Role of climate change in epidemiology of infectious diseases
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Transcript of Role of climate change in epidemiology of infectious diseases
Role of climate change in epidemiology of infectious diseases
Delia Grace
Component Leader: Agriculture Associated Disease
CGIAR Research Program on Agriculture for Nutrition and Health
Field Epidemiology and Laboratory Training Programme in Kenya, 24 October 2012
Invited lecture FELTPK Residents during the “One Health Week
The Field Epidemiology and Laboratory Training Programme (FELTPK) in Kenya is a two-year postgraduate competency based training program in applied epidemiology and public health laboratory management. It was established in April 2004 to enable frontline public health professionals acquire the latest knowledge and skills that address global threats to public health, using training-through-service approach.
The program collaborates closely with the United States Centers for Disease Control and Prevention (CDC).Upon completion of all requirements, FELTPK graduates are awarded degrees in a Master of Science (Msc) inApplied Epidemiology or Msc in Laboratory Management and Epidemiology from Jomo Kenyatta Universityof Agriculture and Technology (JKUAT). Other key collaborating partners include Kenya Medical ResearchInstitute (KEMRI), Ministry of Medical Services and Ministry of Public Health and Sanitation, Ministry ofLivestock Development, World Health Organization (WHO), World Bank and the African Field EpidemiologyNetwork (AFENET).
Following the need to strengthen "One Health" initiatives in Kenya, FELTPK enrolled four (4) veterinaryofficers from the Ministry of Livestock Development this academic year. This was followed by designing a onehealth module that is to be delivered to the cohort 9 residents which constitutes a class of 18 residents.The following lecture “Role of Climate Change in Epidemiology of Infectious was requested by Dr Samuel Amwayi.
International Livestock Research Institute
700 full time staff-1000 total
100 scientists & researchers
54 from 22 developing countries
more than 30 scientific disciplines
2012 budget USD 60 million
ILRI works with a range of research & development partners
across 7 CGIAR research programs
•a member of the CGIAR Consortium, ILRI conducts livestock,
food and environmental research to help alleviate poverty
and improve food security, health & nutrition, while protecting the natural resource base.
Mali
Nigeria
Mozambique
Kenya
Ethiopia
India
China
Laos
Vietnam
Thailand
Overview• Ecohealth/ One Health• Our changing planet
– Warmer, wetter, weirder– Implications for Africa and Kenya– Role of agriculture in climate change
• Climate and infectious disease– How does climate affect infectious disease?– Climate sensitive infectious diseases
• Vector-borne disease• Flood-associated disease• Food-borne disease
– Climate sensitive non-infectious disease• Implications for field epidemiologists• Conclusions
Human healthHuman
health
„One Medicine“EcosystemsSocietiesEconomiesPeaceInstitutions
“Syndromeapproach”
Agroecosystem
Animalhealth
Veterinary Public Health
Ecosystem Approach to Health
Gaia Hypothesis
One world – one health
• One Health is the collaborative effort of multiple disciplines to attain optimal health for people, animals, and our environment.
• Ecohealth is systemic, participatory approaches to understanding and promoting health and well-being in the context of social and ecological interactions (Waltner-Toews D (2009), Can. Vet. J., 50(5): 519–521.).
Key concept
Key definitions
• Climate = average weather in time & place (IPCC)
• Climate change = Statistically significant variations in mean state of the climate or of its variability persisting for decades
• Climate scenario = a plausible representation of future climate based on climatological relationships
• Extreme weather event = often, rarer than the 10th or 90th percentile
• Greenhouse effect = greenhouse gases absorb infra-red radiation effectively trapping heat near the planet surface. Water vapour, CO2, nitrous oxide, methane and ozone are the most important
• Global warming = average increase in the temperature of the near the earth’s surface
• IPCC = Intergovernmental Panel on Climate Change= leading international body for assessment of climate change, established by UNEP and WMO in 1988
Key Resources: IPCC reports
• First assessment report 1990 – several paragraphs on health• Second assessment report 1995 – chapter on potential health risks• Third assessment report 2001 – chapter on human health potential
impacts via:– Thermal stress (heat waves and cold spells)– Extreme events and disasters– Air pollution– Infectious diseases
• Fourth assessment report 2007 – review of health impacts. Evidence suggests climate change has:
– Altered seasonal distribution of some allergenic pollen– Increased heat wave related deaths– Altered distribution of some vectors (mosquito, sand fly)– Climate influences malaria, dengue, TBD, cholera and some diarrhoeal disease
Climate skeptics?
• Consensus– 97-98% of scientists most active in the field
believe global warming is occurring– 90% believe mostly due to human activity
• Caveats– Planet has been warmer in the past – Role of geo-engineering in mitigation
unknown
Our Changing Planet: Warmer, wetter, weirder
“Virtually certain” Over most land areas • Warmer, and fewer cold days and nights.• Warmer, and more frequent hot days and nights
“Very Likely” Over most areas
• Warm spells / heat waves.• Heavy precipitation events.
• Generally (3/4 land area) wetter; some areas (1/4) drier.
“Likely”• Area affected by droughts increases.• Intense tropical cyclone activity increases.• Increased incidence of extreme high sea level.
Source: IPCC Climate Change 2007: The Physical Science Basis: Summary for Policymakers
National Production
Mixed rainfed temperate
Mixed rainfed humid
Mixed rainfed arid
2030 2050 2030 2050 2030 2050 2030 2050
Burundi 9 9 14 18 -2 -9 - -
Kenya 15 18 33 46 -5 -10 -1 -8Rwanda 11 15 13 19 5 4 1 3
Tanzania -3 -8 7 9 -2 -6 -5 -11
Uganda -2 -9 5 3 -5 -13 -1 -6
There may be winners as well as losers …
Simulated percentage pasture production changes to 2030 and 2050, by country and system
Mean of 4 combinations of GCM and emissions scenarios
Thornton et al. (2010)
WinnersLosers
Climate change in drylands
SAHARATemp: +3.6 CRain: -6%Drought yrs:↑
WEST AFRICATemp: +3.3 CRain: +2%Flood yrs: +22%
CENTRAL ASIATemp: +3.7 CRain: -3%Drought yrs: +12%
EAST AFRICATemp: +3.2 CRain: +7%Flood yrs: +30%Drought yrs: +1%
SOUTHERN ASIATemp: +3.3 CRain: +11%Flood yrs: +39%Drought yrs: +3%
Source: IPPC working group 1, 2007
• Livestock:9- 18% anthropogenic emissions• 80% agricultural emissions
Contributors to climate
change
Overview• Ecohealth/ One Health• Our changing planet
– Warmer, wetter, weirder– Implications for Africa and Kenya– Role of agriculture in climate change
• Climate and infectious disease– How does climate affect infectious disease?– Climate sensitive infectious diseases
• Vector-borne disease• Flood-associated disease• Food-borne disease
– Climate sensitive non-infectious disease• Implications for field epidemiologists• Conclusions
Warmer, wetter, wider variation→ sicker?
Warmer Wetter / (drier) Wider variation
D ↑ growth rate
↓ generation time
↑ ↓ survival
↑ season
↑ activity
↑ ↓ Survival in air
↑ Faecal-oral transmission
↑ Movement in water
Post disaster disease
Endemic instability
Spread/shrinkage
I Wildfires Change farming systemsAir Pollution (O3, PM, GHG) Population movementsNuisance Plants Increase in biomassMore intense air movement Change trade patterns
Group work:What important diseases in Kenya
may be climate sensitive
Conceptualising CSDVector-borne disease
Malaria, dengue, WNV, RVF, TBE, Lyme, leishmaniasis, trypanosomosis, schistosomiasis, onchocerciasis
Shifting distribution of vectors
Higher temperatures affect vectorial capacity and feeding frequency
Drought & heavy rain leads to population surges
Water associated Cholera, cryptosporidiosis, leptospirosis
Disaster and lack of sanitation
Flooding and run-off
Higher water temperature
Food borne Salmonella, E. coli, Campy, Listeria
Lack of sanitation
Air borne Meningitis, Q fever (FMD)
Higher RH allows survival
Dust
Soil associated Anthrax
Clostridial disease
Temperature, RH and soil moisture affect spore germination
Heavy rainfall stirs up dormant spores
Rodent borne Hanta virus; Lasa fever virus
Multistage parasites
Fascioliasis Conditions favour intermediate hosts
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
Source: Climate Change and Human Health – Risks and Reponses. Summary (WHO, 2003)
WHO conceptual framework
HOW CLIMATE AFFECTS INFECTIOUS DISEASES OF LIVESTOCK AND PEOPLE
(Vector-borne, parasitic,, air-borne, soil-borne, water-borne, food borne)
Seasonal(within year)
Short-term(1-5 years)
Medium-term(5-15 years)
Long-term(15-40 years)
EnvironmentVegetationLand coverRelative humiditySurface waterSoilAmbient temperature
Animal populations, as definitive, intermediate and amplifier hostsDomestic livestockWildlifeCompanion animals
Human populations as definitive and aberrant hosts, and transporters of fomites Animal ownersRural dwellersConsumers of animal foods
VectorsArthropod and other invertebrate vectors of infectious agents
More extreme events Raising sea levels Increased temperature, increased precipitation
Regional shifts in climate envelopes
20
Annual human deaths early 21st century
All infectious 18,000,000Diarrhoea (50% zoonotic) 3,000,000Road traffic 1,200,000Leptospirosis 123,000 & pig/dairy productionCysticercosis 50,000 & pig production
Extreme weather related 20,000Predicted climate change 150,000
Malaria 1,000,000Dengue 20,000
Sleeping sickness 50,000 & exclusion farming & productionLeishmaniasis 47,000 & companion animalQ fever 3,000 & sheep, goat, dairy production, emergingLyme disease 2,000 & emergingWest Nile fever 100 & equine losses, emergingRift valley fever 45 & sheep production, trade, emerging
Emerging disease ????
Drivers of change
GNDP
Malaysia: climate and malaria
1967-1971: MEP
1982: Vector-borne Diseases Control Program- Policy, program & strategy development
2003: National Drug Resistance Surveillance Program
1961: Pilot Malaria Eradication Project
2006: National Treatment Review Committee: ACT
1990-92: Field trial on insecticide treated bednet
(ITN)
1993: Nationwide Use of ITN
2004: Renewed studies on simian malaria
1972-1981: Anti-Malaria Program
0
50000
300000
1961 1970 1980 1990 2000 2005
Nu
mb
er
of
Ca
se
s
Te
mp
era
ture
25
30
Overview• Ecohealth/ One Health• Our changing planet
– Warmer, wetter, weirder– Implications for Africa and Kenya– Role of agriculture in climate change
• Climate and infectious disease– How does climate affect infectious disease?– Climate sensitive infectious diseases
• Vector-borne disease• Flood-associated disease• Food-borne disease
– Climate sensitive non-infectious disease• Implications for field epidemiologists• Conclusions
Vector-borne diseases• Malaria• Arboviral diseases transmitted by
mosquitoes, midges or biting flies– RVF– Yellow Fever– WNV– Dengue– Japanese encephalitis
• Ticks and tick-borne diseases– Lyme disease– Tick borne encephalitis
• Tsetse-transmitted trypanosomosis• Chagas disease• Onchocerciasis
Flood-borne diseases• Water-borne disease
– Major risk is contaminaiton of drinking water
• Water-borne epidemic– Leptospirosis
• Vector-borne disease– Malaria– Dengue– West Nile virus– Rift Valley fever
• Risk posed by corpses– Most agents do not surrvie in corpses (HIV is an
exception up to 6 days)– Routine handling of corpses puts at risk of TB,
bloodborne viruses, gastro-intestinal illness
• Other risks– Drowning, injurty, trauma– Hypothermia– Psycho socail distess
• Response• Chlorination• Early malaria diganosis• Vaccination high risk groups• Health education
• Long term• Disaster preparedness
Food-borne diseases
• Campylobacteriosis, salmonellosis, Salmonella Typhimurium infections and Salmonella Enteritidis positiviely associated with temperature 2-5 wks earlier (Lake et al., 2009)
• Air temperature: Campylobacteriosis and salmonellosis
• Water temperature: campylobacteriosis and non-cholera vibrio infections
• Precipitation frequency: cryptosporidiosis followed by campylobacteriosis;
• Precipitation events: cryptosporidiosis followed by non-cholera vibrio
• Listeria sp. was not associated with temperature thresholds, extreme precipitation events, or temperature limits (ECDC, 2012).
Emerging disease
• Of 1500 human infectious diseases, 58-65% zoonotic, • Around 150 to 200 EID75% of EID zoonotic
• One new disease emerges every 7 months
Source (Nature, 2004, 430:242-249)
Malaria vector in Africa
A= currentB- D: different climate scenarios
CLIMEX model
West Africa becomes less suitable vectors shift east & south
Tonnang et al, 2010, Malaria journal
Distribution of A. arabiensis
HAT in Africa
A= current geographical range suitable for T. b. rhodesience B= A2 climate change scenario 2055
SEIR model and IPCC data
Range increases by 10%; considerable shifts – foci in Ethiopia disappear
Moore et al 2012; J. R. Soc Interface
Anthrax in Kazakhstan
A= current scenarioB= A2 scenario (drastic)C= B2 scenario (milder)
IPCC & historical anthrax datasets; GARP model
Joyner et al, 2010, PLOS 1
LOW<0.25 m DALY or no data
MODERATE0.25 to 1 m DALY
HIGH1 to 12 m DALY
Very HIGH>12 m Daly
LO
WM
OD
ER
AT
EH
IGH
VE
RY
H
IGH Malaria
RVF
MeningitisCholera
Diarrhoea, Respiratory
Leishmaniaiss
Jap. Enceph, Denge, RVF, West Nile,
Yellow fever, Lyme Worms
ECF, Ectoparasites
Worms, tryps
HIV, Childhood
illness TB, schistosomiasis
STDTrachoma,
onchocerciasis
Filiarisis, sleeping sickness
Dermatophilosisresp. complex
Heartwater
Anthrax, blackleg
Health burden
Cli
mat
e se
nsi
tivi
ty
Which CSD are most important to the poverty/ls nexus: the big five
Animal disease
• Ticks and TBD• Arbovirus: RVF, JE• Internal parasites • Trypanosomosis• Culicoides
transmitted virus – BT, AHS
Zoonotic disease
• Diarrhoea • Arbovirus: Dengue,
YF, JE • Schistosomiasis• Sleeping sickness• Tuberculosis
Human disease
• Malaria• Diarrhoea• Respiratory• Arbovirus• Worms
Overview• Ecohealth/ One Health• Our changing planet
– Warmer, wetter, weirder– Implications for Africa and Kenya– Role of agriculture in climate change
• Climate and infectious disease– How does climate affect infectious disease?– Climate sensitive infectious diseases
• Vector-borne disease• Flood-associated disease• Food-borne disease
– Climate sensitive non-infectious disease• Implications for field epidemiologists• Conclusions
Implications for epidemiologists
•Non infectious disease– Extreme heat, extreme events
•Disease dynamics– Shifts, increase, decrease– Emergence
•Human adaptation– People movement– Irrigation– More and different livestock
Different ways to manage risk: from cows to camels
• Northern Kenya: reduction in cattle numbers (10%) and increase of camels (78%)
• Lower mortality, more milk = more food and income security
Courtesy Mario Herrero, ILRI
But
Coxiella burnetti : 31%Brucellosis: 5%
Trypanosoma: 8%Orf/pox: 35%
(Deem et al., 2012)
0º
20º
-20º
0º 20º 40º
An example of climate-induced livelihood transitions
Areas where cropping of an indicator cereal may
become unviable between now and 2050 and where farmers may
have to rely more on livestock as a livelihood
strategy
Jones & Thornton (2008)
Overview• Ecohealth/ One Health• Our changing planet
– Warmer, wetter, weirder– Implications for Africa and Kenya– Role of agriculture in climate change
• Climate and infectious disease– How does climate affect infectious disease?– Climate sensitive infectious diseases
• Vector-borne disease• Flood-associated disease• Food-borne disease
– Climate sensitive non-infectious disease• Implications for field epidemiologists• Conclusions
Sea level rise
(future)
worse global nutrition
failing governance
Impaired public health
milieu for catastrophic emerging diseases, e.g.
multi-drug –resistant TB, artemisinin-resistant malaria, HIV, others
Large-scale population dislocation
Climate change
Rising food prices
High energy costs
Dependence on fossil fuel, declining in quantity, quality
and accessibility
Increased use of crops for
fuel
conflict
Butler, in press (2012)
39
Less climate change Improved
governance
Stable food prices
Clean abundant energy technologies, especially solar
Less conflict
Better global education and communication, slower
population growth, fairer global society, new ways to
measure progress, new ways of thinking,
less food waste, meat consumption “contracts and
converges”
Improved public health
Butler, in press (2012)40
Further reading courtesy of Jibrin Idris Manu
• Baede A.P.M., Ahlonsou E., Ding Y., Schimel Bolin B., and Pollonais S (-) The Climate System: an Overview
• ANTHONY MCMICHAEL ., ANDREW GITHEKO., R. Akhtar., R. Carcavallo., D. Gubler A. Haines., R.S. Kovats., P. Martens ., J. Patz ., A. Sasaki Human Health
• Anthony J McMichael Jonathan Patz and R Sari Kovats (1998). Impacts of global environmental change on future health and health care in tropical countries. British Medial Bulletin;54 (No. 2): 475-488
• A.J. McMichael., D.H. Campbell-Lendrum., C.F. Corvalán ( 2003) Climate change and human health Risks And Responses
• Van den Bossche & Coetzer, 2008, Climate change and animal health in AfricaRev. sci. tech. Off. int. Epiz., 2008, 27 (2), 551-562
• WHO, Flooding and communicable diseases
• http://www.ipcc.ch/• http://www.who.int/topics/climate/en/
04/11/2341
Climate and health
Definition
• Climate varies from place to place, depending on latitude, distance to the sea, vegetation, presence or absence of mountains or other geographical factors.
• It varies also in time; from season to season, year to year, decade to decade or on much longer time-scales, such as the Ice Ages
• Climate change refers to statistically significant variations of the mean state of the climate or of its variability, typically persisting for decades or longer
04/11/2342
DEFINITION• The climate system is an interactive system
consisting of the atmosphere, hydrosphere, cryosphere, land surface and the biosphere
• The system is influenced by various external forcing mechanisms; the Sun and human activities
• A balance is maintained between incoming solar radiation and the outgoing radiation emitted by the climate system.
• Climate change refers to any significant change in measures of climate, such as temperature, precipitation, wind, and other weather patterns, that lasts for decades or longer. (CDC, climate change Website)
04/11/2343
Greenhouse gases
• Greenhouse gases absorb infrared radiation, emitted by the Earth’s surface, the atmosphere and clouds
• The net result is an upward transfer of infrared radiation from warmer levels near the Earth’s surface to colder levels at higher altitudes.
• The natural greenhouse effect is part of the energy balance of the Earth
• Clouds also play an important role in the Earth’s energy balance and in particular in the natural greenhouse effect.04/11/23
44
Weather
• Weather is the fluctuating state of the atmosphere around us, characterized by the temperature, wind, precipitation, clouds and other weather elements.
04/11/2345
Human activities• Combustion of fossil fuels , biomass burning, produce
greenhouse gases and aerosols• Chlorofluorocarbons (CFCs) and other chlorine and• bromine compounds has an impact on the radiative
forcing and has led to the depletion of the stratospheric ozone layer.
• Land-use change, Urbanization, human forestry, agricultural practices
• Affect the physical and biological properties of the Earth’s surface.
• Change the radiative forcing and have a potential impact on regional and global climate
04/11/2346
IPCC
• The Intergovernmental Panel on Climate Change (IPCC) : – International body for the assessment of climate change. – It was established by the United Nations Environment
Programme (UNEP) and the World Meteorological Organization
– Provide view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts.
– It reviews and assesses the most recent scientific, technical and socio-economic information produced worldwide relevant to the understanding of climate change.
– It does not conduct any research nor does it monitor climate related data or parameters.
04/11/2347
IPCC working groupThe 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: Addresses the vulnerability of socioeconomic and natural systems to climate change, the resultant negative and positive impacts of climate change and the options for adaptations to lessen the impacts.
• Working Group III: Assesses options for limiting greenhouse gas emissions and otherwise mitigating climate change.
• The Task Force on National Greenhouse Gas Inventories defines and disseminates standardized methods for countries to calculate and report GHG emissions.
04/11/2348
controlPreventive: anticipate, prevent or minimize the causes
of climate change and mitigate its adverse effects
• For the benefit of present and future generations of humankind on the basis of equity
• Equitably meet developmental and environmental needs of present and future generations
References• 1. A.J. McMichael., D.H. Campbell-Lendrum., C.F.
Corvalán., K.L. Ebi., A.K. Githeko., J.D. Scheraga., A. Woodward (2003). Climate change and human health : Risks And Responses WHO, GENEVA
• 2. A.P.M. Baede ., E. Ahlonsou., Y. Ding., D. Schimel., B. Bolin, S. Pollonais (-). The Climate System: an Overview
04/11/2350