Epidemiology of Echinococcus multilocularis and E. granulosus in central Europe

Abstract

Two species of Echinococcus are known to occur in central Europe, namely E. multilocularis and Echinococcus granulosus, causing the alveolar and the cystic form of echinococcosis in humans, respectively. Recent studies have shown that in central Europe E. multilocularis occurs further north, south and east than previously anticipated. This parasite is endemic in Belgium, Luxembourg, France, Switzerland, Liechtenstein, Austria, Germany, Poland, and the Czech Republic. The prevalence rates of E. multilocularis in foxes are alarmingly high in some areas with average rates > 40%. Infection rates in dogs and cats are much lower. In recent years accidental infections with the metacestode stage of E. multilocularis have been observed in various animal species (dog, domestic pig, wild boar, nutria and monkeys) and in humans. The mean annual incidence rates of alveolar echinococcosis in humans are low varying between 0.02 and 1.4 cases per 100,000 inhabitants in several European countries and regions. For monitoring of the infection in final host populations new techniques are now available, notably the coproantigen ELISA and for selected cases also egg detection by the Polymerase Chain Reaction. E. granulosus has an uneven geographical distribution in Europe with very low prevalence rates in some of the northern and central European countries, with medium endemicity in others and high endemicity in areas of southern and eastern Europe. Cystic echinococcosis in humans is still a significant public health problem, predominantly in the Mediterranean area. Up to now five strains of E. granulosus have been identified in central Europe which differ in their life cycles as well as in morphological, biochemical, genetic and some other features. Several molecular techniques are now available which allow the identification of Echinococcus species and certain strains using genetic markers. Epidemiological evidence and molecular studies indicate that the so-called sheep, cattle, and cervid strains of E. granulosus are infective to humans whereas the horse strain may have no or low infectivity. Polish patients were found to be infected with E. granulosus similar to a pig strain.