Thursday, August 14, 2014

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. 

The agencies responsible for preparedness plans need to analyze previous events and determine how the public took the warnings and what actions were taken in order to plan for future outbreaks.  Perhaps the most important aspect to implementing early warning disease systems is the inclusion of the end user in the creation and development of forecasts and plans.  International public health organizations can help train national and regional agencies for the use and development of systems.  Those same agencies would thereafter be charged with the strengthening and development of their own systems and lower level agencies.
A good early warning system must be able to regularly supply good climate forecasts for the region, while understanding the link between climate and particular diseases thereby offering a good level of prediction.  The system must allow for sufficient time for response, otherwise what is the point of the system.  The community or region using the system must have the resources to support the additionally required infrastructure for its proper implementation. 
The 1999 New York City outbreak of West Nile Virus is a prime example of how the system could best be used.  The outbreak showed the necessity of interdisciplinary approaches to the problem and the difficulty in coordinating between different government agencies and communication to the public.  The population of New York City found itself most vulnerable to the disease due to very little having been done in mosquito control, persons not practicing avoidance of the vector species, and the population lacking immunity due to no prior exposure to the disease.  Initially the disease was misidentified due to the poor cooperation between animal health and human health agencies, though here the effect was minimal due to the fact that its misidentification was with a very similar disease.  A better plan was later seen in neighboring New Jersey where surveillance units were employed to detect where the virus was from time to time, a pre-emptive mosquito control program, cooperation of lab testing between agencies, and sufficient communication between public health officials, professionals, and the public.

***Previous Week Online Article***
Recent research by scientists at Cornell University has shown that the recent warming trend being experience is the greatest climate change in the previous 5000 years, since the birth of human civilization.  The research focused on the recent influx of fresh water from the melting of glaciers in the Arctic and North Atlantic Oceans, as well as its effect on the oceanic periodic circulation, and changes seen in particular oceanic plant and animal species.  In their studies of the previous 65 million years of climate change on Earth they have found fast cooling periods where temperatures fell as much as ten degrees Celsius in years to decades, but now is the first time that such a quick rise in temperature has been experienced.  The recent warming, and as a result melting of ice sheets and glaciers, has allowed for great shifts in the range of plant and animal species.  In particular one species of algae has migrated from the Pacific Ocean to the North Atlantic due to the warming trend – the first time this species has appeared in the North Atlantic in the last 800 000 years.  Such changes can have great impacts for other species such as phytoplankton, which have seen longer growing seasons, thereby affecting the animals of the food chain all the way up to the top.  The warmer temperatures have caused a reduction in the populations of cod and thereby an increase in shrimp and snow crab populations due to the cooler, glacial melt waters.  Perhaps the greatest effect that the researchers hope will not be seen is the alteration or disruption of today’s ocean circulation systems: if changed or stopped it is likely that many of the atmospheric, glacial, and oceanic process would change in conjunction.

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 November 25th, 2008 for OU IPE 3913 - Human Health, Disease, and the Environment.

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