Comparison of an assumed versus measured leucocyte count in parasite density calculations in Papua New Guinean children with uncomplicated malaria

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• 作者：Moses Laman ; Brioni R Moore ; John Benjamin ; Nixon Padapu…
• 关键词：Malaria ; Parasite density ; Leucocyte density ; Plasmodium falciparum ; Plasmodium vivax
• 刊名：Malaria Journal
• 出版年：2014
• 出版时间：December 2014
• 年：2014
• 卷：13
• 期：1
• 全文大小：237 KB
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• 刊物主题：Parasitology; Infectious Diseases; Tropical Medicine;
• 出版者：BioMed Central
• ISSN：1475-2875

文摘

Background The accuracy of the World Health Organization method of estimating malaria parasite density from thick blood smears by assuming a white blood cell (WBC) count of 8,000/μL has been questioned in several studies. Since epidemiological investigations, anti-malarial efficacy trials and routine laboratory reporting in Papua New Guinea (PNG) have all relied on this approach, its validity was assessed as part of a trial of artemisinin-based combination therapy, which included blood smear microscopy and automated measurement of leucocyte densities on Days 0, 3 and 7. Results 168 children with uncomplicated malaria (median (inter-quartile range) age 44 (39-7) months) were enrolled, 80.3% with Plasmodium falciparum monoinfection, 14.9% with Plasmodium vivax monoinfection, and 4.8% with mixed P. falciparum/P. vivax infection. All responded to allocated therapy and none had a malaria-positive slide on Day 3. Consistent with a median baseline WBC density of 7.3 (6.5-7.8) × 109/L, there was no significant difference in baseline parasite density between the two methods regardless of Plasmodium species. Bland Altman plots showed that, for both species, the mean difference between paired parasite densities calculated from assumed and measured WBC densities was close to zero. At parasite densities Conclusions Diagnostic thresholds and parasite clearance assessment in most PNG children with uncomplicated malaria are relatively robust, but accurate estimates of a higher parasitaemia, as a prognostic index, requires formal WBC measurement.