and improves fetal growth.

Maternal depression attenuates newborn vitamin D concentrations in winter-spring: a prospective population-based study.

We aimed to investigate whether the newborns of mothers with maternal depression (MD) had lower vitamin D levels than newborns of non-MD (NMD) mothers and identify the potential mechanism underlying this association. Maternal depressive symptoms in late pregnancy and concentrations of cord blood 25 hydroxyvitamin D (25(OH)D) were measured in 1491 mother-infant pairs. Data on maternal sociodemographic characteristics, health status, lifestyle and birth outcomes were prospectively collected. For infants born in winter-spring, the infants of MD mothers had significantly reduced concentrations of 25(OH) D (adjusted ß = -3.51 nmol/L; 95% CI: -6.19, -0.84; P = 0.010) and lower birth weight (3267 ± 470 g vs 3348 ± 598 g, F = 4.64, P = 0.031), compared with the infants of NMD mothers. A significant, inverse linear relationship was noted between maternal depression scores and the concentration of 25(OH)D for infants born in winter-spring (adjusted ß = -0.158; 95% CI: -0.259, -0.057). The significant, inverse linear relationship between maternal depression scores and fetomaternal ratios of 25(OH) D was also observed among the infants born in winter-spring (adjusted ß = -0.005; 95% CI: -0.008, -0.003). MD appears to significantly attenuate the vitamin D concentrations and birth weight of infants born in winter-spring. A decreased fetomaternal ratio of 25(OH)D might be involved in this biological pathway.

Sex differences in the effects of prenatal lead exposure on birth outcomes.

Studies on the associations between prenatal lead exposure and birth outcomes have been inconsistent, and few data are available on the sex differences in these associations. We measured the cord blood lead levels of newborns in Shanghai and determined their associations with birth outcomes, which included birth weight, birth length, head circumference, and the ponderal index, in the total sample and within sex subgroups. A total of 1009 mother-infant pairs were enrolled from 10 hospitals in Shanghai between September 2008 and October 2009. The geometric mean of the cord blood lead concentrations was 4.07 µg/dl (95% CI: 3.98-4.17 µg/dl). A significant inverse association was found between cord blood lead levels and head circumference only in the male subgroup, and increasing cord blood lead levels were related to significant decreases in the ponderal index only in females. The birth weights of the male infants were positively associated with cord blood lead levels; after adjusting for the maternal intake frequency of preserved eggs, the estimated mean differences in birth weights decreased by 11.7% for each 1-unit increase in the log10-transformed cord blood lead concentration. Our findings suggest that prenatal lead exposure may have sex-specific effects on birth outcomes and that maternal dietary intake may be a potential confounder in these relationships. Further studies on this topic are highly warranted.

Effects of Humidity Variation on the Hantavirus Infection and Hemorrhagic Fever with Renal Syndrome Occurrence in Subtropical China.

Infection rates of rodents have a significant influence on the transmission of hemorrhagic fever with renal syndrome (HFRS). In this study, four cities and two counties with high HFRS incidence in eastern Hunan Province in China were studied, and surveillance data of rodents, as well as HFRS cases and related environmental variables from 2007 to 2010, were collected. Results indicate that the distribution and infection rates of rodents are closely associated with environmental conditions. Hantavirus infections in rodents were positively correlated with temperature vegetation dryness index and negatively correlated with elevation. The predictive risk maps based on multivariate regression model revealed that the annual variation of infection risks is small, whereas monthly variation is large and corresponded well to the seasonal variation of human HFRS incidence. The identification of risk factors and risk prediction provides decision support for rodent surveillance and the prevention and control of HFRS.

Cord Blood 25-hydroxyvitamin D and Fetal Growth in the China-Anhui Birth Cohort Study.

We determined the association of cord blood 25-hydroxyvitamin D [25(OH)D] with birth weight and the risk of small for gestational age (SGA). As part of the China-Anhui Birth Cohort (C-ABC) study, we measured cord blood levels of 25(OH)D in 1491 neonates in Hefei, China. The data on maternal sociodemographic characteristics, health status, lifestyle, birth outcomes were prospectively collected. Multiple regression models were used to estimate the association of 25(OH)D levels with birth weight and the risk of SGA. Compared with neonates in the lowest decile of cord blood 25(OH)D levels, neonates in four deciles (the fourth, fifth, sixth and seventh deciles) had significantly increased birth weight and decreased risk of SGA. Multiple linear regression models showed that per 10 nmol/L increase in cord blood 25(OH)D, birth weight increased by 61.0 g (95% CI: 31.9, 89.9) at concentrations less than 40 nmol/L, and then decreased by 68.5 g (95% CI: -110.5, -26.6) at concentrations from 40 to 70 nmol/L. This study provides the first epidemiological evidence that there was an inverted U shaped relationship between neonatal vitamin D status and fetal growth, and the risk of SGA reduced at moderate concentration.

Spatiotemporal Clustering Analysis and Risk Assessments of Human Cutaneous Anthrax in China, 2005-2012.

OBJECTIVE: To investigate the epidemic characteristics of human cutaneous anthrax (CA) in China, detect the spatiotemporal clusters at the county level for preemptive public health interventions, and evaluate the differences in the epidemiological characteristics within and outside clusters. METHODS: CA cases reported during 2005-2012 from the national surveillance system were evaluated at the county level using space-time scan statistic. Comparative analysis of the epidemic characteristics within and outside identified clusters was performed using using the χ2 test or Kruskal-Wallis test. RESULTS: The group of 30-39 years had the highest incidence of CA, and the fatality rate increased with age, with persons ≥70 years showing a fatality rate of 4.04%. Seasonality analysis showed that most of CA cases occurred between May/June and September/October of each year. The primary spatiotemporal cluster contained 19 counties from June 2006 to May 2010, and it was mainly located straddling the borders of Sichuan, Gansu, and Qinghai provinces. In these high-risk areas, CA cases were predominantly found among younger, local, males, shepherds, who were living on agriculture and stockbreeding and characterized with high morbidity, low mortality and a shorter period from illness onset to diagnosis. CONCLUSION: CA was geographically and persistently clustered in the Southwestern China during 2005-2012, with notable differences in the epidemic characteristics within and outside spatiotemporal clusters; this demonstrates the necessity for CA interventions such as enhanced surveillance, health education, mandatory and standard decontamination or disinfection procedures to be geographically targeted to the areas identified in this study.

Cord blood vitamin D and neurocognitive development are nonlinearly related in toddlers.

BACKGROUND: Little is known about the relation between vitamin D status in early life and neurodevelopment outcomes. OBJECTIVE: This study was designed to examine the association of cord blood 25-hydroxyvitamin D [25(OH)D] at birth with neurocognitive development in toddlers. METHODS: As part of the China-Anhui Birth Cohort Study, 363 mother-infant pairs with complete data were selected. Concentrations of 25(OH)D in cord blood were measured by radioimmunoassay. Mental development index (MDI) and psychomotor development index (PDI) in toddlers were assessed at age 16-18 mo by using the Bayley Scales of Infant Development. The data on maternal sociodemographic characteristics and other confounding factors were also prospectively collected. RESULTS: Toddlers in the lowest quintile of cord blood 25(OH)D exhibited a deficit of 7.60 (95% CI: -12.4, -2.82; P = 0.002) and 8.04 (95% CI: -12.9, -3.11; P = 0.001) points in the MDI and PDI scores, respectively, compared with the reference category. Unexpectedly, toddlers in the highest quintile of cord blood 25(OH)D also had a significant deficit of 12.3 (95% CI: -17.9, -6.67; P < 0.001) points in PDI scores compared with the reference category. CONCLUSIONS: This prospective study suggested that there was an inverted-U-shaped relation between neonatal vitamin D status and neurocognitive development in toddlers. Additional studies on the optimal 25(OH)D concentrations in early life are needed.

Changes in rodent abundance and weather conditions potentially drive hemorrhagic fever with renal syndrome outbreaks in Xi'an, China, 2005-2012.

BACKGROUND: Increased risks for hemorrhagic fever with renal syndrome (HFRS) caused by Hantaan virus have been observed since 2005, in Xi'an, China. Despite increased vigilance and preparedness, HFRS outbreaks in 2010, 2011, and 2012 were larger than ever, with a total of 3,938 confirmed HFRS cases and 88 deaths in 2010 and 2011. METHODS AND FINDINGS: Data on HFRS cases and weather were collected monthly from 2005 to 2012, along with active rodent monitoring. Wavelet analyses were performed to assess the temporal relationship between HFRS incidence, rodent density and climatic factors over the study period. Results showed that HFRS cases correlated to rodent density, rainfall, and temperature with 2, 3 and 4-month lags, respectively. Using a Bayesian time-series Poisson adjusted model, we fitted the HFRS outbreaks among humans for risk assessment in Xi'an. The best models included seasonality, autocorrelation, rodent density 2 months previously, and rainfall 2 to 3 months previously. Our models well reflected the epidemic characteristics by one step ahead prediction, out-of-sample. CONCLUSIONS: In addition to a strong seasonal pattern, HFRS incidence was correlated with rodent density and rainfall, indicating that they potentially drive the HFRS outbreaks. Future work should aim to determine the mechanism underlying the seasonal pattern and autocorrelation. However, this model can be useful in risk management to provide early warning of potential outbreaks of this disease.

How environmental conditions impact mosquito ecology and Japanese encephalitis: an eco-epidemiological approach.

Japanese encephalitis (JE) is one of the major vector-borne diseases in Southeast Asia and the Western Pacific region, posing a threat to human health. In rural and suburban areas, traditional rice farming and intensive pig breeding provide an ideal environment for both mosquito development and the transmission of JEV among human beings. Combining surveillance data for mosquito vectors, human JE cases, and environmental conditions in Changsha, China, 2004-2009, generalized threshold models were constructed to project the mosquito and JE dynamics. Temperature and rainfall were found to be closely associated with mosquito density at 1, and 4month lag, respectively. The two thresholds, maximum temperature of 22-23°C for mosquito development and minimum temperature of 25-26°C for JEV transmission, play key roles in the ecology of JEV. The model predicts that, in the upper regime, a 1g/m(3) increase in absolute humidity would on average increase human cases by 68-84%. A shift in mosquito species composition in 2007 was observed, and possibly caused by a drought. Effective predictive models could be used in risk management to provide early warnings for potential JE transmission.

Association of a disintegrin and metalloprotease 33 (ADAM33) gene polymorphisms with the risk of COPD: an updated meta-analysis of 2,644 cases and 4,804 controls.

A series of observational studies have been made to investigate the association of the ADAM33 gene polymorphisms with the risk of COPD, but their results were conflicting. Therefore, we performed an updated meta-analysis to quantitatively summarize the associations of ADAM33 gene polymorphisms with the risk of COPD. Thirteen case-control studies referring to nine SNPs were identified: V4 (rs2787094), T+1 (rs2280089), T2 (rs2280090), T1 (rs2280091), S2 (rs528557), S1 (rs3918396), Q-1 (rs612709), F+1 (rs511898) and ST+5 (rs597980). A dominant model (AA+Aa vs. aa), recessive model (AA vs. Aa+aa), additive model (AA vs. aa) and allelic model (A vs. a) were used to evaluate the association of ADAM33 polymorphism with the risk of COPD. The results indicated that significant associations were found for ADAM33 T1, T2, S1, Q-1, F+1 and ST+5 polymorphisms associated with the risk of COPD in different populations. However, no significant associations were found for V4, T+1 and S2 polymorphisms with the risk of COPD in all genetic models, even in the subgroup analysis by ethnicity. This meta-analysis provided evidence that the ADAM33 T1, T2, S1, Q-1, F+1 and ST+5 six locus polymorphisms association with the risk of COPD. Furthermore, T2, Q-1 and ST+5 indicated an association with the risk of COPD in the European populations, whereas T1, T2, S1, F+1 and Q-1 indicated an association with the risk of COPD in the Asian populations.

Spatiotemporal transmission dynamics of hemorrhagic fever with renal syndrome in China, 2005-2012.

BACKGROUND: Hemorrhagic fever with renal syndrome (HFRS) is a rodent-borne disease caused by many serotypes of hantaviruses. In China, HFRS has been recognized as a severe public health problem with 90% of the total reported cases in the world. This study describes the spatiotemporal dynamics of HFRS cases in China and identifies the regions, time, and populations at highest risk, which could help the planning and implementation of key preventative measures. METHODS: Data on all reported HFRS cases at the county level from January 2005 to December 2012 were collected from Chinese Center for Disease Control and Prevention. Geographic Information System-based spatiotemporal analyses including Local Indicators of Spatial Association and Kulldorff's space-time scan statistic were performed to detect local high-risk space-time clusters of HFRS in China. In addition, cases from high-risk and low-risk counties were compared to identify significant demographic differences. RESULTS: A total of 100,868 cases were reported during 2005-2012 in mainland China. There were significant variations in the spatiotemporal dynamics of HFRS. HFRS cases occurred most frequently in June, November, and December. There was a significant positive spatial autocorrelation of HFRS incidence during the study periods, with Moran's I values ranging from 0.46 to 0.56 (P<0.05). Several distinct HFRS cluster areas were identified, mainly concentrated in northeastern, central, and eastern of China. Compared with cases from low-risk areas, a higher proportion of cases were younger, non-farmer, and floating residents in high-risk counties. CONCLUSIONS: This study identified significant space-time clusters of HFRS in China during 2005-2012 indicating that preventative strategies for HFRS should be particularly focused on the northeastern, central, and eastern of China to achieve the most cost-effective outcomes.

Increased risk of emergency hospital admissions for children with renal diseases during heatwaves in Brisbane, Australia.

BACKGROUND: Heatwaves have a significant impact on population health including both morbidity and mortality. In this study we examined the association between heatwaves and emergency hospital admissions (EHAs) for renal diseases in children (aged 0-14 years) in Brisbane, Australia. METHODS: Daily data on EHAs for renal diseases in children and exposure to temperature and air pollution were obtained for Brisbane city from January 1, 1996 to December 31, 2005. A time-stratified case-crossover design was used to compare the risks for renal diseases between heatwave and non-heatwave periods. RESULTS: There were 1565 EHAs for renal diseases in children during the study period. Heatwaves exhibited a significant impact on EHAs for renal diseases in children after adjusting for confounding factors (odds ratio: 3.6; 95% confidence interval: 1.4-9.5). The risk estimates differed with lags and the use of different heatwave definitions. CONCLUSIONS: There was a significant increase in EHAs for renal diseases in children during heatwaves in Brisbane, a subtropical city where people are well accustomed to warm weather. This finding may have significant implications for pediatric renal care, particularly in subtropical and tropical regions.

Spatial analysis of risk factors for transmission of the Barmah Forest virus in Queensland, Australia.

Barmah Forest virus (BFV) disease is the second most common mosquito-borne disease in Australia but few data are available on the risk factors. We assessed the impact of spatial climatic, socioeconomic and ecological factors on the transmission of BFV disease in Queensland, Australia, using spatial regression. All our analyses indicate that spatial lag models provide a superior fit to the data compared to spatial error and ordinary least square models. The residuals of the spatial lag models were found to be uncorrelated, indicating that the models adequately account for spatial and temporal autocorrelation. Our results revealed that minimum temperature, distance from coast and low tide were negatively and rainfall was positively associated with BFV disease in coastal areas, whereas minimum temperature and high tide were negatively and rainfall was positively associated with BFV disease (all P-value.

Spatial dynamic patterns of hand-foot-mouth disease in the People's Republic of China.

Hand-foot-mouth disease (HFMD) is the most common and widespread infectious disease in the People's Republic of China. Although there has been a substantial increase of HFMD in many parts of the country in recent years, its spatial dynamics and determinants remain unclear. When we collected and analysed weekly data on HFMD cases from 1,456 counties and the corresponding meteorological factors from 1 May 2008 to 27 March 2009, it was found that HFMD was spatially dispersed across the country in the summer and winter, while clustered in the spring and autumn. The spatial variation of HFMD was found to be affected by a combination of climate variables, while its spatio-temporal transmission was largely driven by temperature variations with a 7-week lag implying that (i) the dispersal of the disease can be anticipated based on the variation of the temperature and other climate variables; and (ii) the spatial dynamics of HFMD can be robustly predicted 7 weeks ahead of time using temperature data only. The findings reported allow prompt preparation and implementation of appropriate public health interventions to control and prevent disease outbreaks.

Atmospheric moisture variability and transmission of hemorrhagic fever with renal syndrome in Changsha City, Mainland China, 1991-2010.

BACKGROUND: The transmission of hemorrhagic fever with renal syndrome (HFRS) is influenced by environmental determinants. This study aimed to explore the association between atmospheric moisture variability and the transmission of hemorrhagic fever with renal syndrome (HFRS) for the period of 1991-2010 in Changsha, China. METHODS AND FINDINGS: Wavelet analyses were performed by using monthly reported time series data of HFRS cases to detect and quantify the periodicity of HFRS. A generalized linear model with a Poisson distribution and a log link model were used to quantify the relationship between climate and HFRS cases, highlighting the importance of moisture conditions. There was a continuous annual oscillation mode and multi-annual cycle around 3-4 years from 1994 to 1999. There was a significant association of HFRS incidence with moisture conditions and the Multivariate El Niño-Southern Oscillation Index (MEI). Particularly, atmospheric moisture has a significant effect on the propagation of HFRS; annual incidence of HFRS was positively correlated with annual precipitation and annual mean absolute humidity. CONCLUSIONS: The final model had good accuracy in forecasting the occurrence of HFRS and moisture condition can be used in disease surveillance and risk management to provide early warning of potential epidemics of this disease.