Parasite circulating free DNA in the blood of alveolar echinococcosis patients as a diagnostic and treatment-status indicator.

BACKGROUND Alveolar echinococcosis (AE) is a serious parasitic disease caused by infection by larvae of Echinococcus multilocularis; it is the less common but substantially more deadly of the two major echinococcosis diseases that can occur globally but are concentrated in central Asia. METHODS We here analyzed parasite circulating free DNA (cfDNA) in 149 plasma samples using a DNA-sequencing-based method (105 AE, 16 cystic echinococcosis, 4 liver cancer, 4 gallstones and 20 healthy volunteer). After identifying the Echinococcus-specific cfDNA (Em-cfDNA) sequences in the samples, we evaluated the utility of using Em-cfDNA for AE diagnosis and as a potential indicator of the effectiveness of surgical treatment. We also examined potential associations between Em-cfDNA levels and clinical features of AE patients. RESULTS Our work demonstrates that varying reads of Em-cfDNA was detectable in the plasma 100% of preoperative AE patients, and all of the non-AE patients and healthy volunteers were negative. Em-cfDNA has good sensitivity and specificity for the diagnosis of AE, and we also found that Em-cfDNA levels apparently have reference value for evaluating the therapeutic efficacy of surgery interventions against AE lesions. Finally, our analysis revealed that Em-cfDNA levels can reflect meaningful information about lesion size in preoperative AE patients. CONCLUSIONS Our work demonstrated that sequencing-based monitoring of Em-cfDNA can be used in the clinic as a powerful diagnostic indicator for AE and its implications about the strong potential for using such a "liquid-biopsy" method for the ongoing monitoring of disease status in post-intervention AE patients.