Veterinary aspects of alveolar echinococcosis - a zoonosis of public health significance

Human alveolar echinococcosis (AE), caused by the metacestode stage of Echi nococcus multilocularis, is a serious zoonosis which caused up to 100% leth ality in untreated patients before the 1970s, when modern methods of treatm ent were not yet established. AE occurs in large areas of the northern hemi sphere mostly with low country-wide prevalences, but high prevalences of up to 4% have been reported from small population groups in highly endemic fo ci, e.g. from China. AE includes many veterinary aspects which are the topic of this review. Rec ent studies have shown that E. multilocularis has a wider geographic range than previously anticipated. There is evidence for growing populations of r ed foxes (Vulpes vulpes) in some areas, for increasing invasion of cities b y foxes and also for establishment of the parasite cycle in urban areas. Th ese and other factors may lead to an increased infection risk for humans. S ignificant progress has been made in the development of sensitive and speci fic new techniques for the intra vitam and post mortem diagnosis of intesti nal E. multilocularis infection in definitive hosts, notably the detection of coproantigen by enzyme-linked immunosorbent assay and of copro-DNA by PC R. Both tests can also be used for the identification of E. multilocularis in faecal samples collected in the environment. Recommendations are given f or chemotherapy and chemoprophylaxis of the intestinal infection in definit ive hosts. In recent years, infections with the metacestode stage of E. multilocularis have not only been diagnosed in humans in several regions, including at le ast eight countries in central Europe, but also in animal species which do not play a role in the transmission cycle (wild and domestic pigs, dogs etc .). From 1987 to 2000 our group in Zurich has diagnosed 10 cases of AE in d ogs and 15 in captive monkeys. In 2 dogs, concurrent infections of the inte stine and of the liver with adult and larval stages of E. multilocularis. r espectively, were observed for the first time. Clinical data are presented, and methods of diagnosis and treatment (surgery, chemotherapy) are describ ed. Furthermore, small liver lesions caused by E. multilocularis were diagn osed in 10% of 90 slaughter pigs, and 2.9% of 522 breeding sows had specifi c serum antibodies against parasite antigens. In view of the unpredictable epidemiological situation, all possible measur es for preventing E. multilocularis infections in humans and in domestic an imals should be initiated by the veterinary and health authorities. (C) 200 1 Elsevier Science B.V. All rights reserved.