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Viruses Emerging in Australia: The (Likely) Influence of Climate Change Viruses in May, ’10 Katoomba A.J. McMichael National Centre for Epidemiology and Population Health The Australian National University Canberra, 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 to transmission Year infection first reported Ebola 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 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, contacts Peri-urban poverty: privation, under-nutrition, poor hygiene Urbanization: sexual relations, mobility, mixing, etc. Globalization: distance/speed of travel/trade Intensified livestock production: BSE/vCJD, BSE/vCJD Nipah virus, virus bird ’flu flu Live animal food-markets: longer supply lines – SARS, HIV?, etc. Disrupted ecosystems: dams, deforestation, biodiversity loss – e.g. various new Sth American rural haemorrhagic viral diseases Global climate change Biomedical exchange of human tissues: transfusion, transplants Antibiotic use/misuse: humans, livestock production, house-plants Increased human susceptibility: under-nutrition, population ageing, HIV IV drug use, HIV, use etc. etc Temperature and tick-borne encephalitis ((TBE)) in Czech Republic p TBE 500 Cases 1993 to 2002: n=5,873 cases 450 400 350 300 250 200 150 100 y = 0.6536x2.1743 50 R2 = 0.9501 0 −5 0 Source: Daniel, et. al. 2006 5 10 Temperature oC 15 20 Geographical distribution of Aedes albopictus albopictus* mosquito Vector for: • Dengue • West Nile Virus • Chikungunya • Japanese encephalitis Before 1980 Expansion 1981 to 2005 Nipah Virus Disease: Outbreak in Malaysian y Pig g Farmers,, 1997-1999 Fruit bats (~40% carry the virus) Fruit orchards Virus-contaminated fruit, bat droppings Forest clearing El Niño drying (1998!) Forest-fire smoke ? Rain Forest, with seasonal f ii fruiting: bat food Intensive pig farming Eaten by pigs Infected (sick) pigs 265 humans infected: JE-like illness ~40% fatal ~105 deaths Projected Global Warming: IPCC (2007) combined results of multiple model runs published by ~20 different modelling groups around world 2020s 6.0 2090s 5.0 A2 4.0 A2 Av. surface 3.0 warming, oC 2.0 A1B A1B Since 1950: + 0.7oC 1.0 1.8 - 4.0oC B1 0 Reference 1980-99 temperature 1.0 0 -1 1900 2000 Year B1 2100 Temperature projections, for 3 (of 6) different emissions projections: A2 relatively high emissions A1B mid level mid-level B1 low Atmosphere concentrations remain as in 2000 0o 3.5o 7.0o (Temp Rise Rise, oC) INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE, 2007 Earth’s Temperature Chart, since Dinosaur Extinction 65m yrs ago East Antarctic ice sheet begins 5oC warmer than now West Antarctic ice sheet begins 3oC warmer than now Arctic ice sheets appear 1.5oC warmer than now Paleocene 12 Temp oC * (vs 1961-90) s ? 8 s 4 0 1961-90 av temp -4 Last 2m yr = ice-age 60 60myr * Global temperature measured d att deep d ocean 50 50myr 40 40myr 30 30myr Millions of Years Before Present 20 20myr 10 10myr Sea level 25-40 metres higher than now Tripati et al Science 2009 N Now Satellite-based measures of average global temperature (near-surface lower atmosphere), by year (Sept-Feb period), period) 1979-2010 Long-term uptrend continues 0.5 1997-98 0.4 2003-04 2009 10 2009-10 0.3 Temperature 0.2 variation (oC), 0.1 relative to reference 0 temperature Reference temperature, (1979-1998 average) - 0.1 - 0.2 10 years of alleged ‘cooling’ since 1998 (popular ‘sceptic’ argument … i.e., before more recent data appeared) - 0.3 - 0.4 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 Autumn Spring 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 ANNUAL Best estimate ((50th percentile) of change in average temperature (oC) over land by 2030 for A1B emission (‘medium’) scenario BoM: Best estimates of annual % change in precipitation (3 global emissions scenarios) 2030 2070 2050 (low) (high) -40% -20 -10 -5 -2 2 5 10 20 40% Climate and Infectious Disease Climatic conditions set the geographic and seasonal boundaries of potential transmission. Other environmental, social and behavioural public health strategies g – factors – and p determine where/when actual transmission occurs. Lyme L me disease disease: white-footed hite footed mouse and its acorn feed Zoonoses: Climatic and Seasonal Variations in Vector and Host-Species Vector-borne zoonoses mostly maintained by wildlife • Humans are incidental to their ecology Vectors and animal host species undergo seasonal and inter annual variations in numbers and activities inter-annual • Vector activity reflects temperature and humidity • Host 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 Viral replication rate Temperature Climate change Rainfall Surface water Mosquitoes, ticks, etc. Natural habitat Animal reservoir Humidity Winds, drying, dust Under-nutrition; social disruption & p displacement e.g. meningitis in W Africa Vulnerability to ID Human viral ID Spill-overs Human viral ID Human ID Potential weeks of activity of Aedes albopictus mosquito in Europe (current): Spring hatching to Autumn diapause Weeks 0 1-8 9-13 14-15 16-18 19-20 21-22 23-24 Schaffner F, et al. Development of Aedes albopictus risk maps. ECDC, Stockholm 2008. (Forthcoming.) Climate Change and Viral Diseases of Interest in Australia Vector-borne Human only: Dengue fever, Chikungunya (?) Zoonotic: Ross River, Barmah Forest, MVE, K njin Japanese encephalitis Kunjin, Contagious, g , person-to-person p p Influenza (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 2050 Darwin Darwin . . Broome Port Hedland . . Katherine . . . Katherine .. . . Port Hedland Mackay Rockhampton p Townsville Current risk region, for d dengue transmission t i i Townsville . 2050 risk region: Medium GHG. . Cairns . . . Cairns Broome emissions scenario Carnarvon Mackay Brisbane Rockhampton . . Dar in Darwin Brisbane . Katherine . . . . Cairns Broome Townsville Port Hedland . Mackay 2050 risk region: High GHG Carnarvon emissions scenario . . Rockhampton Brisbane * Global Gl b l statistical i i l model d l (H (Hales), l ) applied to Australia: Function of water vapour pressure (rainfall humidity). NCEPH/CSIRO/BoM/UnivOtago, 2003 Areas suitable for dengue transmission in 2100 under 4 climate change scenarios (grey = ≥50% likelihood of transmission) Bambrick et al., 2009, Global Hlth Action 1. Hot & Dry 2. Hot, Median humidity 3. Hot & Wet 4. Warm (strong mitigation) Map-projection of changes to rainfall across Australia to 2100 under ‘dry’ and ‘wet’ scenarios. B Based d on published bli h d literature, then modelled how these changes g would affect disease distribution over space and time. No. of people in regions at high risk (≥50%) of dengue transmission, under four climate change scenarios Modelling done for Garnaut Review,, 200809, by ANU/UWS team 3 h 3. hot/wet / 1. Hot /dry 2. hot/medium humidity 4. Warm (strong mitigation) iti ti ) Is climate change increasing the northern limit of Culicoides vectors of Bluetongue virus in Europe? p Northern range of virus: 2004 Northern limit, C. imicola group: 2004 Northern range of virus: < 1998 Northern limit, C. C imicola group: < 1998 C. pulcaris C. Obselitus C. imicola Northern limit Current northern limit Southern limit Northern limit < 1998 Source: Purse et al, 2005 Nature Reviews Microbiology Bluetongue Virus Zones in Australia, December 2009 Possible transmission Surveillance Free Surveillance data on distribution of bluetongue and culicoides vector from National Arbovirus Monitoring Program, administered by Animal Health Australia Eric Barron: Beyond Climate Science Science 2009; 326: 643 Editorial “Currently, 40 years of intensive climate “Currently model development is being coupled to what amounts to a cottage industry of impact sciences. “Th result “The lt iis th thatt our understanding d t di off how ecosystems, water, human health, agriculture, i lt and d energy will ill respond d to t climate change advances only slowly.”
