Parasitology

• Protozoans


  Single celled eukaryotic organisms with different sizes and shape
• Parasitic protozoans


  • Possess nucleus with different sizes and shape
  • With cytoplasm (2 regions): Ectoplasm (outer) and Endoplasm (inner)
• Ectoplasm


  Outer region of cytoplasm, used for respiration, procurement and digestion of food, excretion of metabolic wastes, and protection
• Endoplasm


  Inner region of cytoplasm, with more fluid present, Hydrophilic
• Nucleus


  • Most important organelle
  • Contains the chromosomes, essential to life
  • For reproduction and genetic transmission of the organism
  • With karyosome (nucleolus), used for identification
• Karyosome


  Nucleolus in parasitic protozoans, located in the center of the nucleus, surrounded by chromatin granules, important for species identification
• Vacuoles


  • Contains food reserve (glycogen and protein)
  • Reproduction: asexual (binary fission) and/or sexual
• Locomotory organelles


  • Flagella, cilia, pseudopodia, arising from the ectoplasm, primary basis of classifying the organisms
• Pseudopodia


  False feet, arising from endoplasm, true from amoeba
• Phyla of protozoans


  • Mastigophora
  • Ciliophora
• Cilia


  Short hair-like structures, outer part of ectoplasm
• Flagella


  Long hair-like structures, ectoplasm
• Subphyla of Sarcomastigophora


  • Sarcodina
  • Mastigophora
• Classes of Sarcodina


  • Lobosea (Amoeba)
  • Zoomastigophora (Flagellates)
• Protozoans inhabiting the digestive tract

  • Entamoeba histolytica (only pathogenic)
  • Entamoeba dispar
  • Entamoeba hartmanni
  • Entamoeba coli
  • Endolimax nana
  • Iodomoeba butschlii
  • Blastocystis hominis
• Entamoeba gingivalis inhabits the oral cavity
• Naegleria sp. and Acanthamoeba sp. are free-living protozoans that can complete their life cycle outside the host and can infect the brain
• SUBPHYLUM MASTIGOPHORA (FLAGELLA) - Species that inhibit:


  • Digestive tract
  • Oral cavity
  • Genitalia
  • Circulatory system (Blood flagellates or Hemoflagellates)
• Species that inhibit the digestive tract

  • Giardia lamblia
  • Trichomonas hominis
  • Chilomastix mesnili
  • Dientamoeba fragilis
• Trichomonas tenax inhibits the oral cavity
• Trichomonas vaginalis inhibits the genitalia
• Blood flagellates or Hemoflagellates

  • Leishmania sp
  • Trypansoma sp
• Class kinetograminophorea, Order Trichostomatida belongs to Ciliates - infect human (Cilia)
• Balantidium coli


  Intestinal protozoans; BIGGEST; Bigger than egg of the smallest helminth
• Phylum Sarcomastigophora and Phylum Ciliophora have locomotory organelles
• PHYLUM APICOMPLEXA has no locomotory organelles but has an Apical Complex with Polar rings, Rhoptries, and Micronemes. It has asexual reproduction.
• Classes and Orders within PHYLUM APICOMPLEXA

  • Class Sporozea
  • Subclass Coccidea
  • ORDER EUCOCIDIIDA
  • SUBORDER EIMERIINA
  • SUBORDER HAEMOSPORINA
  • ORDER PIROPLASMIDA
• SUBORDER EIMERIINA


  • Zygote (not motile); sporozoites are enclosed in sporocyst within oocyst; inhabit the intestinal epithelium
  • Includes Cryptosporidium spp, Isospora sp, Sarcocystis sp, Toxoplasma gondii
• SUBORDER HAEMOSPORINA


  • Zygote motile (ookinete); sporozoites are naked with 3 membrane wall; inhabit the blood
  • Includes Plasmodium sp
• All amoeba develop a cyst stage except E. gingivalis
• E. gingivalis is an oral amoeba
• Amoeba found in the colon

  • All except E. gingivalis
• Commensal amoeba


  • All amoeba except E. histolytica
• E. histolytica


  Pathogenic amoeba
• Trophozoite stage


  Vegetative/feeding stage, possesses locomotory organelles
• Amoeba


  • Locomotory organelles are pseudopodia (immature stage)
• Cyst stage


  Infective stage, more resistant to the environment
• Entamoeba histolytica is the only pathogenic Entamoeba
• Entamoeba histolytica trophozoite


  • Measures 15-60 um
  • Motile with long finger-like pseudopodia
  • Motility is progressive and directional
  • Invasive and pathogenic
  • With ingested RBCs
  • Pseudopodia are cytoplasmic protrusions that may be formed at any surface of the organism
  • Spoke-like radial arrangement
  • Feeding stage (ingests RBC)
  • Nuclear membrane is delicate, lined with a single layer of uniformly distributed fine chromatin granules
• Entamoeba histolytica cyst


  • Spherical (12-20 um)
  • With 1-4 nuclei
  • Central karyosome
  • Mature cyst with 4 nuclei is the infective stage
  • Cytoplasm contains cigar-shaped chromatoidal bodies (refractile, sausage-shaped bars with rounded ends, composed of crystalline ribonucleic acid, function is to produce protein, tend to disappear as the cyst matures)