PLoS ONE (Jan 2011)

Toward a surrogate marker of malaria exposure: modeling longitudinal antibody measurements under outbreak conditions.

  • Joseph J Campo,
  • Timothy J Whitman,
  • Daniel Freilich,
  • Timothy H Burgess,
  • Gregory J Martin,
  • Denise L Doolan

DOI
https://doi.org/10.1371/journal.pone.0021826
Journal volume & issue
Vol. 6, no. 7
p. e21826

Abstract

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BackgroundBiomarkers of exposure to Plasmodium falciparum would be a useful tool for the assessment of malaria burden and analysis of intervention and epidemiological studies. Antibodies to pre-erythrocytic antigens represent potential surrogates of exposure.Methods and findingsIn an outbreak cohort of U.S. Marines deployed to Liberia, we modeled pre- and post-deployment IgG against P. falciparum sporozoites by immunofluorescence antibody test, and both IgG and IgM against the P. falciparum circumsporozoite protein by enzyme-linked immunosorbant assay. Modeling seroconversion thresholds by a fixed ratio, linear regression or nonlinear regression produced sensitivity for identification of exposed U.S. Marines between 58-70% and specificities between 87-97%, compared with malaria-naïve U.S. volunteers. Exposure was predicted in 30-45% of the cohort.ConclusionEach of the three models tested has merits in different studies, but further development and validation in endemic populations is required. Overall, these models provide support for an antibody-based surrogate marker of exposure to malaria.