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1.  Area Differences in Spontaneous Abortion Rates in South Wales and Their Relation to Neural Tube Defect Incidence 
British Medical Journal  1973;4(5883):20-22.
Data are presented from the South Wales Congenital Malformation Survey (92,982 births 1964-6 inclusive) showing that within areas in South Wales there exists an inverse relation between previous spontaneous abortion rate and the prevalence at birth of neural tube defect (anencephaly or spina bifida cystica or both). This relation is independent of social class, parity, and maternal age, and is not likely to be explained by area differences in accuracy of reporting previous spontaneous abortions.
On the basis of these findings a hypothesis is advanced which proposes that the incidence of neural tube defects is uniform throughout South Wales and that the present substantial and relatively stable differences in area prevalence are controlled by small area differences in mortality of malformed embryos. This would seem to suggest that factors initiating the malformation are genetic and that any related environmental factors exert their effect on already abnormal fetuses by influencing, in one way or another, their capacity to survive.
PMCID: PMC1587098  PMID: 4585417
2.  Mortality from congenital malformations in England and Wales: variations by mother's country of birth. 
Archives of Disease in Childhood  1989;64(10):1457-1462.
Stillbirth and infant mortality from congenital malformations in England and Wales during 1981-5 was investigated according to the mother's country of birth. Significant differences remained after standardising for maternal age and social class. The highest overall mortality was in infants of mothers born in Pakistan (standardised mortality ratio 237), followed by infants of mothers born in India (standardised mortality ratio 134), East Africa (standardised mortality ratio 126), and Bangladesh (standardised mortality ratio 118). Caribbean and West African mothers showed an overall deficit. Mortality was inversely related to social class in all groups except the Afro-Caribbean. Infants of mothers born in Pakistan had the highest mortality in every social class except I, and for most anomalies investigated. Their ratios were particularly high for limb and musculoskeletal anomalies (standardised mortality ratio 362), genitourinary anomalies (standardised mortality ratio 268), and central nervous system anomalies (standardised mortality ratio 239). Our findings highlight the need for further research to identify the causes underlying these differences.
PMCID: PMC1792797  PMID: 2817931
3.  Trace elements in water and congenital malformations of the central nervous system in South Wales. 
The concentrations of 20 trace elements were determined by atomic absorption spectrophotometry on representative samples of tap-water collected from 48 local authority areas in South Wales. The associations between twelve trace elements and central nervous system (CNS) malformation rates for the 48 areas were examined. Significant correlations for four trace elements were observed. Of these, Al was positively correlated while for the remaining three-Ca, Ba, and Cu-negative associations were found. Regression analysis of the data suggested that the relationships between Ba and Cu with CNS malformation rates were improtant than those of Al and Ca.
PMCID: PMC478936  PMID: 949571
4.  Disease Presentation in Relation to Infection Foci for Non-Pregnancy-Associated Human Listeriosis in England and Wales, 2001 to 2007▿  
Journal of Clinical Microbiology  2009;47(10):3301-3307.
Listeriosis is a rare but severe food-borne disease, affecting unborn or newly delivered infants, the elderly, and the immunocompromised. The epidemiology of listeriosis in England and Wales changed between 2001 and 2007, with more patients ≥60 years old presenting with bacteremia (but without central nervous system [CNS] involvement). In order to explain this increase and understand the altered disease presentation, clinical, microbiological, and seasonal data on bacteremic cases of Listeria monocytogenes infection identified through national surveillance were compared with those for patients with CNS infections. Logistic regression analysis was applied while controlling for age. Bacteremic patients, who presented more frequently with gastrointestinal symptoms, were more likely to have underlying medical conditions than CNS patients. This was most marked in patients with malignancies, particularly digestive organ malignancies. Treatment to reduce stomach acid secretion modified the effect of nonmalignant underlying conditions on outcome, i.e., patients with an underlying condition who were not taking acid-suppressing medication were equally likely to have a bacteremic or a CNS infection. However, this type of therapy did not modify the effect of malignancies on the likelihood of having a bacteremic or a CNS infection. The increase in the incidence of human listeriosis among patients ≥60 years old in England and Wales between 2001 and 2007 appears to have occurred in those with cancer or other conditions whose treatment included acid-suppressing medication. Therefore, this vulnerable patient group needs specific dietary advice on avoiding risk factors for listeriosis.
PMCID: PMC2756898  PMID: 19675217
5.  Seasonality of coronary artery deaths in New South Wales, Australia 
Heart  2002;88(1):30-34.
Background: Complex temporal variations in coronary deaths, including diurnal, weekly, and seasonal trends, have been reported worldwide.
Objective: To describe the magnitude of seasonal changes in coronary artery deaths in New South Wales, Australia.
Design: Hospital morbidity data, mortality statistics, and meteorological data were modelled using time series techniques to determine seasonality of coronary deaths. Data were also analysed to determine whether there was an increase in deaths before or after the Christmas and New Year holidays.
Results: A clear seasonality of coronary deaths was shown, with a peak in July. A mean of 2.8 excess coronary deaths per 100 deaths was estimated to occur from June to August each year, with a mean annual excess of 224 winter deaths a year. Mortality data did not show an increase in coronary death ratios before (p = 0.626) or after (p = 0.813) the Christmas and New Year holidays in December.
Conclusions: There is a higher incidence of coronary deaths in winter, which may reflect winter respiratory infections, the direct effect of cold, seasonal changes in lipid concentration, and other factors associated with winter. Hospitals should have contingency plans during the winter months to manage larger numbers of cardiac admissions.
PMCID: PMC1767180  PMID: 12067938
coronary artery disease; mortality; seasonality
6.  Neural tube defects in New South Wales, Australia 
Journal of Medical Genetics  1978;15(5):329-338.
Cases of spina bifida cystica, encephalocele, and anencephaly occurring over a 9-year period, 1965 to 1973, in New South Wales, Australia, were identified. A low frequency of 1·1 for spina bifida and encephalocele (SB) and 0·9 for anencephaly (A) was found.
Secular trends parallel to those observed in the northern hemisphere were noted.
Detailed analysis of 1575 cases showed an excess of births in spring, corresponding with conception in the summer months, after correction for shorter gestation in anencephalus, which varies from the peak of spring conceptions observed in British studies.
An excess of female cases for each abnormality and a social class effect with a deficit of cases in classes I and II and an excess in classes IV and V and ex-nuptial births were apparent. The first birth rank for younger mothers did not show a significantly increased risk; however, the effect of high birth rank and older maternal age was more significant. Migration studies showed that in migrating from areas of high incidence these parents maintain a higher risk than the Australian population.
The highest risk group was that in which both parents were born in the UK, and the next highest that in which an English-born mother was married to an Australian father.
Mothers from Malta, and either or both parents from Lebanon, Egypt, and Austria were also at high risk.
Part-aboriginal children had a higher risk rate for ASB than white Australian children.
The proportion of older sibs affected was 4·12% of sibs of both sexes of an index case of spina bifida, and 3·19% of an index case of anencephaly. The abnormalities alternate or recur in families. An increased perinatal mortality rate in sibs was shown.
Twin studies showed a higher concordance rate for monochorionic pairs.
A sequential interaction in an excess of opposite sex sib before an index case was apparent.
The results of this study support a multifactorial aetiology for ASB resulting from genetic environmental interaction.
New South Wales is the eastern coastal state of Australia, with an area of 309 433 square miles and a population of 4 640 800 at the 1971 Census. The continent is geographically isolated with a large migrant population, seasonal reversal, and a hot climate.
PMCID: PMC1013727  PMID: 739521
7.  Seasonal prevalence of major congenital malformations in the Fylde of Lancashire 1957-1981. 
The seasonal prevalence of major congenital malformations was studied in a prospective survey of 88,449 children born in the circumscribed Fylde of Lancashire to residents there over 25 years. Ascertainment was thought to be as complete as was practically possible because cases were recorded daily by one, and for 17 years the only, paediatrician and a very high rate of necropsies was maintained. The number of malformations were classified by month of maternal last menstrual period and seasonal variation was assessed by three statistical models. Neural tube defects showed a significant seasonal variation in month of last menstrual period but not in month of birth. From May 1956 to April 1968, when the prevalence of neural tube defects was high (5.5 per 1000 total births), conceptions were significantly more common in December to May. For anencephaly alone the figures were not significant, but spina bifida and cranium bifidum were more common in March to May. From May 1968 to April 1981, when the prevalence of neural tube defects fell below the national average, the significant variations disappeared. Seasonality for spina bifida and cranium bifidum was seen only in "singles" (cases with no other major lesion), but for anencephaly it was seen only in "multiples" (cases with other lesions). The three types of cardiac septal defect and persistent ductus each showed a higher prevalence of conceptions at some time during May to October. In contrast the commonest group of cyanotic cases showed no such pattern but with greater numbers in winter. There was evidence of a seasonal variation for bilateral renal agenesis and for vesicoureteric reflux as ascertained. Seasonal prevalence in an aetiological factor for certain malformations of the central nervous system, cardiac and urinary systems.
PMCID: PMC1052870  PMID: 2614322
8.  Prospective study of liver dysfunction in pregnancy in Southwest Wales 
Gut  2002;51(6):876-880.
Background: Liver dysfunction in pregnancy has serious consequences. Its frequency and characteristics have not been systematically documented in Britain. We have prospectively determined incidence, causes, and outcome of liver dysfunction in pregnancy in an obstetric unit in Southwest Wales, UK.
Methods: A central laboratory identified all abnormal liver tests (bilirubin >25 μmol/l, aspartate transaminase >40 U/l, or γ glutamyl transpeptidase >35 U/l) from patients in antenatal clinics and wards of an obstetric unit serving a population of 250 000. Patients with abnormal liver tests were assessed and followed through after pregnancy. Medical advice was provided to obstetric teams.
Findings: There were 4377 deliveries during the 15 month study. A total of 142 patients had abnormal liver tests. There were 206 contributing diagnoses, the great majority being pregnancy specific. Among the most important were pre-eclampsia (68), HELLP (haemolysis, elevated liver enzymes, low platelets) syndrome (30), obstetric cholestasis (23), hyperemesis gravidarum (11), acute fatty liver of pregnancy (five), and hepatic infarct (one). Sepsis, postoperative factors, and placental pathology (51) were not uncommonly responsible but incidental or pre-existing hepatobiliary disease was infrequent (17). Sixty five patients were delivered early by induction or caesarean section because of liver dysfunction. Despite substantial liver related morbidity, there were no maternal deaths and only two intrauterine deaths.
Conclusions: Liver dysfunction was seen in 3% of deliveries during a 15 month prospective study and was usually directly related to pregnancy with spontaneous recovery in the puerperium. Incidence of the most serious conditions, acute fatty liver of pregnancy and HELLP syndrome, was much greater than previously reported. Profound effects on maternal and infant health were observed but close medical and obstetric collaboration ensured low mortality.
PMCID: PMC1773454  PMID: 12427793
pregnancy; liver dysfunction; obstetric cholestasis; pre-eclampsia; HELLP syndrome; acute fatty liver of pregnancy
9.  Comparison of central nervous system malformations in spontaneous absortions in Northern Ireland and south-east England. 
British Medical Journal  1979;1(6175):1395-1397.
A study of 1140 pregnancies ending in spontaneous abortion disclosed a central nervous system (CNS) malformation in 4.9% of all complete conceptuses. Life-table analysis suggested that the incidence of CNS malformations is 16/1000 at the beginning of the eighth week of gestation. It was also estimated that only one-fifth of these infants are born alive, 41% being aborted spontaneously and 38% stillborn. A hypothesis that differences in the incidence of CNS malformations result from area differences in the mortality rate of malformed embryos and fetuses was examined by comparing the findings in Northern Ireland, an area of high incidence, with those in south-east England, an area of low incidence. In Northern Ireland 4.6% of complete conceptuses had a CNS malformation compared with 3.0% in south-east England, but the difference was not statistically significant. There is no evidence that in Northern Ireland a lower mortality rate among malformed fetuses and embryos is responsible for the high incidence of malformation at birth. The geographical variation of CNS malformations in the United Kingdom still awaits explanation.
PMCID: PMC1598902  PMID: 445098
10.  Demographic factors associated with smoking cessation during pregnancy in New South Wales, Australia, 2000–2011 
BMC Public Health  2015;15:398.
Smoking during pregnancy increases the risk of adverse health outcomes for both the mother and the child. Rates of smoking during pregnancy, and rates of smoking cessation during pregnancy, vary between demographic groups. This study describes demographic factors associated with smoking cessation during pregnancy in New South Wales, Australia, and describes trends in smoking cessation in demographic subgroups over the period 2000 – 2011.
Data were obtained from the New South Wales Perinatal Data Collection, a population-based surveillance system covering all births in New South Wales. Multivariate logistic regression was used to explore associations between smoking cessation during pregnancy and demographic factors.
Between 2000 and 2011, rates of smoking cessation in pregnancy increased from 4.0% to 25.2%. Demographic characteristics associated with lower rates of smoking cessation during pregnancy included being a teenage mother, being an Aboriginal person, and having a higher number of previous pregnancies.
Between 2000 and 2011, rates of smoking cessation during pregnancy increased dramatically across all demographic groups. However, specific demographic groups remain significantly less likely to quit smoking, suggesting a need for targeted efforts to promote smoking cessation in these groups.
PMCID: PMC4450495  PMID: 25928643
Smoking; Smoking cessation; Smoking in pregnancy; Epidemiology; Australia
11.  Acanthamoeba keratitis in England and Wales: incidence, outcome, and risk factors 
AUTHOR:e-mail address please Aim: To determine the incidence, regional variation in frequency, outcome, and risk factors for acanthamoeba keratitis (AK) in England and Wales.
Methods: AK cases presenting from 1 October 1997 to 30 September 1999 were identified by the British Ophthalmic Surveillance Unit active reporting system. Clinical and patient postal questionnaire data were analysed.
Results: 106 reported cases met study criteria. The annual incidence for the 2 years was 1.26 and 1.13 per million adults and, for contact lens (CL) wearers, 21.14 and 17.53 per million. There was marked regional variation in incidence (0 to 85.13 per million adult CL wearers), with CL wearers in the south having a ninefold increased risk of AK compared with those resident in the north (95% confidence limits: 2.2–38.9, p<0.0001), and a threefold increased risk with hard as opposed to soft domestic water (95% confidence limits: 1.73 to 6.58, p<0.001). Treatment and outcome data were similar to those previously reported. 93/106 (88%) patients were CL wearers. Among these, 46/77 (60%) were disinfecting irregularly, and 20/63 (32%) had been swimming in CLs. One step hydrogen peroxide and chlorine release soft CL (SCL) disinfection systems were significantly over-represented among the cases. Among SCL users, one or more previously established risk factors for AK were identified in 50/55 (91%) patients.
Conclusions: The incidence was considerably higher than most previous estimates, and was static. The geographical variation in incidence may be partly related to the increase in risk associated with hard water. The fact that water quality can have such an effect on the risk of AK suggests that many CL wearers must be letting tapwater come into contact with their lenses or storage cases. Improved education for CL wearers and practitioners about hygiene practice and the variable efficacy of contact lens systems could be expected to reduce the incidence of this disease.
PMCID: PMC1771120  PMID: 11973250
acanthamoeba; keratitis; England and Wales
12.  Mortality from cardiovascular disease among interregional migrants in England and Wales. 
BMJ : British Medical Journal  1995;310(6977):423-427.
OBJECTIVE--To investigate the extent to which geographical variations in mortality from ischaemic heart disease and stroke in Britain are influenced by factors in early life or in adulthood. DESIGN--Longitudinal study of migrants. SUBJECTS--1% sample of residents in England and Wales born before October 1939 and enumerated at the 1971 census (the Office of Population Censuses and Surveys' longitudinal study). MAIN OUTCOME MEASURE--18,221 deaths from ischaemic heart disease and 9899 deaths from stroke during 1971-88 were analysed by areas of residence in 1939 and 1971. These included 2928 deaths from ischaemic heart disease and 1608 deaths from stroke among individuals moving between 14 areas defined by the major conurbations and nine standard administrative regions of England and Wales. RESULTS--The southeast to northwest gradient in mortality from ischaemic heart disease was related significantly to both the 1939 area (chi 2 = 6.09, df = 1) and area in 1971 (chi 2 = 5.05, df = 1). Geographical variations in mortality from stroke were related significantly to the 1939 area (chi 2 = 4.09, df = 1) but the effect of area in 1971 was greater (chi 2 = 8.07, df = 1). The effect of 1971 area on mortality from stroke was largely due to a lower risk of death from stroke among individuals moving into Greater London compared with migrants to the rest of the South East region (chi 2 = 4.54, df = 1). CONCLUSIONS--Geographical variations in mortality from cardiovascular disease in Britain may be partly determined by genetic factors, environmental exposures, or lifestyle acquired early in life, but the risk of fatal ischaemic heart disease and stroke changes on migration between areas with differing mortality. The low risk of death from stroke associated with residence in Greater London is acquired by individuals who move there.
PMCID: PMC2548815  PMID: 7873946
13.  Congenital anterior abdominal wall defects in England and Wales 1987-93: retrospective analysis of OPCS data. 
BMJ : British Medical Journal  1996;313(7062):903-906.
OBJECTIVES: Analysis of incidence and characteristics of congenital abdominal wall defects, with special reference to the differences between the incidence of gastroschisis and exomphalos (omphalocele). DESIGN: Retrospective analysis using data from the Office of Population Censuses and Surveys (recoded to differentiate exomphalos and gastroschisis) and the National Congenital Malformation Notification Scheme. SETTING: England and Wales, 1987 to 1993. RESULTS: 1043 congenital anterior abdominal wall defects were notified within the seven year study period. Of these, 539 were classified as gastroschisis, 448 as exomphalos, 19 as "prune belly syndrome," and 37 as "unclassified." Gastroschisis doubled in incidence from 0.65 in 1987 to 1.35 per 10,000 total births in 1991, with little further change; the incidence of exomphalos decreased from 1.13 to 0.77 per 10000 births. The overall incidence of notified congenital abdominal wall defects was 2.15 per 10000 total births. Gastroschisis was associated with a lower overall maternal age than exomphalos and with a significantly lower proportion of additional reported congenital malformations (5.0%) than in the cohort with exomphalos (27.4%) (odds ratio 0.14, 95% confidence interval 0.09 to 0.22; P < 0.001). The sex ratio of the two cohorts was the same. The incidence of gastroschisis and exomphalos was higher in the northern regions of England than in the south east of the country. CONCLUSIONS: The national congenital malformation notification system showed an increasing trend in the incidence of fetuses born with gastroschisis and a progressive decreasing incidence of exomphalos in England and Wales between 1987 and 1993. Although the reasons for this are likely to be multifactorial, a true differential change seems likely. The observed increase in incidence of gastroschisis relative to exomphalos and the differentiation in maternal age have implications for resource management within the NHS and warrant further epidemiological monitoring. Regional differences may be due to a dietary or environmental factor, which requires further study.
PMCID: PMC2352268  PMID: 8876090
14.  Socio-demographic factors associated with smoking and smoking cessation among 426,344 pregnant women in New South Wales, Australia 
BMC Public Health  2005;5:138.
This study explores the socio-demographic characteristics of pregnant women who continue to smoke during the pregnancy, and identifies the characteristics of the smokers who were likely to quit smoking during the pregnancy period.
This was secondary analysis of the New South Wales (NSW) Midwives Data Collection (MDC) 1999–2003, a surveillance system covering all births in NSW public and private hospitals, as well as home births. Bivariate and multiple logistic regression analyses were performed to explore the associations between socio-demographic characteristics and smoking behaviour during pregnancy.
Data from 426,344 pregnant women in NSW showed that 17.0% continued to smoke during pregnancy. The smoking rate was higher among teenage mothers, those with an Aboriginal (indigenous) background, and lower among more affluent and overseas-born mothers. This study also found that unbooked confinements, and lack of antenatal care in the first trimester were strongly associated with increased risk of smoking during pregnancy. About 4.0% of the smoking women reported they may quit smoking during their pregnancy. Findings showed that mothers born overseas, of higher socio-economic status, first time mothers and those who attended antenatal care early showed an increased likelihood of smoking cessation during pregnancy. Those who were heavy smokers were less likely to quit during pregnancy.
Although the prevalence of smoking during pregnancy has been declining, it remains a significant public health concern. Smoking cessation programs should target the population subgroups of women at highest risk of smoking and who are least likely to quit. Effective antismoking interventions could reduce the obstetric and perinatal complications of smoking in pregnancy.
PMCID: PMC1352372  PMID: 16371166
15.  Characterization of Regional Influenza Seasonality Patterns in China and Implications for Vaccination Strategies: Spatio-Temporal Modeling of Surveillance Data 
PLoS Medicine  2013;10(11):e1001552.
Cécile Viboud and colleagues describe epidemiological patterns of influenza incidence across China to support the design of a national vaccination program.
Please see later in the article for the Editors' Summary
The complexity of influenza seasonal patterns in the inter-tropical zone impedes the establishment of effective routine immunization programs. China is a climatologically and economically diverse country, which has yet to establish a national influenza vaccination program. Here we characterize the diversity of influenza seasonality in China and make recommendations to guide future vaccination programs.
Methods and Findings
We compiled weekly reports of laboratory-confirmed influenza A and B infections from sentinel hospitals in cities representing 30 Chinese provinces, 2005–2011, and data on population demographics, mobility patterns, socio-economic, and climate factors. We applied linear regression models with harmonic terms to estimate influenza seasonal characteristics, including the amplitude of annual and semi-annual periodicities, their ratio, and peak timing. Hierarchical Bayesian modeling and hierarchical clustering were used to identify predictors of influenza seasonal characteristics and define epidemiologically-relevant regions. The annual periodicity of influenza A epidemics increased with latitude (mean amplitude of annual cycle standardized by mean incidence, 140% [95% CI 128%–151%] in the north versus 37% [95% CI 27%–47%] in the south, p<0.0001). Epidemics peaked in January–February in Northern China (latitude ≥33°N) and April–June in southernmost regions (latitude <27°N). Provinces at intermediate latitudes experienced dominant semi-annual influenza A periodicity with peaks in January–February and June–August (periodicity ratio >0.6 in provinces located within 27.4°N–31.3°N, slope of latitudinal gradient with latitude −0.016 [95% CI −0.025 to −0.008], p<0.001). In contrast, influenza B activity predominated in colder months throughout most of China. Climate factors were the strongest predictors of influenza seasonality, including minimum temperature, hours of sunshine, and maximum rainfall. Our main study limitations include a short surveillance period and sparse influenza sampling in some of the southern provinces.
Regional-specific influenza vaccination strategies would be optimal in China; in particular, annual campaigns should be initiated 4–6 months apart in Northern and Southern China. Influenza surveillance should be strengthened in mid-latitude provinces, given the complexity of seasonal patterns in this region. More broadly, our findings are consistent with the role of climatic factors on influenza transmission dynamics.
Please see later in the article for the Editors' Summary
Editors' Summary
Every year, millions of people worldwide catch influenza, a viral disease of the airways. Most infected individuals recover quickly but seasonal influenza outbreaks (epidemics) kill about half a million people annually. These epidemics occur because antigenic drift—frequent small changes in the viral proteins to which the immune system responds—means that an immune response produced one year provides only partial protection against influenza the next year. Annual vaccination with a mixture of killed influenza viruses of the major circulating strains boosts this natural immunity and greatly reduces the risk of catching influenza. Consequently, many countries run seasonal influenza vaccination programs. Because the immune response induced by vaccination decays within 4–8 months of vaccination and because of antigenic drift, it is important that these programs are initiated only a few weeks before the onset of local influenza activity. Thus, vaccination starts in early autumn in temperate zones (regions of the world that have a mild climate, part way between a tropical and a polar climate), because seasonal influenza outbreaks occur in the winter months when low humidity and low temperatures favor the transmission of the influenza virus.
Why Was This Study Done?
Unlike temperate regions, seasonal influenza patterns are very diverse in tropical countries, which lie between latitudes 23.5°N and 23.5°S, and in the subtropical countries slightly north and south of these latitudes. In some of these countries, there is year-round influenza activity, in others influenza epidemics occur annually or semi-annually (twice yearly). This complexity, which is perhaps driven by rainfall fluctuations, complicates the establishment of effective routine immunization programs in tropical and subtropical countries. Take China as an example. Before a national influenza vaccination program can be established in this large, climatologically diverse country, public-health experts need a clear picture of influenza seasonality across the country. Here, the researchers use spatio-temporal modeling of influenza surveillance data to characterize the seasonality of influenza A and B (the two types of influenza that usually cause epidemics) in China, to assess the role of putative drivers of seasonality, and to identify broad epidemiological regions (areas with specific patterns of disease) that could be used as a basis to optimize the timing of future Chinese vaccination programs.
What Did the Researchers Do and Find?
The researchers collected together the weekly reports of laboratory-confirmed influenza prepared by the Chinese national sentinel hospital-based surveillance network between 2005 and 2011, data on population size and density, mobility patterns, and socio-economic factors, and daily meteorological data for the cities participating in the surveillance network. They then used various statistical modeling approaches to estimate influenza seasonal characteristics, to assess predictors of influenza seasonal characteristics, and to identify epidemiologically relevant regions. These analyses indicate that, over the study period, northern provinces (latitudes greater than 33°N) experienced winter epidemics of influenza A in January–February, southern provinces (latitudes less than 27°N) experienced peak viral activity in the spring (April–June), and provinces at intermediate latitudes experienced semi-annual epidemic cycles with infection peaks in January–February and June–August. By contrast, influenza B activity predominated in the colder months throughout China. The researchers also report that minimum temperatures, hours of sunshine, and maximum rainfall were the strongest predictors of influenza seasonality.
What Do These Findings Mean?
These findings show that influenza seasonality in China varies between regions and between influenza virus types and suggest that, as in other settings, some of these variations might be associated with specific climatic factors. The accuracy of these findings is limited by the short surveillance period, by sparse surveillance data from some southern and mid-latitude provinces, and by some aspects of the modeling approach used in the study. Further surveillance studies need to be undertaken to confirm influenza seasonality patterns in China. Overall, these findings suggest that, to optimize routine influenza vaccination in China, it will be necessary to stagger the timing of vaccination over three broad geographical regions. More generally, given that there is growing interest in rolling out national influenza immunization programs in low- and middle-income countries, these findings highlight the importance of ensuring that vaccination strategies are optimized by taking into account local disease patterns.
Additional Information
Please access these websites via the online version of this summary at 10.1371/journal.pmed.1001552.
This study is further discussed in a PLOS Medicine Perspective by Steven Riley
The UK National Health Service Choices website provides information for patients about seasonal influenza and about influenza vaccination
The World Health Organization provides information on seasonal influenza (in several languages) and on influenza surveillance and monitoring
The US Centers for Disease Control and Prevention also provides information for patients and health professionals on all aspects of seasonal influenza, including information about vaccination; its website contains a short video about personal experiences of influenza., a US government website, provides access to information on seasonal influenza and vaccination
Information about the Chinese National Influenza Center, which is part of the Chinese Center for Disease Control and Prevention: and which runs influenza surveillance in China, is available (in English and Chinese)
MedlinePlus has links to further information about influenza and about vaccination (in English and Spanish)
A recent PLOS Pathogens Research Article by James D. Tamerius et al. investigates environmental predictors of seasonal influenza epidemics across temperate and tropical climates
A study published in PLOS ONE by Wyller Alencar de Mello et al. indicates that Brazil, like China, requires staggered timing of vaccination from Northern to Southern states to account for different timings of influenza activity.
PMCID: PMC3864611  PMID: 24348203
16.  Late entry to antenatal care in New South Wales, Australia 
This study aimed to assess the prevalence of women who entered antenatal care (ANC) late and to identify factors related to the late entry to ANC in New South Wales (NSW) in 2004.
The NSW Midwives Data Collection contained data of 85,034 women who gave birth in 2004. Data were downloaded using SAS and transferred to STATA 8.0. Entering ANC after 12 weeks of gestation was classified as late. The Andersen Health Seeking Behaviour Model was used for selection and analyses of related factors. Regression and hierarchical analyses were used to identify significant factors and their relative contributions to the variation of pregnancy duration at entry to ANC.
41% of women commenced ANC after 12 weeks of gestation. Inequality existed between groups of women with predisposing characteristics and enabling resources contributed more to the variation in pregnancy duration at entry to ANC than needs. The groups of women with highest risk were teenagers, migrants from developing countries, women living in Western Sydney, Aboriginal and Torres Strait Islanders, women with three or more previous pregnancies and heavy smokers. The high risk groups with largest number of women were migrants from developing countries and women living in Western Sydney.
A large number of women in NSW entered ANC late in their pregnancies. Efforts to increase early entry to ANC should be targeted on identified high risk groups of women.
PMCID: PMC1562358  PMID: 16916473
17.  Epidemiology and trends for Caesarean section births in New South Wales, Australia: A population-based study 
Caesarean section (CS) rates around the world have been increasing and in Australia have reached 30% of all births. Robson's Ten-Group Classification System (10-group classification) provides a clinically relevant classification of CS rates that provides a useful basis for international comparisons and trend analyses. This study aimed to investigate trends in CS rates in New South Wales (NSW), including trends in the components of the 10-group classification.
We undertook a cross-sectional study using data from the Midwives Data Collection, a state-wide surveillance system that monitors patterns of pregnancy care, services and pregnancy outcomes in New South Wales, Australia. The study population included all women giving birth between 1st January 1998 and 31st December 2008. Descriptive statistics are presented including age-standardised CS rates, annual percentage change as well as regression analyses.
From 1998 to 2008 the CS rate in NSW increased from 19.1 to 29.5 per 100 births. There was a significant average annual increase in primary 4.3% (95%CI 3.0-5.7%) and repeat 4.8% (95% CI 3.9-5.7%) CS rates from 1998 to 2008. After adjusting for maternal and pregnancy factors, the increase in CS delivery over time was maintained. When examining CS rates classified according to the 10-group classification, the greatest contributors to the overall CS rate and the largest annual increases occurred among nulliparae at term having elective CS and multipara having elective repeat CS.
Given that the increased CS rate cannot be explained by known and collected maternal or pregnancy characteristics, the increase may be related to differences in clinical decision making or maternal request. Future efforts to reduce the overall CS rate should be focussed on reducing the primary CS rate.
PMCID: PMC3037931  PMID: 21251270
18.  Myxomatosis in farmland rabbit populations in England and Wales. 
Epidemiology and Infection  1989;103(2):333-357.
The overall pattern and consequences of myxomatosis in wild rabbit populations were studied at three farmland sites in lowland southern England and upland central Wales between 1971 and 1978. When results from all years were combined, the disease showed a clear two-peaked annual cycle, with a main autumn peak between August and January, and a subsidiary spring peak during February to April. Rabbit fleas, the main vectors of myxomatosis in Britain, were present on full-grown rabbits in sufficient numbers for transmission to occur throughout the year, but the observed seasonal pattern of the disease appeared to be influenced by seasonal mass movements of these fleas. However other factors were also important including the timing and success of the main rabbit breeding season, the proportion of rabbits which had recovered from the disease and the timing and extent of autumn rabbit mortality from other causes. Significantly more males than females, and more adults and immatures than juveniles, were observed to be infected by myxomatosis. Only 25-27% of the total populations were seen to be infected during outbreaks. Using two independent methods of calculation, it was estimated that between 47 and 69% of infected rabbits died from the disease (much lower than the expected 90-95% for fully susceptible rabbits with the partly attenuated virus strains that predominated). Thus it was estimated that 12-19% of the total rabbit populations were known to have died directly or indirectly from myxomatosis. Although the effects of myxomatosis were much less than during the 1950s and 1960s, it continued to be an important mortality factor. It may still have a regulatory effect on rabbit numbers, with autumn/winter peaks of disease reducing the numbers of rabbits present at the start of the breeding season.
PMCID: PMC2249516  PMID: 2806418
19.  Temperature-Driven Campylobacter Seasonality in England and Wales 
Campylobacter incidence in England and Wales between 1990 and 1999 was examined in conjunction with weather conditions. Over the 10-year interval, the average annual rate was determined to be 78.4 ± 15.0 cases per 100,000, with an upward trend. Rates were higher in males than in females, regardless of age, and highest in children less than 5 years old. Major regional differences were detected, with the highest rates in Wales and the southwest and the lowest in the southeast. The disease displayed a seasonal pattern, and increased campylobacter rates were found to be correlated with temperature. The most marked seasonal effect was observed for children under the age of 5. The seasonal pattern of campylobacter infections indicated a linkage with environmental factors rather than food sources. Therefore, public health interventions should not be restricted to food-borne approaches, and the epidemiology of the seasonal peak in human campylobacter infections may best be understood through studies in young children.
PMCID: PMC544220  PMID: 15640174
20.  Perinatal mortality and congenital anomalies in babies of women with type 1 or type 2 diabetes in England, Wales, and Northern Ireland: population based study 
BMJ : British Medical Journal  2006;333(7560):177.
Objective To provide perinatal mortality and congenital anomaly rates for babies born to women with type 1 or type 2 diabetes in England, Wales, and Northern Ireland.
Design National population based pregnancy cohort.
Setting 231 maternity units in England, Wales, and Northern Ireland.
Participants 2359 pregnancies to women with type 1 or type 2 diabetes who delivered between 1 March 2002 and 28 February 2003.
Main outcome measures Stillbirth rates; perinatal and neonatal mortality; prevalence of congenital anomalies.
Results Of 2359 women with diabetes, 652 had type 2 diabetes and 1707 had type 1 diabetes. Women with type 2 diabetes were more likely to come from a Black, Asian, or other ethnic minority group (type 2, 48.8%; type 1, 9.1%) and from a deprived area (type 2, 46.3% in most deprived fifth; type 1, 22.8%). Perinatal mortality in babies of women with diabetes was 31.8/1000 births. Perinatal mortality was comparable in babies of women with type 1 (31.7/1000 births) and type 2 diabetes (32.3/1000) and was nearly four times higher than that in the general maternity population. 141 major congenital anomalies were confirmed in 109 offspring. The prevalence of major congenital anomaly was 46/1000 births in women with diabetes (48/1000 births for type 1 diabetes; 43/1000 for type 2 diabetes), more than double that expected. This increase was driven by anomalies of the nervous system, notably neural tube defects (4.2-fold), and congenital heart disease (3.4-fold). Anomalies in 71/109 (65%) offspring were diagnosed antenatally. Congenital heart disease was diagnosed antenatally in 23/42 (54.8%) offspring; anomalies other than congenital heart disease were diagnosed antenatally in 48/67 (71.6%) offspring.
Conclusion Perinatal mortality and prevalence of congenital anomalies are high in the babies of women with type 1 or type 2 diabetes. The rates do not seem to differ between the two types of diabetes.
PMCID: PMC1513435  PMID: 16782722
21.  Geographical variation in the standardized years of potential life lost ratio (SYPLR) in women dying from malignancies of the breast in England and Wales. 
British Journal of Cancer  1997;75(7):1069-1074.
Geographical variation in the standardized years of potential life lost ratio (SYPLR) in women aged 20-74 dying from breast cancer has been mapped by local authority district in England and Wales and compared with the variation as described by the standardized mortality ratio (SMR). The geographical distribution of areas of low and high SMRs is similar to that observed some 15 years earlier, showing an increase from north to south. In contrast, the pattern of SYPLRs shows a less obvious trend. Years of life lost because of breast cancer mortality were particularly high in eight of the 401 county districts (SYPLR 1.22-1.48) and particularly low in nine (0.60-0.86). Mapping SYPLRs for breast cancer gives a different pattern from mapping SMRs, and one which is possibly more appropriate for targeting resources in circumstances in which death at younger age will have major social consequences. Care is required in interpreting maps indicating high and low rates in the presence of multiple comparisons. However, the range of values observed is suggestive of the need to investigate districts with contrasting values of SYPLR with respect to the inter-relationships between sociodemographic characteristics, duration of symptoms, clinical presentation and treatment efficacy.
PMCID: PMC2222757  PMID: 9083345
22.  Suicide and political regime in New South Wales and Australia during the 20th century 
Study objective: Australia has had a two party parliamentary political system for most of the period since its Federation in 1901, dominated either by a social democratic (Labor) or a conservative ideological perspective. This paper investigates whether such political differences at Federal and State levels have influenced suicide rates in the state of New South Wales (NSW) for the period 1901–1998.
Design: Federal government type, NSW State government type, and combinations of both Federal and NSW State government type were examined. Poisson regression models were stratified by sex and controlled for the effects of age, annual change in gross domestic product, sedative availability, drought, and both world wars.
Results: When both Federal and NSW State governments were conservative the relative risk of suicide for NSW men was 1.17 (p<0.001) and for women 1.40 (p<0.001) compared with both governments being Labor (1.00). A statistically significant linear trend (p<0.001) in suicide risk was evident across the continuum of Federal/State government combinations, from both Labor (lowest), to mixed (intermediate), to both conservative (highest).
Conclusion: Significantly higher suicide risk was associated with conservative government tenures compared with social democratic incumbents. Results are discussed in terms of the differences underpinning conservative and social democratic government programme ideology, and their relevance to Durkheim's theories of suicide, social regulation, and integration.
PMCID: PMC1732038  PMID: 12239203
23.  Epidemiology of Influenza-like Illness during Pandemic (H1N1) 2009, New South Wales, Australia 
Emerging Infectious Diseases  2011;17(7):1240-1247.
To rapidly describe the epidemiology of influenza-like illness (ILI) during the 2009 winter epidemic of pandemic (H1N1) 2009 virus in New South Wales, Australia, we used results of a continuous population health survey. During July–September 2009, ILI was experienced by 23% of the population. Among these persons, 51% were unable to undertake normal duties for <3 days, 55% sought care at a general practice, and 5% went to a hospital. Factors independently associated with ILI were younger age, daily smoking, and obesity. Effectiveness of prepandemic seasonal vaccine was ≈20%. The high prevalence of risk factors associated with a substantially increased risk for ILI deserves greater recognition.
PMCID: PMC3381394  PMID: 21762578
data collection; population; influenza; human; disease outbreaks; viruses; influenza-like illness; Australia; pandemic (H1N1) 2009; research
24.  Molybdenum distributions and variability in drinking water from England and Wales 
Environmental Monitoring and Assessment  2014;186(10):6403-6416.
An investigation has been carried out of molybdenum in drinking water from a selection of public supply sources and domestic taps across England and Wales. This was to assess concentrations in relation to the World Health Organization (WHO) health-based value for Mo in drinking water of 70 μg/l and the decision to remove the element from the list of formal guideline values. Samples of treated drinking water from 12 water supply works were monitored up to four times over an 18-month period, and 24 domestic taps were sampled from three of their supply areas. Significant (p < 0.05) differences were apparent in Mo concentration between sources. Highest concentrations were derived from groundwater from a sulphide-mineralised catchment, although concentrations were only 1.5 μg/l. Temporal variability within sites was small, and no seasonal effects (p > 0.05) were detected. Tap water samples collected from three towns (North Wales, the English Midlands, and South East England) supplied uniquely by upland reservoir water, river water, and Chalk groundwater, respectively, also showed a remarkable uniformity in Mo concentrations at each location. Within each, the variability was very small between houses (old and new), between pre-flush and post-flush samples, and between the tap water and respective source water samples. The results indicate that water distribution pipework has a negligible effect on supplied tap water Mo concentrations. The findings contrast with those for Cu, Zn, Ni, Pb, and Cd, which showed significant differences (p < 0.05) in concentrations between pre-flush and post-flush tap water samples. In two pre-flush samples, concentrations of Ni or Pb were above drinking water limits, although in all cases, post-flush waters were compliant. The high concentrations, most likely derived from metal pipework in the domestic distribution system, accumulated during overnight stagnation. The concentrations of Mo observed in British drinking water, in all cases less than 2 μg/l, were more than an order of magnitude below the WHO health-based value and suggest that Mo is unlikely to pose a significant health or water supply problem in England and Wales.
PMCID: PMC4149886  PMID: 25012143
Trace metals; Groundwater; Surface water; Health; Monitoring; WHO
25.  Dental caries in 14- and 15-year-olds in New South Wales, Australia 
BMC Public Health  2013;13:1060.
Dental caries remains one of the most common chronic diseases of adolescents. In Australia there have been few epidemiological studies of the caries experience of adolescents with most surveys focusing on children. The New South Wales (NSW) Teen Dental Survey 2010 is the second major survey undertaken by the Centre for Oral Health Strategy. The survey is part of a more systematic and efficient approach to support State and Local Health District dental service planning and will also be used for National reporting purposes.
Data for the NSW Teen Dental Survey were collected in 2010 from a random sample of Year 9 secondary school students aged 14 to 15 years from metropolitan and non-metropolitan schools under the jurisdiction of the NSW Department of Education and Training, the Catholic Education Commission and Independent Schools in New South Wales. Nineteen calibrated examiners performed 1269 clinical examinations at a total of 84 secondary schools across NSW. The survey was accompanied by a questionnaire looking at oral health related behaviours, risk factors and the usage of the Medicare Teen Dental Plan.
175 schools were contacted, with 84 (48%) accepting the invitation to participate in the study. A total of 5,357 student consent forms and parent information packages were sent out and 1,256 students were examined; leading to a student participation rate of 23%. The survey reported a mean DMFT for 14 and 15 year olds of 1.2 and it was identified that 45.4% of students had an experience of dental caries. Major variations in caries experience reported occurred by remoteness, water fluoridation status, socio-economic status and household income levels.
The NSW Teen Dental Survey provided state-wide data that will contribute to the national picture on adolescent oral health. The mean DMFT score of 1.2 is similar to the national caries experience data for this age group from the Australian Child Dental Health Survey in 2009.
PMCID: PMC3840655  PMID: 24209635
Teen dental survey; School children; Adolescents; Caries experience

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