Parasites are classified as organisms that take advantage of another organism (host) for its necessities such as food. This relationship is non-mutual and the host is mostly unaware of the parasite.
There are different ways that a parasite interacts with the host. Some parasites burrow into the host to lay its eggs in it (the host becomes the food source for the emerging larvae) or as a food source for itself.
Another type of parasite goes one step further. Instead of just passively staying in its host, the parasite affects the behavior and movement of the host. It does this by
taking control of the host's neurological system.
The host basically becomes a mindless zombie under the control of the parasite.
An example of this type of parasite is the the fly, Apocephalus borealis. A borealis deposits its eggs into the abdomen of a bee. After being infected, the bee abandons its hive and hover near lights. This parasite is one of the proposed reasons for Colony Collapse Disorder (CCD), a phenomenon where an entire bee hive suddenly disappear.
Another case would be of the parasite, Toxoplasma gondii. It is usually picked up by humans through cat feces, raw and uncooked meat and vegetables, and drinking contaminated water. The parasite resides in the brain and causes Toxoplasmosis.
Toxoplasmosis, has been linked to mental illness, such as schizophrenia, and changes in behavior. It is said 30% of the world's population is infected with the parasite.
About one-third of the world's population is infected with the parasite, which hides in cells in the brain and muscles, often without producing symptoms. The infection, which is called toxoplasmosis, has been linked to mental illness, such as schizophrenia, and changes in behavior.
Parasites are unpleasant lodgers at the best of times, but there is one group of parasites that is particularly pernicious. These are the parasites that hijack their victims' nervous systems, reducing them to helpless zombies. 'The fact that parasites can so efficiently alter host behaviour is fascinating', says The Journal of Experimental Biology Editor Michael Dickinson, from the University of Washington, USA, adding, 'There is something horrifying and wondrous about a tiny "implant" being able to control such a large animal machine'. What is more, it appears that these minute manipulators can have a significant, and often under-appreciated, impact on ecology, physiology and evolution, orchestrating the behaviour of vertebrates and invertebrates alike. 'Neuroparasitology is a science where science meets science fiction', Dickinson observes.
Video: Parasitic Mind Control
In a special collection of Review articles edited by Shelley Adamo, Dickinson, Joanne Webster and Janis Weeks, the journal covers many branches of the newly emerging field of Neuroparasitology, from the behavioural changes exhibited by hijacked hosts to the complex neurological mechanisms that allow parasites to control their victims and the high-tech approaches that are essential for studying them. Featuring case studies of timid animals that are manipulated by their parasites to become more bold and insects that have lost the ability to move independently – allowing hijackers to use the victims' bodies as incubators and food supplies for their young – the collection also features an entire section dedicated to Toxoplasma gondii, a parasite of rodents and cats that can be picked up by humans and may be a contributory factor in some cases of human schizophrenia. In addition, the collection features a section dedicated to our current understanding of the complex neurological mechanisms that allow parasites to take control of their host's nervous system by co-opting the victim's own immune response to alter its behaviour.
The Company of Biologists
The Journal of Experimental Biology
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