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Sub-National Targeting of Seasonal Malaria Chemoprevention in the Sahelian Countries of the Nouakchott Initiative.

Noor AM, Kibuchi E, Mitto B, Coulibaly D, Doumbo OK, Snow RW - PLoS ONE (2015)

Bottom Line: In 2015 alone, an estimated 49-72 million SP tablets and 148-217 million AQ tablets will be needed to cover all or rural children respectively under the different scenarios of upper age limits.Our proposed framework provides a standardised approach to support targeting and scale up of SMC by the countries of the Nouakchott Initiative.Our analysis suggests that the vast majority of the population in this region are likely to benefit from SMC and substantial resources will be required to reach universal coverage each year.

View Article: PubMed Central - PubMed

Affiliation: INFORM (Information for Malaria - www.inform-malaria.org), Spatial Health Metrics Group, Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya; Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom.

ABSTRACT

Background: Seasonal malaria chemoprevention (SMC) has been shown to be highly efficacious against clinical malaria in areas where transmission is acutely seasonal. SMC targeting depends on a complex interplay of climate, malaria transmission and population distribution. In this study a spatial decision support framework was developed to identify health districts suitable for the targeting of SMC across seven Sahelian countries and northern states of Nigeria that are members of the Nouakchott Initiative.

Methods: A spatially explicit decision support framework that links information on seasonality, age-structured population, urbanization, malaria endemicity and the length of transmission season was developed to inform SMC targeting in health districts. Thresholds of seasonality, population and receptive risks were defined to delineate SMC suitable health districts and define the age range of children for targeting. Numbers of children were then computed for the period 2015-2020 in SMC districts. For 2015, this was combined with maps of length of malaria transmission seasons and WHO recommended treatment regimen to quantify the number of tablets required across the SMC health districts.

Results: A total of 597 Sahelian health districts were mapped, out of which 478 (80.1%) were considered suitable for SMC based on seasonality and endemicity thresholds. These districts had an estimated 119.8 million (85%) of the total population in 2015. In the six years from 2015-2020, it is estimated that a total of 158 million children 3m to <5 years, 121 million of whom were in rural areas, will need SMC to achieve universal coverage in the Sahel. If the upper age limit of SMC targeted children was increased to <10 years in low transmission districts, a total 177 million overall, of whom 135 million were rural children, will require chemoprevention in 2015-2020. In 2015 alone, an estimated 49-72 million SP tablets and 148-217 million AQ tablets will be needed to cover all or rural children respectively under the different scenarios of upper age limits.

Conclusions: Our proposed framework provides a standardised approach to support targeting and scale up of SMC by the countries of the Nouakchott Initiative. Our analysis suggests that the vast majority of the population in this region are likely to benefit from SMC and substantial resources will be required to reach universal coverage each year.

No MeSH data available.


Related in: MedlinePlus

Map of Sahelian health districts (n = 597) showing A) the distribution of population in 2015 at 1 x 1 km spatial resolution [source: www.worldpop.org]; B) areas (orange) where 60% or more of the annual total rainfall occurs in any three consecutive months; C) the median number of malaria transmission months in an average year in seasonal health districts [source: Grover-Kopec et al 2006; D) population adjusted estimates of P. falciparum parasite rate standardized to the ages 2 to 10 years (PAPfPR2-10) for the year 2000 [source: Noor et al 2014].In Nigeria, health districts from the states of Bauchi, Borno, Jigawa, Kano, Katsina, Kebi, Sokoto, Yobe and Zamfara were included in the analysis.
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pone.0136919.g002: Map of Sahelian health districts (n = 597) showing A) the distribution of population in 2015 at 1 x 1 km spatial resolution [source: www.worldpop.org]; B) areas (orange) where 60% or more of the annual total rainfall occurs in any three consecutive months; C) the median number of malaria transmission months in an average year in seasonal health districts [source: Grover-Kopec et al 2006; D) population adjusted estimates of P. falciparum parasite rate standardized to the ages 2 to 10 years (PAPfPR2-10) for the year 2000 [source: Noor et al 2014].In Nigeria, health districts from the states of Bauchi, Borno, Jigawa, Kano, Katsina, Kebi, Sokoto, Yobe and Zamfara were included in the analysis.

Mentions: Fig 2A shows population distribution map at 1 × 1 km spatial resolution, on which the boundaries of the updated health districts overlay, demonstrating an increasing density of population north to south at increasing distance from the Sahara Desert. Areas that have acute malaria seasonality, however, were concentrated in the middle Sahelian belt and excluded several of the extremely arid northern districts and the humid districts in the Equatorial south (Fig 2B). Within the seasonal areas the number of months of transmission increased southwards with most districts having a median 3 of months (Fig 2C). Estimated receptive P. falciparum transmission intensity, as measured by PAPfPR2-10 in 2000 (Fig 2D), showed increasing rates north to south with almost all the districts in northern arid areas having infection rates of <5%.


Sub-National Targeting of Seasonal Malaria Chemoprevention in the Sahelian Countries of the Nouakchott Initiative.

Noor AM, Kibuchi E, Mitto B, Coulibaly D, Doumbo OK, Snow RW - PLoS ONE (2015)

Map of Sahelian health districts (n = 597) showing A) the distribution of population in 2015 at 1 x 1 km spatial resolution [source: www.worldpop.org]; B) areas (orange) where 60% or more of the annual total rainfall occurs in any three consecutive months; C) the median number of malaria transmission months in an average year in seasonal health districts [source: Grover-Kopec et al 2006; D) population adjusted estimates of P. falciparum parasite rate standardized to the ages 2 to 10 years (PAPfPR2-10) for the year 2000 [source: Noor et al 2014].In Nigeria, health districts from the states of Bauchi, Borno, Jigawa, Kano, Katsina, Kebi, Sokoto, Yobe and Zamfara were included in the analysis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4554730&req=5

pone.0136919.g002: Map of Sahelian health districts (n = 597) showing A) the distribution of population in 2015 at 1 x 1 km spatial resolution [source: www.worldpop.org]; B) areas (orange) where 60% or more of the annual total rainfall occurs in any three consecutive months; C) the median number of malaria transmission months in an average year in seasonal health districts [source: Grover-Kopec et al 2006; D) population adjusted estimates of P. falciparum parasite rate standardized to the ages 2 to 10 years (PAPfPR2-10) for the year 2000 [source: Noor et al 2014].In Nigeria, health districts from the states of Bauchi, Borno, Jigawa, Kano, Katsina, Kebi, Sokoto, Yobe and Zamfara were included in the analysis.
Mentions: Fig 2A shows population distribution map at 1 × 1 km spatial resolution, on which the boundaries of the updated health districts overlay, demonstrating an increasing density of population north to south at increasing distance from the Sahara Desert. Areas that have acute malaria seasonality, however, were concentrated in the middle Sahelian belt and excluded several of the extremely arid northern districts and the humid districts in the Equatorial south (Fig 2B). Within the seasonal areas the number of months of transmission increased southwards with most districts having a median 3 of months (Fig 2C). Estimated receptive P. falciparum transmission intensity, as measured by PAPfPR2-10 in 2000 (Fig 2D), showed increasing rates north to south with almost all the districts in northern arid areas having infection rates of <5%.

Bottom Line: In 2015 alone, an estimated 49-72 million SP tablets and 148-217 million AQ tablets will be needed to cover all or rural children respectively under the different scenarios of upper age limits.Our proposed framework provides a standardised approach to support targeting and scale up of SMC by the countries of the Nouakchott Initiative.Our analysis suggests that the vast majority of the population in this region are likely to benefit from SMC and substantial resources will be required to reach universal coverage each year.

View Article: PubMed Central - PubMed

Affiliation: INFORM (Information for Malaria - www.inform-malaria.org), Spatial Health Metrics Group, Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya; Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom.

ABSTRACT

Background: Seasonal malaria chemoprevention (SMC) has been shown to be highly efficacious against clinical malaria in areas where transmission is acutely seasonal. SMC targeting depends on a complex interplay of climate, malaria transmission and population distribution. In this study a spatial decision support framework was developed to identify health districts suitable for the targeting of SMC across seven Sahelian countries and northern states of Nigeria that are members of the Nouakchott Initiative.

Methods: A spatially explicit decision support framework that links information on seasonality, age-structured population, urbanization, malaria endemicity and the length of transmission season was developed to inform SMC targeting in health districts. Thresholds of seasonality, population and receptive risks were defined to delineate SMC suitable health districts and define the age range of children for targeting. Numbers of children were then computed for the period 2015-2020 in SMC districts. For 2015, this was combined with maps of length of malaria transmission seasons and WHO recommended treatment regimen to quantify the number of tablets required across the SMC health districts.

Results: A total of 597 Sahelian health districts were mapped, out of which 478 (80.1%) were considered suitable for SMC based on seasonality and endemicity thresholds. These districts had an estimated 119.8 million (85%) of the total population in 2015. In the six years from 2015-2020, it is estimated that a total of 158 million children 3m to <5 years, 121 million of whom were in rural areas, will need SMC to achieve universal coverage in the Sahel. If the upper age limit of SMC targeted children was increased to <10 years in low transmission districts, a total 177 million overall, of whom 135 million were rural children, will require chemoprevention in 2015-2020. In 2015 alone, an estimated 49-72 million SP tablets and 148-217 million AQ tablets will be needed to cover all or rural children respectively under the different scenarios of upper age limits.

Conclusions: Our proposed framework provides a standardised approach to support targeting and scale up of SMC by the countries of the Nouakchott Initiative. Our analysis suggests that the vast majority of the population in this region are likely to benefit from SMC and substantial resources will be required to reach universal coverage each year.

No MeSH data available.


Related in: MedlinePlus