Malaria epidemiology and stratification of incidence in the malaria elimination setting in Harari Region, Eastern Ethiopia

Abstract Background Ethiopia has shown notable progress in reducing the burden of malaria over the past two decades. Because of this progress, the country has shifted efforts from control to elimination of malaria. This study was conducted to analyse the malaria epidemiology and stratification of incidence in the malaria elimination setting in eastern Ethiopia. Methods A retrospective study was conducted to analyse the epidemiology of malaria by reviewing the district health office data from 2013 to 2019 in Harari Region. In addition, three years of sub-district level malaria data were used to stratify the malaria transmission intensity. Malaria interventions (Long-lasting insecticidal nets [LLIN] and indoor residual spraying [IRS]) employed were reviewed to analyse the intervention coverage at the Regional level. Descriptive statistics were used to show the malaria transmission in terms of years, season and species of the malaria parasite. Incidence rate per 1000 population and death rate per 1 000 000 population at risk were computed using the total population of each year. Results In the Harari Region, malaria incidence showed a more pronounced declining trend from 2017 to 2019. Plasmodium falciparum, P. vivax and mixed infections accounted for 69.2%, 30.6% and 0.2% of the cases, respectively. There was an increment in malaria intervention coverage and improved malaria diagnosis. In the year 2019 the coverage of LLIN and IRS in the Region were 93.4% and 85.1% respectively. The annual malaria incidence rate dropped from 42.9 cases per 1000 population in 2013 to 6.7 cases per 1000 population in 2019. Malaria-related deaths decreased from 4.7 deaths per 1 000 000 people annually in 2013 to zero, and there have been no deaths reported since 2015. The malaria risk appears to be heterogeneous and varies between districts. A higher number of malaria cases were recorded in Erer and Jenella districts, which constitute 62% of the cases in the Region. According to the sub-district level malaria stratification, there was shrinkage in the malaria transmission map and about 70% of the sub-districts have achieved elimination targets. Conclusions In the Harari Region, malaria morbidity and mortality have been significantly declined. Thus, if this achievement is sustained and scaling-up of the existing malaria prevention and control strategies by focusing on those populations living in the higher malaria transmission districts and sub-districts, planning of malaria elimination from the study area might be feasible.

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A Bayesian spatio-temporal analysis of malaria in the Greater Accra Region of Ghana from 2015 to 2019.

10.21203/rs.3.rs-143819/v2 ◽

2021 ◽

Author(s):

Elorm Donkor ◽

Matthew Kelly ◽

Cecilia Eliason ◽

Charles Amotoh ◽

Darren Gray ◽

...

Keyword(s):

Malaria Transmission ◽

Incidence Rate ◽

Malaria Control ◽

Malaria Incidence ◽

Climatic Variables ◽

Maximum Temperature ◽

District Health ◽

South Central ◽

Malaria Incidence Rate ◽

Greater Accra Region

Abstract Efforts towards malaria control in Ghana have had positive impacts. However, these efforts need to be locally tailored to further accelerate progress. The aim of this study was to examine the climatic drivers of malaria transmission in the Greater Accra Region and identify inter-district variation of malaria burden. Monthly malaria cases for the Greater Accra Region were obtained from the Ghanaian District Health Information and Management System. Malaria cases were decomposed using the seasonal-trend decomposition, based on locally weighted regression to analyse the seasonality. A Poisson regression model with a conditional autoregressive prior structure was used to quantify associations between climatic variables and malaria risk, and spatial dependence. Posterior parameters were estimated using Bayesian Markov chain Monte Carlo simulation with Gibbs sampling. A total of 1,105,370 malaria cases was recorded in the region from 2015–2019. The overall malaria incidence rate for the region was approximately 1 per 1,000,000 population. Malaria transmission was highly seasonal with an irregular inter-annual pattern. Malaria incidence was found to increase by 0.1% (95% credible interval [CrI]: 0.02–0.16%) for a 1°C rise in monthly maximum temperature lagged at 6 months and 0.2% (95% CrI: 0.5–0.3%) for 1°C rise in monthly minimum temperature without lag. No spatial dependency was observed after accounting for climatic variables. Only five districts located in the south-central part of the region had a malaria incidence rate that was lower than the regional average at > 95% probability level. The distribution of malaria cases was heterogeneous, seasonal and significantly associated with climatic variables. Targeted malaria control and prevention in high-risk districts at the appropriate time points could result in a significant reduction in malaria transmission in the Greater Accra Region.

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A Bayesian spatio-temporal analysis of malaria in the Greater Accra Region of Ghana from 2015 to 2019.

10.21203/rs.3.rs-143819/v1 ◽

2021 ◽

Author(s):

Elorm Donkor ◽

Matthew Kelly ◽

Cecilia Eliason ◽

Charles Amotoh ◽

Prof. Darren J Gray ◽

...

Keyword(s):

Malaria Transmission ◽

Incidence Rate ◽

Malaria Control ◽

Malaria Incidence ◽

Climatic Variables ◽

Maximum Temperature ◽

District Health ◽

South Central ◽

Malaria Incidence Rate ◽

Greater Accra Region

Abstract Background: Efforts towards malaria control in Ghana have had positive impacts. However, these efforts need to be locally tailored to further accelerate progress. The aim of this study was to examine the climatic drivers of malaria transmission in the Greater Accra Region and identify inter-district variation of malaria burden.Methodology: Monthly malaria cases for the Greater Accra Region were obtained from the Ghanaian District Health Information and Management System from 2015 to 2019. Malaria cases were decomposed using the seasonal-trend decomposition, based on locally weighted regression to analyze the seasonality. A Poisson regression model with a conditional autoregressive prior structure was used to quantify associations between climatic variables and malaria risk, and spatial dependence. Posterior parameters were estimated using Bayesian Markov chain Monte Carlo simulation with Gibbs sampling.Results: A total of 1,105,370 malaria cases was recorded in the region from 2015–2019. The overall malaria incidence rate for the region was approximately 1 per 1,000,000 population. Malaria transmission was highly seasonal with an irregular inter-annual pattern during the study period. Malaria incidence was found to increase by 0.1% (95% credible interval [CrI]: 0.02–0.16%) for a 1°C rise in monthly mean maximum temperature lagged at 6 months and 0.2% (95% CrI: 0.5–0.3%) for 1°C rise in monthly mean minimum temperature without lag. No spatial dependency was observed after accounting for climatic variables. Only five districts located in the south-central part of the region had a malaria incidence rate that was lower than the regional average at > 95% probability level.Conclusion: The distribution of malaria cases was heterogeneous, seasonal and significantly associated with climatic variables. Targeted malaria control and prevention in high-risk districts at the appropriate time points could result in a significant reduction in malaria transmission in the Greater Accra Region.

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Five Year Trend Analysis of Malaria Cases in Adama, Boset and Lume Districts of East Shawa, Oromia, Ethiopia

10.21203/rs.3.rs-151138/v1 ◽

2021 ◽

Author(s):

Temesgen File Hulluka ◽

Bayisa Chala Chala

Keyword(s):

Malaria Transmission ◽

Disease Burden ◽

Malaria Incidence ◽

Reduction Rate ◽

Malaria Prevalence ◽

Retrospective Data ◽

Age Group ◽

Malaria Epidemiology ◽

Malaria Indicator Survey ◽

Regional State

Abstract BackgroundMalaria is an infectious disease caused by Plasmodium parasites. Of the five human malaria parasites Plasmodium falciparum and Plasmodium vivax are the two co-endemic predominant and widely distributed species in Ethiopia greatly affecting public health and socio-economic development. Even though enormous effort have been made countrywide to reduce the disease burden little has been reported about trends of malaria transmission in the several localities of malarious areas like East Shawa Zone of Oromia Regional State, Ethiopia. Thus, the present study was aimed at assessing five- year (2016-2020) trends of malaria transmission at Adama, Boset and Lume districts of East Shawa Zone of Oromia Regional State, Ethiopia. MethodsRetrospective data were collected from the central surveillance of East Shawa Zone Health Office. The data collected was analyzed from September 2020 to December 2020 to examine trends of malaria epidemiology in three malarious districts in the Zone. The result shows, although a remarkable decrease in slide positivity rate (SPR) from (47.8 to 7.9%) and prevalence rate (6 to 1%) in the area, a recent slight increase of malaria SPR and prevalence was observed. Male individuals, particularly the productive section of the society (fifteen years and above age group) were more infected (60%), where falciparum, vivax and mixed malaria cases accounted for (53%), (41%), and (6%) respectively. Conclusion and Recommendations: Although reduction of malaria incidence was recorded in the study area, and higher malaria prevalence compared to the report of the national malaria indicator survey and inconsistency of the reduction rate noted in the study area demands due attention in the sector.

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Trends in malaria cases and stratification of malaria incidence in the malaria elimination setting, Harari Region, Eastern Ethiopia

10.21203/rs.3.rs-34668/v1 ◽

2020 ◽

Author(s):

Endashaw Esayas ◽

Asefa Tufa ◽

Fekadu Massebo ◽

Abdulhamid Ahemed ◽

Ibssa Ibrahim ◽

...

Keyword(s):

Malaria Elimination ◽

Prevention And Control ◽

Malaria Incidence ◽

Control Strategies ◽

Epidemiological Data ◽

Malaria Prevention ◽

Scaling Up ◽

Malaria Risk ◽

Eastern Ethiopia ◽

And Control

Abstract Abstract Background: Ethiopia has shown a notable progress in reducing the burden of malaria over the last two decades. Based on the progress, the country shifted from control to elimination of malaria. This study was conducted to analyse trends in malaria cases and stratification of malaria incidence in the malaria elimination setting in eastern Ethiopia. Methods: A retrospective malaria data recorded from 2013 to 2019 were reviewed from Harari Region, eastern Ethiopia. In addition, three years malaria data were used to assess the sub-district ( kebele ) level stratification of malaria incidence. Results: A total of 44,882 (46.9%) malaria cases were detected from 95,629 malaria-suspected outpatient diagnosed in Harari Region from 2013 to 2019. Of these, 41,046 were confirmed malaria cases (microscopically and rapid diagnostic test) while 3,836 were reported as clinical cases. In the region, malaria trend was fluctuating year to year, the high peak was reported in 2016 but malaria cases showed decreasing trend in number of malaria cases from 2017 to 2019. Plasmodium falciparum , P. vivax and mixed infections were accounted for 69.2%, 30.6% and 0.2% of the cases, respectively. The malaria risk appears to be heterogeneous and varies between districts, higher number of malaria cases were recorded in Jenella, Erer and Amir Nur districts, and about 80% of the cases were from these districts. According to the latest (2019) sub-district ( kebele ) level epidemiological data of malaria stratification, 8.3% of the sub-districts in the Harari region reported no malaria and a majority (61.1%) of sub-districts reported fewer than five cases per thousand population. Furthermore, there were no high malaria strata in the Region. The highest peak of malaria cases in the Region was reported from September to November followed by from April to May. Conclusions: In the Harari Region, the retrospective malaria data showed a significant declining trend. Thus, if this achievement is sustained and scaling-up of the existing malaria prevention and control strategies by focusing on those populations living in the higher malaria transmission districts and sub-districts, planning of malaria elimination from the study area might be feasible. Key words: Elimination, Harari region, Ethiopia, Incidence, Malaria, Sub-district, Stratification

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Demographic and health community-based surveys to inform a malaria elimination project in Magude district, southern Mozambique

BMJ Open ◽

10.1136/bmjopen-2019-033985 ◽

2020 ◽

Vol 10 (5) ◽

pp. e033985 ◽

Cited By ~ 3

Author(s):

Beatriz Galatas ◽

Ariel Nhacolo ◽

Helena Marti ◽

Humberto Munguambe ◽

Edgar Jamise ◽

...

Keyword(s):

Malaria Elimination ◽

Formal Education ◽

Health Centre ◽

Indoor Residual Spraying ◽

Healthcare Services ◽

Malaria Vector Control ◽

Economic Activities ◽

District Health ◽

Inpatient Ward ◽

Registration Number

ObjectivesA Demographic and Health Platform was established in Magude in 2015, prior to the deployment of a project aiming to evaluate the feasibility of malaria elimination in southern Mozambique, named the Magude project. This platform aimed to inform the design, implementation and evaluation of the Magude project, through the identification of households and population; and the collection of demographic, health and malaria information.SettingMagude is a rural district of southern Mozambique which borders South Africa. It has nine peripheral health facilities and one referral health centre with an inpatient ward.InterventionA baseline census enumerated and geolocated all the households, and their resident and non-resident members, collecting demographic and socio-economic information, and data on the coverage and usage of malaria control tools. Inpatient and outpatient data during the 5 years (2010 to 2014) before the survey were obtained from the district health authorities. The demographic platform was updated in 2016.ResultsThe baseline census conducted in 2015 reported 48 448 (92.1%) residents and 4133 (7.9%) non-residents, and 10 965 households. Magude’s population is predominantly young, half of the population has no formal education and the main economic activities are agriculture and fishing. Houses are mainly built with traditional non-durable materials and have poor sanitation facilities. Between 2010 and 2014, malaria was the most common cause of all-age inpatient discharges (representing 20% to 40% of all discharges), followed by HIV (12% to 22%) and anaemia (12% to 15%). In early 2015, all-age bed-net usage was between 21.8% and 27.1% and the reported coverage of indoor residual spraying varied across the district between 30.7% and 79%.ConclusionThis study revealed that Magude has limited socio-economic conditions, poor access to healthcare services and low coverage of malaria vector control interventions. Thus, Magude represented an area where it is most pressing to demonstrate the feasibility of malaria elimination.Trial registration numberNCT02914145; Pre-results.

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Malaria incidence and mortality in Zimbabwe during the COVID-19 pandemic: analysis of routine surveillance data

Malaria Journal ◽

10.1186/s12936-021-03770-7 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Samuel Gavi ◽

Oscar Tapera ◽

Joseph Mberikunashe ◽

Mufaro Kanyangarara

Keyword(s):

Health Services ◽

Malaria Incidence ◽

Indoor Residual Spraying ◽

Population Data ◽

District Level ◽

Mitigation Measures ◽

Spatial And Temporal Variation ◽

Health Management Information System ◽

Unique Challenge ◽

Incidence And Mortality

Abstract Background The coronavirus disease 2019 (COVID-19) pandemic has posed a unique challenge to health care systems globally. To curb COVID-19 transmission, mitigation measures such as travel restrictions, border closures, curfews, lockdowns, and social distancing have been implemented. However, these measures may directly and indirectly affect the delivery and utilization of essential health services, including malaria services. The suspension of indoor residual spraying (IRS) and insecticide-treated net (ITN) distribution, shortages of malaria commodities, and reduced demand for health services have hindered the continued delivery of malaria services. The overall goal of this analysis was to describe the trends in malaria incidence and mortality in Zimbabwe prior to and during the pandemic to understand the consequences of COVID-19-related changes in the delivery and utilization of malaria services. Methods Monthly data on the number of malaria cases and deaths by district for the period January 2017 to June 2020 were obtained from the national health management information system (HMIS). District-level population data were obtained from the 2012 Census. Malaria incidence per 1000 population and malaria deaths per 100,000 population were calculated for 2017, 2018, 2019, and 2020 and mapped to describe the spatial and temporal variation of malaria at the district level. Results Compared to the same period in 2017, 2018 and 2019, there was an excess of over 30,000 malaria cases from January to June 2020. The number of malaria deaths recorded in January to June 2020 exceeded the annual totals for 2018 and 2019. District level maps indicated that areas outside high malaria burden provinces experienced higher than expected malaria incidence and mortality, suggesting potential outbreaks. Conclusions The observed surge in malaria cases and deaths in January to June 2020 coincided with the onset of COVID-19 in Zimbabwe. While further research is needed to explore possible explanations for the observed trends, prioritizing the continuity of essential malaria services amid the COVID-19 pandemic remains crucial.

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Effects of rainfall, temperature and topography on malaria incidence in elimination targeted district of Ethiopia

Malaria Journal ◽

10.1186/s12936-021-03641-1 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Desalegn Dabaro ◽

Zewdie Birhanu ◽

Abiyot Negash ◽

Dawit Hawaria ◽

Delenasaw Yewhalaw

Keyword(s):

Regression Model ◽

Malaria Transmission ◽

Malaria Elimination ◽

Meteorological Factors ◽

Malaria Incidence ◽

Meteorological Variables ◽

Maximum Temperature ◽

Negative Binomial Regression Model ◽

Regional State ◽

Cross Correlation Analysis

Abstract Background Climate and environmental factors could be one of the primary factors that drive malaria transmission and it remains to challenge the malaria elimination efforts. Hence, this study was aimed to evaluate the effects of meteorological factors and topography on the incidence of malaria in the Boricha district in Sidama regional state of Ethiopia. Methods Malaria morbidity data recorded from 2010 to 2017 were obtained from all public health facilities of Boricha District in the Sidama regional state of Ethiopia. The monthly malaria cases, rainfall, and temperature (minimum, maximum, and average) were used to fit the ARIMA model to compute the malaria transmission dynamics and also to forecast future incidence. The effects of the meteorological variables and altitude were assessed with a negative binomial regression model using R version 4.0.0. Cross-correlation analysis was employed to compute the delayed effects of meteorological variables on malaria incidence. Results Temperature, rainfall, and elevation were the major determinants of malaria incidence in the study area. A regression model of previous monthly rainfall at lag 0 and Lag 2, monthly mean maximum temperature at lag 2 and Lag 3, and monthly mean minimum temperature at lag 3 were found as the best prediction model for monthly malaria incidence. Malaria cases at 1801–1900 m above sea level were 1.48 times more likely to occur than elevation ≥ 2000 m. Conclusions Meteorological factors and altitude were the major drivers of malaria incidence in the study area. Thus, evidence-based interventions tailored to each determinant are required to achieve the malaria elimination target of the country.

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Evaluating the Efficacy, Impact and Feasibility of Community-based House Screening as a Complementary Malaria Control Intervention in Southern Africa: a Study Protocol for a Household Randomized Trial.

10.21203/rs.3.rs-458248/v1 ◽

2021 ◽

Author(s):

Peter Onyango Sangoro ◽

Ulrike Fillinger ◽

Kochelani Saili ◽

Theresia Estomih Nkya ◽

Rose Marubu ◽

...

Keyword(s):

Vector Control ◽

Malaria Transmission ◽

Malaria Control ◽

Malaria Incidence ◽

Indoor Residual Spraying ◽

Clinical Malaria ◽

Sub Saharan Africa ◽

Substantial Impact ◽

Transmission Season ◽

The Impact

Abstract Background: Concerted effort to control malaria has had a substantial impact on transmission of the disease in the past two decades. In areas where reduced malaria transmission is being sustained through insecticide-based vector control interventions, primarily long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), non-insecticidal complementary tools will likely be needed to push towards malaria elimination. Once interruption in local disease transmission is achieved, insecticide-based measures can be scaled down gradually and eventually phased out, saving on costs of sustaining control programmes and mitigating any unintended negative health and environmental impacts posed by insecticides. These non-insecticidal methods could eventually replace insecticidal methods of vector control. House screening, a non-insecticidal method, has a long history in malaria control, but is still not widely adopted in sub-Saharan Africa. This study aims to add to the evidence-base for this intervention in low transmission settings by assessing the efficacy, impact and feasibility of house screening in areas where LLINs are conventionally used for malaria control. Methods: A two-armed, household randomized clinical trial will be conducted in Mozambique, Zambia and Zimbabwe to evaluate whether combined use of house screens and LLINs affords better protection against clinical malaria in children between 6 months and 13 years compared to the sole use of LLINs. Eight hundred households will be enrolled in each study area, where 400 households will be randomly assigned the intervention, house screening and LLINs while the control households will be provided with LLINs only. Clinical malaria incidence will be estimated by actively following up one child from each household for 6 months over the malaria transmission season. Cross-sectional parasite prevalence will be estimated by testing all participating children for malaria parasites at the beginning and end of each transmission season using rapid diagnostic tests.CDC light traps and pyrethrum spray catches (PSC) will be used to sample adult mosquitoes and evaluate the impact of house screening on indoor mosquito density, species distribution and sporozoite rates.Discussion: This study will contribute epidemiological data on the impact of house screening on malaria transmission and assess the feasibility of its implementation on a programmatic scale. Trial registration: This trial was retrospectively registered on 11th August 2020. Registration number PACTR202008524310568.

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Retrospective and cross-sectional study on the prevalence of malaria in selected areas under elimination program in Dembiya district, North-western Ethiopia

10.21203/rs.3.rs-376655/v1 ◽

2021 ◽

Author(s):

Mihretu Tarekegn ◽

Habte Tekie ◽

Sisay Dugassa ◽

Yitbarek Wolde-hawariat

Keyword(s):

Malaria Transmission ◽

Malaria Elimination ◽

Indoor Residual Spraying ◽

Public Health Problem ◽

Malaria Prevention ◽

Cross Sectional Study ◽

Malaria Prevalence ◽

Northwest Ethiopia ◽

Malaria Parasites ◽

Cross Sectional

Abstract Background: Ethiopia embarked on combating malaria with an aim to eliminate malaria from low transmission districts by 2030. This involves malaria vector interventions by implementing mainly indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) against endophilic and endophagic female Anopheles mosquitoes. Limited published reports are available about the status of malaria in areas under malaria elimination program in Ethiopia. This study intended to assess the prevalence of malaria in selected areas with a long history of implementing malaria prevention and elimination strategies. Methods: A cross-sectional parasitological survey was conducted in two selected malaria endemic areas in Dembiya District, Northwest Ethiopia. Thin and thick blood smears collected from 735 randomly selected individuals were microscopically examined for malaria parasites. Six years retrospective malaria data was also collected from the medical records of the health centres. Structured questionnaires were prepared to collect information about the socio-economic data of the population. The data were analysed using SPSS version 20 and p ≤0.05 were considered statistically significant. Results: The six-year retrospective malaria prevalence trend indicates an overall malaria prevalence of 22.4%, out of which Plasmodium falciparum was the dominant species. From a total of 735 slides examined for the presence of malaria parasites, 3.5% (n=26) were positive for malaria parasites, in which P. falciparum was more prevalent (n=17; 2.3%), P. vivax (n=5; 0.7%), and mixed infections (n=4; 0.5%). Males were 2.6 times more likely to be infected with malaria than females (AOR = 2.6; 95% CI: 1.0, 6.4), and individuals with frequent outdoor activity were 16.4 times more vulnerable than individuals with limited outdoor activities (AOR= 16.4, 95% CI: 1.8, 147.9). Furthermore, awareness about malaria transmission was significantly associated with the prevalence of malaria.Conclusions: Malaria is still a public health problem in Dembiya district irrespective of the past and existing vector control interventions. A malaria elimination plan might not be successful unless other alternative intervention tools targeting outdoor malaria transmission are included. For this, continuous monitoring of vectors’ susceptibility, density, and behaviour is very important in such areas.

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Incremental impact on malaria incidence following indoor residual spraying in a highly endemic area with high standard ITN access in Mozambique: results from a cluster‐randomized study

Malaria Journal ◽

10.1186/s12936-021-03611-7 ◽

2021 ◽

Vol 20 (1) ◽

Cited By ~ 1

Author(s):

Carlos Chaccour ◽

Rose Zulliger ◽

Joe Wagman ◽

Aina Casellas ◽

Amilcar Nacima ◽

...

Keyword(s):

At Risk ◽

Incidence Rate ◽

Endemic Area ◽

Malaria Incidence ◽

Indoor Residual Spraying ◽

Passive Surveillance ◽

Children Under Five ◽

Under Five ◽

Pirimiphos Methyl ◽

Cluster Randomized

Abstract Background Attaining the goal of reducing the global malaria burden is threatened by recent setbacks in maintaining the effectiveness of vector control interventions partly due to the emergence of pyrethroid resistant vectors. One potential strategy to address these setbacks could be combining indoor residual spraying (IRS) with non-pyrethroids and standard insecticide-treated nets (ITNs). This study aimed to provide evidence on the incremental epidemiological benefit of using third-generation IRS product in a highly endemic area with high ITN ownership. Methods A cluster-randomized, open-label, parallel-arms, superiority trial was conducted in the Mopeia district in Zambezia, Mozambique from 2016 to 2018. The district had received mass distribution of alphacypermethrin ITNs two years before the trial and again mid-way. 86 clusters were defined, stratified and randomized to receive or not receive IRS with pirimiphos-methyl (Actellic®300 CS). Efficacy of adding IRS was assessed through malaria incidence in a cohort of children under five followed prospectively for two years, enhanced passive surveillance at health facilities and by community health workers, and yearly cross-sectional surveys at the peak of the transmission season. Findings A total of 1536 children were enrolled in the cohort. Children in the IRS arm experienced 4,801 cases (incidence rate of 3,532 per 10,000 children-month at risk) versus 5,758 cases in the no-IRS arm (incidence rate of 4,297 per 10,000 children-month at risk), resulting in a crude risk reduction of 18% and an incidence risk ratio of 0.82 (95% CI 0.79–0.86, p-value < 0.001). Facility and community passive surveillance showed a malaria incidence of 278 per 10,000 person-month in the IRS group (43,974 cases over 22 months) versus 358 (95% CI 355–360) per 10,000 person-month at risk in the no-IRS group (58,030 cases over 22 months), resulting in an incidence rate ratio of 0.65 (95% CI 0.60–0.71, p < 0.001). In the 2018 survey, prevalence in children under five in the IRS arm was significantly lower than in the no-IRS arm (OR 0.54, 95% CI, 0.31–0.92, p = 0.0241). Conclusion In a highly endemic area with high ITN access and emerging pyrethroid resistance, adding IRS with pirimiphos-methyl resulted in significant additional protection for children under five years of age. Trial registration: ClinicalTrials.gov identifier NCT02910934, registered 22 September 2016, https://clinicaltrials.gov/ct2/show/NCT02910934?term=NCT02910934&draw=2&rank=1.

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