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Trop Med Int Health. 2018 Sep;23(9):980-991. doi: 10.1111/tmi.13124. Epub 2018 Jul 17.

Validity and reliability of methods to microscopically detect and quantify malaria parasitaemia.

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Division of Infectious Diseases and Tropical Medicine, Department of Medicine I, Medical University of Vienna, Vienna, Austria.
Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.
Institut für Tropenmedizin, German Centre for Infection Research, partner site Tübingen, Universität Tübingen, Tübingen, Germany.
Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine & I. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Malaria Clinical and Operational Research Unit, Melen Hospital, Département de Parasitology, Université des Sciences de la Santé Gabon, Libreville, Gabon.
German Centre for Infection Research (DZIF), partner site Hamburg-Luebeck-Borstel, Hamburg, Germany.



The recommended microscopy method by WHO to quantify malaria parasitaemia yields inaccurate results when individual leucocyte (WBC) counts deviate from 8000 leucocytes/μl. A method avoiding WBC count assumptions is the Lambaréné method (LAMBA). Thus, this study compared validity and reliability of the LAMBA and the WHO method.


Three methods for counting parasitaemia were applied in parallel in a blinded assessment: the LAMBA, the WHO method using a standard factor of 8000 leucocytes/μl ['simple WHO method' (sWHO)] and the WHO method using measured WBC counts ['accurate WHO method' (aWHO)]. Validity was assessed by comparing LAMBA and sWHO to the gold standard measurement of aWHO. Reliability was ascertained by computation of intraclass correlation coefficients (ICCs).


787 malaria-positive thick smears were analysed. Parasitaemia as determined by LAMBA and sWHO increasingly deviated from aWHO the more patients' WBCs diverged from 8000/μl. Equations of linear regression models assessing method deviation in percent from gold standard as function of WBC count were y = -0.00608x (95% CI -0.00693 to -0.00524) + 47.8 for LAMBA and y = -0.0125x (95% CI -0.01253 to -0.01247) + 100.1 for sWHO. Comparison of regression slopes showed that the deviation was twice as high for sWHO as for LAMBA (P < 0.001). ICCs were excellent (>90%) for both methods.


The LAMBA has higher validity than the sWHO and may therefore be preferable in resource-limited settings without access to routine WBC-evaluation.


Paludisme; diagnostics; fiabilité; leucocytes; light microscopy; malaria; methods; microscopie optique; méthodes; plasmodium; prévision; reliability; validity; validité

[Indexed for MEDLINE]

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