Reader technique as a source of variability in determining malaria parasite density by microscopy.
Journal Article (Journal Article)
BACKGROUND: Accurate identification and quantification of malaria parasites are critical for measuring clinical trial outcomes. Positive and negative diagnosis is usually sufficient for the assessment of therapeutic outcome, but vaccine or prophylactic drug trials require measuring density of infection as a primary endpoint. Microscopy is the most established and widely-used technique for quantifying parasite densities in the blood. METHODS: Results obtained by 24-27 expert malaria microscopists, who had independently read 895 slides from 35 donors, were analysed to understand how reader technique contributes to discrepancy in measurements of parasite density over a wide range of densities. RESULTS: Among these 35 donations, standard deviations ranged from 30% to 250% of the mean parasite density and the percent discrepancy was inversely correlated with the mean parasite density. The number of white blood cells indexed and whether parasites were counted in the thick film or thin film were shown to significantly contribute to discrepancy amongst microscopists. CONCLUSION: Errors in microscopy measurements are not widely appreciated or addressed but have serious consequences for efficacy trials, including possibly abandoning promising vaccine candidates.
Full Text
Duke Authors
Cited Authors
- O'Meara, WP; Barcus, M; Wongsrichanalai, C; Muth, S; Maguire, JD; Jordan, RG; Prescott, WR; McKenzie, FE
Published Date
- December 12, 2006
Published In
Volume / Issue
- 5 /
Start / End Page
- 118 -
PubMed ID
- 17164007
Pubmed Central ID
- PMC1712346
Electronic International Standard Serial Number (EISSN)
- 1475-2875
Digital Object Identifier (DOI)
- 10.1186/1475-2875-5-118
Language
- eng
Conference Location
- England