Watch-and-wait approach for inactive echinococcal cysts: scoping review update since the issue of the WHO-IWGE Expert Consensus and current perspectives

PURPOSE OF REVIEW: This work aims to provide an update of knowledge on the evolution of inactive cystic echinococcosis (CE) cysts (CE4-CE5) managed by ‘watch-and-wait’, by means of a scoping review of the literature published after the publication of the WHO-IWGE (Informal Working Group on Echinococcosis) Expert Consensus document in 2010. RECENT FINDINGS: A total of 31 articles were included. Population ultrasound-based studies showed that spontaneously inactivated CE cysts represent 50.2% (95% confidence interval 38.7–61.8) of all detected untreated CE cysts, and that the prevalence of CE4-CE5 cysts tends to increase with age. Four longitudinal population-based studies showed that CE cysts naturally tend to evolve towards inactivation and that spontaneously inactivated cysts reactivate in a minority of cases. This was confirmed by four hospital-based studies, showing that spontaneously inactivated cysts reactivate rarely, while rate of reactivation is higher if inactivity was obtained posttreatment. It was not possible to drive conclusions on any difference in the clinical course of infection in immunocompromised or pregnant patients. SUMMARY: CE cysts tend to evolve spontaneously to inactivation over time. The published literature supports the safety of the watch-and-wait approach for inactive cysts, sparing treatment to a substantial proportion of asymptomatic patients. A regular follow-up with ultrasound of all inactive cysts is required to detect reactivations.