Climate change, water resource development and malaria in Ethiopia

Transcription

1 Climate change, water resource development and malaria in Ethiopia Eline Boelee, Matthew McCartney, Mekonnen Yohannes, Fitsum Hagos, Jonathan Lautze, Solomon Kibret

2 Key message Climate change necessitates water storage, which may increase health risks that can be mitigated

3 Malaria in Ethiopia as example Koka reservoir (Source: MoH & WHO 2007)

4 Impacts of climate change Increased variability of rain Reduced availability of water Reduced water & food security Need for water resources development Water storage has a role to play in adaptation to climate change Impacts on mosquitoes, parasites, transmission cycle

5 Water resources development in Ethiopia Per capita water availability declining Water Sector Development Program River diversion / irrigation systems Rainwater harvesting ponds Large multipurpose dams Small reservoirs DWSS (Source: Awulachew et al. 2005) Per Capita Water Available (Cu. m)

6 Water storage Focus on water for agriculture, incl. livestock Integrated into most water systems Save water over time for access at critical periods Diverted from rivers, rainwater harvesting, aquifers High variety Tanks, reservoirs Groundwater Large / small Open / closed Man made / natural

7 Water storage continuum (Source: McCartney & Smakhtin 2010)

8 Reduced climate vulnerability Increased adaptive capacity Present climate vulnerability pre-adaptation Water storage adaptation strategy Increased availability and access to water Increased agricultural productivity Increased water security Future climate vulnerability post-adaptation Future climate vulnerability < present climate vulnerability (Source: McCartney & Smakhtin 2010)

9 Health risks of open water Expanded water surface for longer periods Drowning, water quality, vector borne diseases Increased malaria transmission associated with Small reservoirs < 100 Surface irrigation (estates & small scale) Rainwater harvesting ponds > 100,000 Increasingly higher altitudes Current control strategies insufficient Bednets, house spraying Shift in biting rhythm Foreign currency, resistance

10 Malaria at Koka Lake, Rift Valley Increased transmission near lake Decision support for dam operation Potential for larval control by dam operation (water level fluctuation)

11 y = ln(x) R² = Malaria cases/1000 people Koka Malaria cases correlate with Distance from reservoirs Water level Distance f rom the reservoir (km) fluctuations (Source: Kibret et al. 2009) Jan Jan Jan Jan Jan Jan Jan Jan Feb Feb Feb Feb Feb Feb Feb Mar Mar Mar Mar Mar Mar Mar Mar Apr Apr Apr Apr Apr Apr Apr Apr May May May May May May May Jun Jun-00 Malaria cases/1000 people Observed Predicted Water level change (Source: Lautze 2008)

12 Koka Adult Anopheles more abundant closer to reservoir More breeding sites near shore line, mainly in hoof prints Aug-06 Sep-06 Oct-06 Nov-06 Dec-06 Jan-07 Feb-07 Mar-07 Apr-07 May-07 Jun-07 Jul-07 Aug-07 Sep-07 Oct-07 Mean no. mosquitoes per trap per night Nov-07 Dec-07 An. arabiensis (Reservoir villages) An. pharoensis (Reservoir villages) An. arabiensis (Control villages) An. pharoensis (Control village) (Source: Lautze 2008)

13 Koka Reservoir crucial for livestock watering

14 Koka Anopheles larval abundance related to drawdown rate Can malaria control be incorporated into dam management? y = x R² = Total larval abundance in the shoreline puddles of both Ejersa and Siree Robe (Source: Kibret et al. 2009) Rate of falling water levels (mmd -1 ) -20

15 Small reservoirs, Tigray Mosquito breeding in seepage areas Increased transmission, year round, near microdams Limited impact on agricultural productivity

16 Water harvesting ponds Even tiny plots require labor at critical times

17 Water harvesting ponds Significantly more malaria near ponds Determinants of malaria House type Distance to wells Toilets Bed net Season Malaria prevalence (%) 60 Nov Dec Mar May High land ponds High land control Mid Land ponds Mid Land control Low land ponds Low land control

18 50 Shift in biting rhythm % hourly catches Indoor (n = 12 light trap nights) Outdoor (n = 12 light trap nights) Tigray Main vector Anopheles arabiensis Peak in biting activity after midnight Change to early evening 0 18:00-19:00 19:00-20:00 20:00-21:00 21:00-22:00 22:00-23:00 23:00-24:00 24:00-01:00 01:00-02:00 02:00-03:00 03:00-04:00 04:00-05:00 05:00-06:00 06:00-07:00 (Source: Yohannes & Boelee, in press) Rift Valley (Source: Kibret et al. 2010)

19 Reduced climate vulnerability Increased adaptive capacity Present climate vulnerability pre-adaptation Water storage adaptation strategy Increased availability and access to water Increased agricultural productivity Increased water security Future climate vulnerability post-adaptation Increased malaria Future climate vulnerability > present climate vulnerability

20 Way forward In Ethiopia No additional small dams Large hydropower dams <10 Upgrading and expansion of irrigation Water harvesting: ponds and in situ No capacity for mitigating measures Try to influence policy, planning and design

21 Intervention options Complementary to early diagnosis and treatment Transmission reduction Zooprohylaxis? Source reduction Participatory approaches Engineering / agricultural measures Alternative water storage options Aquifers Soil moisture Wetlands

22 Reduced climate vulnerability Increased adaptive capacity Present climate vulnerability pre-adaptation safe Water storage Increased availability and access to water Increased agricultural productivity Increased water security Future climate vulnerability post-adaptation adaptation strategy Increased malaria Future climate vulnerability < present climate vulnerability

23 Key message Climate change necessitates water storage, which may increase health risks that can be mitigated Thank you!