Giardia duodenalis is responsible for several waterborne gastrointestinal outbreaks worldwide. In addition to limitations presented by the main disinfection methods, assessing the inactivation efficiency of cysts after the treatment also poses challenges. Thus, this study aimed to use the 5-carboxyfluorescein diacetate acetoxymethyl ester (CFDA-AM) staining protocol to evaluate the viability of G. duodenalis cysts inactivated by different UV and chlorination doses and boiling times. Under epifluorescent microscopy, metabolically active cysts that presented green fluorescence were considered viable. In contrast, when no green fluorescence could be observed, organisms were considered non-viable. Although statistical analysis revealed that increasing the UV dose did not significantly decrease the percentage of viable cysts, the fluorescence signal intensity decreased considerably when the cysts were irradiated with a dose equal to or greater than 80 mJ cm⁻². Regarding chlorination and boiling treatments, this study demonstrated that no cyst showed fluorescence at the lowest NaClO concentration (0.5 mg/L) and in the shortest boiling time (2 min). Despite some limitations regarding the use of metabolic activity as a viability marker, this methodology is rapid, easy to run and cost-effective. Thus, we conclude that the CFDA-AM staining protocol has the potential to be used to assess Giardia cyst inactivation, although further research is required.

十二指肠贾第鞭毛虫是全球数次水传播胃肠道疾病爆发的罪魁祸首。除了主要消毒方法存在的局限性外，评估治疗后包囊的灭活效率也带来了挑战。因此，本研究旨在使用 5-羧基荧光素二乙酸乙酰氧基甲酯 (CFDA-AM) 染色方案来评估十二指肠杆菌的活力通过不同的紫外线和氯化剂量和煮沸时间灭活的包囊。在落射荧光显微镜下，呈现绿色荧光的代谢活跃的囊肿被认为是可行的。相反，当没有观察到绿色荧光时，生物被认为是不可行的。尽管统计分析表明，增加紫外线剂量并没有显着降低存活囊肿的百分比，但当囊肿受到等于或大于 80 mJ cm ^{-2的剂量照射时，荧光信号强度显着降低}. 关于氯化和煮沸处理，本研究表明，在最低 NaClO 浓度（0.5 mg/L）和最短煮沸时间（2 分钟）下，没有孢囊显示荧光。尽管在使用代谢活动作为活力标记方面存在一些限制，但这种方法快速、易于运行且具有成本效益。因此，我们得出结论，尽管需要进一步研究，但 CFDA-AM 染色方案有可能用于评估贾第鞭毛虫囊肿失活。