The spatial distribution of the Duffy negative phenotype map in 2010 globally

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This maps shows the proportion of the population predicted to be Duffy negative stratified into 12 classes of prevalence.

We are interested in Duffy negativity because Duffy negative individuals tend to be resistant to Plasmodium vivax malaria. The frequency of Duffy negativity in the population, therefore, modulates our estimates of the population at risk of Plasmodium vivax malaria. These estimates can be found using the Resource Browser.

Data from community surveys of both the Duffy genotype and phenotype were used in a Bayesian geostatistical model to generate predictions of the phenotype prevalence. The model generates a range of estimates at each location (a posterior distribution) and this map shows the median estimate for each posterior distribution. This approach allows us to assess the uncertainty in our predictions and the second map below shows the interquartile ranges of the posterior distributions.

You can find out more about our use of Bayesian model-based geostatistics here.

Tables of the mean estimates of Duffy negativity prevalence for each country can also be found on this site using the Resource Browser.


Tools used to create map & published version

Data Protocol [462.4 KB] (PDF)

Modelling Protocol [428.9 KB] (PDF)

Global surface in Binary Float format [873.5 KB] (None)

Global surface in GeoTiff format [595.6 KB] (None)

Howes, Rosalind E., Patil, Anand P., Piel, Frederic B., Nyangiri, Oscar A, Kabaria, Caroline W, Gething, Peter W., Zimmerman, Peter A., Barnadas, Celine, Beall, Cynthia M., Gebremedhin, Amha, Menard, Didier, Williams, Thomas N., Weatherall, David J., Hay, Simon I. (2011) The global distribution of the Duffy blood group. Nature Communications 2, Article number: 266.