Parasiten sind zur Erhaltung der Art auf die Übertragung von einem Wirt zum nächsten
angewiesen. Wie ausgeklügelt Parasiten ihren Wirt benutzen und ob eine Verhaltensänderung
des Wirts auf einer adaptiven Manipulation im Sinne einer Ursachen-Wirkungs-Beziehung
beruht, erörtert dieser Beitrag.
Abstract
Bacteria, archaeae, fungi and viruses of the intestinal microbiome play an important
role as symbionts in the complex human ecosystem. Parasites, which account for about
40 % of the earth’s biodiversity, depend on hosts to complete their life cycle. This
article explains how they use them and which signalling pathways play a role in this,
using toxoplasmosis and malaria as examples. The parasitic manipulation hypothesis
is based on impressive observations in the wild and under laboratory conditions, especially
in invertebrates. For the assumption of an adaptive manipulation, every step from
the genotype, the translated messenger, and its source via the used signalling pathways
to the altered host behaviour must be proven. The assumption of an adaptive manipulation
of humans by T. gondii in the sense of a cause-effect relationship is not proven.
Alternative explanations include the inflammatory and immunological processes on the
host side, which change the neuronal signal transduction as concomitant symptoms of
an infection. Even without confirmation of parasitic manipulation in humans, it could
be worthwhile to further investigate the observed associations in order to develop
new possibilities for diagnosis and therapy, e. g. for schizophrenia.
Schlüsselwörter
Parasiten - Verhaltensmanipulation - Toxoplasma gondii - Malaria - Mikrobiom
Key words
parasites - behaviour manipulation - toxoplasma gondii - malaria - microbiome
