An Observational Analysis of the Impact of IRS in the
Ségou Region of Mali: 2012 - 2014Joseph Wagman1*, Christelle Gogue1, Kenzie Tynuv1, Jules Mihigo2, Diadier Diallo3, Elie Bankineza4, Mamadou Bah4, Andrew Saibu5, Jason Richardson6 ,Diakalkia Kone7, Seydou
Fomba7, Laurence Slutsker1, Molly Robertson1
1PATH, Washington, DC, USA, 2US President’s Malaria Initiative, Bamako, Mali, 3MEASURE Evaluation, Bamako, Mali, 4Abt Associates, AIRS Project, Bamako, Mali,
5Abt Associates, NgenIRS Project, Accra, Ghana, 6IVCC, Washington, DC, USA,7Programme National de Lutte contre le Paludisme, Ministère de la Sante, Bamako, Mali; *[email protected]
Introduction
#1129
Project Partners
The annual IRS campaigns from 2012 – 2015 in Ségou were good public health
investments
o Around 500,000 people protected for 3 years at around $7 USD or less per
person per year, regardless of which chemical was sprayed
o Around 300,000 cases of malaria were likely averted,
PMI/Abt entomological surveillance results 3 indicate that the IRS campaigns were
also broadly associated in time and space with reductions in overall An. gambiae
s.l. indoor resting and biting densities.
It is encouraging that, despite the continued and obvious need for an
expanded IRS toolkit, campaigns with currently available non-pyrethroid
products (including 3rd generation IRS products) can have a sizable, cost-
effective impact in areas of high pyrethroid resistance and widespread use of
LLINs.
Additionally, this work highlights the critical importance of quality-assured,
validated, routine surveillance and well defined observational analyses to asses the
impact of malaria control interventions in various operational settings – helping to
empower evidence-based decisions and to grow the evidence base needed to
better understand when and where to utilize new vector control tools as they
become available.
*The NgenIRS (Next Generation IRS) project is a partnership, led by IVCC, that includesthe US President’s Malaria Initiative, Abt Associates, and PATH. NgenIRS works in close
collaboration with leading insecticide manufacturers, national malaria control programs,
the Global Fund, and other stakeholders to save lives and protect health by reducingtransmission of malaria through affordable indoor residual spraying of long lasting, non-
pyrethroid insecticides. It is funded by UNITAID. For more information please visit
www.ngenirs.com or email David McGuire ([email protected]).
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Fig. 1. (a) The location of Mali in West Africa, with Ségou Region highlighted. (b) The locations of the community health facilities inSégou that reported malaria rapid diagnostic test results during the months analyzed here (Jan 2012 to Jan 2016). The IRS Districts ofBarouéli and Bla are shown in dark and light green, respectively; non-IRS comparator districts are shown in blue.
References1 2015 Estimates; Direction Nationale de la Population, Republique du Mali
2 2013 DHS3 PMI, 2016. Mali: Entomological Monitoring of 2015 IRS Activities
4 Cisse, et al. 2015. Mal J. 14:327, 5 Noor, et al. 2015. PLoS One;10e0136919
6 Johns and Cico, 2016. PM/AID-OAA-TO-14-000357 PMI. The PMI Africa IRS (AIRS) Project IRS 2 Task Order Four
Mali Entomological Monitoring Reports. 2012 – 2014. https://www.pmi.gov/where-we-work/mali
Table 1. Summary of the malaria control landscape in Ségou Region, Mali 2012 - 2015
1 Active Ingredient. CA = Carbamate; OP = organophosphate 2 % of structures targeted for IRS that were sprayed3 Universal Distribution Campaigns undertaken in 2012 and 2015 4 % of target population receiving at least 2 courses of SMC with SP+A
A set of retrospective, observational (ecological), time-series analyses were
performed using 1,382,202 RDT-confirmed cases of malaria reported by routine
health systems (Système Numérique d'Information Sanitaire Intégré) from January
2012 to January 2016.
Weather Station
Mauritania
Senegal
Guinea
Côte d’Ivoire
Burkina Faso
Niger
Algeria
Non-IRS DistrictsIRS 2012-2015
Community Health FacilityIRS 2012-2014
50km
a. b.
PMI/AIRS Entomological Surveillance Site
• 9,138 monthly reports from 202 community health centers in Ségou
• Community health center catchment area population estimates obtained from
the Ministry of Health
• Health center incidence rates per 10,000 person-months at risk were
stratified by IRS status for comparative analyses
• Total population ~3 million; ~590K
under 5 years old (u5)1
• 2013 u5 malaria prevalence = 56%2
• Malaria transmission highly seasonal,
typically highest June - October
• Primary vector is Anopheles gambiae
s.s.
• High levels of pyrethroid and DDT
resistance widely reported3,4
• High access to and use of LLINs2
o 90% of households with at least 1
LLIN
o 60% of total population report
sleeping under the LLIN
• Scale up of seasonal malaria chemo-
prevention (SMC) began in 2013
• 7 total administrative districts (cercles),
similar to one another in terms of 5
o Population density
o Rainfall patterns
o Malaria transmission seasonality
o Malaria prevalence
• 2 districts, Barouéli and Bla, participated
in the PMI/AIRS project during the study
period
o Bendiocarb WP (Ficam®; Bayer
CropScience) sprayed in 2012 &
2013
o Pyrimiphos-methyl CS (Actellic®300
CS; Syngenta AG) sprayed in 2014 &
2015
Ségou Region
Study Location
Approach Results, continued
Fig. 2. Epidemiological curves showingthe monthly incidence of RDT+confirmed malaria cases in Ségou,stratified by district IRS status. Thearea of the tan curve illustrates thedifference between the incidencerates observed in the IRS districts(green) and the non-IRS districts(blue). The duration of each year’s IRScampaign is also illustrated.
Also shown are the cumulativeincidence reductions observed in IRSdistricts, relative to non-IRS districts,during the 6 months that followedeach year’s IRS campaign.
321.3 fewer cases per
10,000 person-months
289.7 fewer cases per
10,000 person-months
491.5 fewer cases per
10,000 person-months
Table 2. A crude estimate of the cost-effectiveness of IRS in Bla and Barouéli Districts, 2012 - 2014
Estimates of the cost-effectiveness of IRS
Reported IRS expenditures and costs were compiled from Revised PMI Obligation
Tables and the PMI IRS Country Programs 2015 Comparative Cost Analysis6.
Crude estimates of the cost-effectiveness for each year’s IRS campaign were
calculated using the corresponding PMI/AIRS cost estimates for that year, adjusted
for the proportional number of structures sprayed per district included in this
analysis.
Results
Conclusions
Fig. 3. Comparing the entomologicaland epidemiological trends showingthe impact of IRS in Ségou Region,2012-2014. The monthly malariaincidence curves are presented withthe results of routine PMI/Abt AIRSentomological surveillance activities7.
*Bendiocarb was sprayed in 2012 and2013, while pirimiphos methyl wassprayed in 2014
Transmission Season 1
Reduced Incidence Observed in IRS
Districts (number of RDT+ cases per
10,000 person-months)
Total Population of IRS
Districts
Estimated Cases
Averted 2
Estimated Cost of IRS
Campaign 3
Crude Cost
per person
covered
Crude Cost
per case
averted
2012 321.3 563,359 108,604 $ 3,426,834.00 $6.08 $31.55
2013 289.7 586,125 101,880 $ 4,339,328.78 $7.40 $42.59
2014 491.5 258,598 76,261 $ 1,778,893.77 $6.88 $23.33
Total 1102.5 1,408,082 286,745 $ 9,545,056.55 $6.78 $33.29
1 Defined here as the six months following the IRS campaign2 (Reduced incidence)*(population of IRS districts)*(6 months)3 Annual Revised PMI Expenditures from Africa Indoor Residual Spray (AIRS) Mali Program,
in adjusted 2014 USD, multiplied by proportional number of houses sprayed per district analyzed
2012 2013 2014 2015
IRS IRS IRS IRS
District AI1
Coverage
Estimate2
LLINs
Distributed3 SMC4 AI1
Coverage
Estimate2
LLINs
Distributed3 SMC4 AI1
Coverage
Estimate2
LLINs
Distributed3 SMC4 AI1
Coverage
Estimate2
LLINs
Distributed3 SMC4
Barouéli CA 98% Universal - CA 98% ANC/EPI - OP 96% ANC/EPI - OP 98% Universal 86%
Bla CA 99% Universal - CA 98% ANC/EPI - OP 98% ANC/EPI 104% none - Universal 98%
Macina none - Universal - none - ANC/EPI - none - ANC/EPI - none - Universal 82%
Segou none - Universal - none - ANC/EPI - none - ANC/EPI - none - Universal 82%
Niono none - Universal - none - ANC/EPI - none - ANC/EPI - none - Universal 68%
San none - Universal - none - ANC/EPI 94% none - ANC/EPI 102% none - Universal Unknown
Tominian none - Universal - none - ANC/EPI - none - ANC/EPI - none - Universal 96%
The widespread adoption of new products for indoor residual spraying (IRS) is
challenged by concerns about increased cost as well as gaps in the evidence
needed to evaluate their public health impact and cost-effectiveness across various
malaria transmission settings. To provide evidence to address this gap, we present
a retrospective, observational analysis of the epidemiological and entomological
impact of IRS with two different non-pyrethroid insecticides using routine indicators
of malaria transmission in the Ségou Region of Mali.