Intro to Parasitology

• Parasitology


  science that deals with organisms that live temporarily or permanently on or within other living organisms for the purpose of procuring food
• Types of Parasites

  • obligate
  • facultative
  • permanent
  • incidental
  • definitive
  • intermediate
  • reservoir
  • paratenic
• Obligate parasite


  completely dependent on the host at some stage of its development
• Facultative parasite


  having free-living or parasitic existence

  ex. Naegleria fowleri
• Temporary parasite


  free-living parasite
• Permanent parasite


  lives in from early life to maturity
• Incidental parasite


  parasite that does not normally live
• Parasite acc. to habitat

  • ectoparasite
  • endoparasite
• Ectoparasite


  parasite that lives outside the body of host. It cause infestation.

  ex. Lice, ticks, fleas
• Endoparasite


  parasite that lives inside the body of host. It causes infection.

  ex. helminths, protozoans
• Parasite acc. to number of host

  • monoxenous
  • heteroxenous
• monoxenous


  parasite requires only single host
• heteroxenous


  parasite requires more than one host
• Parasite acc. to sexes

  • monoecious
  • dioecious
• Monoecious


  • hermaphroditic
  • complete functional set of sex organs in one individual
  • ex. Flukes (Trematodes) and Cestodes (tapeworm)
• Dioecious


  • sexes are separated
  • ex. Nematodes
• Parasite acc. to the number of cells

  • Protozoans
  • Metazoans
• Definitive parasite

  • adult sexual stage
• Intermediate parasite

  asexual larval stage
• Reservoir 


  • adult stage
  • source of transmission
• Paratenic


  • arrested stage of development
• Infection


  presence of parasite in the host
• Disease


  manifestation of symptoms
• Pathogenicity


  capability of parasite to produce disease
• Virulence


  degree of pathogenicity
• 2 types of vector

  • Biological vector
  • Mechanical vector
• Biological vector


  type of vector that is essential to life cycle
• Mechanical / Phoretic vector


  type of vector that is not essential to life cyle
• zoonotic infections


  type of infection that is normally transmitted only among animals
• Carrier


  harbors pathogen without manifesting any signs and symptoms
• Exposure


  process of inoculation
• Infection


  establishment of infective agent to host
• incubation period


  period between infections and evidence of symptoms
• Pre-patent or Biological incubation


  period between infection and evidence of infection
• autoinfection / one's self


  own direct source of infection
• Superinfection / Hyperinfection


  individual further infected by a particular parasite
• Epidemiology


  study of patterns, distribution and occurrence of disease
• incidence 


  number of new cases
• prevalence


  number of individual in a population estimated to be infected
• Cumulative prevalence


  percentage of individual infected by least one parasite