DIRECT ACRIDINE-ORANGE FLUORESCENCE EXAMINATION OF BLOOD SLIDES COMPARED TO CURRENT TECHNIQUES FOR MALARIA DIAGNOSIS

The renewed interest in the use of fluorochromes for malaria diagnosis prompted us to evaluate the acridine orange fluorescence technique on blood slides, and to compare it with established techniques using thi ck and thin blood films and the QBC(TM) malaria test, using the Giemsa -stained thick film technique as our standard method for comparison. W e compared 123 positively diagnosed cases and 120 negative cases. For primary samples (day 0), the sensitivity of the thin blood film fluore scence acridine orange technique (AO) was 96.4%, and its specificity w as 95.1%. In cases of imported malaria, with a prevalence rate of 16.2 %, the positive predictive value was 79.2% and the negative predictive value 99.3%. Sensitivity of AO was significantly higher than that of Giemsa-stained thin blood films for parasitaemias < 5000/mu L. The pot ential of AO for species diagnosis of Plasmodium was 85.2%, using Giem sa-stained thin films as the reference technique. Where QBC(TM) impose s a cost limitation, especially in developing countries, despite its h igh performance, the AO diagnostic technique is a valuable alternative , because of its simplicity, almost negligible cost, and its diagnosti c reliability. The method may also have potential value in the diagnos is of other microbiological diseases.