Viruses Emerging in Australia:The (Likely) Influence of Climate Change

Viruses in May, ’10KatoombaKatoomba

A.J. McMichaelNational Centre for Epidemiology and Population Health

The Australian National University Canberra, AustraliaCanberra, Australia

Newly Emerging Diseases (Morens et al, 2004)13 of 17 are viral

Re-Emerging Diseases (Morens et al, 2004)7 of 21 are viral

Breaches in the species barrier: Selected emerging infections in humans since 1976

Infection Animal linked Year infectionto transmission first reported

Ebola virus Bats 1976Ebola virus Bats 1976

HIV-1 Primates 1981

E. coli O157:H7 Cattle 1982

Borrelia burgdorferi Rodents 1982

HIV-2 Primate 1986

Hendra virus Bats 1994

BSE/vCJD Cattle 1996

Austn lyssavirus Bats 1996

H5N1 influenza A Chickens 1997H5N1 influenza A Chickens 1997

Nipah virus Bats 1999

SARS coronavirus Palm civets 2003

Influenza (H1N1) Swine 2009

Major factors enhancing infectious disease emergence and spread

Population growth, urban density: crowds, contactsPeri-urban poverty: privation, under-nutrition, poor hygieneUrbanization: sexual relations, mobility, mixing, etc.Globalization: distance/speed of travel/trade Intensified livestock production: BSE/vCJD Nipah virus bird ’fluIntensified livestock production: BSE/vCJD, Nipah virus, bird fluLive animal food-markets: longer supply lines – SARS, HIV?, etc.Disrupted ecosystems: dams, deforestation, biodiversity loss – e.g. various new Sth American rural haemorrhagic viral diseasesvarious new Sth American rural haemorrhagic viral diseasesGlobal climate changeBiomedical exchange of human tissues: transfusion, transplantsAntibiotic use/misuse: humans, livestock production, house-plantsIncreased human susceptibility: under-nutrition, population ageing, HIV IV drug use etcHIV, IV drug use, etc.

Temperature and tick-borne encephalitis (TBE) in Czech Republic

500

450

( ) p1993 to 2002: n=5,873 casesTBE

Cases450

400

350

300

250

200200

150

100y = 0.6536x2.1743

R2 = 0.9501

100

50

0

Source: Daniel, et. al. 2006

−5 0 5 10 15 20Temperature oC

Geographical distribution of Aedes albopictus* mosquitoof Aedes albopictus mosquito

Vector for:• Dengue

Before 1980

• Dengue• West Nile Virus• Chikungunya

Expansion 1981 to 2005• Japaneseencephalitis

Nipah Virus Disease: Outbreak in Malaysian Pig Farmers, 1997-1999y g ,Fruit bats (~40% carry the virus)

Forest clearing

Fruit orchardsVirus-contaminated fruit, bat droppings

Intensivepig farming Eaten by pigs

Infected (sick) pigs

El Niño drying (1998!)

Forest-fire smoke ?

Rain Forest, with seasonal f i i

265 humans infected:JE-like illness

fruiting: bat food

~40% fatal~105 deaths

2020s 2090s

Projected Global Warming: IPCC (2007)combined results of multiple model runs published by ~20 different modelling groups around world

2020s 2090s

A2

6.0

5.0

4.0

A1B

3.0

2.0

Av. surface warming, oC

A2

A1B

1.8 - 4.0oC

B1

Since 1950: + 0.7oC

1.0

0

-1 0

Reference 1980-99 temperature

B1

1900 2000 2100Year 0o 3.5o 7.0o

(Temp Rise oC)

1.0

Temperature projections, for 3 (of 6) different emissions projections:A2 relatively high A1B mid level emissions

(Temp Rise, oC)

A1B mid-levelB1 low

INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE, 2007

emissions

Atmosphere concentrations remain as in 2000

Earth’s Temperature Chart, since Dinosaur Extinction 65m yrs agoDinosaur Extinction 65m yrs ago

West Antarctic ice sheet begins

Arctic ice sheets appear

East Antarctic ice sheet begins

12

5oC warmer than now

Paleocene

3oC warmer than now

1.5oC warmerthan now

1284

Temp oC*(vs 1961-90)

?s

s

60 50 40 30 20 10 N

1961-90 av temp0-4 Last 2m yr

= ice-age

60myr 50myr 40myr 30myr 20myr 10myr Now

Millions of Years Before Present* Global temperature

d t d

Sea level 25-40 metres higher

measured at deep ocean

than nowTripati et al Science 2009

Satellite-based measures of average global temperature (near-surface lower atmosphere),

by year (Sept-Feb period) 1979-2010by year (Sept-Feb period), 1979-2010

2009 100.5

Long-term uptrend continues

1997-982003-04

2009-100.4

0.3

0.2

0.1

Temperature variation (oC),relative to reference 10 years of alleged

Reference temperature,(1979-1998 average)

0

- 0.1

- 0.2

reference temperature ‘cooling’ since 1998

(popular ‘sceptic’ argument … i.e., before more recent

- 0.3

- 0.4

data appeared)

1980 1985 1990 1995 2000 2005 2010

Monthly data from: http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts+dSST.txt

Aust. Bureau of Meteorology: Projected Temperature Rises to 2030

Summer Winter ANNUAL

Best estimate (50thSpringAutumn(

percentile) of change in average temperature (oC) over land by 2030( C) over land by 2030 for A1B emission (‘medium’) scenario

0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3

BoM: Best estimates of annual % change in precipitation (3 global emissions scenarios)

2030 2050 2070

(low)

(high)

-40% -20 -10 -5 -2 2 5 10 20 40%

Climate and Infectious DiseaseClimate and Infectious Disease

Climatic conditions set the geographic andClimatic conditions set the geographic and seasonal boundaries of potential transmission.

Other environmental, social and behavioural factors – and public health strategies –p gdetermine where/when actual transmissionoccurs.

Zoonoses: Climatic andSeasonal Variations inSeasonal Variations in

Vector and Host-SpeciesL me disease hite footed

Vector-borne zoonoses mostly maintained by wildlife

Lyme disease: white-footed mouse and its acorn feed

• Humans are incidental to their ecology

Vectors and animal host species undergo seasonal and inter annual variations in numbers and activitiesinter-annual variations in numbers and activities

• Vector activity reflects temperature and humidity• Host species population size and distribution affected by weather andHost species population size and distribution affected by weather and

(climate-related) resource availability

Pathogen may also be affected by climatic conditions

Climatic Influences on Viral Disease Occurrence

Temperature

Viral replication rate

Climate change

Temperature

Surface Natural

Mosquitoes, ticks, etc. Human

viral ID

Rainfall water

Humidity

Natural habitat

Animal reservoir

Human viral ID

Spill-overs

Winds, drying, dust

viral ID

e.g. meningitis in W Africa Human

Under-nutrition;social disruption & displacement

Vulnerability to ID

ID

p

Potential weeks of activity of Aedes albopictus mosquito in Europe (current): Spring hatching to Autumn diapause

Weeks01-89-1314-1516-1819-2021-2223-24

Schaffner F, et al. Development of Aedes albopictus risk maps. ECDC, Stockholm 2008. (Forthcoming.)

Climate Change and Viral Diseases of Interest in AustraliaDiseases of Interest in Australia

Vector-borneHuman only: Dengue fever, Chikungunya (?)

Zoonotic: Ross River, Barmah Forest, MVE, K njin Japanese encephalitisKunjin, Japanese encephalitis

Contagious, person-to-persong , p pInfluenza (emergence and spread of new strains)Respiratory syncytial virus?? Changes in contact probabilities and behaviours

- hep B, hep C, HPV, HIV

DENGUE FEVER: Estimated geographic region suitable* for A. aegypti vector, and hence transmission:

Climate conditions now and in alternative scenarios for 2050Climate conditions now and in alternative scenarios for 2050

Darwin

Katherine

..

2050 risk region: Medium GHG

Cairns

Mackay

Rockhampton

Townsville

Port Hedland

Broome.. .. .Darwin

Katherine

CairnsBroome

..

.. 2050 risk region: Medium GHG

emissions scenariop.

Carnarvon.Mackay

Rockhampton

Townsville

Port Hedland

Broome ... ..Current risk region, for d t i i Dar in

Brisbane

Brisbane.dengue transmission Darwin

Katherine

Cairns

TownsvilleBroome.

. ...

Mackay

Rockhampton

Port Hedland. ..Carnarvon. 2050 risk region: High GHG

emissions scenario Brisbane

* Gl b l i i l d l (H l )

NCEPH/CSIRO/BoM/UnivOtago, 2003

* Global statistical model (Hales), applied to Australia: Function of water vapour pressure (rainfall humidity).

Areas suitable for dengue transmission in 2100 under 4 climate change scenarios (grey = ≥50% likelihood of transmission)

Bambrick et al., 2009, Global Hlth Action

Map-projection of changes to rainfallchanges to rainfall across Australia to 2100 under ‘dry’ and ‘wet’ scenarios. B d bli h d

2. Hot, Median humidity1. Hot & Dry

Based on published literature, then modelled how these changes would affect gdisease distribution over space and time.

4. Warm (strong mitigation)3. Hot & Wet

No. of people in regions at high risk (≥50%) of dengue transmission, under four climate change scenarios

3 h /

Modelling done for Garnaut Review, 2008-

3. hot/wet,

09, by ANU/UWS team

1. Hot/dry

2. hot/medium

4. Warm (strong iti ti )

2. hot/mediumhumidity

mitigation)

Is climate change increasing the northern limit of Culicoidesvectors of Bluetongue virus in Europe?

Northern limit, C. imicola group: 2004

Northern range of virus: 2004

p

C

Northern range of virus: < 1998

Northern limit, C. imicola group: < 1998

C. pulcaris C. Obselitus C. imicolaCurrent northern limitNorthern limit

Source: Purse et al, 2005 Nature Reviews Microbiology

Northern limit < 1998Southern limit

Bluetongue Virus Zones in Australia, December 2009

Possible transmissionSurveillance

Surveillance data on distribution of bluetongue and culicoides vector from National Arbovirus Monitoring Program, administered by Animal Health Australia

SurveillanceFree

Eric Barron: Beyond Climate ScienceScience 2009; 326: 643Editorial

“Currently 40 years of intensive climate“Currently, 40 years of intensive climate model development is being coupled to what amounts to a cottage industry ofwhat amounts to a cottage industry of impact sciences. “Th lt i th t d t di f“The result is that our understanding of how ecosystems, water, human health,

i lt d ill d tagriculture, and energy will respond to climate change advances only slowly.”