Abstract

The ability of parasites to alter the behaviour of their hosts fascinates both scientists and non-scientists alike. One reason that this topic resonates with so many is that it touches on core philosophical issues such as the existence of free will. If the mind is merely a machine, then it can be controlled by any entity that understands the code and has access to the machinery. One key example is the potential epidemiological and neuropathological association between some cases of schizophrenia with exposure to the protozoan Toxoplasma gondii. T. gondii establishes persistent infection within the CNS and can alter host behaviour. Altered dopamine levels have been reported for both T. gondii infection and schizophrenia. Moreover, several of the medications used to treat schizophrenia and other psychiatric disease demonstrate a anti-T. gondii, properties in vivo and vitro. Furthermore, it appears that the parasite itself may actually be a source of this neurotransmitter. Using the epidemiologically and clinically applicable rat-T. gondii model system, I present a series of studies and discuss them in terms of their theoretical and applied implications for animal and human health.