Die Rolle des Europäischen Igels (Erinaceus europaeus) in der ...

Summary
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Summary
Title: The role of the European hedgehog (Erinaceus europaeus) in the epidemiology of
tick-borne diseases (Borrelia spp., Anaplasma spp., Rickettsia spp. and TBE-virus).
Vector-borne pathogens circulate in nature between blood-sucking arthropods and vertebrate
hosts via a variety of transmission cycles through which they can also reach humans. Basic
investigations on the pathogen-vector-host relationship are therefore necessary in order to
understand such a complex epidemiological situation.
The work presented focuses on the role of hedgehogs, notably Erinaceus europaeus, in the
circulation of tick-borne pathogens in Western and Central Europe. New data are presented
particularly with regard to various genospecies of the Borrelia burgdorferi s.l. complex, but
also involving the epidemiology of Anaplasma species, Rickettsia species and tick-borne
encephalitis (TBE) virus. For the molecular investigation of these pathogens, organs of
dissected animals, as well as ticks (Ixodes hexagonus and Ixodes ricinus) removed from
hedgehogs, were used. In addition blood samples from living animals were tested by a
modified ELISA and an immunoblot for specific antibodies against Borrelia genospecies. The
B. burgdorferi s.l. investigation was supplemented by xenodiagnosis on experimentally and
naturally infected hedgehogs.
The results obtained demonstrate that hedgehogs play a significant role in the circulation of
tick-borne pathogens with pathogenic potential for humans. The data acquired prove the
reservoir potential of hedgehogs for certain Borrelia genospecies (Borrelia afzelii, Borrelia
bavariensis and Borrelia spielmanii). In particular juvenile hedgehogs or individuals with a
reduced health status seem to be susceptible to infection. In contrast to this, high IgG-titers
against specific Borrelia antigens and the low transmission rate from adult animals to ticks
indicate a reduction in the reservoir competence of hedgehogs presumably caused by adaptive
immunity.
Hedgehogs are also involved in the circulation of Anaplasma phagocytophilum. My results
show that they are susceptible to a specific “hedgehog variant”, but also to other genotypes.
In a similar way, hedgehogs play a role in the epidemiology of Rickettsia species. Rickettsial
DNA could be detected in a skin sample of one animal, as well as in all life history stages of