[Increased risk of infection by Echinococcus multilocularis for people in the endemic "Schwaebische Alb" region?]

Abstract

The infestation by the larva of Echinococcus multilocularis, also known as alveolar echinococcosis, is the most dangerous parasitic disease of man in Middle Europe. This is due to the location in the liver but still more so because of the proliferative and infiltrating growth of the larval tissue. The basic infective cycle of the parasite is a zoonosis between foxes as final hosts and small rodents such as common voles as intermediate hosts. Man can be a false intermediate host and thus a carrier of the larval stage. The infection arises from oral ingestion of the tapeworm eggs either on wild berries or in dust. Dogs and cats are a further important source of infection. They can be facultative carriers of adult E. multilocularis and are thus able to excrete eggs or proglottids of the tapeworm. In west Germany, in particular the "Schwäbische Alb" must be regarded as an endemic region for E. multilocularis. According to the examinations of Zeyhle, the infection rate of foxes here is more than 15% on an average, in some local areas as for example in the district of Reutlingen it is over 25%. In order to estimate the danger of infection for man in hyperendemic areas the population of two villages of this district and also specially endangered occupational groups (hunters, foresters) of the whole "Schwäbische Alb" have been examined for echinococcosis by serological means. A stepless ELISA was used as screening test. Thus circa 2200 persons liable to E. multilocularis could be examined. Among the population of the district of Reutlingen nine highly suspective sera could be detected. Computer tomography of these nine persons showed only one case of Echinococcus which could be identified as E. multilocularis after operation. Presumably serological positive cases come up as a consequence of a real contact with E. multilocularis. But in most cases the larval cestode tissue might soon degenerate because man is a relatively poor intermediate host. It cannot be excluded, however, that the Echinococcus-larva could not yet be identified clinically because of its early stage. According to most cautious estimation the prevalence of E. multilocularis in this endemic area might be one per thousand, the contact frequency, however, up to one per cent.