Four identified plasma HEV RNA kinetic patterns during ribavirin monotherapy. Eight representative subjects are plotted. Blue rectangles represent time of ribavirin therapy. Four viral kinetic patterns were identified: (A,B) monophasic decline, (C,D) biphasic decline, (E,F) triphasic decline and (G,H) flat-partial response. Circles = quantifiable HEV RNA; squares = undetectable HEV RNA; stars = detectable but non quantifiable HEV RNA; +/− = positive/negative HEV RNA in stool. Solid curves were used to illustrate each identified kinetic phase. SVR = sustained virological response. Patients (Pt) 12 and 34 were retreated with ribavirin for 24 weeks and achieved SVR (not shown).