Health Effect of Health Effect of Climatic Change: Climatic Change:

Malaysian Malaysian SenariosSenarios

Dr Rozlan IshakDr Rozlan IshakEnvironmental Health UnitEnvironmental Health Unit

Disease Control DivisionDisease Control DivisionMinistry of Health MalaysiaMinistry of Health Malaysia

Situations 50 years agoSituations 50 years ago

Malaria was rampant in MalaysiaMalaria was rampant in Malaysia 460,000 cases a year460,000 cases a year High mortality and morbidityHigh mortality and morbidity Every parts of the country were under Every parts of the country were under

malariamalaria Even the Island of Penang has malariaEven the Island of Penang has malaria Some urban areas were free from Some urban areas were free from

malariamalaria

Health problemsHealth problems

Water supply was inadequate.Water supply was inadequate. Hygiene and sanitation was poorHygiene and sanitation was poor Latrines were lacking in most parts of Latrines were lacking in most parts of

the country.the country. Bucket latrines was the style of the day.Bucket latrines was the style of the day. Infectious disease such as cholera, Infectious disease such as cholera,

typhoid, dysentery, worms infestation typhoid, dysentery, worms infestation were very common.were very common.

Dengue is not a problem!Dengue is not a problem!

Mosquito borne Mosquito borne diseasesdiseases50 years later50 years later

MalariaMalariaMalaria in Malaysia from 1961 to 2006

0

100,000

200,000

300,000

400,000

500,000

600,000

Years

Nu

mb

er c

ases

malaria

Dengue FeverDengue FeverDengue Fever In Malaysia from 1980 to 2006

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

Years

Nu

mb

er

of

Cases

Dengue Fever

Viral EncephalitisViral EncephalitisViral Encephalitis in Malaysia from 1980 to 2006

0

50

100

150

200

250

300

350

Years

Nu

mb

er o

f C

ases

Viral Encephalitis

Water Borne Water Borne DiseasesDiseases

50 years later50 years later

CholeraCholeraCholera incidence in Malaysia from 1980 to 2006

0

500

1000

1500

2000

2500

Years

Nu

mb

er

of

Cases

Cholera

DysenteryDysenteryDysentery Incidence in Malaysia from 1980 to 2006

0

200

400

600

800

1000

1200

1400

1600

1800

Years

Num

ber

of C

ases

Dysentery

Food PoisoningFood Poisoning

Food Poisoning incidence in Malaysia from 1980 to 2006

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

Years

Nu

mb

er

of

Cases

Food Poisoning

TyphoidTyphoidTyphoid incidence in Malaysia from 1980 to 2006

0

500

1000

1500

2000

2500

3000

3500

Years

Nu

mb

er

of

Cases

Typhoid

Hepatitis (all forms)Hepatitis (all forms)Hepatitis (all form) reported in Malaysia from 1980 to 2006

0

1000

2000

3000

4000

5000

6000

7000

8000

Years

Nu

mb

er

of

Cases

Hepatitis (all form)

Climate ChangeClimate ChangeFacts !Facts !

Global WarmingGlobal Warming

21002100

Climate ChangeClimate Change

PathwaysPathways

Climate change and health: pathway from driving forces, Climate change and health: pathway from driving forces, through exposures to potential health impact.through exposures to potential health impact.

Source: Climate Change and Human Health – Risks and Reponses. Summary (WHO, 2003)

Driving forces

Population dynamics

Unsustainable economic

development

Natural causes

Adaptive capacity

Mitigative capacity

Mitigation measures

Greenhouse gases (GHG)

emissions

CLIMATE CHANGE

Microbial contamination

pathways

Transmission dynamics

Agro-ecosystems, hydrology

Socioeconomics, demographics

Regional weather changes

Heatwaves

Extreme weather

Temperature

Precipitation

Health effects

Temperature-related illness and death

Extreme weather-related health effects

Air pollution-related health effects

Water and food-borne diseases

Vector-borne and rodent-borne diseases

Effects of food and water shortages

Mental, nutritional, infectious and other

health effects

Modulating influences

Health-specific adaptation measures

Research needs

Evaluation of adaptation

Biological Biological FactorsFactors

Biologic response to changes in Biologic response to changes in climateclimate

Global warming and wider fluctuation in Global warming and wider fluctuation in weather help to spread diseasesweather help to spread diseases

Temperatures – affect growth, development Temperatures – affect growth, development and survival of microbes and the vectorsand survival of microbes and the vectors

Weather affects the timing and intensity of Weather affects the timing and intensity of disease outbreaks (McMichael et al, 2003)disease outbreaks (McMichael et al, 2003)

Biologic response to changes in Biologic response to changes in climate: Infectious diseasesclimate: Infectious diseases

Warmer environment and Warmer environment and mosquitoesmosquitoes Boost rate of reproductionBoost rate of reproduction Increase the number of blood mealIncrease the number of blood meal Prolongs their breeding seasonProlongs their breeding season Shorten the maturation period of Shorten the maturation period of

microbes they carrymicrobes they carry

Heavy downpoursHeavy downpours Drive rodents from burrows: risk of zoonotic Drive rodents from burrows: risk of zoonotic

diseasesdiseases Create mosquito breeding sitesCreate mosquito breeding sites Faster fungal growth in housesFaster fungal growth in houses Flush pathogens and chemicals into Flush pathogens and chemicals into

waterwayswaterways Milwaukee’s cryptosporidiosis outbreak in Milwaukee’s cryptosporidiosis outbreak in

19931993 Katrina’s flood 2005: water-borne Katrina’s flood 2005: water-borne

pathogens and toxins spread.pathogens and toxins spread. Johor flood 2007 and leptospirosisJohor flood 2007 and leptospirosis

Common communicabale diseases Common communicabale diseases sensitive to climate (WHO, 2004)sensitive to climate (WHO, 2004)

Climate is the primary factor in Climate is the primary factor in epidemicepidemicCholera, MalariaCholera, Malaria

Climate plays significant roleClimate plays significant role Meningococcal meningitis, leishmaniasis, Meningococcal meningitis, leishmaniasis,

dengue, Japanese encephalitis, Rift valley dengue, Japanese encephalitis, Rift valley fever, Ross river virus, St. Louis fever, Ross river virus, St. Louis encephalitis, Murray valley feverencephalitis, Murray valley fever

Infection & Climate: Potential impact Infection & Climate: Potential impact on endemic diseases in Malaysia on endemic diseases in Malaysia

DiseaseDisease Trans-Trans-missionmission

Evidence Evidence for inter-for inter-annual annual variabilityvariability

Climate-Climate-epidemic epidemic linklink

Strength Strength of climate of climate sensitivitsensitivityy

Climate-Climate-epidemic epidemic relationsrelationship hip quantifiequantifiedd

CholeraCholera Food & Food & water-water-borneborne

********** Increase Increase in sea & in sea & air temp. air temp. SanitatioSanitationn

**********

√√

MalariaMalaria MosquitoMosquito ********** Temp. & Temp. & rainfall. rainfall. Many Many othersothers

********** √√

DengueDengue MosquitoMosquito ******** Temp., Temp., humidity humidity & rainfall& rainfall

****** √√

Temperature, vectorial capacity of Temperature, vectorial capacity of Ann. maculatusAnn. maculatus and projected number of malaria cases (Ambu et al. and projected number of malaria cases (Ambu et al.

2003)2003)

0

2000

4000

6000

8000

10000

12000

14000

16000

27 28 29 30 31 32 33 34

Temp (oC)N

o. M

alar

ia c

ases

0

0.05

0.1

0.15

0.2

0.25

VC

No. of cases Vectorial Capacity (VC)

Temp Temp ((ooC)C)

Esti. Esti. MaMa

Esti. AEsti. A Esti. NEsti. N CC

2727 2020 0.0430.043 1010 0.0690.069

2828 2121 0.0430.043 9.99.9 0.0750.075

2929 2222 0.0430.043 9.89.8 0.0810.081

3030 2525 0.0500.050 9.79.7 0.0960.096

3131 2727 0.0500.050 9.69.6 0.120.12

3232 3030 0.0500.050 9.59.5 0.140.14

3333 3535 0.0500.050 9.49.4 0.170.17

3434 4040 0.0500.050 9.39.3 0.200.20

Rainfall and dengue outbreak in Rainfall and dengue outbreak in MalaysiaMalaysia

Modification of Mogi et Modification of Mogi et al. 1990 modelal. 1990 model

Study the threshold of Study the threshold of rainfall actually required rainfall actually required to trigger an outbreakto trigger an outbreak

Dengue incidence and Dengue incidence and rainfall data in 1986-rainfall data in 1986-19971997

Model indicated Model indicated relatively fewer raining relatively fewer raining days are required for days are required for high transmissionhigh transmission

Heavy rain flushes off Heavy rain flushes off breeding habitatsbreeding habitats

No. days No. days examined examined for rainfor rain

Low Low transmission: transmission: no. raining no. raining days required days required for an for an outbreakoutbreak

High High transmission: transmission: no. raining no. raining days required days required for an for an outbreakoutbreak

3030 2.892.89 0.470.47

6060 4.574.57 2.152.15

9090 6.256.25 3.833.83

120120 7.937.93 5.515.51

150150 9.619.61 7.197.19

180180 11.2911.29 8.878.87

210210 12.9712.97 10.5510.55

240240 14.6514.65 12.3312.33

270270 16.3316.33 13.9113.91

300300 18.0118.01 15.5915.59

330330 19.6919.69 17.2717.27

360360 21.3721.37 18.9518.95

Potential Health Potential Health Effects from Effects from

Global WarmingGlobal WarmingYear 2100Year 2100

Malaria Year 2100Malaria Year 2100Possible Pattern of Malaria in Worst Cases Senario in Malaysia

from Year 1960 to 2100

0

100,000

200,000

300,000

400,000

500,000

600,000

Year

Num

ber

of

Mala

ria C

ases

Malaria With Control measures Without Control measures

Dengue Fever Year 2100Dengue Fever Year 2100

Dengue Fever In Malaysia from Year 1980 to 2100

0

100000

200000

300000

400000

500000

600000

700000

Years

Nu

mb

er

of

Ca

se

s

Dengue Fever with Control Measures Without Control Measures

What is our What is our plans?plans?Thank youThank you

rozlan@dph.gov.myrozlan@dph.gov.my