Control of Echinococcus multilocularis: strategies, feasibility and cost-benefit analyses

Echinococcus multilocularis, the zoonotic agent of human alveolar echinococcosis, has considerably extended its range and became more prevalent in many parts of the endemic areas. Accordingly, there is an increasing demand for measures to prevent human infections. Rising public awareness of this zoonosis and individual protective actions should be part of every prevention program. Considering the high reproduction of E. multilocularis in domestic dogs which live in close contact to humans, a monthly deworming scheme for domestic dogs with access to rodents is likely to be of high importance. This holds true if only low prevalences in domestic dogs are recorded, as high densities of these pets can easily outweigh low infections rates. Thus, in central Europe their estimated contribution to environmental contamination with E. multilocularis eggs ranges between 4% and 19%. The estimated contribution of domestic cats is insignificant (<0.3%) due to low parasite reproduction in this species. Control of the parasite by reducing its main wildlife hosts (foxes, vole species) is barely achievable on a larger scale and is generally not well accepted due to ecological considerations and animal welfare concerns. In general, the frequency of the parasite sharply decreases when anthelmintic baits are regularly distributed to foxes. However, eradication of the parasite is unlikely and long-term baiting campaigns are actually the most effective tool to significantly lower the infection pressure with parasite eggs. Regarding the long latency of 5-15 years of alveolar echinococcosis, however, such measures can only be cost effective if they are pursued for several decades and concentrate on restricted areas which are most relevant for the transmission of alveolar echinococcosis such as highly endemic areas in densely populated zones. Thus, the implementation of this approach strongly depends on factors such as public attitude, available financial resources and priority setting of political decision-makers.