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Mapping the receptivity of malaria risk to plan the future of control in Somalia.

Noor AM, Alegana VA, Patil AP, Moloney G, Borle M, Yusuf F, Amran J, Snow RW - BMJ Open (2012)

Bottom Line: Of these, 23% of the districts, home to 13% of the population, were under transmission of <1% PfPR(2-10).About 58% of the districts and 55% of the population were in the risk class of 1% to <5% PfPR(2-10).In contrast, the receptivity map estimated 65% of the districts and 69% of the population were under mesoendemic transmission (>10%-50% PfPR(2-10)) and the rest as hypoendemic.

View Article: PubMed Central - PubMed

Affiliation: Malaria Public Health and Epidemiology Group, Centre for Geographic Medicine Research-Coast, Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya.

ABSTRACT

Objectives: To measure the receptive risks of malaria in Somalia and compare decisions on intervention scale-up based on this map and the more widely used contemporary risk maps.

Design: Cross-sectional community Plasmodium falciparum parasite rate (PfPR) data for the period 2007-2010 corrected to a standard age range of 2 to <10 years (PfPR(2-10)) and used within a Bayesian space-time geostatistical framework to predict the contemporary (2010) mean PfPR(2-10) and the maximum annual mean PfPR(2-10) (receptive) from the highest predicted PfPR(2-10) value over the study period as an estimate of receptivity.

Setting: Randomly sampled communities in Somalia.

Participants: Randomly sampled individuals of all ages.

Main outcome measure: Cartographic descriptions of malaria receptivity and contemporary risks in Somalia at the district level.

Results: The contemporary annual PfPR(2-10) map estimated that all districts (n=74) and population (n=8.4 million) in Somalia were under hypoendemic transmission (≤10% PfPR(2-10)). Of these, 23% of the districts, home to 13% of the population, were under transmission of <1% PfPR(2-10). About 58% of the districts and 55% of the population were in the risk class of 1% to <5% PfPR(2-10). In contrast, the receptivity map estimated 65% of the districts and 69% of the population were under mesoendemic transmission (>10%-50% PfPR(2-10)) and the rest as hypoendemic.

Conclusion: Compared with maps of receptive risks, contemporary maps of transmission mask disparities of malaria risk necessary to prioritise and sustain future control. As malaria risk declines across Africa, efforts must be invested in measuring receptivity for efficient control planning.

No MeSH data available.


Related in: MedlinePlus

(A) Map of the posterior annual meanPfPR2–10 prediction to 2010(contemporary) at 1×1 km grid location in Somalia. (B) Map of themaximum mean PfPR2–10 prediction (receptive)at 1×1 km grid location as computed from the posterior annualmean PfPR2–10 prediction for each year from2007 to 2010. (C) Map of the coefficient of variation (the SD/the meanPfPR2–10 prediction) of the contemporaryprediction at 1×1 km grid location. (D) Map of the coefficient ofvariation at 1×1 km grid location of the receptive prediction.The thick black lines show the zone boundaries, the thin black lines show theregional boundaries and the thin grey lines show the district boundaries.Higher coefficient of variation of the predictions suggests higheruncertainties of the PfPR2–10 predictions.The scale bar for the continuous PfPR2–10ends at 50, which is the upper limit of mesoendemic transmission. The blueslines show the location of the Juba (lower) and Shabelle (upper) Rivers.
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fig2: (A) Map of the posterior annual meanPfPR2–10 prediction to 2010(contemporary) at 1×1 km grid location in Somalia. (B) Map of themaximum mean PfPR2–10 prediction (receptive)at 1×1 km grid location as computed from the posterior annualmean PfPR2–10 prediction for each year from2007 to 2010. (C) Map of the coefficient of variation (the SD/the meanPfPR2–10 prediction) of the contemporaryprediction at 1×1 km grid location. (D) Map of the coefficient ofvariation at 1×1 km grid location of the receptive prediction.The thick black lines show the zone boundaries, the thin black lines show theregional boundaries and the thin grey lines show the district boundaries.Higher coefficient of variation of the predictions suggests higheruncertainties of the PfPR2–10 predictions.The scale bar for the continuous PfPR2–10ends at 50, which is the upper limit of mesoendemic transmission. The blueslines show the location of the Juba (lower) and Shabelle (upper) Rivers.

Mentions: The continuous 2010 malaria endemicity map for SomaliaPfPR2–10 showed the majority of locations werepredicted to have parasite prevalence of <5% indicating largely hypoendemictransmission (figure 2A). The majority ofareas in North East and North West zones were predicted to be underPfPR2–10 <1%. In contrast, the maximumannual mean PfPR2–10 map showed a substantiallydifferent risk landscape, with the majority of the Central South zone havingPfPR2–10 of >10% and an a maximumpredicted mean of 38%, suggesting that peak malaria transmission in all of CentralSouth zone and southern parts of North East zone is mesoendemic (figure 2B). In the northern zones, maximum mean risks werepredicted to be predominantly between 5% and <10%PfPR2–10.


Mapping the receptivity of malaria risk to plan the future of control in Somalia.

Noor AM, Alegana VA, Patil AP, Moloney G, Borle M, Yusuf F, Amran J, Snow RW - BMJ Open (2012)

(A) Map of the posterior annual meanPfPR2–10 prediction to 2010(contemporary) at 1×1 km grid location in Somalia. (B) Map of themaximum mean PfPR2–10 prediction (receptive)at 1×1 km grid location as computed from the posterior annualmean PfPR2–10 prediction for each year from2007 to 2010. (C) Map of the coefficient of variation (the SD/the meanPfPR2–10 prediction) of the contemporaryprediction at 1×1 km grid location. (D) Map of the coefficient ofvariation at 1×1 km grid location of the receptive prediction.The thick black lines show the zone boundaries, the thin black lines show theregional boundaries and the thin grey lines show the district boundaries.Higher coefficient of variation of the predictions suggests higheruncertainties of the PfPR2–10 predictions.The scale bar for the continuous PfPR2–10ends at 50, which is the upper limit of mesoendemic transmission. The blueslines show the location of the Juba (lower) and Shabelle (upper) Rivers.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4400533&req=5

fig2: (A) Map of the posterior annual meanPfPR2–10 prediction to 2010(contemporary) at 1×1 km grid location in Somalia. (B) Map of themaximum mean PfPR2–10 prediction (receptive)at 1×1 km grid location as computed from the posterior annualmean PfPR2–10 prediction for each year from2007 to 2010. (C) Map of the coefficient of variation (the SD/the meanPfPR2–10 prediction) of the contemporaryprediction at 1×1 km grid location. (D) Map of the coefficient ofvariation at 1×1 km grid location of the receptive prediction.The thick black lines show the zone boundaries, the thin black lines show theregional boundaries and the thin grey lines show the district boundaries.Higher coefficient of variation of the predictions suggests higheruncertainties of the PfPR2–10 predictions.The scale bar for the continuous PfPR2–10ends at 50, which is the upper limit of mesoendemic transmission. The blueslines show the location of the Juba (lower) and Shabelle (upper) Rivers.
Mentions: The continuous 2010 malaria endemicity map for SomaliaPfPR2–10 showed the majority of locations werepredicted to have parasite prevalence of <5% indicating largely hypoendemictransmission (figure 2A). The majority ofareas in North East and North West zones were predicted to be underPfPR2–10 <1%. In contrast, the maximumannual mean PfPR2–10 map showed a substantiallydifferent risk landscape, with the majority of the Central South zone havingPfPR2–10 of >10% and an a maximumpredicted mean of 38%, suggesting that peak malaria transmission in all of CentralSouth zone and southern parts of North East zone is mesoendemic (figure 2B). In the northern zones, maximum mean risks werepredicted to be predominantly between 5% and <10%PfPR2–10.

Bottom Line: Of these, 23% of the districts, home to 13% of the population, were under transmission of <1% PfPR(2-10).About 58% of the districts and 55% of the population were in the risk class of 1% to <5% PfPR(2-10).In contrast, the receptivity map estimated 65% of the districts and 69% of the population were under mesoendemic transmission (>10%-50% PfPR(2-10)) and the rest as hypoendemic.

View Article: PubMed Central - PubMed

Affiliation: Malaria Public Health and Epidemiology Group, Centre for Geographic Medicine Research-Coast, Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya.

ABSTRACT

Objectives: To measure the receptive risks of malaria in Somalia and compare decisions on intervention scale-up based on this map and the more widely used contemporary risk maps.

Design: Cross-sectional community Plasmodium falciparum parasite rate (PfPR) data for the period 2007-2010 corrected to a standard age range of 2 to <10 years (PfPR(2-10)) and used within a Bayesian space-time geostatistical framework to predict the contemporary (2010) mean PfPR(2-10) and the maximum annual mean PfPR(2-10) (receptive) from the highest predicted PfPR(2-10) value over the study period as an estimate of receptivity.

Setting: Randomly sampled communities in Somalia.

Participants: Randomly sampled individuals of all ages.

Main outcome measure: Cartographic descriptions of malaria receptivity and contemporary risks in Somalia at the district level.

Results: The contemporary annual PfPR(2-10) map estimated that all districts (n=74) and population (n=8.4 million) in Somalia were under hypoendemic transmission (≤10% PfPR(2-10)). Of these, 23% of the districts, home to 13% of the population, were under transmission of <1% PfPR(2-10). About 58% of the districts and 55% of the population were in the risk class of 1% to <5% PfPR(2-10). In contrast, the receptivity map estimated 65% of the districts and 69% of the population were under mesoendemic transmission (>10%-50% PfPR(2-10)) and the rest as hypoendemic.

Conclusion: Compared with maps of receptive risks, contemporary maps of transmission mask disparities of malaria risk necessary to prioritise and sustain future control. As malaria risk declines across Africa, efforts must be invested in measuring receptivity for efficient control planning.

No MeSH data available.


Related in: MedlinePlus