Assembling a global database of malaria parasite prevalence for the Malaria Atlas Project

Abstract

Background: Open access to databases of information generated by the research community can synergize individual efforts and are epitomized by the genome mapping projects. Open source models for outputs of scientific research funded by tax-payers and charities are becoming the norm. This has yet to be extended to malaria epidemiology and control.

Methods: The exhaustive searches and assembly process for a global database of malaria parasite prevalence as part of the Malaria Atlas Project (MAP) are described. The different data sources visited and how productive these were in terms of availability of parasite rate (PR) data are presented, followed by a description of the methods used to assemble a relational database and an associated geographic information system. The challenges facing spatial data assembly from varied sources are described in an effort to help inform similar future applications.

Results: At the time of writing, the MAP database held 3,351 spatially independent PR estimates from community surveys conducted since 1985. These include 3,036 Plasmodium falciparum and 1,347 Plasmodium vivax estimates in 74 countries derived from 671 primary sources. More than half of these data represent malaria prevalence after the year 2000.

Conclusion: This database will help refine maps of the global spatial limits of malaria and be the foundation for the development of global malaria endemicity models as part of MAP. A widespread application of these maps is envisaged. The data compiled and the products generated by MAP are planned to be released in June 2009 to facilitate a more informed approach to global malaria control.

Figure 1

Flow chart for the geo-positioning of PR data points.

Figure 2

The global distribution of P. falciparum PR points from the MAP database. MECs are coloured by the WHO regional office to which they belong. Refer to the legend of Table 3 for abbreviations. The blue dots indicate presence (PR > 0) and white dots absence (PR = 0).

Figure 3

The global distribution of P. vivax PR points from the MAP database. MECs are coloured by the WHO regional office to which they belong. Refer to the legend of Table 3 for abbreviations. The blue dots indicate presence (PR > 0) and white dots absence (PR = 0).

Figure 4

The number of PR records retrieved by country.

Figure 5

The number of PR records retrieved by malarious area by country. The scale expresses the number of PR surveys for every 1,000 km² of area malarious. The latter is as determined by the spatial limits of malaria in each country [36, 37]. Mayotte, Sao Tome and Principe, Gambia, Vanuatu and Cape Verde were excluded for visualization purposes because their very small malarious areas biased these calculations. These countries ranked top in the order listed.