dicrocoelium

In the context of biology, parasites are organisms that typically associate with other organisms, their hosts, such that the hosts are damaged while the parasites are benefited. This non-mutual association is known as parasitism. Parasites do not form an evolutionarily distinct group; instead they are part of many different lineages. For example, there are parasites that are protozoa, plants, fungi and animals. Parasitology refers to the study of parasites, with an emphasize on protozoan (single-celled organisms that belong to Kingdom Protista) parasites. This article examines some of the parasites that cause behavioural changes in their host which help the perpetuation of the parasites; either their spread or their lifecycle completion. Specifically, the article examines the tactics of Toxoplasma gondii, lancet liver fluke, guinea worm, the influenza virus, and the parasitic wasp, which are by all means 'evolution's neurobiologists', and are indeed extraordinary in many aspects.