PARASITE, FUNGI & VIRUSES

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

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.

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

Cilia: Example: Balantidium coli non motile: Example : Plasmodium species (ring stage)

Entamoeba Trophozoite Cyst

Protozoa Balantidium coli cyst Protozoa Trypanosoma Protozoa Balantidium coli cyst

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.

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.

Helminths Ascaris lumbricoides egg

Helminths Tenia saginata adult and ova

Helminths Schistosoma ova

Arthropods Are insects such as bugs ,fleas, biting flies, mosquitoes etc. Harmful effects of arthropods: 1) Discomfort, transmission of diseases ( malaria, yellow fever, typhus). 2) cause disease (amoebic dysentery, bilharzias).

Mycology: The Study of Fungi Fungi: Group of Heterotrophic Eukaryotes cells. Fungi are called Saprophytes because they obtain nutrients from dead organic material. Some fungi can absorb organic nutrients from living tussue. Classification of Fungi: Yeast. Mold.

1)Yeast: Oval, spherical, tear drop shape. Single cell (unicellular). One nucleus. Multiply asexual by budding resulting in production of two cells.

2)Mold: Consist of branching hyphae forming mycelium. Multicellular. Multinucleated cell. Reproduce sexually and asexually.

What are the best conditions for fungal growth? 1) PH: Grow within a wide range pH especially acidic (4-6). 2) Temp: Room temperature: superficial infections. 37C: Systemic infection (pathogenic Fungi). Cold temp: Spoilage of food. 3) Humidity: Prefer moist or humid atmospheres.

4) Media: Sabouraud Dextrose agar media (SDA). Contains: source of protein ----(peptone). source of carbohydrate ---(dextrose). Potato Dextrose Agar (PDA). made from potato and dextrose

Yeast /Molds on SDA Yeast Mold

LACTO-PHENOL-COTTON BLUE (LPCB): Reagent used to stain fungi for microscopic examination. Why do we cultivate? Diagnosis Research Production of vaccines

Fungi Yeast LPCB x40

Benefits of fungi: Harmful effects: Baking: by using yeast. Antibiotic: penicillin extracted from penicillium. Saprophytes: Breaking down of dead organic material. Wine production. Harmful effects: cause a lot of diseases in skin, hair, nail and systemic diseases.

Fungi Molds using LPCB x40 Alternaria species

Fungi Molds using LPCB x40 Penicillium

Fungi Molds using LPCB x40 Aspergillus species

Tools used for fungi Iron needles: made from iron because fungi dig into the agar.

Virology: Study of viruses Viruses are obligate intracellular agents: can multiply only in living cells. Consist of 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.

Some viruses are enveloped others are naked. Vary in size from 20-300 nm

Viruses are examined only by Electron microscope. Viruses Can infect humans, animals, plants and bacteria. Viruses that infect bacteria are called bacteriophages.

Cultivation of viruses : A) Animal inoculation eg: mice b) Embryonated egg inoculation. C) Tissue cell culture (see CPE).

Cytopathic effects (CPE): Is the morphological changes in cell caused by the viral infection. Figure: a. Monolayer of normal fetal tonsil cells. b. tonsil cells with adenovirus. c. tonsil cells with herpes simplex infection and monolayer destroyed.