Global Environmental Change and Infectious Disease

Global Environmental Change and Infectious Disease
Environment consists of not only the natural world but also the built and social environments, and
it plays an important role in shaping human health. Anthropogenic (human-induced) changes are
increasingly linked to the processes of globalization. Over the past 50 years, huge increases in economic
and industrial activity have led to unprecedented effects on air, land and water environments, and the
resulting changes have important and wide-ranging implications for human health, with different
populations facing varying degrees of vulnerability to positive and negative impacts.
Global Warming
- Substantial evidence: global average land and sea surface temperature
UN Intergovernmental Panel Climate Change (IPCC)

- Predict that average global temperatures would increase by 1.4-5.8 degree Celsius by 2100.
- Concluded that much of the warming observed in the last 50 yrs. can be attributed to human
activity, principally due to excessive and inefficient combustion of fossil fuels, leading to the
build up of greenhouse gases that trap heat within the atmosphere.
Global warming may alter the range and prevalence of many infections. Higher ambient air
temperatures, along with changes in precipitation and humidity, can affect the biology and ecology of
disease vectors and intermediate hosts, the pathogens that they transmit, and consequently the risk of
transmission.
Diseases carried by mosquito vectors are particularly sensitive to meteorological conditions, since
insects have fastidious temperature thresholds for survival and are especially susceptible to changes in
average ambient temperature. Anopheles spp. mosquito can only transmit Plasmodium falciparum
malaria parasites if temperature remains above 16 degree Celsius. Aedes aegpypti mosquitoes, spread
dengue fever and yellow fever are killed by temperatures below 10 degree Celsius.
Global warming are beneficial, the incidence of schistosomiasis may drop if temperature is too warm to
sustain the small host. Malaria transmission may diminish in an sestablished endemic zone if this
becomes too hot and dry.
 Warmth accelerates the biting range of mosquitoes. Pathogens multiply quicker and more
infectious in warmer temperature.
Vulnerability of Global Climate Change

Health Impact: depends on the biological consequences and overall vulnerability of societies and
population.
High Income Countries which are more likely to be located at the temperature-sensitive edge of disease
transmission, public health measures are sufficiently effective to prevent diseases like malaria from re-
emerging even when rising temperatures support the survival of vectors.
In contrast, in many low-income countries in tropical climates, already in the midst of transmission
zones, public health infrastructures are often much weaker, and the increasing vogue for cutting back
government expenditure. There continues to be debate on the relative vulnerability of popula-
tions, with the UN (2001) reporting that lower-income countries would be worst hit by the predicted
rises in global temperatures during the next century.
Water Supply
Water is essential for human life. People must have enough water to drink and produce food, and a
dependable source is a prerequisite for reliable, intensive agriculture and industrial growth.
Communities which lack sufficient supplies for simple ablution are at risk for high rates of mortality and
ill health. However, the amount of water accessible for these needs is severely limited, available
freshwater amounting to less than 0.5% of all the water on Earth. Most water is sea water, or is frozen in
polar ice, and we are heavily reliant on river flow and rainfall which, in many parts of the world, are
intermittent, unreliable and insufficient.
Increasing pressure on the available stocks of water can lead to growing social tensions, or even to out-
right conflict, and access to both surface water and groundwater is an increasingly contentious issue.
Agricultural and industrial growth in many poor countries remain seriously constrained by shortage of
reliable water supplies, and there is increasing competition among the three largest users of water in
global terms – agriculture (67% of withdrawals), industry (19%), and municipal and domestic users (9%).
Some argue that, if climate change leads to greater weather variability, increased water storage may be
necessary to offset the effects of more frequent drought.
Land Clearance and Deforestation
Land clearance and deforestation are practices as old as human civilization. In order to provide space
for settlements, crop cultivation and commercial activities, humans have cleared almost half of the
world’s forests in the last 10 000 years. However, the rate of destruction, particularly of tropical
rainforests, has increased dramatically in the last half century. The Global Forest Resources Assessment
(FAO, 2000) estimates that worldwide forest area declined by 9.4 million hectares annually in the 1990s.
To develop their national economies, many countries have cleared land for
agriculture or to build roads to improve access to economically important regions. This activity, the most
formidable destruction of rainforest in human history, has often yielded minimal or transient economic
benefit.
Deforestation influences health in diverse ways. For instance, rainforests play important roles in
absorbing carbon dioxide, solar radiation and extreme levels of rainfall. Loss of these functions may lead
to more extreme global and local climate conditions.

Global Environmental Change and Infectious Disease

Uploaded by

Copyright:

Available Formats

Global Environmental Change and Infectious Disease

Uploaded by

Document Information

Original Description:

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Global Environmental Change and Infectious Disease

Uploaded by

Copyright:

Available Formats

Global Environmental Change and Infectious Disease

UN Intergovernmental Panel Climate Change (IPCC)

Vulnerability of Global Climate Change

Land Clearance and Deforestation

You might also like