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Journal of Clinical Microbiology, January 2005, p. 528, Vol. 43, No. 1
0095-1137/05/$08.00+0 doi:10.1128/JCM.43.1.528.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
| LETTER TO THE EDITOR |
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Distilled water was used for dilution purposes many years ago by chemists because of its purity. Since distilled water is slightly acid, it was necessary to buffer it to obtain a pH of 7.0 to 7.4, with the optimum pH being 7.2 to 7.4. This buffered distilled water-Giemsa stain solution is excellent for the staining of blood parasites and particularly for use in cases of malaria, where Maurer's clefts, characteristic of Plasmodium falciparum, are readily evident in blood smears (4).
The preparation of buffered water, however, is time-consuming. Certain spring waters, without organic matter but with their own characteristic mineral composition, have buffering power. Some of the commercially available spring waters have pH values between 7.0 and 7.4; among them is the Evian brand (5) which is easily found in many countries (Table 1).
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This pH of 7.36 is about the same as the pH of human arterial blood. Other spring waters from various countries also have pH values suitable for staining procedures. With reference to blood smear staining procedures, the advantages of these spring waters are that they are ready to use, remain stable for weeks after opening, can be kept at room temperature, and have a low cost compared to chemicals for preparation of appropriate buffers.
Use of bottled water for diluting Giemsa stain has proven reliable for the detection of malaria-causing parasites on thin and thick blood smears. Importantly, it allows for the demonstration of Maurer's clefts (3). With this procedure we have been able to show these characteristic clefts in 90% of 205 cases of malaria caused by P. falciparum.
Maurer's clefts are slow to appear during the morphological stages of P. falciparum. Only red blood cells containing older trophozoites show dots that later become the typical spots. The dots can be round or irregular in shape, triangular, or loop-like and have a red-brown or even purplish color. They are always few in number (1 to 20 dots per cell) and easy to count. They are very important for the diagnosis of severe P. falciparum infestation. Schuffner's stippling (6) also appears when staining is carried out in cases of Plasmodium vivax or Plasmodium ovale infestation.
Diagnosis of malaria can also be done by molecular biology techniques involving PCR or immunochromatographic testing (ImmunoChromatic test (Amrad ICT, Sydney, Australia). However, several tests are necessary to detect the four species of Plasmodium, microfilariae, and trypanosomes. Giemsa stain diluted with spring water is very useful not only for the detection and study of blood parasites (5) but also for studies of blood cytology.
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Jean-Claude Petithory* Françoise Ardoin Lawrence R. Ash Qualité en Parasitologie Centre Hospitalier 95500 Gonesse, France School of Public Health University of California Los Angeles, Calif.
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| * Phone: 33 1 34 53 90 12,Fax: 33 1 34 53 90 46, E-mail: petithory.parasito{at}wanadoo.fr |
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| Antimicrob. Agents Chemother. | Clin. Microbiol. Rev. |
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