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Understanding Parasites: From Protozoa to Viruses

Explore the world of parasites, from eukaryotic organisms to viruses, and learn about their life cycles, classifications, and harmful effects. Discover how protozoa move, helminths' complex life cycles, characteristics of arthropods, and the unique features of fungi. Delve into the microscopic examination of fungi and the essential role of viruses as obligate intracellular parasites. Gain insights into different types of parasites, their transmission methods, and the effects they have on humans, animals, and plants.

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Understanding Parasites: From Protozoa to Viruses

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  1. Parasites ,Fungi, Viruses

  2. Parasites • Are eukaryotes that depend on another host for their nutrients and metabolic activities. • Divided to 1-Protozoa: Unicellular. 2-Helminths: Multicellular. 3-Arthropods: Multicellular.

  3. Protozoa • Common stages of life cycle 1- Trophozoite: active growing stage 2- Cyst: resting non active stage • Can infect all major tissues and organs of the body • Transmission of protozoan parasites by 1- injection via bites of blood sucking insects 2- ingestion of infective stages

  4. Protozoa • Protozoa move by : • Psuedopod: (extending part of protoplasm towards direction of movement) Example: Entamoeba species • Flagella : Example: Trypanosoma species, GiardiaLamblia

  5. Protozoa • Cilia: Example: Balantidium coli • non motile: Example : Plasmodium species

  6. Trophozoite Cyst Entamoeba

  7. ProtozoaTrypanosoma

  8. ProtozoaBalantidium coli cyst

  9. ProtozoaRing stage))Plasmodium

  10. Helminths(worms) • Multicellular organisms with organ systems as digestive, nervous , excretory system. • Have complicated life cycle • Mostly have different stages of life cycle which are: ova(egg), larvae (Adult) • Adult worms can measure centimeters or even meters long • Extracellular parasites

  11. Helminths • Are classified according to shape into: 1- Nematodes (round worms) cylindrical thin Example: Ascaris lumbricoides 2- Cestodes ( tape worms)flat long worms Example: Tenia saginata,tenia solium 3- Trematodes( Flukes)leaf like flat worms Example: Schistosoma species

  12. HelminthsAscaris lumbricoides egg

  13. HelminthsTenia saginata adult and ova

  14. HelminthsSchistosoma ova

  15. Arthropods • Are insects such as bugs ,fleas, biting flies, mosquitoes etc. • Harmful effects of parasites Discomfort, transmission of diseases( malaria, yellow fever, typhus), cause disease(amoebic dysentery, bilharzias), damage to crops.

  16. Fungi • Heterotrophic eukaryotes • Saprophytes: obtain nutrients from dead organic material • Nucleated achlorophyllous organisms • Reproduce sexually and asexually • Surrounded by true cell wall • 2 groups Yeast and mold

  17. Fungi • Grow within a wide range pH(acidic-alkaline) • Grow at room temperature (can grow at cold temp) • Prefer moist or humid atmospheres • Can be cultured in Sabouraud Dextrose agar media (SDA) or potato dextrose agar (PDA) that contains a source of protein (peptone) and a source of carbohydrate (dextrose)

  18. Fungi • The commonest microscopic examination of fungi is LACTO-PHENOL- COTTON BLUE tease mount or reagent (LPCB) • Benefits of fungi: important in baking , pharmaceutical(antibiotic),brewing industries. Also as saprophytes and as food. • Harmful effects: cause a lot of diseases in skin, hair, nail and systemic diseases.

  19. Fungi • Yeast Unicellular, round or oval( tear drop)shape Multiply asexually by budding resulting in production of 2 cells • Molds Multicellular branching hyphea forming a mycelium.

  20. Fungi Molds using LPCB x40 Alternaria species

  21. FungiMolds using LPCB x40 Penicillium

  22. Fungi Molds using LPCB x40 Aspergillus species

  23. FungiYeast LPCB x40

  24. Fungi /Molds on SDA

  25. Tools used for fungi • Iron needles made from iron because fungi dig into agar thus it is difficult to culture them with wire loop

  26. Viruses • Virus in Latin means poison • All viruses are obligate intracellular parasites( can multiply only in living cells) • Possess a single type of nucleic acid either DNA or RNA (Ss or Ds) • Nucleic material is enclosed in a protein coat called capsid. ( both capsid and nucleic acid are called nucleocapsid)

  27. Viruses • Vary in size from 20-300nm • Cannot be seen by bright field microscope • Can be examined by Electron microscope • Can infect humans, animals, plants and bacteria • Viruses that infect bacteria are called bacteriophages

  28. Viruses • Isolation of viruses : a- animal inoculation b- embrynoted egg inoculation c- cell culture • Cytopathic effects are morphological changes in cell lines due to virus infection.

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