Transcript Is the Climate Right for Predicting and Mitigating an Outbreak of

Pilot Project for Predicting and
Mitigating an Outbreak of Dengue
Fever – Capacity Building and Learning
Experience Based on SIS06
A.Anthony Chen, Climate Studies Group Mona,
Department of Physics, UWI, Mona
The Dengue-Climate Problem
The water problem:
•In times of rain, pools of water
collect in discarded coconut
shells, automobile tyres and
other nonbiodegradable
containers providing breeding
habitats.
The water storage problem:
•In dry periods, water is stored
in open containers which
provide breeding habitats
The Temperature Problem:
•The extrinsic incubation period (period of incubation of
parasite inside the vector or EIP) shortens at higher
temperature
•Focks et al (1995) - dengue type 2 has an EIP of 12
days at 30○ C but only 7 days at 32-35○ C.
•Koopman et al. (1991) - decreasing the incubation
period by 5 days can lead to a threefold higher
transmission rate of dengue.
•Higher temperatures increase the amount of feeding
and the probability of dengue transmission to new hosts.
•Moderately high temperatures hasten the larval
stage, leading to smaller mosquitoes, which then
require more frequent blood meal.
•Increased temperature also enhance metabolism.
The El Nino Problem:
•Taylor (1999) - El Niño years in the Caribbean produce
drier than normal conditions in the latter half of the year
• This drying tendancy was also reported by others,
including Ropelewski and Halpart (1996)
The above leads to the storing of water problem
•The air temperature increases during El Niño conditions
in the Caribbean (Malmgren et al, 1998).
This leads to the temperature problem.
•Chen et al (1997), Taylor (1999), Chen and Taylor
(2001) showed how rainfall increases during May to July
in the El Niño + 1 year
This leads to the water problem.
The Climate Change Problem:
•Santer (2001) found that a mean temperature increase of
up to 2ºC is projected for Caribbean after 70 years of CO2
doubling.
•Expected modulation of temperature by future El Niño
events will further enhance above increase periodically.
• Timmermann et al (1999) found an increase in El Niño
frequency in a climate model forced by future greenhouse
warming.
All the above lead to the temperature problem
•IPCC (1998), based on 1996 WHO source, show a likely
alteration of the global distribution of dengue due to climate
change, with 2.5 billion at risk in the tropics and sub tropics.
Solution to Problem: (A) Because
Climate is Predictable
Climate - average over season or longer
as opposed to Weather - day by day. No
predictability of weather beyond 10 days:
Why is climate predictable?
Slow variation over the season:
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Sea surface temperature
Solar radiation
Land vegetation
Soil Moisture
Ice cover
For example:
Observed Precip vs Predicted Precip
14
12
10
Obs Precip
Pred Precip
Avg Obs
Avg Predict
mm
8
6
4
2
Days
39
37
35
33
31
29
27
25
23
21
19
17
15
13
11
9
7
5
3
1
0
However there are uncertainties,
especially Precipitation
 Cannot replicate exactly all processes, e.g., for
a given location
 Probability statement, e.g., CIMH seasonal
prediction:
•
•
•
IRI - ECHAM, CCM3, NCEP
UK - UKMO
Knowledge of Caribbean Climate
Dealing with uncertainty
Solution to Problem: (B) Because of Link
Between Dengue and Climate One link:
 Entomology studies
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EIP (Type 2): 12 days at 30○ C , 7 days at 3235○ C.
5 day decrease in EIP  threefold higher
transmission rate of dengue.
3.5○ C rise  threefold higher transmission rate
of dengue
However uncertainties:
Uncertain relationships
Socio-economic factors
For example:
Transmission rate
x
9
6
3
x
x
x
30°
33.5°
Temp
Dealing with uncertainties
TEMPERATURE
High
Low
RAINFALL
Heavy
Medium Light
Medium Higher
Higher
probability probability probability
Lower
Medium Medium
probability probability probability
Pilot Project: Possible solution to mitigate
the impact of climate related dengue
 Short term
Predict and mitigate climate related impact of dengue over 5 10 years
 A plan for project is to be produced as part of SIS06 based on
results of studies within the project
 Execution of pilot project not in SIS06 budget
 Plan to be as cost effective as possible taking into account
existing agencies.
 Workshop to be held for decision makers to market the plan
 A learning and capacity building exercise for future adaptation
strategies
Global Forecasts
IRI, NCEP, etc
Policy Makers/
Funding Agents
Network
Climate/Health Directorate
Climate
Prediction Centre
Health Surveillance
CSGM
Watch/warning
IM
CIMH
Public Health Officials, Media, etc
Public Health Officers/Sanitation/etc
Outline of structure
Problems to be encountered
 Uncertainty and usefulness of climate
forecasts
 Deciding how to use the climate forecast to
issue a dengue alert
 Dissemination of the alert
 Acceptance of the alert by the population
 Determining the value of the process.
Questions
How do we generate the required
forecast/alert?
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What are the methodologies?
What are the resource groups providing
information for making the forecasts/alert?
How do we measure the skill rate of the
forecast/alert?
How can the accuracy of the forecasts and of
linking climate to dengue be improved?
What lead times are required?
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How and when do we disseminate the alert?
How do we educate the vulnerable population and
what can we learn from the population to make the
message more effective?
-What are the limitations of the alerts?
-What is the value of the alert?
-How are the alerts used or applied?
-What are the limitations to the use of the alerts?
-What are the impediments to the use of the alerts?
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To whom are these forecasts valuable?
-How valuable?
-In what form are the forecasts valuable?
Steps to overcome problems:
I) improve prediction
•
•
•
•
Advances in the prediction of El Niño,
International centers which make gross predictions
for the Caribbean
Work of researchers in the islands (IM, CSGM,
CIMH) and in the region (CR and Mexico)
5 to 10 years time: climate prediction in the
Caribbean will become as routine as weather
prediction?
Steps to overcome problem:
II) Research on linkage
 Retrospective studies - determining the characteristics of the
epidemiological patterns of dengue fever and its vectors in
relation to climate in 21 CAREC Member Countries (CMCs)
using past climate and epidemiology data.
 Prospective studies of dengue fever / dengue haemorrhagic
fever (DHF) in the same 21 CMCs over the first two and half
years of this study in relation to changing climate, and of
vector abundance using various indicators ( house, container
and breteau indices), over the same period and climatic
conditions.
Steps to overcome problems:
III) showing the way forward
 Institutions such as IRI (climate/social
scientists, psychologists)
 Publication (‘Under the Weather’)
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climate forecasts, epidemiology and environmental
fieldwork  predictive models
vulnerability assessment,
risk analysis
Watch/warning
response strategy and
communication.
Risk analysis,
Climate
vulnerability
forecasts
assessment
Disease
Public
watch/warning
communication
Ongoing epidemiological
surveillance and
environmental observations
Response
strategy
Evaluation,
feedback
Have Faith in Science
Nevertheless we should have faith in science:
•Twenty years ago, we knew very little about
predicting climate and El Niño events, much less
the connection between Climate Change, El Niño
and dengue. What will we know twenty years
from now?
“Everybody talks about the weather but nobody does
anything about it” Mark Twain (1835-1910)
SIS06: “We can’t change the weather, but we can
do something about it”
The End