Intro to parasitology.docx

Organism, animal, or plant that lives on or in a host and draws nutrients directly from it and benefits from it. Parasite may be unicellular (protozoa) or multicellular organism (worms) which exploits its host for the purpose of staying alive. The parasite offers nothing in the relationship but harm...

Organism, animal, or plant that lives on or in a host and draws nutrients directly from it and benefits from it. Parasite may be unicellular (protozoa) or multicellular organism (worms) which exploits its host for the purpose of staying alive. The parasite offers nothing in the relationship but harm. Some parasitic relationships are harmless whilst other kills or damages the host. Ectoparasites lives on the host whereas endoparasites which lives within the host. There are 2 groups of parasites. Protozoa- can cause systemic or gastrointestinal infections. Helminths- can cause systemic or gastrointestinal infections. Gastrointestinal parasite exists in 2 stages (Protozoa and Helminths) Exists in 2 stages. Protozoa Active- causes the symptoms, Infective (CYST)- resistant, survives for a long time. Helminths Active (worms and larvae)- causes the symptoms, Infective (eggs)- resistant, survives for a long time. Parasite host harbours a parasite providing shelter and nourishment. 2 types of hosts. Definitive host- it supports the sexually mature, reproducing adult parasite. Intermediate host- supports the immature and non-reproducing forms of parasite. General characteristics of Protozoa Unicellular Eukaryotic Asexually reproduction Classified according to their locomotive apparatus. General characteristics of Helminths Multicellular Produces eggs. Can be male or female. Reproduces sexually. General characteristics of Cestodes (tape worms) Have 4 suckers and 2 rings of hooks. No mouth or digestive system General characteristics of trematodes (flukes) Flat Usually, small Complicated reproduction cycle which includes both sexual and asexual reproduction.