Mc3

• Parasite


  A living organism which receives nourishments and shelter from another organism where it lives
• Parasite

  An organism that is entirely dependent on another organism (host)
• Criteria used in classification of parasite

  • Pathogenicity
  • Pathogen-Parasite
• Pathogenicity

  The pathogenic mechanism of parasitic infection varies according to species and quantity of parasites as well as parasite-host adaptation and host responses. The damage caused by parasites can be either confined within the parasitic site or extend into other parts in host. The damages are commonly caused by mechanical pressure, capturing nutrition, toxins, responses and anaphylaxis of host to the stimulation from parasites as well as passage for other pathogens invading the host.
• Pathogen

  An organism that causes diseases to the host after infection
• Parasite

  An organism that lives on or in another organism of another species. It usually derives nutrients at the expense of its host.
• Pathogen

  Usually kill their host through diseases
• Parasite

  Most do not kill their host but do cause some damage
• Pathogen

  Typically do not require a host to complete its life cycle
• Parasite

  Will have to depend on their host to complete their life cycle
• Pathogenicity


  The ability of an organism to infect another organism (host)
• Parasitism


  A kind of interaction between two species, where one species is benefitted, and the other is harmed
• Types of hosts

  • Definitive or Primary Host
  • Intermediate or Secondary Host
  • Reservoir Host
  • Paratenic or Storage Host
  • Incidental or Accidental host
• Definitive or Primary Host

  The host which harbors the adult parasites or where the parasite replicates sexually
• Definitive hosts


  • Sheep for Fasciola gigantica
  • Dog for Echinococcus granulosus
  • Female anopheles mosquito for Plasmodium spp.
• Intermediate or Secondary Host

  The host which harbors the larval stages of a parasite or in which the parasite undergoes asexual multiplication
• Intermediate host


  • Humans for Plasmodium (malarial parasites)
• Reservoir Host


  A host, which harbors the parasites, possibly grow, and multiply and serves as an important source of infection to other susceptible hosts. They do not get the disease carried by the pathogen or it is asymptomatic and non-lethal.
• Reservoir host


  • Dog for cystic echinococcosis
• Paratenic or Storage Host

  A host that serves as a temporary refuge and vehicle for reaching an obligatory host, usually the definitive host. It harbors the sexually immature parasite, but it cannot develop further in this host.
• Paratenic host

  • Lizards for Spirocerca lupi in dogs
• Incidental or Accidental host


  A host organism that shelters the parasite, but since it can't progress the life cycle development, it is dead-end for it.
• Incidental host


  • Humans for Japanese encephalitis virus (JEV)
• Types of symbiotic relationships

  • Parasitism
  • Mutualism
  • Commensalism
  • Phoresis
• Mutualism

  A symbiotic relationship where both organisms benefit from each other's existence
• Parasitism


  A non-mutual symbiotic relationship where the parasite benefits at the expense of the host, while the host is harmed. The parasite lives on or in the body of the host.
• Commensalism


  A symbiotic relationship where one partner benefits while the second partner (the host) are neither helped nor harmed
• Commensals

  • Entamoeba gingivalis in the human mouth
• Parasitic adaptations

  • Structural Adaptations (Morphological and Anatomical Adaptations)
• Structural Adaptations

  Features that enable parasites to exist under conditions of their habitat, such as:

  • Feeding organs are usually absent in endoparasites
  • Presence of well-developed piercing devices to invade host tissue
  • Reduced or absent locomotory organs due to restricted movements
  • Presence of attachment organs like rostellum, hooks or suckers to connect securely to host
  • Resistant outer covering to host enzymatic digestion
  • Highly muscular pharynx for easy absorption of food from host
• Types of parasites

  • Ectoparasite
  • Endoparasite
  • Permanent Parasite
  • Temporary Parasite
  • Facultative Parasite
  • Obligatory Parasite
  • Occasional Parasite
• Ectoparasite

  Parasites that live on the surface of the host's body
• Ectoparasites


  • Head louse, blood sucking fleas, flies, lice, mites
• Endoparasite


  Parasites that live inside the host's body
• Endoparasites


  • Entamoeba, Trypanosoma, Plasmodium, Leishmania, Fasciola
• Permanent Parasite


  Leads a parasitic condition throughout its whole life
• Temporary Parasite


  Visits its host for a short period
• Facultative Parasite


  Can live either a parasitic or non-parasitic existence
• Facultative parasite


  • Larvae of Sarcophaga macroauriculata fly
• Obligatory Parasite


  Cannot exist without a parasitic life, incapable of surviving outside the host's environment