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Utility of the detection of Plasmodium parasites for the diagnosis of malaria in endemic areas

BACKGROUND: In populations where the prevalence of infection with Plasmodium parasites is high, blood tests that identify Plasmodium parasites in patients with fever may lead to false positive diagnosis of malaria-disease. We characterised the diminishing value of the parasite detection test as a fu...

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Autores principales: Perneger, Thomas V, Szeless, Thomas, Rougemont, André
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2006
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1475866/
https://www.ncbi.nlm.nih.gov/pubmed/16670024
http://dx.doi.org/10.1186/1471-2334-6-81
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author Perneger, Thomas V
Szeless, Thomas
Rougemont, André
author_facet Perneger, Thomas V
Szeless, Thomas
Rougemont, André
author_sort Perneger, Thomas V
collection PubMed
description BACKGROUND: In populations where the prevalence of infection with Plasmodium parasites is high, blood tests that identify Plasmodium parasites in patients with fever may lead to false positive diagnosis of malaria-disease. We characterised the diminishing value of the parasite detection test as a function of the prevalence of infection. METHODS: We computed the ability of the parasite detection test to identify malaria at various levels of prevalence (0% to 90%), assuming plausible estimates of sensitivity (95% and 85%) and specificity (99% and 95%) for the detection of parasites. In each situation, we computed likelihood ratios of malaria (or absence of malaria) for positive and negative parasite detection tests. Likelihood ratios were classified as clinically useful (≥ 10), intermediate (5–10), or unhelpful (<5). RESULTS: Likelihood ratios of positive tests were strongly related to the prevalence of infection in the general population: a positive test was unhelpful when the prevalence was 20% or more, and useful only when prevalence was 5% or less. The sensitivity and specificity of the test had little influence on these results. Likelihood ratios of negative tests were clinically useful when prevalence was 70% or less, but only for high levels of sensitivity (95%). If sensitivity was low (85%), the negative test was at best of intermediate utility, and was unhelpful if the prevalence of asymptomatic infection exceeded 30%. CONCLUSION: Identification of Plasmodium parasites supports a diagnosis of malaria only in areas where the prevalence of Plasmodium infection is low. Wherever this prevalence exceeds about 20%, a positive test is clinically unhelpful.
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spelling pubmed-14758662006-06-12 Utility of the detection of Plasmodium parasites for the diagnosis of malaria in endemic areas Perneger, Thomas V Szeless, Thomas Rougemont, André BMC Infect Dis Research Article BACKGROUND: In populations where the prevalence of infection with Plasmodium parasites is high, blood tests that identify Plasmodium parasites in patients with fever may lead to false positive diagnosis of malaria-disease. We characterised the diminishing value of the parasite detection test as a function of the prevalence of infection. METHODS: We computed the ability of the parasite detection test to identify malaria at various levels of prevalence (0% to 90%), assuming plausible estimates of sensitivity (95% and 85%) and specificity (99% and 95%) for the detection of parasites. In each situation, we computed likelihood ratios of malaria (or absence of malaria) for positive and negative parasite detection tests. Likelihood ratios were classified as clinically useful (≥ 10), intermediate (5–10), or unhelpful (<5). RESULTS: Likelihood ratios of positive tests were strongly related to the prevalence of infection in the general population: a positive test was unhelpful when the prevalence was 20% or more, and useful only when prevalence was 5% or less. The sensitivity and specificity of the test had little influence on these results. Likelihood ratios of negative tests were clinically useful when prevalence was 70% or less, but only for high levels of sensitivity (95%). If sensitivity was low (85%), the negative test was at best of intermediate utility, and was unhelpful if the prevalence of asymptomatic infection exceeded 30%. CONCLUSION: Identification of Plasmodium parasites supports a diagnosis of malaria only in areas where the prevalence of Plasmodium infection is low. Wherever this prevalence exceeds about 20%, a positive test is clinically unhelpful. BioMed Central 2006-05-02 /pmc/articles/PMC1475866/ /pubmed/16670024 http://dx.doi.org/10.1186/1471-2334-6-81 Text en Copyright © 2006 Perneger et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( (http://creativecommons.org/licenses/by/2.0) ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Article
Perneger, Thomas V
Szeless, Thomas
Rougemont, André
Utility of the detection of Plasmodium parasites for the diagnosis of malaria in endemic areas
title Utility of the detection of Plasmodium parasites for the diagnosis of malaria in endemic areas
title_full Utility of the detection of Plasmodium parasites for the diagnosis of malaria in endemic areas
title_fullStr Utility of the detection of Plasmodium parasites for the diagnosis of malaria in endemic areas
title_full_unstemmed Utility of the detection of Plasmodium parasites for the diagnosis of malaria in endemic areas
title_short Utility of the detection of Plasmodium parasites for the diagnosis of malaria in endemic areas
title_sort utility of the detection of plasmodium parasites for the diagnosis of malaria in endemic areas
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1475866/
https://www.ncbi.nlm.nih.gov/pubmed/16670024
http://dx.doi.org/10.1186/1471-2334-6-81
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