Comparative evaluation of four techniques for the diagnosis of Plasmodium falciparum infections.
ABSTRACT Four diagnostic techniques for Plasmodium falciparum infection were evaluated against serial parasite dilutions and on identical field samples. These were (i) Giemsa-stained thick blood films (GTF), (ii) acridine orange-stained thick (AOTF) and thin (AOTnF) blood films, (iii) the quantitative buffy coat technique (QBC); and (iv) the ParaSight-F dipstick test (PS). PS had a consistently higher sensitivity and speed, was easiest to learn, and required no laboratory facility. The 100% sensitivity cut-off points against known parasite densities (per mm3) were: PS, 30; GTF, 84; QBC, 84; AOTnF, 84; AOTF, 149. In the field study, test sensitivities compared with examination of 800 microscope fields of a Giemsa-stained thin blood film were PS, 96.6%; AOTF, 93.1%; GTF, 91.4%; QBC, 89.7%; AOTnF, 82.8%. In the dilution study, one false positive result was recorded with QBC; in the field study there was one false positive each with PS, AOTnF and AOTF. When a newly trained microscopist examined samples of the parasite dilutions, the 100% sensitivity cut-off points were AOTF, 84; GTF, 140; QBC, 390. Total handling time was shortest with PS regardless of whether samples were processed individually or in batches of 10 or 100. The ParaSight-F test is recommended as the diagnostic tool for the future.
Article: Fluorescent microscope objective.Transactions of the Royal Society of Tropical Medicine and Hygiene 01/1992; 86(1):108. · 1.82 Impact Factor
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ABSTRACT: The diagnostic performance of commercial capillary tubes containing acridine orange dye (QBC) was compared with the standard diagnosis of malaria by microscopical examination of Giemsa-stained thick blood films (GTS) in remote field conditions. The comparison was conducted among 165 volunteers living in northeastern Irian Jaya, Indonesia, an area having hyperendemic malaria transmission. By GTS, 65 volunteers were positive for malaria, but only 49 were judged positive by QBC. Among the 100 blood films found negative by GTS, 5 were considered positive by QBC. Thus, relative to a GTS standard, the sensitivity and specificity of the QBC was 75% and 95%, respectively. The mean limit of detection for the QBC was approximately 60 parasites per microliter blood, whereas the limit of detection for GTS was 20 parasites per microliter blood. Also, a number of practical difficulties were encountered using the QBC at the field site. The QBC approach to diagnosis of malaria was less sensitive and more inconvenient than GTS under the conditions in remote Irian Jaya.Transactions of the Royal Society of Tropical Medicine and Hygiene 01/1992; 86(1):3-5. · 1.82 Impact Factor
- Parasitology Today 05/1989; 5(4):132-4. · 5.51 Impact Factor