Greek: parasitos: men sitting at King’s table tasting food in order to find out whether poison is in. Later the term was transferred to people/animals which live on other than own costs.
An animal that lives completely at the expense of plants, animals, or humans is defined as parasite. Some authors also consider viruses, bacteria, and fungi as parasites.
They must develop successful strategies for host finding.
They must find methods for attachment and/or for partial or total penetration into their prospective hosts (Host Cell Invasion).
They must become able to feed on their host’s tissues or fluids and must be able to metabolize the nutrients obtained (Metabolism).
Last but not least, parasites have to establish a...