Introduction to Parasitism

Introduction
Parasitism - an association where one of two organisms (parasite) benefits, lives and gain shelter and nutrition at the expense of the other (the host). The host may suffer from wide range of functional and organic disturbances E.g. worms like Ascaris lumbricoides reside in the gastrointestinal tract of man, and feed on of intestinal food causing various illnesses.
Parasitology: is the science of parasitism and parasites, its study of host-parasite relationships.
Medical Parasitology: is the branch of medical sciences dealing with organisms
(parasites) which live temporarily or permanently, on or within the human body (host). Medical Parasitology consists of: medical protozoology, medical helminthology and medical arachnoentomology.
Parasite It is organisms lives upon or within another living organism (host), it obtains its nourishment and other needs from a host; the host supports the parasite
Types of Parasites
1-Location
- An ectoparasite (External parasite) a parasitic organism that lives on the outer surface of its host on skin or hair of host e.g. lice, ticks, mites etc.
- An endoparasite (Internal parasite) a parasitic organism that lives inside the body of the host may be just under the surface or deep in the body e.g. Entamoeba histolytica.
2– Required or not
- Obligatory parasite this parasite is completely dependent on the host during a segment or all of its life cycle i.e can’t live apart from its hoost e.g. Plasmodium spp. can not survive without a host i.e. completely adapted for parasitic existence.
- Facultative parasite is an organism that can exist in a free living state or as a parasite and hence does not absolutely depend on the parasitic way of life. Its can change its life style between free-living in the environment and parasitic according to the surrounding conditions. e.g. Strongyloides stercoralis.