PARASITOLOGY

• Symbiont


  Organism living together
• Symbiosis


  Association / relationship of two or more organisms living together
• Types of symbiosis

  • Mutualism
  • Commensalism
  • Parasitism
• Mutualism


  Biological relationship between two or more organisms when both the host and organism benefit from one another
• Mutualism


  • Flagellates inside the digestive system of termites
• Commensalism


  One organism benefits but there is no beneficial or harmful effect to the host
• Commensalism


  • Entamoeba coli in intestinal lumen of man
• Parasitism


  One species (microbe) benefits at the expense of the other (host)
• Parasite


  Living organism that takes nourishment and other need through contact with another species
• Host


  Organism that supports parasite, and may later develop disease
• Parasitism


  • Entamoeba histolytica derives nutrients from human host causing intestinal ulcers and amoebic dysentery
• Parasitology


  Branch of science that deals with the study of parasites
• Medical parasitology


  Studying those parasites that are living in or on the human body, their geographic distribution, the diseases caused by them, clinical picture and the response generated by human against them
• Ectoparasites


  Parasitic organisms that live on the outer surface of its host
• Ectoparasites


  • Lice, ticks, mites
• Endoparasites


  Parasitic organisms that live inside the body of their host
• Endoparasites


  • Entamoeba histolytica
• Infestation


  Presence of ectoparasites
• Infection


  Presence of endoparasites
• Obligate parasite


  Completely dependent on the host during a segment or all of its life cycle
• Obligate parasite


  • Plasmodium spp - MALARIA
• Facultative parasite


  Exhibits both parasitic and non-parasitic modes of living and hence does not absolutely depend on the parasitic way of life, but is capable of adapting to it if placed on a host
• Facultative parasite


  • Strongyloides stercoralis - COCHIN CHINA DIARRHEA
• Accidental/Incidental parasite


  Parasite attacks an unnatural host and survives but may or may not complete life cycle
• Accidental/Incidental parasite


  • Echinococcus granulosus: Humans are accidental host, dogs are definite host
• Erratic parasite


  Parasite that wanders into an organ in which it is not usually found
• Erratic parasite


  • Ascaris lumbricoides in humans wandering into the lung, Entamoeba histolytica reaching the liver or lung
• Intermittent/Temporary parasite


  Those that only visit the host from time to time for feeding
• Intermittent/Temporary parasite


  • Mosquito in MALARIA
• Permanent parasite


  Remains on the host for life
• Permanent parasite


  • Trypanosoma brucei gambiense, Trypanosoma brucei rhodesiense (SLEEPING SICKNESS), Wuchereria bancrofti (FILARIASIS/ELEPHANTIASIS)
• Spurious parasite


  Organisms that have been swallowed and passed through the alimentary tract without causing any effect
• Spurious parasite


  • Capillaria sp. from fish
• Hyperparasite


  Parasite that parasitizes another parasite
• Hyperparasite


  • Female Ixodes angustus tick with a male Ixodes angustus attached to its underside - VECTOR for Lyme disease
• Definitive host


  Host that harbors a parasite in the adult stage or where the parasite undergoes sexual reproduction
• Definitive host


  • Humans in taeniasis
• Intermediate host


  Harbors the larval stages of the parasite or an asexual cycle of development takes place
• Intermediate host


  • Pigs in Taenia solium (pig tapeworm), cattle in Taenia saginata (bovine)
• First intermediate host


  In some cases, larval development is completed in two different intermediate hosts