MIDTERMS: Kato-Katz Flashcards
It was developed in____ by the Japanese physician,______ (1913-2011), together with his adviser,______ (1891-1989)
1954
Dr. Katsuya Kato
Dr. Momoshige Miura
The technique was modified for use in field studies in_____ by a Brazilian team of researchers led by the Brazilian Parasitologist,______ (1940)
1972
Naftale Katz
Kato-Katz from the names..
Katsuya Kato
Naftale Katz
Advantages
Kato-Katz technique is used for qualitative and quantitative diagnosis of intestinal helminthic infestations; caused by Ascaris lumbricoides, Trichuris trichiura, hookworm, and especially Schistosoma spp.
Uses larger amount of stool
Qualitative & Quantitative
Mass screening purposes (WHO)
High sensitivity
Disadvantages
Can be used for formed stool only
Protozoan cysts and trophozoites can not be seen using this technique
Inter and intra - specimen variation of egg output
Lacks sensitivity for the diagnosis of low intensity infections
In the Kato-Katz technique, feces are pressed through a_____ to remove large particles/debris.
mesh screen
A portion of sieved sample is then transferred to the hole of a ______ on a slide.
Template
After filling the hole, the template is removed and the remaining sample is covered with a piece of ______ soaked in______.
cellophane
glycerol
The_____ clears the fecal material from around the eggs.
The eggs are then counted and the number calculated_____ of feces.
glycerol
per gram
Kato-set
Template with hole
screen, nylon or plastic
plastic spatula
Cellophane as cover slip, soaked in ______ or ______
glycerol-malachite green or glycerol-methylene blue solution.
Pre-analytical
Specimen:
Fresh stools collected within _______ after passage
30 minutes to 1 hour
Criteria for rejection:
Formed stool greater than 24 hours after passage before processing or preservation
Stool specimen less than a thumb size if formed
Watery stools cannot be used
The screen stainless steel, nylon or plastic should have a hole size of_____
60 - 105 um.
50% Glycerol Solution
100mL Distilled Water + 100mL Glycerine
3% Malachite Green
3% 1mL of MG or MB + 200mL Glycerol Solution
Templates used:
9 mm hole 1 mm thickness = 50mg
6 mm hole x 1.5 mm thickness = 41.7mg
6.5 mm hole x 0.5 mm thickness = 20mg
9 mm hole 1 mm thickness = ____
50mg
6 mm hole x 1.5 mm thickness =____
41.7mg
6.5 mm hole x 0.5 mm thickness =____
20mg
Specification of the plastic templates included in the Kato-Katz kits provided by
Vestergaard Frandsen
Chinese Center for Disease Control and Prevention (China CDC)
Analytical - Procedure
- Label a glass slide with the sample_____
- Place a small amount of the fecal sample on a newspaper and press a piece of_____ on top.
Using a spatula, scrape the sieved fecal material through the screen so that only the debris remains.
number/name
nylon screen
Analytical phase
- Scrape up some of the sieved feces to fill the hole in the_____, avoiding air bubbles and leveling the feces off to remove any excess.
- Carefully lift off the template and place it in a bucket of water mixed with______ so that it can be reused.
template
concentrated detergent
Analytical phase
- Place one piece of the cellophane, which has been soaked overnight in_________ solution, over the fecal sample.
- Place a clean slide over the top and press it evenly downwards to spread the feces in a circle. Carefully remove the slide by gently sliding it sideways to avoid separating the cellophane strip. If done well, it should be possible to read newspaper print through the stool smear. Place the slide with the cellophane upwards.
methylene blue glycerol
Examination & Results
Place the slide under a microscope and examine the whole area in a__________ pattern.
systematic zigzag
Examination & Results
Record _____ and _____ of each egg of each species on a recording form alongside the sample number.
Finally, multiply the number of eggs by the appropriate number (see inlet-information of the kato-set) to give the number of________- the standard measurement to assess the intensity of infection.
type and number
eggs per gram (epg)
If hookworm is present in the area the slide should be read within_______
After that time, the hookworm eggs disappear.
30-60 minutes.
Post-Analytical/Reporting
Uses_____ in proportion to the amount of stool examined.
template
Post-Analytical/Reporting
Templates = Factor (To be used to compute for EPG)
50 mg =
41.7 mg =
20 mg =
20
24 (commonly used)
50
(To be used to compute for EPG)
Factor
Reporting criteria
Formula for epg
of ova per species x template factor = # of eggs per gram (EPG) of stool
Example: You counted 951 A. lumbricoides ova in the whole Kato-Katz slide using the 20mg template. So it will be…
951 x 50 = 47,550 eggs per gram stool.
Kato-Katz or Kato Thick-Smear technique for feces
is satisfactory for detecting
medium and large helminth eggs in feces
Kato-Katz or Kato Thick-Smear technique for feces
not good for
small trematode eggs
Kato-Katz or Kato Thick-Smear technique for feces
Its chief advantage is that
a _______ of feces can be placed on the slide than the usual direct wet mount.
larger quantity
may collapse and disappear shortly after clearing, and unless preparations are examined as soon as the fecal film has cleared, _____ infections may be missed.
Hookworm eggs
This technique is of little value or no value in detecting____ infections.
protozoa
Hydrophilic cellophane -
_____thick
strips______ or ______ in size
40-50 um thick
25 x 30 or 25 x 35 mm
Glycerol-malachite green or glycerol-methylene blue solution
______of 3% aqueous malachite green or 3% methylene blue is added to____ of distilled water and mixed well.
1 ml
100 ml
To speed up clearing and examination, the slide can be placed in a_______ incubator or kept in______ for several minutes.
40°C
direct sunlight
…will remain visible and recognizable for many months in these preparations.
…clear rapidly and will no longer be visible after 30-60 minutes.
…may be recognizable for up to several months but it is preferable in a schistosomiasis endemic area to examine the slide preparations within 24. hours.
Ascaris and Trichuris eggs
Hookworm eggs
Schistosome eggs
With high egg counts, to maintain a rigorous approach while reducing reading time, the ____________ with 0.1 mol/liter NaOH may be recommended (Basic Laboratory Methods in Medical Parasitology, WHO, 1991).
Stoll quantitative dilution technique
is a clearing solution
Glycerine
Purpose of malachite green is to
give color to the cellophane in order to give a pale green background to the eggs
to minimize the brightness of the microscopic field
If malachite green is not available, green ________ may be used.
cellophane soaked in glycerine
The preparation is best examined within…
10 to 20 minutes
It is very good in detecting eggs with thick shells…
but not eggs with thin shells…
(e.g., Ascaris and Trichuris)
(e.g., hookworm).
In many instances, if the preparation is kept too long before examination, ________ become too transparent or distorted, making identification very difficult.
hookworm eggs
Usefulness is limited if stools are ______.
Likewise, it is not able to detect_____ and _____
diarrheic or watery
protozoan cysts and trophozoites
…is the main determinant for the sensitivity of this technique, since well-formed stools yield higher egg counts than moist ones.
Consistency of the stool
For the identification of Schistosoma ova,_________ can be layered over the cellophane paper.
This method can help in the visualization of the_____.
1% eosin solution
miracidium
Percentage of glycerol sol
50%
Percentage of malachite green
3%
Most commonly used factor
24
