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| Year : 2003 | Volume
: 21
| Issue : 1 | Page : 66 |
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Shortcomings of acridine orange staining for malarial parasite
S Das
Department of Microbiology, University College of Medical Sciences, Guru Tegh Bahadur Hospital, New Delhi - 110 095, India
Correspondence Address:
Department of Microbiology, University College of Medical Sciences, Guru Tegh Bahadur Hospital, New Delhi - 110 095, India
How to cite this article:
Das S. Shortcomings of acridine orange staining for malarial parasite. Indian J Med Microbiol 2003;21:66 |
Dear Editor,
A definite diagnosis of malaria is established by the demonstration of malarial parasite in peripheral blood. The diagnostic accuracy by blood film examination is 75% for Plasmodium falciparum, 62.8% for Plasmodium vivax, 29.4% for P. ovale and 25% for Plasmodium malariae.[1] Even though various serological and immunological techniques are currently available and others are under development, probably the most accurate way of detecting all species of human malaria is by examination of peripheral smear.
To increase the sensitivity of detection of malarial parasite, several variations in microscopic examination of smears have been employed. Staining of blood slides with flourochrome dyes is a widely used procedure and has been recognised as a standard, rapid and sensitive method for detecting large volume of potentially infected blood.[2] This observation does not hold true in our study, which was done at microbiology department, University College of Medical Sciences and Guru Tegh Bahadur Hospital, Delhi.
The study included 100 patients with clinical suspicion of malaria. All blood samples were subjected to conventional Giemsa staining and Acridine orange staining (AO). By Giemsa stain 11 smears were positive for P. falciparum and 6 were positive for P. vivax. Only one sample was found to have mixed infection of P. falciparum and P. vivax. Independent masked examination of the smears with AO staining showed only eight smears positive for P. falciparum and two positive for P. vivax giving a sensitivity of 66.3% and 16.7% respectively. There was difficulty in differentiating trophozoites and leukocytes as both emitted green fluorescence. Except for the gametocyte of P. falciparum (because of their typical morphology) other stages were difficult to distinguish. Moreover, failure to discriminate between the species of malarial parasite, reduces the reliability of AO method. Therefore, in areas where malarial parasite burden is not high, one should not attempt such sophisticated and expensive equipment for detection of malarial parasite for screening. It is thus recommended that in low parasitaemic zones, 5 -10 minutes examination of a thick/thin film should be mandatory for general diagnosis of malarial parasite.
| ~ References | |  |
| 1. | Pandey J, Talib VH, Range S, Gulati I. Diagnosis of Malaria - An overview. Ind J Pathol Microbiol 1995;38(4):441-447.  |
| 2. | Rickman LS, Long GW, Oberst R, Cabanban A, Sangalang R, Smith JI, Chulay JD, Hoffman SL. Rapid diagnosis of malaria by Acridine orange staining of centrifuged blood parasites. Lancet 1989;334:68-71. |
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