The former Pathology Unit (until December 2017)

Alveolar echinococcosis in non-human primates

The fox tapeworm (Echinococcus (E.) multilocularis), widespread in Central Europe, is the agent of alveolar echinococcosis, a dangerous zoonosis. Main final host of this tapeworm with a length of 2 to 4 mm is the fox. In general, alternate hosts get infected by oral intake of eggs, which are excreted by the fox together with the feces. After eclosion the larvae nearly always infest the liver of their alternate hosts, where the larvae grow infiltratively. Originating from a germ epithelium, buds are developing and permeate the liver tissue, where they induce massive alterations. This inflammatory process, which resembles a tumor, may result in hepatomegaly, cholestasis, jaundice, cirrhosis, portal hypertension and the Budd-Chiari-syndrome. Alternate hosts are e. g. humans and non-human primates.

The clinical course of an alveolar echinococcosis in non-human primates is highly variable. After peroral intake of eggs of the small fox tapeworm the human liver gets infected, however, this infection mostly remains unnoticed for many years. The course of disease in non-human primates is considerably shorter. The larvae proliferate in the liver tissue, and an alveolar tumor develops within a short time period after infection.

For years clinical cases of echinococcosis are regularly diagnosed in the animal population of the German Primate Center (GPC) (BLANKENBURG et al. 2002). In the last 12 years 25 animals got infected, 15 of these animals died presenting the characteristic disease pattern (TAPPE et al. 2007). Apart from lion-tailed macaques and rhesus monkeys, cynomolgus monkeys are most often affected. It was not possible to significantly diminish the fox population by prophylactic measures, as e. g. intense population control using live traps, approved by the authorities, since other animals follow on from the forested environments of the GPC.

Currently a vaccination as a prophylactic measure is tested. In E. multilocularis-infections, a vaccination of intermediate hosts would also be possible. Experimentally, the vaccines 14-3-3 and Em95 have delivered an optimal performance in mice (SILES-LUCAS et al. 2003, SILES-LUCAS and GOTTSTEIN 2003, GOTTSTEIN 2005). However, for practical reasons it is virtually impossible to use a field vaccine for the interruption of the cycle since the parasitic development cycle mainly takes place in wild animals (mice). Given the current disease problematic in our animal population, we are seeking to apply a vaccine in non-human primates and try to establish further diagnostic methods (ELISA) for the diagnosis of the disease. A doctoral thesis deals with diagnostic procedures and prophylaxis of echinococcosis in non-human primates.