Combining Entomological,
Epidemiological, and
Space Mapping data for
Malaria Risk-mapping in
Northern Uganda
Findings and Implications
Ranjith de Alwis, Abt Associates
November 15, 2012
Contents
 Malaria and malaria control in Uganda
 Indoor residual spraying (IRS) in Uganda
 Impact of IRS on malaria prevalence
 Entomological monitoring activities and findings
 Risk mapping
 Lessons learned
 Recommendations
Abt Associates | pg 2
Malaria and Malaria Control
 Malaria transmission
 highly endemic and
perennial
 90% of population at risk
 99% Plasmodium falciparum
 Major vectors
 Anopheles gambiae
 Anopheles funestus
 Interventions
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IRS
ITNs/LLINs
IPT
Improved diagnosis/case
management
Abt Associates | pg 3
Indoor Residual Spraying (IRS)
 IRS—most effective malaria vector control method
 Currently, the primary factor for deciding where to
use IRS is malaria incidence, which results in
expensive blanket coverage
 Stratification based on risk—more effective strategy
but requires reliable and representative data over
time
Abt Associates | pg 4
Indoor Residual Spraying (IRS)
Data needed for planning IRS
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Vector bionomics (species and behaviour)
Vector susceptibility to insecticides
Suitability of structures and population compliance
Malaria prevalence patterns to determine time to spray
On-going monitoring needs for decision making
 Vector bionomics
 Vector susceptibility
 Residual efficacy of insecticide
Data needed for decisions on phase-out or scale-up of IRS
 Malaria epidemiological data over the time
 Meteorological information
 Feasibility of carrying out of other interventions
Abt Associates | pg 5
Indoor Residual spraying (IRS)
 Started in 2006 in
South Western districts
 Moved to Northern
districts in 2007
 7-8 rounds have
completed
 Started with Lambda-Cyhalothrin
 Then moved to Alpha-Cypermethrin
 DDT was used in 2 districts for one
round
 Since 2010 Bendiocarb
Target Population – 2.8 million
Approx. 900,000 structures
Abt Associates | pg 6
Impact of IRS on Malaria
Prevalence
 Marked reduction in
malaria cases,
especially after
Bendiocarb
Abt Associates | pg 7
Impact of IRS on Malaria
Prevalence
 Location based data not available
in health institutions
 Difficulties in combining
epidemiological data with other
information
Abt Associates | pg 8
Entomological Monitoring Activities
 Pre- and post-spraying
PSCs
 Post-spraying wall
bioassays
 Monthly wall bioassays
 National Susceptibility
Study (2011)
 Vector bionomics ****
Abt Associates | pg 9
Pyrethroid Spray Collections
(2009-12)
Abt Associates | pg 10
Monthly Wall Bioassays (200912)
Abt Associates | pg 11
National Susceptibility Study
Abt Associates | pg 12
Risk Mapping
2005 risk map based on malaria endemicity.
2012 risk map detailed at district level to facilitate
development of national vector control policy.
 Planned to used a spatial model based on district-level
information:
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Malaria prevalence data
Entomological data
Intervention data
Meteorological data
Demographic, physical and geographical data
 Data challenges
 Malaria data is not representative or reliable
 No recent entomological data
 Low, predictive power of the risk map model – Need to
improve.
Abt Associates | pg 13
Malaria Risk Maps
Abt Associates | pg 14
Lessons Learned
 IRS effectiveness
 Combining all these data help us to
– Use correct insecticide
– Manage resistance
– Understand residual efficacy
 Indoor resting behavior
 Reduction of malaria prevalence / When to phase out IRS
Strengthen other control methods.
 Importance of location based data at lower administration
levels
 Risk mapping in project area
 Will allow scale up of malaria control activities nationally
while phasing out/reducing IRS in on-going areas
Abt Associates | pg 15
Recommendations
To scale up vector control nationally while reducing IRS
in on-going areas, we will need:
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Location based data
Confirmed malaria cases
Establishment of indicators institutions
Spatial analysis of population distribution
Spraying time and frequency
Vector bionomics
Resistance status
Abt Associates | pg 16