Selected Readings on Human Health, Disease, and the Environment

The following are responses and summaries of various readings related to Human Health, Disease, and the Environment. 

Rx for Survival: The Forgotten Link Between Health and Wealth

Globally nations have begun to promote an increase in aid beginning with the Millennium Development Project, though little action has actually been taken since.  According to Adam Smith the government has three main duties: providing for its own defense, development of a justice system, and the construction and maintenance of public facilities and services.  Britain was the first to really get the building of public works aspect with its construction of the sewage and water system, which put a stop to the cholera epidemic that swept the European continent and Britain in the 19^th century.  The Asiatic cholera had decimated the port towns of Germany and Russia, having proceeded up the Caspian from India in previous years.  Cholera was a disease alike none other than had been seen before in the Isles; it was a quick killer, acting at a furious pace and spreading quickly.  During the epidemic nearly half of those who became infected died.  It first appeared in the port town of Sunderland, which would later order the port closed and the city quarantined.  Locals, denying its existence, revolted against the quarantine.  Only six months later more than 20,000 throughout England had died from the cholera that had spread from Sunderland.  It took much time and work, but thanks to the efforts of Edwin Chadwick and John Snow it was proven to the powers that be that the disease was transmitted through the water, specifically the water which was becoming contaminated by the sewage.  They proposed to Parliament the construction of a great water and sewage system.  Though they had sufficiently proven that source of the illness was not that the people were poor and bad off, it was that the conditions they were forced in to – poor housing and sanitation – was only making things worse, Parliament did not act until the stench of the open sewers forced them to evacuate the Parliament building.  The construction of the system was perhaps the most expensive public works project in the world’s history at the time, but the results were instantaneous with the cholera epidemic ceasing.  After this the rest of the industrial world soon followed suit in their public works efforts.  The wellness of the nations created a huge economic boom.  The link between health and disease prevention and the economy was lost after the Second World War.  After WWII the World Bank was created with the motif that if a company is going to grow economically, then it is required to have great capital for investment in industry, transportation, and business.  From this idea it was expected that the leading nations would aid the poorer nations with copious capital enabling them to pull themselves up.  The idea of human capital, the health and wealth of the people, was overlooked in the formation of these development projects.  Too much money had been dedicated to building roads and factors and not enough to the health of the population. 

Investing in Health

With the 1993 publication of Investing in Health by the World Bank, the idea of investing in the health and education of the people as a way to stimulate economic growth in the poor nations of the world was relit.  Much of the progress which humanity has made is due to the creation and distribution of wealth, but health and wellbeing plays a large part as well.  The easiest way for governments of poor nations to improve the health of its citizens is to spend less money on the bigger, more ineffective measures like hospitals and to focus more on smaller services such as immunizations and prevention combined with clinics.  The economic-health link has been restated with data collected that shows, all other things being equal between similar nations, the country with a longer life span will have an economic increase of .3 to .5 percent in addition each year.  A healthier population is more productive and misses less time from work due to illness, often strive for higher education or knowledge, save and invest money for old age, and has less children as a whole.  Recently a trend has developed to shift from the old ways of analysis, the Gross Domestic Product, to newer statistics such as full income and DALY.  The full income includes a figure for life expectancy to the data set, while the DALY is the disability-adjusted life year, which allows for a measure of those between health and death, where before there was none.  The central issues for why investment into human capital is necessary are that without assistance these poorer countries could become trapped in a situation that they could not revive themselves from, disease is the greatest barrier to economic growth, and the simplest or most easily treated diseases are the ones which wreak the most havoc.  The failure of poorer nations is best forecasted by partial democracy regimes and most notably high rates of infant mortality.  Human health is a great issue for national and international security and stability and as such needs to be addressed financially in order to avoid catastrophe. 

If Not Now, When?

The Global Fund, recently created, is a new type of aid organization: it collects funds from donor nations and private parties and gives them out as grants, not as loans which can cause a burden on the receiving nation.  It analyzes the proposal projects, developed within the nations themselves, monitors the spending of the project’s funds, and measures the efficiency of the projects.  The Global Fund is what new aid organizations should use as a template for their activity.  Since the end of World War II, specifically the end of the Marshall Reconstruction Plan, foreign aid given by the United States has fallen from 3 percent of the GDP to .16 percent, though many U.S. citizens believed that we were spending much more.  According to a 2001 study by the WHO currently the world is spending about $6 billion on aid, while it sees that $27 billion is the minimum to cover the most basic of necessities.  This increase would only be about .1 percent of the GDPs of the world’s wealthier nations.  The nations of the world have agreed that more money is needed, but have not acted as such.  The major nations need to commit to large sums of money for aid purposes and the world’s aid agencies need to be reformed and made more transparent.  The most recent globalization is at a point of strife; if action is not taken soon against the plagues of the poorer nations, it could spell disaster just as the globalizations of the 19^th century led to World War I and the failure to address those same issues led to the re-ignition of the European fire that was World War II.

Conclusion

Studies and research has shown that health aid projects can be successful.  The projects must be large, national or global in scale, address major public health problems, with the effects being obvious, be very cost-effective over a long time period.  It is possible to achieve success in even the most poor of nations, regardless of the corruption in government.  The governments, while poor, are still very important in the utilization and creation of health means.  Technology and modern medicine is great, however the simplest of ideas can create a great change in people’s wellbeing.  The governments of poor nations and nongovernmental organizations can work together on projects of their own without the assistance of donor nations. 

 Readings above may have been drawn from the following sources:

Six Modern Plagues and How We are Causing Them, Mark Jerome Walters; Shearwater Books, 2003, ISBN 155963992X

Life Support, The Environment and Human Health, Michael McCally, editor, MIT Press, 2002, ISBN 0-262-63257-8

Rx for Survival,  Philip Hilts, Pengquin Books.  ISBN 0-7394-6974-6

Emerging Infectious Diseases,  Stuart A. Hill, Pearson Eductation Inc., publishing as Benjamin Cummings.  ISBN 0-8053-3955-8

Under the Weather:  Climate, Ecosystems and Infectious Disease, National Research Council, National Academy Press.  ISBN 0-309-07278-6

This article originally written December 8th, 2008 for OU IPE 3913 - Human Health, Disease, and the Environment.

Selected Readings on Human Health, Disease, and the Environment

The following are responses and summaries of various readings related to Human Health, Disease, and the Environment. 

Under the Weather: Key Findings and Recommendations

            Many infectious diseases are influenced by weather and climate change as can be seen by the varying distribution of different diseases.  Temperature, precipitation, and humidity directly influence the behavior of diseases and their carriers.  Other factors including government health services, clean water and properly maintained sewage, population variations and travel, as well as land use can affect diseases.  Many models for studying the dynamics of disease have been developed, however they are not intended to be used as predictive or early warning systems.  It is not currently known for certain what impact global climate change could have on disease: while global warming could alter the range of current diseases, other factors such as improved housing, sanitation, and public health systems could offset any negative impacts from climate change.  New diseases may emerge from the increased rate of evolution in pathogens due to climate change, though this is highly uncertain.  It is an extremely slippery slope when attempting to extrapolate the data from one time and region to a larger scale; global climate change may have an effect on regional or seasonal climate patterns that is unforeseen.  The ever-increasing technological backing will only help to increase the accuracy and speed with which models and predictive systems can be developed. 

Selected Readings on Human Health, Disease, and the Environment

The following are responses and summaries of various readings related to Human Health, Disease, and the Environment. 

Under the Weather: Toward the Development of Disease Early Warning Systems

Until now there has been very little progress made in the development of early warning systems for infectious disease.  However, just like weather forecasts, earlier warnings are usually much less certain.  The simplest and most used warning system is the use of sentinel animals in regions of high risks: these practices give highly predictive results but leave officials with very little reaction time for prevent further spread of disease.  The best method to be used is through ecological observation and climate forecasts issuing disease watches in order to minimize its transmission.  These watches can be used to determine which areas need to be most carefully surveyed for disease outbreaks, much like watches and warnings are used in the informing of communities on the potential of severe weather in an area.  Early warning systems should be used as devices which will enable national and local institutions as well as individuals to make decisions regarding a potential threat and to improve the coordination between them.  An early warning systems consists of watches and warnings about a particular risk, combined with vulnerability assessments which determine which groups are most susceptible to a disease, and risk analysis which will help determine the potential fallout of a disease on an area or group.  A good system must end with a response strategy and public communication system to quickly inform the public about the risks, potential outcomes, how best to be prepared.  The systems need make use of the epidemiological surveillance systems that are currently in use and follow a standard method of practice and allow for quick analysis and dissemination of information.  Up until now most surveillance methods have focused on the particular effect and end result of a disease, but need to include changes in vector populations which may employ using sentinel animals for analysis.  The systems will need to make use of new remote-sensing technologies for the analysis of ecology.  The vulnerability assessment is a description of how sensitive a population is to a particular disease and should be combined with surveillance systems thereby allowing the development of control strategies.  Risk analysis provides the probability that a particular hazard will affect an area or population.  Usually the development of scientific prediction methods greatly outpaces the development of warning systems which use this information; from this response plans need to be developed which consider the costs and potential pitfalls of possible response plans for local communities.  The people and organizations disseminating the system information need to have good credibility and trust by the persons within the community and must be sure to properly explain and educate the public on the risks in order to prevent overreaction and panic. 

Selected Readings on Human Health, Disease, and the Environment

The following are responses and summaries of various readings related to Human Health, Disease, and the Environment. 

Under the Weather: Temporal and Spatial Scaling

Though climate varies naturally over time, recent global warming is of great concern.  The many parts of an area’s ecology such as soil fertility, species variability, and organic growth rates and reproductive cycles vary with changes in altitude and latitude; these differences are known as the spatial climate gradients.  Too cold nights and winters and too warm days and summers have drastic impact on the populations and geographic range of disease carriers and can also have an effect on the organisms of disease as well.  Climate variability taking place over the time frame from biyearly to every decade is due to atmospheric, oceanic, and cosmological influences, such as sunspots.  These changes can result in multi-year droughts, monsoons lasting for decades, and vastly different hurricane activities, which have all been shown to affect productivity of plant life, likelihood of bird reproduction, and an increase in insect population.  Longer time scales such as that of the little ice age can cause great population range shifts or possibly extinction.  The recent global warming has resulted in earlier springs, declines in the populations of birds, mammals, and amphibians, and a change in geography for butterfly, bird, and marine invertebrates.  While the average temperature has been increasing globally over the last century, of greater concern is the extreme temperature increases, higher in mid-day and lower in mid-night, which has been shown to have a greater impact on animal and plant species’ population and range.  Recently experimental manipulation has been used in either localized outdoor environments or in laboratories to analyze what effects climate change could have on the ecosystem by altering the temperature of soil and air and type and amount precipitation or combination of the alterations: the growth rates of plants, invertebrate organism population, plant reproduction, and soil organism and chemical make-up have all been shown to be affected.

Selected Readings on Human Health, Disease, and the Environment

The following are responses and summaries of various readings related to Human Health, Disease, and the Environment. 

Linkages Between Climate, Ecosystems, and Infectious Disease

Weather and climate are different ideas in similar fields of study.  Weather is the measurement of temperature, humidity, precipitation, and wind daily whereas climate measures these factors over a long period of time.  Climate is an average and varies with geography and time.   The average temperature of an area decreases by 6.5 degrees C with every 1000 meter change vertically and decreases 5 degrees C with every 1000 kilometer change from the equator.   The range with which temperature fluctuates due to the seasons is greater towards the poles, with much less change experienced near the equator.  There are many climate cycles occurring from yearly to millennially and some occurring as little as every 100,000 years; these oscillations can cause temperature shifts as high as 10 degree C.  Since the Industrial Revolution, and more notably in the last twenty years, the global average temperature has begun to increase yearly and is predicted to continue increasing several degrees in the next century.  The basis for good predictive weather and climate models does not rest solely on the atmosphere but also in surface variations, especially the oceans.  Currently weather prediction is only effective on a timescale of less than two weeks, while climate models are limited to seasonal or greater timescales.  Including the effects of ocean, atmosphere, and land may make climate models sufficient for shorter timescales and weather prediction for greater timescales.  With infectious disease, the number of cases that indicates and epidemic will vary with each particular disease, region, and time.  Emerging disease can be due to climatic or ecological change, which causes a greater number of people to come into contact with a natural reservoir of infection.  Diseases can be transmitted either directly, due to contact with an agent, or indirectly, through a natural reservoir or host.  Many studies of infectious disease use the SEIR framework:  S. The proportion of people who are able to become infected E. Within that same group, those who have had contact with the agent but who have not become infected I.  The number of people within S group who have contracted the disease R. The number of people who have been removed from the original group S due to either death or immunity.   SEIR attempts to account for the many different factors in disease studies such as population size and density, demographics, connectivity patterns, and immunity.  Diseases and natural reservoirs have environmental conditions that are both favorable and not for the spread of particular diseases which include precipitation, temperature, humidity, and ultraviolet radiation.  Most diseases are sensitive to changes in temperature with regards to their dissemination, replication, and movement.  Climate change over the long-term may result in increased intensity and occurrence in extreme weather events, where the direct impact is obviously more deaths due to disasters, though potentially and indirectly an increase in infectious disease outbreaks.  The diseases associated with flooding are well known while droughts are not nearly as studied, though a disease would not affect a crisis area should it not have been present in the system before the extreme event and had not be introduced.  There are many other factors that influence disease dynamics including land use, migration of disease and hosts, the societal makeup of populations, and public health services.

Selected Readings on Human Health, Disease, and the Environment

The following are responses and summaries of various readings related to Human Health, Disease, and the Environment. 

Under the Weather: Executive Summary

Changes in climate can affect the movement pattern of infectious diseases due to the fact that the microorganisms and their carriers are equally prey to changes in temperature, moisture, and other environmental changes, though other diseases such as HIV or Hepatitis do not have the same causal relationship with the environment because they are transmitted through direct human interaction.  In 2001 the National Research Council was asked to study the issue of the environment, its change, and the possible effect on human health and disease.  Specifically they reviewed: 1. possible connections between the variations of time and space with respect to the climate and the transmission of disease 2. Studying the possibility of creating warning and surveillance systems for climate affected diseases 3. Investigating possible future studies on the relationship of disease, climate, and human health.  Multiple disciplines, whom usually do not work together or in similar fashion, were required for the project due to the multidisciplinary nature of the issue.  Temperature, precipitation, and humidity directly and indirectly change the life of many infectious diseases and their vectors, though they are also affected by the sanitation and health services provided within a region, the density of human or vector population, changes in ecology, and organism travel habits.  Many studies have been conducted on the effect of climate change on disease however they have not been able to account for the many variables that lie under the function of diseases and are not reliable for predicting future change.  The impact of climate change on disease has yet to be well sorted out, though many believe that global warming could have an adverse impact, however human adaptations and health services could potentially prevent or reduce such impacts.  New diseases may emerge or old diseases reemerge in newly evolved forms due to ecosystem changes.  Studies of the relationship are dependent on local, small scale which make it difficult to enlarge the results to a larger scale relationship.  Long term climate change could have a vastly different effect than short term climate change such as ENSO.  Advances in technology will allow for the analysis and more detailed studies.  Historically the strategy has been to survey and respond to disease threats, but in the future hope is for a predict and prevent strategy.  Climate forecasts and observations could be used in identifying high risk areas and preventing the or reducing their occurrence.  A general understanding of the relationship may allow for some form of early warning system at a low cost, but some may require a more costly prediction system, depending on the particular disease and region.  Systems will only be beneficial if the operating agency has the sufficient resources to act upon their results.  Climate forecasts must also be combined with meteorological, ecological, and epidemiological systems to work properly as an advanced warning system.  Public health officials and government agencies must work in conjunction with one another for the systems to have their desired effect.  The research into these relationships has only just begun and has a long road to traverse before it can become effective.  The data set involving disease, climate, and geography need be greatly increased for prediction models to even be a possibility.  The interdisciplinary collaboration in universities and private institutions need be greatly increased.  New disease will always have the upper hand in the battle, however the goal should be to reduce people vulnerability to disease.

Selected Readings on Human Health, Disease, and the Environment

The following are responses and summaries of various readings related to Human Health, Disease, and the Environment. 

Life Support: Environmental Endocrine Disruption

Chemicals found in the environment have effects on fetuses much more than on adults because even the slightest of changes in the hormone levels of the undeveloped human can have very drastic consequences.  These chemicals are able to directly bind to or block the hormone receptors making gene transcription initiated by the hormone receptors erroneous.  Similar exposure levels in adults do not show nearly as great physiological changes.  Possible abnormalities include feminization of males, abnormal sexual behavior, birth defects, altered sex ratio, lower sperm density, decreased testis size, altered time to puberty, cancers of the mammary glands or testis, reproductive failure and thyroid dysfunction.  Studies that have been conducted have difficulty in consistency due to the time between exposure and the resultant effects, such as cancer showing decades after first exposure, and finding a control population, since any control population is going to already have some degree of exposure.  Organochlorine contaminated food has been shown to affect the brain development of lab animals and children exposed have shown delayed psychomotor development and increased distractibility.  Some pesticides result in decreased brain density of some nerve receptor types and hyperactive behavior.  Because hormones act at such low levels even the slightest of chemical exposure can result in very bad developmental effects.  One of the main failures of past studies is their focus on the individual rather than the population as a whole, though the size and seriousness of the health threat is still uncertain.  Work by the International Joint Commission, United States and Canada, has begun striving towards the elimination of volatile chemicals.  They hope for zero discharge of chemicals from human activities, analysis of chemical effects from creation to destruction and afterwards, and reversing the burden of proof from showing that a chemical is harmful to showing that a chemical is not harmful before it is allowed to be used.