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Climate change and animal health


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Presentation by Bernard Bett at the 14th conference of the International Society for Veterinary Epidemiology and Economics (ISVEE), Merida, Yucatan, Mexico, 3-7 November 2015.

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Climate change and animal health

  1. 1. Climate change and animal health Bernard Bett 14th Conference of the International Society for Veterinary Epidemiology and Economics Merida, Yucatan, Mexico 3–7 November 2015
  2. 2. Acknowledgements Part of this work falls under the project ‘Dynamic Drivers of Disease in Africa: Ecosystems, livestock/wildlife, health and wellbeing: REF:NE/J001422/1” partly funded with support from the Ecosystem Services for Poverty Alleviation Programme (ESPA). The ESPA program is funded by the Department for International Development (DFID), the Economic and Social Research Council (ESRC) and the Natural Environment Research Council (NERC). This work received funding from the Europeans Union Horizon 2020 research and innovation programme under the research agreement No. 641918 Joseph Ogutu, University of Hohenheim Mohammed Said, ILRI Johanna Lindahl, ILRI Delia Grace, ILRI John McDermott, IFPRI Ian Dohoo, UPEI, Canada
  3. 3. Outline • Introduction • Drivers of climate change • Climate change and animal health • Applications • Conclusions
  4. 4. Introduction • Climate change influences the dynamics and distributions of: o individual organisms and populations o interactions • Interest on its effects on disease patterns, vector and pathogen distribution • Mitigation and adaptation practices
  5. 5. Challenges of climate change-disease research • Scales: Climate change is measured in broad/global scales while requirements for disease transmission defined at local/ecosystem levels • Data: Baseline data to evaluate extent of geographical shifts in suitable habitats • Socio-economic factors : Effects of climate overlap/influenced by socio-economic changes • Current knowledge Direct verses indirect effects
  6. 6. Drivers of climate change • Earth’s temperature balance: difference between inward and outward energy from the sun • Main drivers of climate change o Natural processes i. changes in the amount of solar intensity reaching the earth ii. reflectivity of the earth surface iii. volcanic eruptions o Anthropogenic factors – concentration on GHG i. Burning fossil fuels ii. Deforestation iii. Some agricultural practices Huber and Knutti, 2012
  7. 7. GHG and livestock • Human-induced climate change – mainly from increasing atmospheric concentrations of heat-trapping greenhouse gases Herrero et al. 2013 GHG per kg of animal protein produced
  8. 8. Temperature and CO2 levels Karl et al., 2009
  9. 9. Effects of climate change on animal health • Effects of climate change on animal health: o Direct effects: - Vectors, pathogens and hosts and their interactions o Indirect effects: - Land use changes - Biodiversity changes • Climate affects suitability of a habitat for pathogens/vectors/hosts, while weather influences timing/severity of outbreaks
  10. 10. Vector Pathogen Host Environment Direct and indirect effects: elements of a disease transmission cycle
  11. 11. Direct effects of climate change
  12. 12. Vectors: survival/fitness and phenology Tsetse flies: 10 – 36°C Culicoides imicola: 17 – 36°C • Fitness and survival • Phenology – timing of seasonal activities
  13. 13. Vectors: Feeding intervals and development rates Graphs based on degree days for Culex quiquefaciatus
  14. 14. Pathogens –replication/development rates Temperature: • Influences development/repli cation rates of some pathogens, e.g. Bluetongue virus (BTV) • Affects pathogen dissemination rates within the vector • Influences ability of a pathogen to infect a vector 0 500 1000 1500 2000 2500 0 10 20 30 40 50 BTV -1 polymerase activity Temperature Incorporationofradiolabelled substratesintoRNA P. Mertens, Pirbright Inst.
  15. 15. Hosts: susceptibility to pathogens • Homeotherms sensitive to air temperature, air velocity, and relative humidity • Chronic stress: o wears down neuroendocrine responses o elicits viral-bacterial synergy, causing fatal respiratory infections e.g. BRD • Ultraviolet radiations suppresses T cell immunity • Access to nutritious forage and disease resistance o Lignification of forages o Replacement of pasture with invasive shrubs Bett, 2014
  16. 16. Case studies – evidence of climate impacts Expansionofsuitableniches Epidemicsassociatedwith extremeevents Reductioninsuitableniches Increasedtransmissionriskinsome areas Bett, B. 2015
  17. 17. Case study 1: Expansion of suitable niches • Vectors that have recently expanded their geographical range Vector Pathogen Culicoides imicola Bluetongue virus (BTV) Ixodes ricinus Tick-borne encephalitis, Lyme borreliosis Dermacentor reticulatus Canine babesiosis, tularemia, Q-fever Aedes albpictus Dengue virus
  18. 18. Bluetongue – evidence of impacts of climate change P. Mellor, M. Baylis and P. Mertens, 2009
  19. 19. Case study 2: Declining spatial range • Shifting ranges • Data limitations – used predictions to 2020 and 2080 Disease Vector Trypanosomosis Tsetse flies East Coast fever Rhipicephalus appendiculatus
  20. 20. Rhipicephalus appendiculatus • Predictions to 2020 – with an expected drier conditions on the eastern side of the African continent • Contraction in climatic suitability for this species by an area of about 199,400 sq. km • East to west Africa shift • Hosts predicted to have range reduction of 8 to 33% Leta et al. 2013
  21. 21. Tsetse and trypanosomosis • Tsetse transmitted animal trypanosomosis affects 45-50 million cattle in sub-Saharan Africa • Tsetse control could increase livestock productivity by 52% • Climate change impacts to 2080: o A reduction in the overall tsetse population by 7% o 1.5-fold decrease in habitats o Increased transmission in a few countries, e.g. Swaziland, Zambia, Zimbabwe
  22. 22. Case study 2: Epidemics from extreme events • Diseases that occur as epidemics following extreme events Vector Pathogen Rift Valley fever High/persistent rainfall Leptospirosis Flooding
  23. 23. Rift Valley fever • Rift Valley fever – mosquito- borne viral disease of sheep, goats, cattle, camels with zoonotic potential • RVF virus – single stranded RNA with 3 segments • Impacts: extensive abortions in animals, perinatal mortality, haemorrhagic syndrome in people Bird et al., 2009
  24. 24. Studies on RVF • Drivers – climate and land use changes • Spatial distribution and transmission dynamics • Intervention measures
  25. 25. El Niño and Rift Valley fever (Oct, 2015) • Six of the seven documented RVF outbreaks in EA since 1960s associated with El-Niño • El Niño – a random event but its frequency expected to increase with climate change
  26. 26. Rainfall anomalies IRI, 2015
  27. 27. Rainfall anomalies
  28. 28. Hazard mapping • Ecological niche models • Risk factors • Risk-based surveillance and quantification of vaccines • Co-occurrence of diseases Bett, 2015
  29. 29. Response: Hazard and vulnerability mapping • IPCC –hazard and vulnerability mapping • Vulnerability: o Education o Poverty o Livelihood options o Access to health services o Knowledge Kienberger and Hagenlocher, 2014
  30. 30. RVF virus transmission dynamics EFSA, 2005
  31. 31. Modelling RVF - Climate variability Rainfall and temperature satellite data Floodwater Aedes mcinthoshi Culex spp.
  32. 32. Choice of RVF vaccines Existing vaccines • Attenuated Smithburn vaccine • Clone 13- naturally attenuated strain • Formalin- inactivated field strain Periodic vaccination
  33. 33. RVF vaccination strategies Perfect vaccine Vaccine with 50% efficacy
  34. 34. Indirect effects of climate change J. Ogutu, Univ of Hohenheim
  35. 35. Indirect effects of climate change • Land use change influencing vector-host- pathogen interactions Deforestation – irrigation – urban development • Biodiversity changes
  36. 36. Land use change • Erratic rainfall and increasing human population, expected to hit 9.6 billion by 2050, prompting land use changes, e.g. irrigation to alleviate food insecurity • Irrigation potential: Sub-Saharan Africa To increase by 39.3 m ha Southeast Asia 10.6% of area irrigated and will expand to 22.4%
  37. 37. Land use change and disease transmission 1 10 100 1000 10000 Aedes spp Anopheles spp Culex spp Mansonia spp irrigated area non-irrigated area Villages Mosquito species Lognumberofmosquitoes 1 10 100 1000 10000 Aedes spp Anopheles spp Culex spp Mansonia spp irrigated area non-irrigated area Farms Mosquito species Lognumberofmosquitoes 1 10 100 1000 10000 Aedes spp Anopheles spp Culex spp Mansonia spp irrigated area non-irrigated area Villages Mosquito species Lognumberofmosquitoes 1 10 100 1000 10000 Aedes spp Anopheles spp Culex spp Mansonia spp irrigated area non-irrigated area Farms Mosquito species Lognumberofmosquitoes I FallowperiodIrrigationseason
  38. 38. Biodiversity changes • The increasing frequency of droughts in eastern Africa linked to warming of the Indian Ocean • The Indian Ocean has warmed much faster because of encroachment from Tropical Warm Pool Hans Olff, Univ Groningen
  39. 39. Droughts and wildlife populations Drought year Description 1991 Moderate 1993 Severe 1994 Moderate 1997 Severe 1999/2000 Extreme 2005/2006 Moderate 2008/2009 Moderate Dublin et al. 2015
  40. 40. Host diversity and disease transmission • Dilution effect – Can biodiversity provides ecosystem services of disease transmission reduction? • Assumptions: o Reservoir hosts vary in competence o Increase in non-competent hosts leads to lower prevalence in vectors o Increase in biodiversity favours non-competent hosts • Observations: high biodiversity associate with high disease risk
  41. 41. Practical applications • Mean intervals between key events in 2006/07 RVF outbreak, based on pastoralists’ recall in North Eastern Province, Kenya Results Events Mean Interval (days) Average Reported Start Date Per Event Start of heavy rains and appearance of mosquito swarms 23.6 Start of heavy rains: mid October 2006 First appearance of mosquito swarms and first suspected RVF case in livestock 16.8 Appearance of mosquito: late October 2006 First suspected RVF case in livestock and first suspected human case 17.5 First suspected RVF case in livestock: mid November 2006 First suspected RVF case in livestock and first veterinary service response 61.7 First suspect RVF case in humans: late November 2006 First suspected RVF case in livestock and first public health service response 50.0 First veterinary service response: mid January 2007 First suspected human case and first public health service response 30.0 First public health service response: mid December 2006
  42. 42. Rift Valley Decision Support Framework Current version:
  43. 43. Conclusions • Improve disease surveillance and response with climate data being used for risk mapping/prediction • Improve animal health service delivery, with good disease control technologies e.g. vaccines • Increase the resilience of livestock systems – breeds, feed