Intro

• Symbiosis


  Association/relationship of two 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. No body is harmed in this relationship.
• Mutualism


  • Flagellates inside digestive system of termites
  • Lactobacilli in women's urogenital tract
• Commensalism


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


  • Entamoeba coli in intestinal lumen of humans
  • Proteus mirabilis in GIT
• Parasitism


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


  Living organism that takes nourishment and other needs 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 dysentery

  
• Parasitology


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


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

  
• Types of parasitic infections


  • Anthroponosis
  • Zooanthroponosis
  • Anthropozoonosis
• Types of Parasites - By Location


  • Ectoparasite
  • Endoparasites

  
• Infestation


  Presence of ectoparasites
• Infection


  Presence of endoparasites
• Ectoparasite


  • Head and pubic lice, ticks, mites
• Endoparasites


  • Entamoeba histolytica, Ascaris lumbricoides
• Types of Parasites - Need of Host


  • Obligate parasite
  • Facultative parasite
• Obligate parasite


  Completely dependent on the host during a segment or all of its life cycle, cannot complete its life cycle without the presence of a host

  
• Obligate parasite


  • Plasmodium spp. (causes 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
• Other types of Parasites


  • Accidental/Incidental Parasite
  • Erratic or Aberrant Parasite
  • Intermittent or Temporary Parasite
  • Permanent Parasite
  • Spurious or Coprozoic Parasite
  • Pseudoparasite
  • Hyperparasite

  
• Accidental/Incidental Parasite


  Parasite attacks an unnatural host and survives but may or may not complete life cycle

  
• Accidental/Incidental Parasite


  • Echinococcus granulosus
• Erratic or Aberrant Parasite


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

  
• Erratic or Aberrant Parasite


  • Ascaris lumbricoides in humans
  • Entamoeba histolytica reaching the liver or lung
• Intermittent or Temporary Parasite


  Those that only visit the host from time to time for feeding
• Intermittent or Temporary Parasite


  • Mosquito (Aedes aegypti)
• Permanent Parasite


  Remains on the host for life

  
• Permanent Parasite

  • Trypanosomes, Wuchereria - Filarial worms

  
• Spurious or Coprozoic Parasite


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

  
• Pseudoparasite


  An artifact that is mistakenly identified as a parasite. Not a true parasite but mistaken as parasite

  
• Pseudoparasite


  • Thread, seeds, air bubbles
• Hyperparasite


  Parasite that parasitizes other parasites

  
• Hyperparasite


  • Female Ixodes tick with a male Ixodes angustus attached to its underside

  
• Types of Hosts


  • Definitive host
  • Intermediate host
• Definitive host


  A host that harbors a parasite in the adult stage or where the parasite undergoes a sexual reproduction

  
• Intermediate host


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