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






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






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






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)






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

http://www.ipcc.ch/

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