The Kato technique (also called the Kato-Katz technique) is a laboratory method for preparing human stool samples prior to searching for parasite eggs.
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Indications
The Kato technique is now most commonly used for detecting schistosome eggs. It has in the past been used for other helminth eggs as well. It cannot be used to identify hookworm eggs because they collapse within 30 to 60 minutes of preparation using this method. One study of 299 subjects infected with Schistosoma mansoni found that the method had poor reproducibility and is therefore no longer recommended for primary health care settings: the problem may be that eggs of Schistosoma mansoni tend to clump together which means that even slides prepared from the same specimen may contain widely different egg counts. The other main argument against the Kato technique is that it is messy and therefore exposes technicians to an unnecessarily high risk of infection.
Method
The published methods vary in detail, however one involves staining a sieved fecal sample and examining it under a microscope. The total number of stained eggs are counted and used to calculate the number of eggs per gram.