Laboratory: Parasitology

• The base ensures that the microscope is planted firmly on the table.
• The base is one of the parts of the microscope that is supported when moving the microscope around
• The flat mirror is used when viewing specimens in bright or natural light conditions.
• The concave mirror is used when there islittle light available.
• The mirror serves to supply the light by reflecting lightfrom a light source.
• The arm is attached to the base of the microscope
• The inclination joint is found between the arm and the base of the microscope
• The inclination point allows a person to incline the microscope for convenient viewing of the specimen
• The stage is where the specimen is placed for observation
• The stage clip is where it serve to hold the specimen in place
• The condenser is a lens serves to concentrate light rays on the specimen
• The iris diaphragm regulates the amount of light that illuminates the specimen
• The adjustment knobs used for focusing the image of the specimen
• The adjustment knobs may be found near the base or on the arm of the microscope
• The coarse adjustment knob is used for the low-power and scanning objectives
• The fine adjustment knob is used for the high power and oil immersion objectives
• The revolving nose piece is found at one end of the body near the stage or where the specimen is to be placed
• The revolving nosepiece contains the objective lens
• The revolving nose piece is often covered by a structure called dust field
• Scanning (4x)

  Low power (10x)

  High power (40x)

  Oil immersion (100x)
• The objective lenses are often parfocal
• The objective lenses are often equipped with a spring device to prevent damage to the lens in case it accidentally touches the specimen
• The eye piece is found at the other end of the draw tube
• The eye piece contains the ocular lens
• The saline direct mounts provides opportunity to study the motility of any trophozoites present
• The addition of iodine stains the internal structures necessary for identification of the cysts of some amoeba and other protozoa, trophozoites are rapidly killed and are sometimes unidentifiable.
• Low power is used to scan for large helminth eggs or larvae.
• High power is used to detect and identify smaller parasites and larger helminth eggs and larvae.
• Rare (Protozoa and Helminths)

  2 to 5 organisms per 22 mm square coverslip
• Few (Protozoa)

  1 organism per 5 to high-power fields (44x)
• Moderate (Protozoa)

  1 to 2 organisms per high-power field, to as few as 1 organism per 2 to 3 high-power fields
• Few (Helminths)


  1 egg/larva per 5 to 10 low-power fields (10x)
• Moderate (Helminths)


  1 to 2 eggs/larvae per low-power field
• Many (Helminths)

  Several eggs/larvae in every low-power field
• Many(Protozoa)

  Several organisms in every high-power field
• Iodine wet preparations are most useful for protozoan less so for helminths.
• A transparent adhesive (cellophane) tape test (sometimes called a "Scotch tape" test) refers to the collection and examination of a sample from the skin around the anus.
• The scotch tape method is used to identify pinworms and pinworms eggs
• The female pinworm (Enterobius vermicularis) migrates out of the anus at night to deposit her eggs on the perianal region
• The specimen should be obtained first thing in the morning before the patient bathes or defecates