Echinococcus multilocularis: epidemiology, surveillance and state-of-the-art diagnostics from a veterinary public health perspective

Alveolar echinococcosis (AE), caused by the larval (metacestode) stage of Echinococcus multilocularis, is considered one of the most serious parasitic zoonoses in Central and Eastern Europe and is emerging also in large parts of Asia. The red fox represents the main definitive host of E. multilocularis in Europe, but the raccoon dog, the domestic dog and to a much lesser extent the domestic cat also represent potential definitive hosts. The natural intermediate hosts of E. multilocularis are mainly voles. The spectrum of accidental hosts is broad and includes many species of monkeys, pigs, dogs and humans which get infected by oral uptake of the viable eggs. Yet, human AE is a very rare disease in Europe; incidences have increased in recent years, while the infection is widely distributed in foxes with high prevalences reaching up to 70% in some areas. Generally, infected foxes represent a zoonotic risk, which may be particularly relevant in urban areas. Furthermore, there is concern that the risk for humans to acquire AE may rise due to the suspected geographical spread of the parasite as assessed by infections in its definitive hosts and the high prevalences in some regions. Monitoring and surveillance activities have therefore been initiated in a few European countries. Several diagnostic strategies have been developed and validated in recent years, applying classical worm detection by microscopy, but also immunological (ELISA for coproantigen detection) and molecular tests (copro-DNA detection by PCR). However, there is an urgent need for defining minimal requirements and harmonised approaches for these activities to allow for a reliable assessment of the epidemiological situation in Europe and comparable results from different countries.