ACRIDINE-ORANGE FLUORESCENCE TECHNIQUES AS ALTERNATIVES TO TRADITIONAL GIEMSA STAINING FOR THE DIAGNOSIS OF MALARIA IN DEVELOPING-COUNTRIES

Traditional Giemsa-stained thick blood films were compared with 2 fluo rescence microscopy techniques, acridine orange (AO) staining of thin blood films and the quantitative buffy coat (QBC(TM)) method, for the microscopical diagnosis of malaria. Of 200 samples examined, 141 were positive by Giemsa staining, 146 by AO and 137 by QBC(TM). Overall sen sitivities for the 2 fluorescence techniques compared to Giemsa staini ng were good: AO 97.9% and QBC(TM) 93.6%. However, with parasitaemias < 100/mu L the QBC(TM) sensitivity fell to 41.7% whereas that of AO wa s 83.3%. Both AO and QBC(TM) were unable to differentiate accurately b etween individual malaria species. We conclude that the QBC(TM) techni que alone cannot replace Giemsa-stained thick blood films for most pur poses in an African setting. However, apart from species differentiati on, the AO method is an appropriate technique for the laboratory diagn osis of malaria in developing countries.