1. No category

Stool Sample Preparation and estimation of worm load using Kato Katz method
( Source: http://www.who.int/wormcontrol/documents/benchaids/training_manual/en/)
1. Materials and Reagents
i.
Plastic Templates
ii.
1.5mm*6mm hole= 41.7mg of formed faeces
iii. Plastic Spatulas
iv. Nylon Screen-80mm, Mesh-20m
v. Hydrophilic Cellophane-34µm Thick-20mm
vi. Template with hole
vii. Screen Nylon or Plastic
viii. Plastic Spatula
ix. News Paper/Glazed Tile
x. Microscopic Slide
xi. Cellophane as cover slip, soaked in glycerol distilled water
xii.
Fresh Stool
xiii.
Gloves (In Kato-Katz technique for Helminth eggs Use Gloves)
2. Outline of the Procedure
i. Place a small amount of faecal material on the newspaper or the glazed tile.
ii.
Press the screen on top so that some of the faeces filter though and scrape with
the flat spatula across the upper surface to collect the filtered faeces, add the
collected faeces in the hole of the template so that it is completely filled.
iii. Remove the template carefully so that the cylinder of faeces is lift on the slide.
b.
Cover the faecal material with the pre-soaked cellophane strip.
i. Invert the microscopic slide and firmly press the faecal sample against the
cellophane strip on a smooth hard surface such as a tile.
ii.
The material will be spread evenly.
iii.
Carefully remove the slide by gently sliding it sideways to avoid separately the
cellophane slip place the slide with the cellophane upwards.
iv. The smear should be examined in a systematic manner and the eggs of each
species reported, Later multiply by the appropriate no: see inlet information of
the kato set to give no of the eggs per gm faeces.
c.
Preparation:
i. Nylon screen, Hydrophilic cellophane cut into appropriate number of pieces
4*5cm
ii. Cellophane strips placed in a Koplin Jar
iii. Allowed to soak for atleast 24hrs in 50% glycerol solution
iv. Adding 3% aqueous malachite green methylene solution - improve visibility
d. Procedure:
i. Slide uninverted and pressed against a hand smooth surface.
ii. Faecal material spreads evenly
iii. Clarification- by glycerol, for approximately one hour.
iv. Smear- newsprint can be visualized through it
v. Small amount of faecal material is placed on scrap paper
vi. Nylon screen piece placed on top and pressed
vii. Flat - Sided spatula scraped across upper surface of screen
viii. Sieved faeces is collected
ix. Template placed on center of glass slide
x.
Hole completely filled with faces from spatula excess faces removed.
xi.
Template removed carefully, leaving a cylinder of faeces on slide.
xii. Covered with a pre-soaked cellophane strip
e.
Grading the Intensity of Infections:
Smears should be examined in a systematic manner
Number of eggs of each helminth should be reported
Multiplying this by 24 gives eggs per gram of faces = EPG
3.
WHO Proposed Gradation of Infection
Grade of Infection
Helminth
Light
Moderate
Heavy
Ascaris Lumbricoides.
1-4,999epg
5,000-49,999epg
50,000epg or more
1-999epg
1,000-9,999epg
10,000epg or more
1-1999epg
2,000-3,999epg
4000 epg or more
(Round Worm)
Trichuris. Trichiura
(Whip Worm)
Ancylostoma duodenale
(Hookworm)