Insights from past millennia into climatic impacts on human health and survival.

Climate change poses threats to human health, safety, and survival via weather extremes and climatic impacts on food yields, fresh water, infectious diseases, conflict, and displacement. Paradoxically, these risks to health are neither widely nor fully recognized. Historical experiences of diverse societies experiencing climatic changes, spanning multicentury to single-year duration, provide insights into population health vulnerability--even though most climatic changes were considerably less than those anticipated this century and beyond. Historical experience indicates the following. (i) Long-term climate changes have often destabilized civilizations, typically via food shortages, consequent hunger, disease, and unrest. (ii) Medium-term climatic adversity has frequently caused similar health, social, and sometimes political consequences. (iii) Infectious disease epidemics have often occurred in association with briefer episodes of temperature shifts, food shortages, impoverishment, and social disruption. (iv) Societies have often learnt to cope (despite hardship for some groups) with recurring shorter-term (decadal to multiyear) regional climatic cycles (e.g., El Niño Southern Oscillation)--except when extreme phases occur. (v) The drought-famine-starvation nexus has been the main, recurring, serious threat to health. Warming this century is not only likely to greatly exceed the Holocene's natural multidecadal temperature fluctuations but to occur faster. Along with greater climatic variability, models project an increased geographic range and severity of droughts. Modern societies, although larger, better resourced, and more interconnected than past societies, are less flexible, more infrastructure-dependent, densely populated, and hence are vulnerable. Adverse historical climate-related health experiences underscore the case for abating human-induced climate change.

Keyhole limpet haemocyanin - a model antigen for human immunotoxicological studies.

Immunization with a T-cell dependent antigen has been promoted as a reliable and sensitive tool for assessing the influence of putative immunotoxic exposures or agents on immune function. Keyhole limpet haemocyanin (KLH) is a very large, copper-containing protein molecule derived from the haemolymph of the inedible mollusc, Megathura crenulata. KLH is a highly immunogenic T-cell dependent antigen that is used increasingly in immunotoxicological studies, particularly in those involving animals. This report systematically reviews the human clinical studies that have used trans-cutaneous KLH immunization for assessment of the influence of various physiological and disease states and exposures on immune function over the last 20 years (1994-2013). These studies varied in their immunization protocols, formulation of KLH, dose, site and route of administration and immunoassay platforms developed to assess KLH-specific responses. KLH immunization has been well tolerated with only mild to moderate adverse effects reported. Though very promising as a model antigen candidate in immunotoxicology research, more work on standardizing immunization and immunoassay protocols is required.

Shifts in the seasonal distribution of deaths in Australia, 1968-2007.

Studies in temperate countries have shown that both hot weather in summer and cold weather in winter increase short-term (daily) mortality. The gradual warming, decade on decade, that Australia has experienced since the 1960s, might therefore be expected to have differentially affected mortality in the two seasons, and thus indicate an early impact of climate change on human health. Failure to detect such a signal would challenge the widespread assumption that the effect of weather on mortality implies a similar effect of a change from the present to projected future climate. We examine the ratio of summer to winter deaths against a background of rising average annual temperatures over four decades: the ratio has increased from 0.71 to 0.86 since 1968. The same trend, albeit of varying strength, is evident in all states of Australia, in four age groups (aged 55 years and above) and in both sexes. Analysis of cause-specific mortality suggests that the change has so far been driven more by reduced winter mortality than by increased summer mortality. Furthermore, comparisons of this seasonal mortality ratio calculated in the warmest subsets of seasons in each decade, with that calculated in the coldest seasons, show that particularly warm annual conditions, which mimic the expected temperatures of future climate change, increase the likelihood of higher ratios (approaching 1:1). Overall, our results indicate that gradual climate change, as well as short-term weather variations, affect patterns of mortality.

Energy and human health.

Energy use is central to human society and provides many health benefits. But each source of energy entails some health risks. This article reviews the health impacts of each major source of energy, focusing on those with major implications for the burden of disease globally. The biggest health impacts accrue to the harvesting and burning of solid fuels, coal and biomass, mainly in the form of occupational health risks and household and general ambient air pollution. Lack of access to clean fuels and electricity in the world's poor households is a particularly serious risk for health. Although energy efficiency brings many benefits, it also entails some health risks, as do renewable energy systems, if not managed carefully. We do not review health impacts of climate change itself, which are due mostly to climate-altering pollutants from energy systems, but do discuss the potential for achieving near-term health cobenefits by reducing certain climate-related emissions.

The physical anthropometry, lifestyle habits and blood pressure of people presenting with a first clinical demyelinating event compared to controls: the Ausimmune study.

INTRODUCTION: Lifestyle factors prior to a first clinical demyelinating event (FCD), a disorder often preceding the development of clinically definite multiple sclerosis (MS), have not previously been examined in detail. Past tobacco smoking has been consistently associated with MS. METHODS: This was a multicentre incident case-control study. Cases (n = 282) were aged 18-59 years with an FCD and resident within one of four Australian centres (from latitudes 27°S to 43°S), from 1 November 2003 to 31 December 2006. Controls (n = 558) were matched to cases on age, sex and study region, without CNS demyelination. Exposures measured included current and past tobacco and marijuana, alcohol and beverage use, physical activity patterns, blood pressure and physical anthropometry. RESULTS: A history of smoking ever was associated with FCD risk (AOR 1.89 (95%CL 1.82, 3.52)). Marijuana use was not associated with FCD risk after adjusting for confounders such as smoking ever but the estimates were imprecise because of a low prevalence of use. Alcohol consumption was common and not associated with FCD risk. No case-control differences in blood pressure or physical anthropometry were observed. CONCLUSIONS: Past tobacco smoking was positively associated with a risk of FCD but most other lifestyle factors were not. Prevention efforts against type 2 diabetes and cardiovascular disease by increasing physical activity and reducing obesity are unlikely to alter MS incidence, and more targeted campaigns will be required.

Planetary stewardship in an urbanizing world: beyond city limits.

Cities are rapidly increasing in importance as a major factor shaping the Earth system, and therefore, must take corresponding responsibility. With currently over half the world's population, cities are supported by resources originating from primarily rural regions often located around the world far distant from the urban loci of use. The sustainability of a city can no longer be considered in isolation from the sustainability of human and natural resources it uses from proximal or distant regions, or the combined resource use and impacts of cities globally. The world's multiple and complex environmental and social challenges require interconnected solutions and coordinated governance approaches to planetary stewardship. We suggest that a key component of planetary stewardship is a global system of cities that develop sustainable processes and policies in concert with its non-urban areas. The potential for cities to cooperate as a system and with rural connectivity could increase their capacity to effect change and foster stewardship at the planetary scale and also increase their resource security.

The role of latitude, ultraviolet radiation exposure and vitamin D in childhood asthma and hayfever: an Australian multicenter study.

Observations of increasing allergy prevalence with decreasing distance from the Equator and positive associations with ambient ultraviolet radiation have contributed to a growing interest in the possible role of vitamin D in the etiology of allergy. The aims of this study were to describe any latitudinal variation in the prevalence of childhood allergy in Australia and to evaluate, in parallel, the individual associations between ultraviolet radiation (UVR)- and vitamin D-related measures and hayfever asthma and both conditions. Participants were population-based controls who took part in a multicenter case-control study, aged 18-61 yr and resident in one of four study regions ranging in latitude from 27°S to 43°S. Data were derived from a self-administered questionnaire, interview and examination by a research officer and biologic sampling. Latitude and longitude coordinates were geocoded from participants' residential locations and climatic data were linked to postcodes of current residence. Stored serum was analyzed for 25-hydroxyvitamin D concentrations and silicone rubber casts of the skin were used as an objective measure of cumulative actinic damage. There was an inverse latitude gradient for asthma (a 9% decrease per increasing degree of latitude); however, this pattern did not persist after adjusting for average daily temperature. There was no association between any of the UVR- or vitamin D-related measures and childhood asthma, but greater time in the sun in winter between the ages 6-15 yr was associated with an increase in the odds of having hayfever [adjusted odds ratios (OR) 1.29; 95% CI 1.01-1.63]. Oral supplementation with cod liver oil in childhood increased the odds of a history of having both asthma and hayfever (2.87; 1.00-8.32). Further investigation of the possible role of early vitamin D supplementation in the development of allergy is warranted. Our results also suggest that solar exposure during childhood may be important in allergic sensitization. Plausible explanations, including biologic mechanisms, exist for both observations.

Social and environmental risk factors in the emergence of infectious diseases.

Fifty years ago, the age-old scourge of infectious disease was receding in the developed world in response to improved public health measures, while the advent of antibiotics, better vaccines, insecticides and improved surveillance held the promise of eradicating residual problems. By the late twentieth century, however, an increase in the emergence and re-emergence of infectious diseases was evident in many parts of the world. This upturn looms as the fourth major transition in human-microbe relationships since the advent of agriculture around 10,000 years ago. About 30 new diseases have been identified, including Legionnaires' disease, human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS), hepatitis C, bovine spongiform encephalopathy (BSE)/variant Creutzfeldt-Jakob disease (vCJD), Nipah virus, several viral hemorrhagic fevers and, most recently, severe acute respiratory syndrome (SARS) and avian influenza. The emergence of these diseases, and resurgence of old ones like tuberculosis and cholera, reflects various changes in human ecology: rural-to-urban migration resulting in high-density peri-urban slums; increasing long-distance mobility and trade; the social disruption of war and conflict; changes in personal behavior; and, increasingly, human-induced global changes, including widespread forest clearance and climate change. Political ignorance, denial and obduracy (as with HIV/AIDS) further compound the risks. The use and misuse of medical technology also pose risks, such as drug-resistant microbes and contaminated equipment or biological medicines. A better understanding of the evolving social dynamics of emerging infectious diseases ought to help us to anticipate and hopefully ameliorate current and future risks.

Paleoclimate and bubonic plague: a forewarning of future risk?

Pandemics of bubonic plague have occurred in Eurasia since the sixth century AD. Climatic variations in Central Asia affect the population size and activity of the plague bacterium's reservoir rodent species, influencing the probability of human infection. Using innovative time-series analysis of surrogate climate records spanning 1,500 years, a study in BMC Biology concludes that climatic fluctuations may have influenced these pandemics. This has potential implications for health risks from future climate change.

Public health benefits of strategies to reduce greenhouse-gas emissions: food and agriculture.

Agricultural food production and agriculturally-related change in land use substantially contribute to greenhouse-gas emissions worldwide. Four-fifths of agricultural emissions arise from the livestock sector. Although livestock products are a source of some essential nutrients, they provide large amounts of saturated fat, which is a known risk factor for cardiovascular disease. We considered potential strategies for the agricultural sector to meet the target recommended by the UK Committee on Climate Change to reduce UK emissions from the concentrations recorded in 1990 by 80% by 2050, which would require a 50% reduction by 2030. With use of the UK as a case study, we identified that a combination of agricultural technological improvements and a 30% reduction in livestock production would be needed to meet this target; in the absence of good emissions data from Brazil, we assumed for illustrative purposes that the required reductions would be the same for our second case study in São Paulo city. We then used these data to model the potential benefits of reduced consumption of livestock products on the burden of ischaemic heart disease: disease burden would decrease by about 15% in the UK (equivalent to 2850 disability-adjusted life-years [DALYs] per million population in 1 year) and 16% in São Paulo city (equivalent to 2180 DALYs per million population in 1 year). Although likely to yield benefits to health, such a strategy will probably encounter cultural, political, and commercial resistance, and face technical challenges. Coordinated intersectoral action is needed across agricultural, nutritional, public health, and climate change communities worldwide to provide affordable, healthy, low-emission diets for all societies.

Public health benefits of strategies to reduce greenhouse-gas emissions: overview and implications for policy makers.

This Series has examined the health implications of policies aimed at tackling climate change. Assessments of mitigation strategies in four domains-household energy, transport, food and agriculture, and electricity generation-suggest an important message: that actions to reduce greenhouse-gas emissions often, although not always, entail net benefits for health. In some cases, the potential benefits seem to be substantial. This evidence provides an additional and immediate rationale for reductions in greenhouse-gas emissions beyond that of climate change mitigation alone. Climate change is an increasing and evolving threat to the health of populations worldwide. At the same time, major public health burdens remain in many regions. Climate change therefore adds further urgency to the task of addressing international health priorities, such as the UN Millennium Development Goals. Recognition that mitigation strategies can have substantial benefits for both health and climate protection offers the possibility of policy choices that are potentially both more cost effective and socially attractive than are those that address these priorities independently.

Latitudinal variation in incidence and type of first central nervous system demyelinating events.

Increasing prevalence and variable geographic patterns of occurrence of multiple sclerosis suggest an environmental role in causation. There are few descriptive, population-level, data on whether such variability applies to first demyelinating events (FDEs). We recruited 216 adults (18-59 years), with a FDE between 1 November 2003 and 31 December 2006 in a multi-center incident case-control study in four locations on the south-eastern and eastern seaboard of Australia, spanning latitudes 27 degrees south to 43 degrees south. Population denominators were obtained from the Australian Bureau of Statistics censuses of 2001 and 2006. Age and sex adjusted FDE incidence rates increased by 9.55% (95% confidence interval (CI) 7.37-11.78, p < 0.001) per higher degree of latitude. The incidence rate gradient per higher degree of latitude varied by gender (male: 14.69% (95% CI 9.68-19.94, p < 0.001); female 8.13% (95% CI 5.69-10.62, p < 0.001)); and also by the presenting FDE type: optic neuritis 11.39% (95% CI 7.15-15.80, p < 0.001); brainstem/cerebellar syndrome 9.47% (95% CI 5.18-13.93, p < 0.001); and spinal cord syndrome 5.36% (95% CI 1.78-9.06, p = 0.003). Differences in incidence rate gradients were statistically significant between males and females (p = 0.02) and between optic neuritis and spinal cord syndrome (p = 0.04). The male to female ratio varied from 1 : 6.7 at 27 degrees south to 1 : 2.5 at 43 degrees south. The study establishes a positive latitudinal gradient of FDE incidence in Australia. The latitude-related factor(s) influences FDE incidence variably according to subtype and gender, with the strongest influence on optic neuritis presentations and for males. These descriptive case analyses show intriguing patterns that could be important for understanding the etiology of multiple sclerosis.

Climate change and Australia's healthcare system - risks, research and responses.

Climate change will affect human health, mostly adversely, resulting in a greater burden on the health care system, in addition to any other coexistent increases in demand (e.g. from Australia's increasingly ageing population). Understanding the extent to which health is likely to be affected by climate change will enable policy makers and practitioners to prepare for changing demands on the health care system. This will require prioritisation of key research questions and building research capacity in the field. There is an urgent need to better understand the implications of climate change for the distribution and prevalence of diseases, disaster preparedness and multidisciplinary service planning. Research is needed to understand the relationship of climate change to health promotion, policy evaluation and strategic financing of health services. Training of health care professionals about climate change and its effects will also be important in meeting long-term workforce demands.

Global health equity and climate stabilisation: a common agenda.

Although health has improved for many people, the extent of health inequities between and within countries is growing. Meanwhile, humankind is disrupting the global climate and other life-supporting environmental systems, thereby creating serious risks for health and wellbeing, especially in vulnerable populations but ultimately for everybody. Underlying determinants of health inequity and environmental change overlap substantially; they are signs of an economic system predicated on asymmetric growth and competition, shaped by market forces that mostly disregard health and environmental consequences rather than by values of fairness and support. A shift is needed in priorities in economic development towards healthy forms of urbanisation, more efficient and renewable energy sources, and a sustainable and fairer food system. Global interconnectedness and interdependence enable the social and environmental determinants of health to be addressed in ways that will increase health equity, reduce poverty, and build societies that live within environmental limits.

Socio-environmental predictors of Barmah forest virus transmission in coastal areas, Queensland, Australia.

OBJECTIVE: To assess the socio-environmental predictors of Barmah forest virus (BFV) transmission in coastal areas, Queensland, Australia. METHODS: Data on BFV notified cases, climate, tidal levels and socioeconomic index for area (SEIFA) in six coastal cities, Queensland, for the period 1992-2001 were obtained from the relevant government agencies. Negative binomial regression models were used to assess the socio-environmental predictors of BFV transmission. RESULTS: The results show that maximum and minimum temperature, rainfall, relative humidity, high and low tide were statistically significantly associated with BFV incidence at lags 0-2 months. The fitted negative binomial regression models indicate a significant independent association of each of maximum temperature (beta = 0.139, P = 0.000), high tide (beta = 0.005, P = 0.000) and SEIFA index (beta = -0.010, P = 0.000) with BFV transmission after adjustment for confounding variables. CONCLUSIONS: The transmission of BFV disease in Queensland coastal areas seemed to be determined by a combination of local social and environmental factors. The model developed in this study may have applications in the control and prevention of BFV disease in these areas.