MICP MID 2

• Parasitology


  Deals with the parasites which causes human infection and diseases
• Symbiosis


  Form of relationship by 2 unlike organisms
• Parasitism


  1 species (symbiont/ parasite) benefits to the detriment of the other, parasite deprives the host of essential nutrients
• Elements in Parasitism


  • Parasite - lives on and in other living organism for survival
  • Host - harbor the parasite and provide its nourishment
• Commensalism


  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
• Mutualism


  Relationship where two organisms mutually benefit each other
• Classification of Parasites based on Major Forms


  • Protozoa - Single celled
  • Metazoan (Helminths) - Multicellular

  
• Protozoa


  • Sporozoan (sporozoans) - No movement
  • Sarcodina (amoebas) - No feet
  • Mastigophora (flagellates) - Flagella
  • Ciliata (ciliates) - Cilia; hairlike structures

  
• Metazoan (Helminths)


  • Platyhelminthes - flatworms
  • Cestode - tapeworms
  • Trematoda - flukes
  • Nemathelminths - roundworms

  
• Parasites based on habitat


  • Ectoparasites - Live outside of host body
  • Endoparasites - Live inside the body of host
• Infestation


  Invasion of the body by ectoparasites
• Infection


  Invasion of the body by endoparasites
• Parasites based on ability to live independently of the host

  • Facultative parasites - Can live independently of the host
  • Obligate parasites - Must exist as parasite inside a host
• Parasites based on mode of living

  • Permanent parasites - Remain in a host from early life to maturity
  • Intermittent parasites - Simply visit the host during feeding time
  • Incidental parasites - Occur on an unusual host
  • Transitory parasites - Larva develops in a host while the free-living during adult stages
  • Erratic Parasites - Becomes fixed in an unusual organ, different form that which it ordinarily parasitized
  • Aberrant Parasites - Wandering parasites infects host where it cannot develop any further

  
• Types of Host


  • Definitive Host - Harbors the adult stage or sexual stage
  • Intermediate Host - Harbor the larval or asexual stage of the parasite
  • Reservoir Host - Vertebrate hosts which harbor parasite and act as source of infection in man
  • Paratenic Host - Serve as means of transport for parasites
  • Accidental Host - Living organism that can serve as a host in a particular parasites life cycle but is not a usual host in the life cycle
• Sources of Exposure to Infection or Infestation

  • Contaminated soil
  • Contaminated water
  • Food
  • Insect vectors - biological/ mechanical
  • Animal - domestic/ wild
  • Other persons - his clothing, bedding or immediate environment
  • Self - autoinfection
• Mode of transmission


  • Oral transmission
  • Skin Transmission
  • Direct transmission
  • Transmammary
  • Transplacental/congenital infection or Vertical transmission
  • Inhalation of airborne
  • Vector Transmission
  • Iatrogenic Transmission
• Portal of Exit


  • Anus
  • Urine
  • Sputum
• Pathogenesis of Parasitic Infection

  The development of a disease and the chain of events leading to that disease
• Inapparent Infection


  No symptoms, infection can remain inapparent continuously for long periods of time
• Lytic necrosis


  Enzymes produced by parasite for them to digest food available in the immediate environment may cause harm to the host tissues
• Traumatic/ Physical Damage


  Entry of infective larvas of hookworms or blood flukes may produce slight physical damage, Acute intestinal obstruction may be produced from large worms

  
• Stimulation of host tissue reaction

  Increases eosinophile – one of the body's defense against parasites, destruction of RBC
• Stimulation of neoplastic growth


  Cancer growth, e.g. in GIT - Schistosoma japonicum (liver cancer), Clonorchis sinensis (biliary duct cancer)
• Toxic and Allergy Phenomena (Immunopathology)


  • Type 1: Allergy or anaphylactic
  • Type 2: Anti-body mediated
  • Type 3: Immune complex
  • Type 4: Cell-mediated
• Opening of pathways for entry of other pathogens into tissues


  The presence of parasites and that damage they produce to the tissues may favor the entry and proliferation of other organisms, especially bacteria
• General Life Cycle of Parasites


  • The Infective Stage
  • The Pathogenic Stage
  • The Diagnostic Stage
• Protozoa


  Unicellular eukaryotic microorganism, live in other plants, animals or humans where they cause disease, usually they're parasitic, feed on organic matter such as other microorganisms or organic tissues and debris
• Characteristics of Protozoa


  • Mostly unicellular organism with fully functional cell
  • Live freely, may be parasitic or symbiotic
  • Protozoa are chemo heterotrophs – derives energy from chemicals and needs to consume other organism in order to live
  • They are motile because have locomotive organelles. E.g., Flagella and Cilia for movement
• Morphology of the Protozoa

  • Eukaryotic resemble to animal cell
  • Their organelles are highly specialized for feeding, reproduction and movement
  • The cytoplasm of protozoa is divided into an outer layer called Ectoplasm and an inner layer called Endoplasm
  • The size of Protozoa is range between 3 to 300 micrometers
  • Few ciliate and Amoeba are larger enough to be seen with naked eyes
  • Except Sporozoite's, all types of protozoa are motile either through Flagella, cilia or Pseudopodia
  • Have Eyespot that can detect change in light

  
• Nutrition of Protozoa


  Most feed on dead plants and animal debris while some (trophozoites) feed on bacteria and Algae, Parasitic Protozoa feeds on the fluids and tissues of their host
• Types of Protozoa


  • Amoebas
  • Ciliates
  • Flagellates
  • Apicomplexans

  
• Amoebas (Sarcodines)


  Move using pseudopia, most are harmless, Entameba is the largest phylum
• Ciliates/ Phylum Ciliophora


  Use cilia (fine hairlike structures) for movement, most are harmless, Balantidium coli causes Dysentery

  
• Flagellates/ Sacromastigophora


  • Trichomonas spp - Agent of trichomoniasis
  • Giardia Lamblia - Infects a variety of domestic and wild animals, the most common intestinal parasite of people in North America

  
• Trichomonas Vaginalis


  Trich is caused by a one celled protozoan organism, transmitted sexually
• Giardiasis (lambliasis)


  A human parasite of the gastrointestinal tract, spread direct contact or through contaminated food and water, Giardia spp. are pear shaped, with hair-like flagella for motility

  
• Apixocomplexan/ Sporozoates


  • Are non-motile, intracellular parasites, large phylum of parasitic alveolates, Plasmodium falciparum: Malaria, Toxoplasma Gondii: Toxoplasmosis

  
• Apicoplasts


  A relict, non-photosynthetic plastid found in most protozoan parasites

  
• Reproduction in Protozoa


  • Binary fission
  • Plasmotomy
  • Multiple fission/ Schizogony
  • Budding