Impact of the koka reservoir on malaria
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Impact of the koka reservoir on malaria, Solomon Kibret, Matthew McCartney and Jonathan Lautze. Challenge Program on Water and Food, 2nd International Forum on Water and Food, Addis Ababa, Ethiopia ...

Impact of the koka reservoir on malaria, Solomon Kibret, Matthew McCartney and Jonathan Lautze. Challenge Program on Water and Food, 2nd International Forum on Water and Food, Addis Ababa, Ethiopia
November 2008

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    Impact of the koka reservoir on malaria Impact of the koka reservoir on malaria Presentation Transcript

    • Solomon Kibret, Matthew McCartney and Jonathan Lautze Impact of the Koka Reservoir on Malaria Challenge Program on Water and Food, 2nd International Forum on Water and Food, Addis Ababa, Ethiopia November 2008 Cover slide photo credit: Solomon Kibret (Koka reservoir), Jonathan Lautze
    • Introduction
      • Investment in hydraulic infrastructure, including large dams, is crucial for
      • economic growth and poverty reduction in many parts of sub-Saharan Africa.
      • Dams are built to cope with climate variability and may help
      • to mitigate climate change.
      • Inadequate consideration of both environmental and public health
      • impacts can seriously undermine the benefits to be gained from such investments.
      • Key among the potential negative effects of large dams is intensified malaria
      • transmission, resulting from changes in environmental conditions.
      • Several large dams are currently being built in Ethiopia
              • Research is required to understand the link between reservoirs and malaria
        • transmission in the different hydro-climatic conditions
      • characterize mosquitoes breeding habitat associated with Koka dam and reservoir
      • shoreline
      • compare vector density in villages at close proximity to the reservoir with those
      • further away.
      • compare malaria incidence in villages at close proximity to the reservoir with
      • those further away.
      • correlate water level changes over a period of time with the abundance and
      • maturity of Anopheles larvae in shoreline sites and malaria transmission
      • surrounding the Koka reservoir.
      Objectives of the study
    • The study area Source: Kibret, S.; McCartney, Matthew; Lautze, Jonathan; Jayasinghe, G. 2009. Malaria transmission in the vicinity of impounded water: evidence from the Koka Reservoir, Ethiopia. Colombo, Sri Lanka: International Water Management Institute (IWMI). 39p. (IWMI Research Report 132)
    • Climate Malaria is seasonally demarcated, with peak transmission following the long wet season, generally lasting from mid-September to mid-November. Source: Created by S.Kibret using IWMI data, 2008
      • Epidemiological survey:
        • Records of malaria diagnoses were obtained for all kebeles (i.e. a total of 22
        • kebeles) located within 10 km of the reservoir for the period October 1994 to
        • August 2002.
        • These data were obtained from three malaria control centers located close to
        • the reservoir: Adama, Mojo and Alem Tena.
        • malaria case-rates (malaria diagnoses per 1000 person-month) for each kebele
        • was generated.
      Materials and Methods
      • Entomological survey:
        • Four villages selected
            • Ejersa, Siree-Robe (<1 km from the reservoir) = Reservoir Villages
            • Kuma and Gudedo (> 6km from the reservoir) = Control Villages
        • both larval and adult mosquitoes were collected fortnightly in the four study
        • villages for 16-months (between August 2006 and December 2007)
        • Potential mosquito breeding habitats in the study area included:
              • seepage at the base of the dam,
              • reservoir shoreline puddles,
              • man-made pools,
              • agricultural field puddles
              • rain puddles
      Materials and Methods…..
    • Photo Credit: Jonathan Lautze Photo Credit: Jonathan Lautze Photo Credit: Jonathan Lautze
    • Malaria cases passively reported in terms of proximity to the Koka Reservoir. Results Impact of the reservoir on malaria incidence Source: Preliminary figures compiled for Research report 132, S.Kibret 29.6-40.2 34.9 6-9 46.8-63.6 55.2 3-6 69.6-92.2 80.9 0-3 95% CI Annual cases per 1000 persons Distance from reservoir (km)
    • Results…... Seasonal distribution of malaria cases:
      • The reservoir’s main impact on malaria
      • transmission is during and after the rainy
      • season.
      Source: Lautze, J et al.. 2007. Effect of a large dam on malaria risk: The Koka Reservoir in Ethiopia . Tropical Medicine and International Health, 12(8):982-989
    • Results…... Species of malaria:
      • the proportion of P. falciparum infections is greater in communities located
      • close to the reservoir.
      Source: Lautze, J et al.. 2007. Effect of a large dam on malaria risk: The Koka Reservoir in Ethiopia . Tropical Medicine and International Health, 12(8):982-989 45.4 3,564 54.2 4,257 7,852 6-9 38.6 2,560 61.3 4,069 6,637 3-6 34.1 1,660 65.8 3,202 4,863 0-3 % No. % No. P. vivax P. falciparum Total Plasmodium cases Distance from reservoir (km)
    • Results…... Impact of the reservoir on vector abundance Larval abundance in reservoir and control villages Aug 2006 – Dec 2007.
      • Overall, approximately 7-times more positive larval sites and 3-times higher larval
      • density in the reservoir villages than in the control villages
      Source: Kibret, S.; McCartney, Matthew; Lautze, Jonathan; Jayasinghe, G. 2009. Malaria transmission in the vicinity of impounded water: evidence from the Koka Reservoir, Ethiopia. Colombo, Sri Lanka: International Water Management Institute (IWMI). 39p. (IWMI Research Report 132) 3.1 – 16.5 9.8 0.5 – 4.1 2.3 Control Villages < 0.0001 19.8 – 46.4 33.1 <0.0001 9.3 – 21.1 15.2 Reservoir Villages p-value 95% CI Mean larval density p-value 95% CI Mean number of positive larval sites
    • Results…... Seasonal Anopheles larval density in the reservoir and control villages. Source: Preliminary figures created for Research Report 132, S. Kibret
    • Results…... Summary of adult Anopheles mosquitoes collected August 2006 and December 2007. Source: Kibret, S.; McCartney, Matthew; Lautze, Jonathan; Jayasinghe, G. 2009. Malaria transmission in the vicinity of impounded water: evidence from the Koka Reservoir, Ethiopia. Colombo, Sri Lanka: International Water Management Institute (IWMI). 39p. (IWMI Research Report 132) 438 0 (0.0) 68 (15.5) 92 (21.0) 278 (63.5) Control Villages 2514 29 (1.2) 342 (13.6) 787 (31.3) 1356 (53.9) Reservoir Villages Total An. funestus An. coustani An. pharoensis An. arabiensis
    • Results…... Density of An . arabiensis and An . pharoensis between August 2006 and December 2007 Source: Preliminary figures created for Research Report 132, S. Kibret
    • Results…... Bloodmeal sources of Anopheles mosquitoes, Aug 2006–Dec 2007 Source: Kibret, S.; McCartney, Matthew; Lautze, Jonathan; Jayasinghe, G. 2009. Malaria transmission in the vicinity of impounded water: evidence from the Koka Reservoir, Ethiopia. Colombo, Sri Lanka: International Water Management Institute (IWMI). 39p. (IWMI Research Report 132) 319 238 (74.6) 69 (21.6) 31 (9.7) 385 240 (62.3) 111 (28.8) 72 (18.7) 103 44 (42.7) 63 (61.2) 16 (15.5) 8 2 (25.0) 4 (50.0) 3 (37.5) 136 85 (62.5) 41 (30.1) 29 (21.3) 45 26 (57.8) 15 (33.3) 8 (17.8) 23 5 (21.7) 13 (56.5) 6 (26.1) 0 0 0 0 Reservoir An. arabiensis An. pharoensis An. coustani An. funestus Control An. arabiensis An. pharoensis An. coustani An. funestus No. tested No. positive No. positive Unidentified for HB for BB Village Species
    • Results…... Plasmodium falciparum sporozoite rates between August 2006 and December 2007 Source: Kibret, S.; McCartney, Matthew; Lautze, Jonathan; Jayasinghe, G. 2009. Malaria transmission in the vicinity of impounded water: evidence from the Koka Reservoir, Ethiopia. Colombo, Sri Lanka: International Water Management Institute (IWMI). 39p. (IWMI Research Report 132) 824 0.97 574 0.70 252 0.00 20 0.00 532 1.32 213 0.47 90 0.00 9 0.00 161 0.00 42 0.00 45 0.00 0 0 117 0.00 50 0.00 23 0.00 0 0 Ejersa Siree-Robe Gudedo Kuma An. arabiensis An. pharoensis An. coustani An. funestus no. tested positive (%) no. tested positive (%) no. tested positive (%) no. tested positive(%) Village
      • Dam has increased malaria incidence in the villages in close proximity to the reservoir
      • Reservoir significantly increases breeding habitat for malaria vectors
      • Outdoor questing of mosquitoes in the early evening may limit the effectiveness
      • of current malaria control strategies (i.e. ITN*)
      • Requires further investigation but preliminary results indicate that reservoir
      • management (i.e. manipulation of water-levels) can impact vector abundance
      • and malaria transmission
      Conclusions * ITN: Insect Treated Net
    • Related Publications
      • Kibret, S., McCartney, M., Lautze, J, Jayasinghe, G. 2009. Malaria Transmission in the vicinity of impounded water: Evidence from the Koka Reservoir, Ethiopia. Colombo, Sri Lanka: International Water Management Institute. Research Report 132 .
      • Lautze, J., and Kirshen, P. September, 2007. Dams, Health, and Livelihoods: Lessons from the Senegal, Suggestions for Africa. International Journal of River Basin Management 5(3).
      • Lautze, J., McCartney, M., Kirshen, P., Olana, D., Jayasinghe, G., and Spielman, A. 2007. The Effect of a Large Dam on Malaria Risk: The Koka Reservoir, Ethiopia. Tropical Medicine and International Health 12(8): 982-989.
      • THANK YOU!!
      • For complete publication please visit:
      • http://www.iwmi.cgiar.org/Publications/IWMI_Research_Reports/PDF/PUB132/RR132.pdf
      • (2009)
      • N.B :Some of the data used in this presentation was based on preliminary results (2008)