[Alveolar echinococcosis: from an incurable rural disease to a controlled urban infection]

Abstract

Human alveolar echinococcosis is a parasitic zoonosis with intermediate (rodents and small lagomorphs) and final (carnivores) hosts. The latter can transmit the parasite to humans, by their feces, which are contaminated by the oncospheres of Echinococcus multilocularis, the larvae of which develop in the liver like a slow cancer. Political, socioeconomic, and ecological factors can affect the intermediate and final hosts and thus influence the long-term emergence and stability of endemic areas. The past 20 years have been marked by: Epidemiologic changes: discovery of an endemic area in China, the largest in the world; extension of the European endemic range to the east and north; extension of the French endemic range to the west and south; and the settlement of contaminated foxes in urban centers, which will modify the populations at risk over time. Progress in diagnosis: initial use of liver ultrasound to screen for asymptomatic disease; value of magnetic resonance imaging to confirm diagnosis and assess extension of disease before beginning treatment; mastery of immunological and genetic diagnosis; and the introduction of positron emission tomography combined with computed tomography to assess the functional activity of the lesions and monitor treatment. Consensus has defined the main directions of a multidisciplinary treatment approach: radical liver resection when possible; avoidance of palliative surgical procedures; use of interventional radiology or endoscopy to treat biliary and vascular complications, whenever possible; consideration of liver transplantation only when all other treatment possibilities have been exhausted; and treatment of all patients, without exception, by albendazole for at least two years after radical surgery and long term (at least several years) in other cases. In France, survival and quality of life have improved very substantially, due to earlier diagnosis, clinical classification of cases, and rigorous follow-up as part of the FrancEchino network. Better understanding of the immunological and immunogenetic mechanisms that underlie the course of disease may open up the possibility of immunomodulation that could replace or round out the current treatments. These are far from satisfactory, in view of the constraints of prolonged, most often life-long treatment by benzimidazoles and their side effects.