Micropara Lec

• Parasitology


  The science that deals with parasites
• Medical Parasitology


  The study of parasites that causes disease in man
• Parasite


  An organism living temporarily or permanently in or on another organism (host) from which is physically or physiologically dependent upon other
• Nature of Parasites


  • Unicellular
  • Worm
  • Arthropod
• Parasites


  • Smaller than their host
  • Outnumber the host
  • Short life span than their host
  • Have greater reproductive potential than their host
• Mutualism


  Mutual benefit is derived from the association
• Symbiosis


  Permanent association between two different organisms, so dependent on each other, that their life part is impossible
• Commensalism


  When the parasite benefited from the host while the host neither benefited nor harmed
• Parasitism


  One organism live at the expense of the other. The later usually suffers from the association
• Commensalism


  • Tree frogs using plants as protection
  • Cattle egrets eating insects stirred up by cattle
  • Golden jackals trailing a tiger to feed on its kills
• Commensalism is a relationship between individuals of two species in which one species obtains food or other benefits from the other without either harming or benefiting the latter
• Parasitism is a parasitic relationship in which one organism, the parasite, lives off of another organism, the host, harming it and possibly causing death
• Types of Associations


  • Mutualism
  • Commensalism
  • Parasitism
• Ectoparasites


  Parasites living on or affecting the skin surface of the host
• Endoparasites


  Parasites living within the body of the host
• Permanent (obligate) parasites


  The parasite depends completely on its host for metabolites, shelter, and transportation. This parasite CANNOT live outside its host
• Permanent (obligate) parasites


  • Plasmodium species
  • Trichomonas vaginalis
• Temporary (facultative) parasite


  The parasite is capable of independent existence in addition to parasitic life
• Temporary (facultative) parasites


  • Strongyloides stercoralis
  • Naegleria fowleri
• Pathogenic parasites


  Parasites that cause disease in the host
• Pathogenic parasites


  • Entamoeba histolytica
• Non-Pathogenic (commensal) parasite


  Parasites that derive food and protection from the host without causing harm to the host
• Non-Pathogenic (commensal) parasites


  • Entamoeba coli
• Opportunistic parasites


  Parasites that cause mild disease in typically healthy individuals
• Opportunistic parasites


  • Pneumocystis carinii
• Host


  Organism which harbors the parasite
• Definitive host/Primary host


  Host which harbors the adult stage of a parasite or most highly developed form of the parasite occurs; or sexually mature stages of a parasite and fertilization takes place in it
• Definitive host


  • Man is the definitive host of Taenia saginata
  • Human is the definitive host for trypanosomes that cause African trypanosomiasis
• Intermediate host


  Host harboring sexually immature or larval stage of a parasite and in which no fertilization takes place
• Intermediate host


  • Cow is the intermediate host for Taenia saginata
• Amplifier host


  Intermediate hosts in which parasites undergo multiplication
• Reservoir host


  A wild or domestic animal which harbors a parasite and acts as sources of infection to humans
• Carrier host


  A host harboring and disseminating a parasite but exhibiting no clinical sign
• Accidental (Incidental) host


  Infection of a host other than the normal host species. A parasite may or may not continue full development in this host
• Paratenic or Transport host


  No development occurs but the parasite is alive. May go dormant or may cause damage
• Vectors


  Any arthropod or other living carrier which transports a pathogenic organism from an infected to an uninfected host
• Biological vectors


  Vectors that complete the life cycle of a parasite
• Mechanical (Parathenic or transport) Vectors


  Passive carriers of parasites, not essential in the life cycle
• Mechanical Vectors


  • House fly and Cockroach as a mechanical vector for Amoebae and Giardia
• Diagnostic Stage


  A developmental stage of a pathogenic organism that can be detected in stool, blood, urine, sputum, CSF or other human body secretions