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CLIMATE CHANGE AND CLIMATE CHANGE AND EMERGING AND RE-EMERGING AND RE-

EMERGING DISEASES IN EMERGING DISEASES IN AFRICAAFRICA

BYBY Paa-Kobina TURKSONPaa-Kobina TURKSON, , BVM. MSc. PhDBVM. MSc. PhD

PROFESSOR AND VETERINARY EPIDEMIOLOGISTPROFESSOR AND VETERINARY EPIDEMIOLOGISTANIMAL SCIENCE DEPARTMENTANIMAL SCIENCE DEPARTMENT

SCHOOL OF AGRICULTURESCHOOL OF AGRICULTUREUNIVERSITY OF CAPE COAST, GHANAUNIVERSITY OF CAPE COAST, GHANA

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PRESENTATION PLAN

• General overviewGeneral overview

• DefinitionsDefinitions

• Emerging and Re-emerging DiseasesEmerging and Re-emerging Diseases

• Factors influencing Disease EmergenceFactors influencing Disease Emergence

• Impact/Effects of climate on diseasesImpact/Effects of climate on diseases

• ConclusionsConclusions

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Overview IOverview I

• The last 200 years The last 200 years have seen greater have seen greater environmental environmental change than the last change than the last 2000; 2000;

• The last 20 years The last 20 years have seen greater have seen greater change than the last change than the last 200 (Myers and 200 (Myers and Tickell, 2001). Tickell, 2001).

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NEWS FLASH!NEWS FLASH!2010 hits global temperature high2010 hits global temperature highBy Richard Black Environment correspondent, BBC News 20 January 2011 By Richard Black Environment correspondent, BBC News 20 January 2011

• 2010 was the warmest year since global temperature 2010 was the warmest year since global temperature records began in 1850 - although margins of uncertainty records began in 1850 - although margins of uncertainty make it a statistical tie with 1998 and 2005.make it a statistical tie with 1998 and 2005.

• The World Meteorological Organization (WMO) The World Meteorological Organization (WMO) concludesconcludes that 2010 was 0.53C warmer than the average for the that 2010 was 0.53C warmer than the average for the period 1961-90, a period commonly used as a baseline.period 1961-90, a period commonly used as a baseline.

• The 10 warmest years have all occurred since 1998. The 10 warmest years have all occurred since 1998. • Regions of the world experiencing particularly warm Regions of the world experiencing particularly warm

conditions during 2010 included Africa, southern and conditions during 2010 included Africa, southern and western Asia, and the northern extremities of North western Asia, and the northern extremities of North America, including Greenland.America, including Greenland.

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Overview IIOverview II• Recent global research provides evidence of Recent global research provides evidence of

climate change-related disease outbreaks already climate change-related disease outbreaks already occurring through the spread of different types of occurring through the spread of different types of pathogens—viruses, bacteria, fungi and parasites. pathogens—viruses, bacteria, fungi and parasites.

• By 2050, 6 billion people around the world will be By 2050, 6 billion people around the world will be at risk to the ‘big 7’ climate-related diseases: at risk to the ‘big 7’ climate-related diseases: malaria, dengue and other haemorrhagic fever malaria, dengue and other haemorrhagic fever viruses, schistosomiasis, sleeping sickness, Chagas’ viruses, schistosomiasis, sleeping sickness, Chagas’ disease, Leishmaniasis and river blindness; 4 of disease, Leishmaniasis and river blindness; 4 of the big 7 are zoonoses (transmissible between man the big 7 are zoonoses (transmissible between man and animals) (Benniston, 2002). and animals) (Benniston, 2002).

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Overview IIIOverview III

• At the moment there is little evidence of At the moment there is little evidence of causal changes in disease transmission due causal changes in disease transmission due to climate change within Africa to climate change within Africa (Climate Change and (Climate Change and

Health Initiative 2008).Health Initiative 2008). • This lack of evidence does not mean that This lack of evidence does not mean that

these changes do not exist. these changes do not exist. • Rather, it may reflect the lack of available Rather, it may reflect the lack of available

epidemiological data as a result of poor or epidemiological data as a result of poor or absent surveillance data and health absent surveillance data and health information systems. information systems.

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Definition of Climate ChangeDefinition of Climate Change

• UNFCCC (United Nations Framework UNFCCC (United Nations Framework Convention on Climate Change) definition:Convention on Climate Change) definition:

Climate change is a change in climate Climate change is a change in climate attributed directly or indirectly to human attributed directly or indirectly to human activity that alters the composition of the activity that alters the composition of the global atmosphere and which is in global atmosphere and which is in addition to natural climate variability addition to natural climate variability observed over comparable time periodsobserved over comparable time periods. .

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Definitions of Emerging Diseases IDefinitions of Emerging Diseases I

• Defined as Emergence of a pathogen in a human or animal population which is related to the increase in distribution, increase in incidence or increase in virulence or other factors. (Jones et al 2008)

• Emerging infections (EIs) are defined as “Infections that have newly appeared in a population or have existed previously but are rapidly increasing in incidence or geographic range”

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Definition of Emerging Diseases IIDefinition of Emerging Diseases II

• The term ‘emerging disease’ is broad and in general, covers any one of three disease situations:

– a known agent appearing in a new geographic a known agent appearing in a new geographic areaarea

– a known agent or its close relative occurring in a a known agent or its close relative occurring in a hitherto unsusceptible specieshitherto unsusceptible species

– a previously unknown agent detected for the first a previously unknown agent detected for the first time.time.

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Emerging Diseases IEmerging Diseases I

• Since 1980, a new disease has emerged on Since 1980, a new disease has emerged on average every 7 months. average every 7 months. (Climate Change and Health (Climate Change and Health Initiative 2008).Initiative 2008).

• Majority (60.3%) of 335 Emerging Infectious Majority (60.3%) of 335 Emerging Infectious Diseases events between 1940 and 2004 analysed Diseases events between 1940 and 2004 analysed by Jones et al (2008) were caused by zoonotic by Jones et al (2008) were caused by zoonotic pathogens. pathogens.

• 71.8% of these zoonotic EID events caused by 71.8% of these zoonotic EID events caused by pathogens originated from wild life e.g.. The pathogens originated from wild life e.g.. The emergence of Nipah Virus in Perak, Malaysia and emergence of Nipah Virus in Perak, Malaysia and SARS (Severe Acute Respiratory Syndrome) in SARS (Severe Acute Respiratory Syndrome) in Guandong Province, China.Guandong Province, China.

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Emerging Diseases IIEmerging Diseases II

• Of 335 EID events from 1940-2004, the Of 335 EID events from 1940-2004, the causes were as follows (Jones et al, 2008):causes were as follows (Jones et al, 2008):

• Bacteria/ RickettsiaBacteria/ Rickettsia 54.3%54.3%

• Viruses/ PrionsViruses/ Prions 25.4%25.4%

• ProtozoaProtozoa 10.7%10.7%

• FungiFungi 6.3% 6.3%

• HelminthsHelminths 3.3% 3.3%

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Examples of Recent Emerging Zoonoses Examples of Recent Emerging Zoonoses (modified after Brown, 2004)(modified after Brown, 2004)

• Ebola virusEbola virus• Bovine Spongiform Encephalopathy (Mad Cow)Bovine Spongiform Encephalopathy (Mad Cow)• Nipah VirusNipah Virus• Severe Acute Respiratory Syndrome (SARS)Severe Acute Respiratory Syndrome (SARS)• Alveolar EchinococcosisAlveolar Echinococcosis• MonkeypoxMonkeypox• Rift Valley FeverRift Valley Fever• Highly Pathogenic Avian Influenza (Bird Flu)Highly Pathogenic Avian Influenza (Bird Flu)• ““Swine Flu” (H1N1)Swine Flu” (H1N1)• Monkey Herpes B virus ( Ghana; January 2011)Monkey Herpes B virus ( Ghana; January 2011)

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Re-emerging Zoonotic Diseases (After Bengis et al 2004)

• ViralViral• Rabies and related Lyssavirus infectionsRabies and related Lyssavirus infections• Rift Valley FeverRift Valley Fever• Marburg VirusMarburg Virus

• BacterialBacterial• Bovine TuberculosisBovine Tuberculosis• Brucella species in wild animalsBrucella species in wild animals• TularaemiaTularaemia• PlaguePlague• LeptospirosisLeptospirosis

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Emerging Diseases in Farm animals I Emerging Diseases in Farm animals I (After Vourc’h et al 2006(After Vourc’h et al 2006))

Emerging Disease (Cause)Emerging Disease (Cause) SpeciesSpecies Location/DateLocation/Date

Blue tongue (Reoviridae)Blue tongue (Reoviridae) SheepSheep Mediterranean Basin 1996-2001Mediterranean Basin 1996-2001

Border Disease (Flaviviridae)Border Disease (Flaviviridae) SheepSheep France 1994France 1994

Bovine Leukocyte Adhesion Deficiency Bovine Leukocyte Adhesion Deficiency (CD18 gene mutation)(CD18 gene mutation)

Holstein Holstein cattlecattle

Various countries 1980sVarious countries 1980s

Bovine Spongiform EncephalopathyBovine Spongiform Encephalopathy CattleCattle UK 1980UK 1980

Complex vertebral malformation Complex vertebral malformation (SLC35A3 gene mutation)(SLC35A3 gene mutation)

Dairy Dairy cattlecattle

Denmark 2000Denmark 2000

Epizootic Rabbit Enteropathy Epizootic Rabbit Enteropathy (Unidentified virus)(Unidentified virus)

RabbitsRabbits Europe 1996Europe 1996

Hendra Disease (Paramyxovirus)Hendra Disease (Paramyxovirus) Horses/ Horses/ HumansHumans

Australia, Papua N. Guinea 1984Australia, Papua N. Guinea 1984

Highly Pathogenic Avian Influenza Highly Pathogenic Avian Influenza (H5N1)(H5N1)

Poultry/ Poultry/ HumansHumans

South East Asia, 2003-4. South East Asia, 2003-4. Now a Now a pandemicpandemic

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Emerging Diseases in Farm animals I Emerging Diseases in Farm animals I (After Vourc’h et al 2006(After Vourc’h et al 2006))

Emerging Disease (Cause)Emerging Disease (Cause) SpeciesSpecies Location/DateLocation/Date

Nipah Virus (Paramyxovirus)Nipah Virus (Paramyxovirus) Pigs/ Pigs/ HumansHumans

Malaysia and Malaysia and Singapore 1998Singapore 1998

Porcine Dermatitis and Nephropathy Porcine Dermatitis and Nephropathy Syndrome (Suspected porcine circovirus)Syndrome (Suspected porcine circovirus)

PigsPigs UK 1993UK 1993

Porcine Reproductive and Respiratory Porcine Reproductive and Respiratory Syndrome (Arteriviridae)Syndrome (Arteriviridae)

PigsPigs North America North America 19871987

Post-weaning multi-systemic wasting Post-weaning multi-systemic wasting syndrome (Suspected porcine circovirus)syndrome (Suspected porcine circovirus)

PigsPigs Canada 1990Canada 1990

Rabbit haemorrhagic disease Rabbit haemorrhagic disease (Calciviridae)(Calciviridae)

RabbitsRabbits China 1984China 1984

West Nile Fever (Flaviviridae)West Nile Fever (Flaviviridae) Humans/ Humans/ crowscrows

US 1999US 1999

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Causes of re-emergenceCauses of re-emergence

• The re-emergence of well-documented The re-emergence of well-documented zoonotic diseases appears to be driven by zoonotic diseases appears to be driven by climatic, habitat and population density climatic, habitat and population density factors that affect hosts, pathogens or factors that affect hosts, pathogens or vectors – frequently causing natural vectors – frequently causing natural increases and decreases in disease activity in increases and decreases in disease activity in different geographical areas and over different geographical areas and over various periods of time.various periods of time.

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Factors contributing to emergence /re-emergence of Factors contributing to emergence /re-emergence of infectious diseases Iinfectious diseases I

Include genetic, biological, and social, political economic factors.Include genetic, biological, and social, political economic factors.

1.1. Microbial adaptation and changeMicrobial adaptation and change2.2. Human susceptibility to infectionHuman susceptibility to infection

3.3. Climate and weatherClimate and weather

4.4. Changing ecosystemsChanging ecosystems

5.5. Human demographics and behaviourHuman demographics and behaviour

6.6. Economic development and land useEconomic development and land use

7.7. Technology and industryTechnology and industry

8.8. Breakdown of public health measures Breakdown of public health measures

9.9. Poverty and social inequalityPoverty and social inequality

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Factors contributing to emergence /re-emergence of Factors contributing to emergence /re-emergence of infectious diseases IIinfectious diseases II10.10. War and famineWar and famine

11.11. Lack of political willLack of political will

12.12. Intent to harm (Bio-terrorism)/ Bio-warfare.Intent to harm (Bio-terrorism)/ Bio-warfare.

13.13. Altered landscape which bring hosts into contact with new Altered landscape which bring hosts into contact with new pathogenspathogens

14.14. Greater population densities which facilitate their rapid Greater population densities which facilitate their rapid spreadspread

15.15. Faster, longer-distance travel and trade which carry diseases Faster, longer-distance travel and trade which carry diseases to new populationsto new populations

16.16. Natural disaster or war which disrupt the ability to keep Natural disaster or war which disrupt the ability to keep diseases in checkdiseases in check

17.17. Climate change, of natural or anthropogenic origin, which Climate change, of natural or anthropogenic origin, which could be a driver to changes in disease dynamics.could be a driver to changes in disease dynamics.

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Effect of climate on disease causation I Effect of climate on disease causation I ((CHCD 2008)• Climate may affect certain pathogens directly. Climate may affect certain pathogens directly.

Many pathogens must spend a period of time in the Many pathogens must spend a period of time in the environment to be able to get from one host to environment to be able to get from one host to another. During this transit they are exposed to the another. During this transit they are exposed to the weather. The time period can be months /years weather. The time period can be months /years (e.g.. Spores causing anthrax) or as short as seconds (e.g.. Spores causing anthrax) or as short as seconds or minutes (e.g. human cold and influenza viruses or minutes (e.g. human cold and influenza viruses and rinderpest virus in animals.) and rinderpest virus in animals.)

• In most cases, climate and weather affect the ability In most cases, climate and weather affect the ability of the pathogen to survive or reach and enter a new of the pathogen to survive or reach and enter a new host and result in seasonality of certain diseases.host and result in seasonality of certain diseases.

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Effect of climate on disease causation IIEffect of climate on disease causation II

• Many pathogens use vectors to facilitate Many pathogens use vectors to facilitate transmission between primary hosts: transmission between primary hosts: mosquitoes, fleas, ticks, non-biting flies etc.mosquitoes, fleas, ticks, non-biting flies etc.

• Climate often plays a dominant role in Climate often plays a dominant role in determining the spatial and temporal determining the spatial and temporal distribution of arthropod vectors so that distribution of arthropod vectors so that vector-borne diseases are often climatically vector-borne diseases are often climatically restricted in both time and space.restricted in both time and space.

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Impact of climate on infectious diseases I (CHCD 2008)

1.1. Climate directly influences the ability for Climate directly influences the ability for pathogens and vectors to survive, pathogens and vectors to survive, replicate, move or attack hosts. For replicate, move or attack hosts. For exampleexample

– Vector-borne diseases: malaria, Vector-borne diseases: malaria, trypanosomosis, Rift Valley Fevertrypanosomosis, Rift Valley Fever

– Parasites with free-living stages: soil Parasites with free-living stages: soil helminthshelminths

– Air-borne parasites e.g. meningitisAir-borne parasites e.g. meningitis

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Impact of climate on infectious diseases II

2.2. Climate influences ecology which in turn Climate influences ecology which in turn influences pathogen/vector availability or influences pathogen/vector availability or host susceptibility. For examplehost susceptibility. For example

• Excessive rainfall leads to ground saturation Excessive rainfall leads to ground saturation resulting in increased hatching of vectors and resulting in increased hatching of vectors and outbreaks of Rift Valley Feveroutbreaks of Rift Valley Fever

• Food production. Malnourishment often leads Food production. Malnourishment often leads to iron deficiency and can exacerbate anaemia to iron deficiency and can exacerbate anaemia which is the major cause of death in malariawhich is the major cause of death in malaria

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Impact of climate on infectious diseases III

3.3. Climate influences human (animal?) Climate influences human (animal?) behaviour.behaviour.

• Cold weather leads to closer contact and Cold weather leads to closer contact and higher transmission of influenza virus.higher transmission of influenza virus.

• Extreme weather events leads to population Extreme weather events leads to population displacement and disruption of sanitation and displacement and disruption of sanitation and water/food supplies, a pre-disposition for water/food supplies, a pre-disposition for pathogens spread by faecal/oral route. pathogens spread by faecal/oral route.

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OIE confirms impact of climate change OIE confirms impact of climate change on animal diseases in a world-wide on animal diseases in a world-wide study.study.• ““More and more countries are indicating that climate More and more countries are indicating that climate

change has been responsible for at least one change has been responsible for at least one emerging or re-emerging disease occurring on their emerging or re-emerging disease occurring on their territory. This is a reality we cannot ignore…”territory. This is a reality we cannot ignore…” Dr Dr Bernard Vallat , DG, OIE.Bernard Vallat , DG, OIE.

• Of 126 OIE's Member Countries and Territories who Of 126 OIE's Member Countries and Territories who took part in a study in 2006, 71% stated they were took part in a study in 2006, 71% stated they were extremely concerned at the expected impact of extremely concerned at the expected impact of climate change on emerging and re-emerging climate change on emerging and re-emerging diseases. diseases.

• 58% identified at least one emerging or re-emerging 58% identified at least one emerging or re-emerging disease on their territory that was believed to be disease on their territory that was believed to be associated with climate change. associated with climate change.

• The three animal diseases most frequently The three animal diseases most frequently mentioned were: Bluetongue, Rift Valley fever and mentioned were: Bluetongue, Rift Valley fever and West Nile fever. West Nile fever.

• The majority of countries also consider that human The majority of countries also consider that human influence on the environment has an impact on influence on the environment has an impact on climate change and therefore on the emergence or climate change and therefore on the emergence or re-emergence of animal diseases. re-emergence of animal diseases.

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Some Effects of Climate Change on Infectious Diseases of Animals in Africa (Baylis 2006)

• Moisture-sensitive diseases will be affected, Moisture-sensitive diseases will be affected, including anthrax, blackleg, including anthrax, blackleg, dermatophilosis, haemorrhagic septicaemia, dermatophilosis, haemorrhagic septicaemia, PPR, haemonchosis and vector–borne PPR, haemonchosis and vector–borne diseases. These diseases may decline in some diseases. These diseases may decline in some areas and spread to others.areas and spread to others.

• Increase in Fascioliasis due to Increase in Fascioliasis due to F. hepaticaF. hepatica in in Central, East and parts of West Africa; Central, East and parts of West Africa; decline in Fascioliasis due to decline in Fascioliasis due to F. hepaticaF. hepatica and and F. giganticaF. gigantica in northern and southern in northern and southern Africa, depending on measures to preserve Africa, depending on measures to preserve water supplies.water supplies.

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Some Effects of Climate Change on Infectious Diseases of Animals in Africa (Baylis 2006)

• Possible increase in frequency of epidemics Possible increase in frequency of epidemics of diseases linked to El Nino Southern of diseases linked to El Nino Southern Oscillation (i.e. Rift Valley fever, Blue Oscillation (i.e. Rift Valley fever, Blue tongue)tongue)

• Possible increases in pathogen transmission Possible increases in pathogen transmission between wildlife and livestock.between wildlife and livestock.

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Examples of climate-disease linksExamples of climate-disease links ( (After Baylis, After Baylis, 2007)2007)

AnthraxAnthrax

• Worldwide zoonosisWorldwide zoonosis

• Spores remain infective for Spores remain infective for 10-20 years in pasture.10-20 years in pasture.

• Temperature, RH and soil Temperature, RH and soil moisture affect spore moisture affect spore germinationgermination

• Heavy rainfall stirs up Heavy rainfall stirs up dormant spores.dormant spores.

• Outbreaks often Outbreaks often associated with alternating associated with alternating heavy rainfall and drought, heavy rainfall and drought, and high temperaturesand high temperatures

Spotted hyena eating a zebra dead from anthrax, Ethosha Park, Namibia

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Examples of climate-disease links Examples of climate-disease links (After (After Baylis, 2007)Baylis, 2007)

Fascioliasis (liver fluke)Fascioliasis (liver fluke)

• Caused by theCaused by the Fasciola, Fasciola, a a trematode/fluketrematode/fluke

• Of economic importance Of economic importance to cattle and sheep to cattle and sheep producers in many parts producers in many parts of the world.of the world.

• Associated with Associated with environmental conditions environmental conditions favouring the favouring the intermediate snail host. intermediate snail host. Eg. low lying wet pasture, Eg. low lying wet pasture, areas subject to periodic areas subject to periodic flooding, and temporary flooding, and temporary or permanent bodies of or permanent bodies of waterwater

Liver fluke life cycle

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Examples of climate-disease links Examples of climate-disease links (After Baylis, (After Baylis, 2007)2007)

African horse sicknessAfrican horse sickness• Lethal infectious disease Lethal infectious disease

of horsesof horses• Caused by a virus Caused by a virus

transmitted by transmitted by Culicoides Culicoides biting midges. biting midges.

• Large outbreaks of AHS Large outbreaks of AHS in the Republic of South in the Republic of South Africa over the last 200 Africa over the last 200 years are associated years are associated with the combination of with the combination of drought and heavy drought and heavy rainfall brought by the rainfall brought by the warm-phase of the El warm-phase of the El Niño Southern Niño Southern Oscillation (ENSO)Oscillation (ENSO)

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Some Effects of Climate Change on Infectious Diseases of Humans in Africa (Baylis 2006)• Uncertain impact on acute respiratory infectionsUncertain impact on acute respiratory infections• Possible increase in cholera in response to more Possible increase in cholera in response to more

coastal floodingcoastal flooding• Increased impact of diarrhoeal diseasesIncreased impact of diarrhoeal diseases• Greater areas of risk of vector-borne diseases Greater areas of risk of vector-borne diseases

such as Rift Valley Fever, dengue, leishmaniasis, such as Rift Valley Fever, dengue, leishmaniasis, schistosomiasis, malaria, West Nile Fever.schistosomiasis, malaria, West Nile Fever.

• Uncertain effect on meningococcal meningitis, Uncertain effect on meningococcal meningitis, filariasis, trypanosomosis. filariasis, trypanosomosis.

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Pathways for Weather to Affect Health: Pathways for Weather to Affect Health:

Diarrhoeal DiseasesDiarrhoeal Diseases ((AfterAfter Ebi, 2006)Ebi, 2006)

TemperatureHumidityPrecipitation

Distal Causes Proximal Causes Infection Hazards Health Outcome

Living conditions(water supply andsanitation)

Food sources andhygiene practices

Survival/ replicationof pathogens in theenvironment

Contamination ofwater sources

Rate of personto person contact

Consumption ofcontaminated water

Consumption ofcontaminated food

Contact withinfected persons

Incidence of mortality andmorbidityattributableto diarrhoea

Vulnerability(e.g. age andnutrition)

Contamination of food sources

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Potential Health Effects of ClimatePotential Health Effects of Climate

Variability and ChangeVariability and Change ((After Ebi, 2006After Ebi, 2006))

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Examples of links between Examples of links between climate, animal health and climate, animal health and human health in Africa. Ihuman health in Africa. I

1.1. Changes in the distribution and impacts of the Changes in the distribution and impacts of the vector-borne diseases of man and animals. vector-borne diseases of man and animals.

Diseases such as malaria, Rift Valley fever, Diseases such as malaria, Rift Valley fever, African horse sickness, and bluetongue vary African horse sickness, and bluetongue vary considerably with seasonal and longer-term considerably with seasonal and longer-term climatic variations. climatic variations.

Climate change is said to directly contribute to Climate change is said to directly contribute to changes in the geographic distribution of vector-changes in the geographic distribution of vector-borne diseases such as malaria and epidemics of borne diseases such as malaria and epidemics of meningococcal meningitis and Rift Valley fever meningococcal meningitis and Rift Valley fever and cholera in previously unaffected areas.and cholera in previously unaffected areas.

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Examples of links between Examples of links between climate, animal health climate, animal health and human health in Africa. IIand human health in Africa. II

2.2. Some diseases—because of climate change—Some diseases—because of climate change—are moving into new areas where people have are moving into new areas where people have little natural immunity (e.g. schistosomiasis, little natural immunity (e.g. schistosomiasis, yellow fever, malaria, Chikungunya fever, yellow fever, malaria, Chikungunya fever, Onyong-nyong fever, Dengue, West Nile.) Onyong-nyong fever, Dengue, West Nile.)

3.3. Water-borne infectious diseases are Water-borne infectious diseases are exacerbated by flooding and complicated by exacerbated by flooding and complicated by inadequate access to water by people and inadequate access to water by people and animals. animals.

4.4. Droughts force peoples and their livestock to Droughts force peoples and their livestock to move, potentially exposing them to different move, potentially exposing them to different environments with health risks to which they environments with health risks to which they have never been exposed. have never been exposed.

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Conclusion IConclusion I• CHCD 2008 stated that CHCD 2008 stated that ““The emergence The emergence

of infectious diseases and their spread and of infectious diseases and their spread and impact, relate to how pathogens interact with a impact, relate to how pathogens interact with a complex of social, technological and complex of social, technological and environmental processes. environmental processes.

• These processes are highly interdependent, These processes are highly interdependent, non-linear and often context-specific. They non-linear and often context-specific. They operate over varied and sometimes operate over varied and sometimes overlapping temporal and spatial scales. overlapping temporal and spatial scales.

• Some disease drivers and effects involve short-Some disease drivers and effects involve short-term shocks- as in an ecosystem switch that term shocks- as in an ecosystem switch that triggers a sudden epidemic outbreak- while triggers a sudden epidemic outbreak- while others involve longer-term trends and stresses. others involve longer-term trends and stresses.

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Conclusion I continuedConclusion I continued

• Disease responses themselves can feed back to Disease responses themselves can feed back to shape these dynamics- either positively, for shape these dynamics- either positively, for instance where the disease is brought under instance where the disease is brought under control, or in less intended ways- for instance control, or in less intended ways- for instance where drugs contribute to emerging pathogenic where drugs contribute to emerging pathogenic resistance. resistance.

• Understanding emerging infectious diseases thus Understanding emerging infectious diseases thus requires an appreciation of such complex social, requires an appreciation of such complex social, technological and environmental dynamics.” technological and environmental dynamics.”

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Conclusion IIConclusion IIMatthew Baylis (2006) argues that Matthew Baylis (2006) argues that

• ““There is considerable uncertainty arising There is considerable uncertainty arising from the many, often conflicting, forces that from the many, often conflicting, forces that climate imposes on infectious diseases, the climate imposes on infectious diseases, the complex interaction between climate and other complex interaction between climate and other drivers of change and uncertainty in climate drivers of change and uncertainty in climate itself. itself.

• Effects of climate change that act indirectly on Effects of climate change that act indirectly on infectious diseases, via effects on other drivers, infectious diseases, via effects on other drivers, are particularly hard to predict. are particularly hard to predict.

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Conclusion II continuedConclusion II continued

• Nevertheless, there is a consensus that some, and Nevertheless, there is a consensus that some, and possibly many infectious diseases of animals, humans possibly many infectious diseases of animals, humans and plants will be affected by climate change. and plants will be affected by climate change.

• Many of the diseases we commonly face are kept at Many of the diseases we commonly face are kept at least partly in check by lifestyles, behaviours, farming least partly in check by lifestyles, behaviours, farming systems or control measures that we have learned to systems or control measures that we have learned to use, sometimes over millennia, to help keep us, our use, sometimes over millennia, to help keep us, our livestock and our crops healthy. livestock and our crops healthy.

• By contrast, when a new disease emerges or a familiar By contrast, when a new disease emerges or a familiar disease spreads to a new region, there is a long lead-in disease spreads to a new region, there is a long lead-in time before we know its significance and how it can be time before we know its significance and how it can be controlled or avoided.”controlled or avoided.”

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Conclusion IIIConclusion III • Need for closer collaboration between veterinary, Need for closer collaboration between veterinary,

medical and environmental sciences to improve medical and environmental sciences to improve disease surveillance and control relating to climate disease surveillance and control relating to climate change, as this is lacking in many countries. change, as this is lacking in many countries.

• Rudolf Virchow said “Rudolf Virchow said “Between animal and human Between animal and human medicine there are no dividing lines. The object is medicine there are no dividing lines. The object is different but the experience obtained constitutes the different but the experience obtained constitutes the basis of all medicinebasis of all medicine.”.”

• Underscores the concept of or movement forUnderscores the concept of or movement for

““One world, one health”One world, one health”

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AcknowledgementsAcknowledgements

• I acknowledge with gratitude the use of I acknowledge with gratitude the use of information from various authors and information from various authors and particularly work by Matthew Baylis of particularly work by Matthew Baylis of Liverpool University and the Climate and Liverpool University and the Climate and Health Challenge Dialogue 2008. They made Health Challenge Dialogue 2008. They made my work easier.my work easier.

• I thank the organisers for the opportunity I thank the organisers for the opportunity given me for this presentation.given me for this presentation.

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THANK YOU THANK YOU FOR YOUR ATTENTIONFOR YOUR ATTENTION

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Impact of climate change on African AgricultureImpact of climate change on African Agriculture (After Chemnitz and Hoeffler 2011)(After Chemnitz and Hoeffler 2011)

Effects are at two levelsEffects are at two levels• BiophysicalBiophysical

Include changes in crop-growing conditions and animal Include changes in crop-growing conditions and animal productivity as a result of rising temperature and highly productivity as a result of rising temperature and highly variable precipitationvariable precipitation

• SocioeconomicSocioeconomic– Falling incomes from agricultureFalling incomes from agriculture– Higher risks and greater vulnerability in the rural Higher risks and greater vulnerability in the rural

population due to changes in their cultural and population due to changes in their cultural and economic livelihoodseconomic livelihoods

– Risk of rural areas sliding deeper into povertyRisk of rural areas sliding deeper into poverty

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Impact of Climate on Livestock-Keeping IImpact of Climate on Livestock-Keeping I

• According to Spore (August 2008), According to Spore (August 2008), climate change in Africa may modify climate change in Africa may modify the distribution and nutritional quality the distribution and nutritional quality of forage plants, factors that will of forage plants, factors that will influence milk production and influence milk production and production. Nutrition-related diseases production. Nutrition-related diseases may therefore become important.may therefore become important.

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Impact of Climate on Livestock-KeepingImpact of Climate on Livestock-Keeping IIII

• Climate change will also influence the type of Climate change will also influence the type of livestock species kept. “If the climate becomes livestock species kept. “If the climate becomes hotter and drier, goats and sheep will take hotter and drier, goats and sheep will take precedence over cattle and chickens which are precedence over cattle and chickens which are very sensitive to heat. The humid zones will in very sensitive to heat. The humid zones will in turn become more suited to poultry and large turn become more suited to poultry and large livestock especially in high altitudes. But, if livestock especially in high altitudes. But, if rainfall increases in these areas, goats and rainfall increases in these areas, goats and chickens will become more attractive options” chickens will become more attractive options” (Spore 2008). This may influence the types of (Spore 2008). This may influence the types of diseases that will have to be handled.diseases that will have to be handled.