Dengue in the Caribbean and El Nino years and year after an El Nino - El Nino +1

The Threat of Dengue Fever - Assessment of Impacts and Adaptation to Climate Change in Human Health in the CaribbeanAn AIACC Project at The University of the West Indies, Mona and Caribbean Epidemiology Centre

Dengue in the Caribbean and El Nino years and year after an El Nino - El Nino +1

El Nino

El Nino + 1

The Culprit (Vector)

Also the dengue mosquito

The Problem

The water problem:

•In times of rain, pools of water collect in 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 (EIP) (period of incubation of parasite inside the vector) 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.

The Temperature Problem (Cont.):•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• 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 and temperature increases during May to July in the El Niño + 1 year

This leads to the temperature and water problem.

The Climate Change Problem:

•Santer (2001): 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): likely alteration of the global distribution of dengue due to climate change, with 2.5 billion at risk in the tropics and sub tropics.

The Project

The Threat of Dengue Fever

AIACC in Human Health in the Caribbean

Objectives:•to determine the extent of the association between climate and the incidence of dengue across the Caribbean region;•to identify and evaluate adaptive options to ameliorate the impact of climate on this disease;•to use the knowledge gained above to determine future impacts (long term - next 50 -100 yrs) and adaptation based on global change scenarios;•to make the knowledge gained accessible and useful to decision makers.

Co-Principal Investigators:A. Anthony Chen, Atmospheric PhysicistDept of Physics, University of the West Indies (UWI), Mona,JamaicaSamuel C. Rawlins, Entomologist/ParasitologistCaribbean Epidemiology Centre (CAREC),Trinidad & TobagoResponsible Institution: UWI, Mona

UWI Team:A. Dharmeratne Amarakoon, PhysicistWilma Bailey, Health GeographerAlbert Owino, MeteorologistMichael A. Taylor, Meteorologist

CAREC Team:Karen Polson, Epidemiologist

Others

• Dave Chadee, Ministry of Health, T&T and UWI Department of Life Science, St. Augustine

• Rohit Doon, Ministry of Health, T&T

• Karen Webster, Sherine Huntley, Ministry of Health, Ja.

Post Graduate Students

• Rainaldo Crosbourne, Data base management

• Charmaine Heslop-Thomas, Medical Geography

• Cassandra Rhoden, Scenario generation

• Roxann Stennett, Impact Studies

Consultants:Dr. Joan L. Aron1, Science Communication StudiesProf. Ulisses E.C. Confalonieri2, Fundacao Oswaldo Cruz Dr. Henry F. Diaz3, NOAA/CDCDr. Roger Pulwarty3, NOAADr. Benjamin D. Santer4, Lawrence Livermore National LaboratoryDr. Neil Ward5, International Research Institute Dr. Tom Wigley5, National Center for Atmospheric ResearchDr. Rob L. Wilby5, King’s College, London 1. Mathematical Modeller, 2.Epidemiologist, 3. Climatologist4. Atmospheric Physicist, 5. Climate Modeller

Methodology in Epidemiology

•Development of historical epidemiology database managed by CAREC and collection of current Dengue/ dengue haemorrhagic fever (DHF) data.

•Retrospective studies of the disease in the last 15 years

•past climate association with dengue fever

•Prospective studies carried out in the first two and half years of the project on Vector abundance, climate and dengue occurrence.

Methodology in Climate:

•Development of climate database managed by CSGM and collection of current data

•Generating future climate change scenarios.

>Using statistical downscaling techniques to regionalize climate change projections from global climate models (GCM’s) that use Special Report Emission Scenarios (SRES) as inputs

> PC-based Statistical Downscaling Model (SDSM) [Wilby et al, 2001],

Assessment of Impact and Adaptation Strategies • Socio-economic study

identify the socio-economic groups most at-risk for infection; estimate the ability to respond

•Knowledge, Attitude and Practices (KAP) survey

population's perception of climate change impacting on dengue;

readiness of the community to modify vector production behaviour, based on the forecast of conditions favourable to vector and disease increase.

Recommendations for Adaptation

• Analysis of adaptation strategies based on impact and scenario studies

• Early warning system

Results: Retrospective Study

Moving Average Temperature (MAT) =

M

NNT

M 1

1

TN is the average temperature during the Nth 4 week period or month

M = 1, 2, 3,…13 or 12.

Examples:

For 1st 4 week period or 1st month, M=1 and

For 2nd period or month, M=2 and

For 4th period or month M= 4 and

11T

MAT

212

1TTMAT

43214

1TTTTMAT

Qualitative model of the first prospective year (2002): distribution of dengue cases, vector density and climate

(Trinidad)

0

200400

600800

1000

12001400

1600

J F M A M J J A S O N D

Months

No.

den

gue

case

s

0

5

10

15

20

25

rainfall

Aed

es a

egyp

ti in

dex

Dengue Cases

Rainfall

Breteau index

Results: Prospective Study

Results: Socio-economic Study

Results: KAP Survey

Results: Scenario generation: Ja. Temperature

Scenario generation: Barbados Precip

Consequences

• Increase in temperature of about 2ºC expected by 2080

• Not much change in precipitation expected

• 2ºC is expected to give rise to a 3-fold increase in the rate of transmission of dengue

Early Warning using MAT index:

RC, Moving Average T vs 4-Week periods (1996, 1997, 1998, & 2000) T&T

0

100

200

300

400

500

600

700

800

900

1000

1 2 3 4 5 6 7 8 9 10 11 12 13

4-WEEK PERIODS

Rep

ort

ed C

ases

(R

C)-

4 W

EE

KL

Y

25.5

25.75

26

26.25

26.5

26.75

27

27.25

27.5

27.75

28

28.25

28.5

28.75

29

MA

T i

n C

RC-1996

RC-1997

RC-1998

RC-2000

MAT-1996

MAT-1997

MAT-1998

MAT-2000

27.2 C Lline

Avg MAT

Early crossing of Avg. MAT in 1998 associated with early onset; slow approach in 1997 assocated with late onset; crossing in 1996 and 2000 coincides with onset

Early Warning System for Dengue Epidemic

Check List:Climate Surveillance

MAT index

Epidemiology Control (Surveillance)Breteau index

Pupae/person IndexPresence of dengue below epidemic level Response within means

MAT

• The time the average MAT is approached or reached can be used to gauge the potential for the onset of an epidemic– An analog approach can be used

• Especially useful for timing early or late epidemic

• Easiest of items on check list to monitor• Next step – remaining items on check list

MEASURES Cost

Effective-ness

Social accepta-bility

Friendly for environ-ment

Neigh-bour effects

Technical challenges and socio-economic change

Score

Short term

1. Adulticide (ULV or thermal fog sprays) in truck or air

2. Education (disease symptoms, sanitizing the environment).

3. Surveillance for vector or larval/pupal control.

H

M

H

L

M

M

L

H

M

L

H

M

L

H

M

H

M

L

6

24

18

Long Term

1. Surveillance for vector or larval/pupal control and environmental sanitation

2. Community education and involvement.

3. Chemical control

4. Biological control

5. Adult Control

- Physical-mesh windows

- Personal protection

6. Use of physical control-low cost secure drums

7. Granting security of tenure to squatters

8. Early warning system

H

M

H

H

M

M

H

H

M

M

H

M

H

H

M

H

H

H

M

H

M

M

H

M

M

H

H

M

H

L

H

H

M

H

M

H

L

H

M

M

H

M

H

H

H

L

M

L

M

H

H

H

H

H

16

26

16

20

24

16

20

20

24

Adaptation: Short and long term measures

MEASURES Cost

Effective-ness



Neigh-bour effects


Score

Short term




H

M

H

L

M

M

L

H

M

L

H

M

L

H

M

H

M

L

6

24

18

Long Term



3. Chemical control


5. Adult Control






H

M

H

H

M

M

H

H

M

M

H

M

H

H

M

H

H

H

M

H

M

M

H

M

M

H

H

M

H

L

H

H

M

H

M

H

L

H

M

M

H

M

H

H

H

L

M

L

M

H

H

H

H

H

16

26

16

20

24

16

20

20

24

Weighting Low - 1, Medium -2 High – 3

Reversed for Cost and Technical Challenge

Assignment based on expert opinion (MOH’s)

MEASURES Cost

Effective-ness



Neigh-bour effects


Score

Short term




H

M

H

L

M

M

L

H

M

L

H

M

L

H

M

H

M

L

6

24

18

Long Term



3. Chemical control


5. Adult Control






H

M

H

H

M

M

H

H

M

M

H

M

H

H

M

H

H

H

M

H

M

M

H

M

M

H

H

M

H

L

H

H

M

H

M

H

L

H

M

M

H

M

H

H

H

L

M

L

M

H

H

H

H

H

16

26

16

20

24

16

20

20

24

Climate Change and biodiversity

• How will climate change?

IPCC: The World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) established the Intergovernmental Panel on Climate Change (IPCC) in 1988. . The IPCC has three Working Groups and a Task Force Working Group I assesses the scientific aspects of the climate system and climate change. Working Group II assesses the vulnerability of socio-economic and natural systems to climate change, negative and positive consequences of climate change, and options for adapting to it. Working Group III assesses options for limiting greenhouse gas emissions and otherwise mitigating climate change.

Summary for Policy Makers (Global ProjectionsWorking Group 1)

FINAL FIGURES & TABLES FROM PLENARY

Updated: 20 Feb 2007

Conclusions about projected climate change for Caribbean region:

• Sea levels will likely continue to rise on average during the century around the islands of the Caribbean Sea. (Models indicate that the rise will not be geographically uniform globally but large deviations among models make estimates of distribution across the Caribbean, Indian and Pacific Oceans uncertain.)

• All Caribbean islands are very likely to warm during this century. The warming is likely to be somewhat smaller than the global, annual mean warming in all seasons.

• Rainfall in the vicinity of the Greater Antilles is likely to decrease in JJA but changes elsewhere and in DJF are uncertain.

For More details

• Climate Change Conference at UWI

• June

Climate Change and Biodiversity

Some topics in biodiversity• Loss of habitat• Shift in Ecological Zones• Erosion of beaches• Inundation of coastal lands• Cost to protect coastal community• Fisheries• Declining area for turtle nesting• Change in forestation• Forest Health and productivity• Carbon sequestration• Modelling• Adaptation

Dengue in the Caribbean and El Nino years and year after an El Nino - El Nino +1

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