Dengue virus

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Climate changes might play an important role in
sustaining the transmission cycle between vectors
and human hosts and the spread of transmission.
Dengue virus
Weather
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7. 8. 9?
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For assessing the health effects of climate
change, these large scale models had adopted
general circulation models (GCMs) in predicting
climate change scenarios to result in a
projection for longer time period and expanded
global geographical areas of intensive dengue
fever transmission.
Many site-specific differences in those factors
affecting disease transmission, such as mosquito
density and immunity status, could not be
adequately assessed in any large-scale prediction
models for the often-low geographical resolutions
in data of both weather parameters and disease
incidence.
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A more localized and comprehensive analysis by
using site-specific data is therefore more
applicable to design an early warning and disease
prevention program.
Taiwan
Time-series
Weather variability vs. Dengue fever
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Study area
46.3 of total dengue fever cases
the Center for Disease Control Taiwan
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Taiwan is located in both subtropical and
tropical regions with relatively high temperature
and relative humidity year-round, which are ideal
conditions for the dissemination and growth of
the vector of dengue fevermosquito.
Subtropical region Tropical region
??? 100 ??? 48 ???? 100 ??? 64
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Study area
46.3 of total dengue fever cases
the Center for Disease Control Taiwan
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29 imported cases notified annually in Kaohsuing
City Warmer winter and in less humid months
Quantitation of effect of several stimuli on
landing and probing by Aedes aegypti, Khan, A.A.
et al J. Econ. Entomol. 1967
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Weather variables were significantly associated
with incidence rate of dengue fever using
cross-correlations.
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ARIMA
auto-regressive integrated moving average
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The predicted values and actual incidence rate
matched very well, and when cross-comparison with
the actual historical records, these identified
peaks were exactly the years and months when the
outbreak was reported to our registry system.
Fig. 3. The actual incidence rate and predicted
incidence rate by auto-regressive integrated
moving average (ARIMA) model of weather variation
in Kaohsiung City, Taiwan.
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General circulation models (GCMs)
The past global prediction model could not
accurately predict the actual impacts in Taiwan
for only using 2 grid data to represent the
weather variations in Taiwan.
The ultimate importance in establishing a
site-specific model for future prediction in the
actual risk of diseases occurrence.
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• Climate change and health global to local
  influences on disease risk

Patz, J.A. and Olson, S.H. Annals of Tropical
Medicine and Parasitology, 2006.
The World Health Organization has concluded that
the climatic changes that have occurred since the
mid 1970s could already be causing annually over
150,000 deaths and five million
disability-adjusted life-years (DALY), mainly in
developing countries. The less developed
countries are, ironically, those least
responsible for causing global warming. Many
health outcomes and diseases are sensitive to
climate, including heat-related mortality or
morbidity air pollution-related illnesses
infectious diseases, particularly those
transmitted, indirectly, via water or by insect
or rodent vectors and refugee health issues
linked to forced population migration. Yet,
changing landscapes can significantly affect
local weather more acutely than long-term climate
change. Land-cover change can influence
micro-climatic conditions, including temperature,
evapo-transpiration and surface run-off, that are
key determinants in the emergence of many
infectious diseases. To improve risk assessment
and risk management of these synergistic
processes (climate and land-use change), more
collaborative efforts in research, training and
policy-decision support, across the fields of
health, environment, sociology and economics, are
required.
Overall increasing temperature in different
regions of the world might allow these vectors to
survive over winter and help to extend into
regions previously free of disease or
exacerbation of transmission in endemic regions
and also change the transmission season.
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Thanks for your attention
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General circulation model A general circulation
model (also known as a global climate model, both
labels are abbreviated as GCM) uses the same
equations of motion as a numerical weather
prediction (NWP) model, but the purpose is to
numerically simulate changes in climate as a
result of slow changes in some boundary
conditions (such as the solar constant) or
physical parameters (such as the greenhouse gas
concentration).
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