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Standardizing estimates of the Plasmodium falciparum parasite rate

Abstract:
Background
The Plasmodium falciparum parasite rate (PfPR) is a commonly reported index of malaria transmission intensity. PfPR rises after birth to a plateau before declining in older children and adults. Studies of populations with different age ranges generally report average PfPR, so age is an important source of heterogeneity in reported PfPR data. This confounds simple comparisons of PfPR surveys conducted at different times or places.

Methods
Several algorithms for standardizing PfPR were developed using 21 studies that stratify in detail PfPR by age. An additional 121 studies were found that recorded PfPR from the same population over at least two different age ranges; these paired estimates were used to evaluate these algorithms. The best algorithm was judged to be the one that described most of the variance when converting the PfPR pairs from one age-range to another.

Results

The analysis suggests that the relationship between PfPR and age is predictable across the observed range of malaria endemicity. PfPR reaches a peak after about two years and remains fairly constant in older children until age ten before declining throughout adolescence and adulthood. The PfPR pairs were poorly correlated; using one to predict the other would explain only 5% of the total variance. By contrast, the PfPR predicted by the best algorithm explained 72% of the variance.

Conclusion
The PfPR in older children is useful for standardization because it has good biological, epidemiological and statistical properties. It is also historically consistent with the classical categories of hypoendemic, mesoendemic and hyperendemic malaria. This algorithm provides a reliable method for standardizing PfPR for the purposes of comparing studies and mapping malaria endemicity. The scripts for doing so are freely available to all.
Publication status:
Published
Peer review status:
Peer reviewed

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Files:
Publisher copy:
10.1186/1475-2875-6-131

Authors

More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Zoology
Research group:
Spatial Ecology and Epidemiology Group
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MSD
Department:
NDM
Sub department:
Tropical Medicine - KWTRP (Kenya)
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Zoology
Research group:
Spatial Ecology and Epidemiology Group
Role:
Author


More from this funder
Funder identifier:
https://ror.org/029chgv08
Funding agency for:
Snow, RW
Grant:
079080
Programme:
Principal Research Fellow
More from this funder
Funder identifier:
https://ror.org/029chgv08
Funding agency for:
Hay, SI
Grant:
079091
Programme:
Senior Research Fellowship
More from this funder
Funder identifier:
https://ror.org/029chgv08
Funding agency for:
Guerra, CA
Grant:
076951
More from this funder
Funder identifier:
https://ror.org/034thb936
Funding agency for:
Guerra, CA


Publisher:
BioMed Central
Journal:
Malaria Journal More from this journal
Volume:
6
Issue:
1
Article number:
131
Publication date:
2007-09-25
Acceptance date:
2007-09-25
Edition:
Publisher's version
DOI:
ISSN:
1475-2875


Language:
English
Keywords:
Subjects:
UUID:
uuid:af677b2d-f3f0-4d63-8ec2-ede280cd89e3
Local pid:
ora:2414
Deposit date:
2008-10-29
ARK identifier:

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