Appraisal of the acridine orange method for rapid malaria diagnosis at three Tanzanian district hospitals

The need to have rapid and accurate confirmation of malaria parasitaemia pr ompted us to evaluate the direct Acridine Orange (AO) stain method in compa rison to the traditional Giemsa Stain (GS) method in the detection of malar ia parasites in patients with presumptive diagnosis of malaria. We evaluate d the sensitivity and specificity of the AO method as well as the durabilit y of the fluorescence microscope. Out of 400 patients with presumptive diag nosis of malaria, 209 (52.3%) and 197 (49.3%) had malaria parasites as dete cted by GS and AO methods respectively, the difference being statistically insignificant, The sensitivity and specificity of AO method compared to the gold standard (GS) method were 94.1% and 100% respectively, At parasite co unt below 5,000 per microlitre of blood, the sensitivity of AO method decre ased to 90.2% but the difference was not statistically significant. The pos itive and negative predictive values were 100% and 94.1% respectively at al l levels of parasite count. The mean duration to get results of malaria par asite diagnosis by GS and AO methods were 35 and 5 minutes respectively. Th e limitation of the AO method was frequent blowing of the fluorescence micr oscope bulb, It is concluded that if the bulb system of the fluorescence mi croscope can be improved, the AO method could be included among other metho ds for the detection of malaria parasites in clinical settings.