CLIMATE CHANGE AND EMERGING AND RE-EMERGING DISEASES IN AFRICA

1. CLIMATE CHANGE AND EMERGING AND RE-EMERGING DISEASES IN AFRICA BY Paa-Kobina TURKSON, BVM. MSc. PhD PROFESSOR AND VETERINARY EPIDEMIOLOGIST ANIMAL SCIENCE DEPARTMENT SCHOOL OF AGRICULTURE UNIVERSITY OF CAPE COAST, GHANA

2. PRESENTATION PLAN • General overview • Definitions • Emerging and Re-emerging Diseases • Factors influencing Disease Emergence • Impact/Effects of climate on diseases • Conclusions

3. Overview I • The last 200 years have seen greater environmental change than the last 2000; • The last 20 years have seen greater change than the last 200 (Myers and Tickell, 2001).

4. NEWS FLASH! 2010 hits global temperature high By Richard Black Environment correspondent, BBC News 20 January 2011 • 2010 was the warmest year since global temperature records began in 1850 - although margins of uncertainty make it a statistical tie with 1998 and 2005. • The World Meteorological Organization (WMO) concludesthat 2010 was 0.53C warmer than the average for the period 1961-90, a period commonly used as a baseline. • The 10 warmest years have all occurred since 1998. • Regions of the world experiencing particularly warm conditions during 2010 included Africa, southern and western Asia, and the northern extremities of North America, including Greenland.

5. Overview II • Recent global research provides evidence of climate change-related disease outbreaks already occurring through the spread of different types of pathogens—viruses, bacteria, fungi and parasites. • By 2050, 6 billion people around the world will be at risk to the ‘big 7’ climate-related diseases: malaria, dengue and other haemorrhagic fever viruses, schistosomiasis, sleeping sickness, Chagas’ disease, Leishmaniasis and river blindness; 4 of the big 7 are zoonoses (transmissible between man and animals) (Benniston, 2002).

6. Overview III • At the moment there is little evidence of causal changes in disease transmission due to climate change within Africa (Climate Change and Health Initiative 2008). • This lack of evidence does not mean that these changes do not exist. • Rather, it may reflect the lack of available epidemiological data as a result of poor or absent surveillance data and health information systems.

7. Definition of Climate Change • UNFCCC (United Nations Framework Convention on Climate Change) definition: Climate change is a change in climate attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods.

8. Definitions 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”

9. Definition 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 area • a known agent or its close relative occurring in a hitherto unsusceptible species • a previously unknown agent detected for the first time.

10. Emerging Diseases I • Since 1980, a new disease has emerged on average every 7 months. (Climate Change and Health Initiative 2008). • Majority (60.3%) of 335 Emerging Infectious Diseases events between 1940 and 2004 analysed by Jones et al (2008) were caused by zoonotic pathogens. • 71.8% of these zoonotic EID events caused by pathogens originated from wild life e.g.. The emergence of Nipah Virus in Perak, Malaysia and SARS (Severe Acute Respiratory Syndrome) in Guandong Province, China.

11. Emerging Diseases II • Of 335 EID events from 1940-2004, the causes were as follows (Jones et al, 2008): • Bacteria/ Rickettsia 54.3% • Viruses/ Prions 25.4% • Protozoa 10.7% • Fungi 6.3% • Helminths 3.3%

12. Examples of Recent Emerging Zoonoses (modified after Brown, 2004) • Ebola virus • Bovine Spongiform Encephalopathy (Mad Cow) • Nipah Virus • Severe Acute Respiratory Syndrome (SARS) • Alveolar Echinococcosis • Monkeypox • Rift Valley Fever • Highly Pathogenic Avian Influenza (Bird Flu) • “Swine Flu” (H1N1) • Monkey Herpes B virus ( Ghana; January 2011)

13. Re-emerging Zoonotic Diseases (After Bengis et al 2004) • Viral • Rabies and related Lyssavirus infections • Rift Valley Fever • Marburg Virus • Bacterial • Bovine Tuberculosis • Brucella species in wild animals • Tularaemia • Plague • Leptospirosis

14. Emerging Diseases in Farm animals I (After Vourc’h et al 2006) 14

15. Emerging Diseases in Farm animals I (After Vourc’h et al 2006) 15

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

17. Factors contributing to emergence /re-emergence of infectious diseases I Include genetic, biological, and social, political economic factors. • Microbial adaptation and change • Human susceptibility to infection • Climate and weather • Changing ecosystems • Human demographics and behaviour • Economic development and land use • Technology and industry • Breakdown of public health measures • Poverty and social inequality

18. Factors contributing to emergence /re-emergence of infectious diseases II • War and famine • Lack of political will • Intent to harm (Bio-terrorism)/ Bio-warfare. • Altered landscape which bring hosts into contact with new pathogens • Greater population densities which facilitate their rapid spread • Faster, longer-distance travel and trade which carry diseases to new populations • Natural disaster or war which disrupt the ability to keep diseases in check • Climate change, of natural or anthropogenic origin, which could be a driver to changes in disease dynamics.

19. Effect of climate on disease causation I (CHCD 2008) • Climate may affect certain pathogens directly. Many pathogens must spend a period of time in the environment to be able to get from one host to another. During this transit they are exposed to the weather. The time period can be months /years (e.g.. Spores causing anthrax) or as short as seconds or minutes (e.g. human cold and influenza viruses and rinderpest virus in animals.) • In most cases, climate and weather affect the ability of the pathogen to survive or reach and enter a new host and result in seasonality of certain diseases.

20. Effect of climate on disease causation II • Many pathogens use vectors to facilitate transmission between primary hosts: mosquitoes, fleas, ticks, non-biting flies etc. • Climate often plays a dominant role in determining the spatial and temporal distribution of arthropod vectors so that vector-borne diseases are often climatically restricted in both time and space.

21. Impact of climate on infectious diseases I (CHCD 2008) • Climate directly influences the ability for pathogens and vectors to survive, replicate, move or attack hosts. For example • Vector-borne diseases: malaria, trypanosomosis, Rift Valley Fever • Parasites with free-living stages: soil helminths • Air-borne parasites e.g. meningitis

22. Impact of climate on infectious diseases II • Climate influences ecology which in turn influences pathogen/vector availability or host susceptibility. For example • Excessive rainfall leads to ground saturation resulting in increased hatching of vectors and outbreaks of Rift Valley Fever • Food production. Malnourishment often leads to iron deficiency and can exacerbate anaemia which is the major cause of death in malaria

23. Impact of climate on infectious diseases III • Climate influences human (animal?) behaviour. • Cold weather leads to closer contact and higher transmission of influenza virus. • Extreme weather events leads to population displacement and disruption of sanitation and water/food supplies, a pre-disposition for pathogens spread by faecal/oral route.

24. OIE confirms impact of climate change on animal diseases in a world-wide study. • “More and more countries are indicating that climate change has been responsible for at least one emerging or re-emerging disease occurring on their territory. This is a reality we cannot ignore…”Dr Bernard Vallat , DG, OIE. • Of 126 OIE's Member Countries and Territories who took part in a study in 2006, 71% stated they were extremely concerned at the expected impact of climate change on emerging and re-emerging diseases. • 58% identified at least one emerging or re-emerging disease on their territory that was believed to be associated with climate change. • The three animal diseases most frequently mentioned were: Bluetongue, Rift Valley fever and West Nile fever. • The majority of countries also consider that human influence on the environment has an impact on climate change and therefore on the emergence or re-emergence of animal diseases.

25. Some Effects of Climate Change on Infectious Diseases of Animals in Africa (Baylis 2006) • Moisture-sensitive diseases will be affected, including anthrax, blackleg, dermatophilosis, haemorrhagic septicaemia, PPR, haemonchosis and vector–borne diseases. These diseases may decline in some areas and spread to others. • Increase in Fascioliasis due to F. hepatica in Central, East and parts of West Africa; decline in Fascioliasis due to F. hepatica and F. gigantica in northern and southern Africa, depending on measures to preserve water supplies.

26. Some Effects of Climate Change on Infectious Diseases of Animals in Africa (Baylis 2006) • Possible increase in frequency of epidemics of diseases linked to El Nino Southern Oscillation (i.e. Rift Valley fever, Blue tongue) • Possible increases in pathogen transmission between wildlife and livestock.

27. Examples of climate-disease links (After Baylis, 2007) Anthrax Worldwide zoonosis Spores remain infective for 10-20 years in pasture. Temperature, RH and soil moisture affect spore germination Heavy rainfall stirs up dormant spores. Outbreaks often associated with alternating heavy rainfall and drought, and high temperatures Spotted hyena eating a zebra dead from anthrax, Ethosha Park, Namibia

28. Examples of climate-disease links (After Baylis, 2007) Fascioliasis (liver fluke) Caused by the Fasciola, a trematode/fluke Of economic importance to cattle and sheep producers in many parts of the world. Associated with environmental conditions favouring the intermediate snail host. Eg. low lying wet pasture, areas subject to periodic flooding, and temporary or permanent bodies of water Liver fluke life cycle

29. Examples of climate-disease links (After Baylis, 2007) African horse sickness Lethal infectious disease of horses Caused by a virus transmitted by Culicoides biting midges. Large outbreaks of AHS in the Republic of South Africa over the last 200 years are associated with the combination of drought and heavy rainfall brought by the warm-phase of the El Niño Southern Oscillation (ENSO)

30. Some Effects of Climate Change on Infectious Diseases of Humans in Africa (Baylis 2006) • Uncertain impact on acute respiratory infections • Possible increase in cholera in response to more coastal flooding • Increased impact of diarrhoeal diseases • Greater areas of risk of vector-borne diseases such as Rift Valley Fever, dengue, leishmaniasis, schistosomiasis, malaria, West Nile Fever. • Uncertain effect on meningococcal meningitis, filariasis, trypanosomosis.

31. Pathways for Weather to Affect Health: Diarrhoeal Diseases(AfterEbi, 2006) Distal Causes Proximal Causes Infection Hazards Health Outcome Survival/ replication of pathogens in the environment Temperature Humidity Precipitation Consumption of contaminated water Incidence of mortality and morbidity attributable to diarrhoea Contamination of water sources Consumption of contaminated food Living conditions (water supply and sanitation) Contact with infected persons Contamination of food sources Food sources and hygiene practices Vulnerability (e.g. age and nutrition) Rate of person to person contact

32. Potential Health Effects of Climate Variability and Change(After Ebi, 2006)

33. Examples of links between climate, animal health and human health in Africa. I • Changes in the distribution and impacts of the vector-borne diseases of man and animals. • Diseases such as malaria, Rift Valley fever, African horse sickness, and bluetongue vary considerably with seasonal and longer-term climatic variations. • Climate change is said to directly contribute to changes in the geographic distribution of vector-borne diseases such as malaria and epidemics of meningococcal meningitis and Rift Valley fever and cholera in previously unaffected areas.

34. Examples of links between climate, animal health and human health in Africa. II • Some diseases—because of climate change—are moving into new areas where people have little natural immunity (e.g. schistosomiasis, yellow fever, malaria, Chikungunya fever, Onyong-nyong fever, Dengue, West Nile.) • Water-borne infectious diseases are exacerbated by flooding and complicated by inadequate access to water by people and animals. • Droughts force peoples and their livestock to move, potentially exposing them to different environments with health risks to which they have never been exposed.

35. Conclusion I • CHCD 2008 stated that “The emergence of infectious diseases and their spread and impact, relate to how pathogens interact with a complex of social, technological and environmental processes. • These processes are highly interdependent, non-linear and often context-specific. They operate over varied and sometimes overlapping temporal and spatial scales. • Some disease drivers and effects involve short-term shocks- as in an ecosystem switch that triggers a sudden epidemic outbreak- while others involve longer-term trends and stresses.

36. Conclusion I continued • Disease responses themselves can feed back to shape these dynamics- either positively, for instance where the disease is brought under control, or in less intended ways- for instance where drugs contribute to emerging pathogenic resistance. • Understanding emerging infectious diseases thus requires an appreciation of such complex social, technological and environmental dynamics.”

37. Conclusion II Matthew Baylis (2006) argues that • “There is considerable uncertainty arising from the many, often conflicting, forces that climate imposes on infectious diseases, the complex interaction between climate and other drivers of change and uncertainty in climate itself. • Effects of climate change that act indirectly on infectious diseases, via effects on other drivers, are particularly hard to predict.

38. Conclusion II continued • Nevertheless, there is a consensus that some, and possibly many infectious diseases of animals, humans and plants will be affected by climate change. • Many of the diseases we commonly face are kept at least partly in check by lifestyles, behaviours, farming systems or control measures that we have learned to use, sometimes over millennia, to help keep us, our livestock and our crops healthy. • By contrast, when a new disease emerges or a familiar disease spreads to a new region, there is a long lead-in time before we know its significance and how it can be controlled or avoided.”

39. Conclusion III • Need for closer collaboration between veterinary, medical and environmental sciences to improve disease surveillance and control relating to climate change, as this is lacking in many countries. • Rudolf Virchow said “Between animal and human medicine there are no dividing lines. The object is different but the experience obtained constitutes the basis of all medicine.” • Underscores the concept of or movement for “One world, one health”

40. Acknowledgements • I acknowledge with gratitude the use of information from various authors and particularly work by Matthew Baylis of Liverpool University and the Climate and Health Challenge Dialogue 2008. They made my work easier. • I thank the organisers for the opportunity given me for this presentation.

41. THANK YOU FOR YOUR ATTENTION

43. Impact of climate change on African Agriculture(After Chemnitz and Hoeffler 2011) Effects are at two levels • Biophysical Include changes in crop-growing conditions and animal productivity as a result of rising temperature and highly variable precipitation • Socioeconomic • Falling incomes from agriculture • Higher risks and greater vulnerability in the rural population due to changes in their cultural and economic livelihoods • Risk of rural areas sliding deeper into poverty

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

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