Parasitology - Introduction and Basic Principles PDF

Parasitology Dr. Muhammad Nauman Zahid [email protected] Introduction  Parasitology  What are parasites and what do they cause? Parasites  Word parasite derived from the Greek  and means literally “situated beside”  A living organism which gets nourishment from another living organi...

Parasitology Dr. Muhammad Nauman Zahid [email protected] Introduction  Parasitology  What are parasites and what do they cause? Parasites  Word parasite derived from the Greek  and means literally “situated beside”  A living organism which gets nourishment from another living organism where it lives is called parasite.  Parasites-live on or within some other organisms (host) Shelter Food Reproduction Why do we study parasites? o Parasites provide unique examples of biological phenomena not found in free-living organisms o Medical importance ✓ Veterinary importance o Economic importance Why do we study parasites?  Cause disease-animals and humans  Transmit disease-act as vector  Debilitating effects-prone to other diseases Major Groups of Parasites ✓Protozoan (Protozoolgy) Single celled eukaryotes Malaria, Giardia, Trichomonas ✓ Helminths (Helminthology) Multicellular Flukes, tapeworms, roundworms ✓ Ectoparasites (Entomology) Multicellular Live outside the body Insects (mosquitoes, lice, and fleas) & Arachnids (ticks and mites) Parasitism and its Types Two species association- one species ( parasite) lives on or in second species (host).  Symbiosis- is any type of a close and long- term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasitic. Example: Termite and their protozoa Parasitism  Commensalism – one benefits while the other is neither harmed nor helped. Example: Non pathogenic protozoa, mites travelling on fly  Mutualism – both benefits from the relationship. Example: Ruminant and their microflora A large percentage of herbivores have mutualistic gut flora to help them digest plant matter, This gut flora is made up of cellulose- digesting protozoans or bacteria living in the herbivores' intestines. Coral reefs are the result of mutualisms between coral organisms and various types of algae which live inside them. Parasitism  Parasitasis –one potentially pathogenic but not cause sign/symptoms of the disease  Parasitosis- one injure the other cause sign/symptoms and disease lesion Classification of parasites  Endoparasite -within body of host e.g. Entamoeba histolytica, Ascaris lumbricoides, etc.  Ectoparasites -on the body of host e.g. ticks, mites, lice  Erratic- invade body organs that they do not normally invade e.g.  E. histolytica is a good example of erratic parasites. Typically, this anaerobic parasite is found in the gastrointestinal tract where they cause amoebiasis (bloody diarrhea).  However, the parasite has been shown to wander and invade such organs as the liver and lungs in human beings. Classification of parasites  Obligate parasite (who must spend some part of their life cycle in or on host, e.g. plasmodium).  Facultative parasite (may be free living but can obtain the nutrition from hosts too). E.g. Nargleria Fowleri  Accidental parasite (when parasite attacks unnatural host). E.g. Rat tapeworm  Aberrant parasite (when the parasite comes to a site, during migration where it cannot live or develop further). E.g. For example, the tapeworm Taenia solium may migrate to the brain and remain there unless removed via an operation. Terminology  Infection-disease condition due to endoparasites  Infestation-disease condition due to ectoparasite  Parasitemia-parasite in blood circulation  Pathogenic-disease causing  Pathogenesis-pattern of disease occurrence  Immunity-ability to ward off a disease Terminology  Anthroponoses-human diseases can be transmitted to animals  Zoonosis-animal diseases may be transmit to human  Epidemic-disease effect large no. of human, spread rapidly  Epizootic-disease effect large no. of animals  Epizoic-living on the surface; skin parasite  Incidence-no. of cases of an infection occur during a given period of time in relation to population  Prevalence-no. of cases of an infection occur at any time in a population Terminology  Virulence-relative infectiousness  Juvinile stage- sexually mature adult stage  Haematophagus-eating of blood by a parasite  Host specificity-restriction of parasite to one or more host  Hyperparasitisim-presence of parasite in/on other parasite