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:[2] the problem may be that eggs of S. mansoni tend to clump together which means that even slides prepared from the same specimen may contain widely different egg counts.
[3] A comparison with the point-of-care circulating cathodic antigen (POC-CCA) method showed that the Kato technique was less sensitive.
[4] The other main argument against the Kato technique is that it is messy and therefore exposes technicians to an unnecessarily high risk of infection.
The published methods vary in detail, but generally involves a standardized amount of sieved feces being examined under light microscopy, and subsequently get a standardized count of the amount of eggs therein, in terms of number of eggs per gram.
[6][7] The technique was modified for use in field studies in 1972 by a Brazilian team of researchers led by Brazilian parasitologist Naftale Katz (b.1940),[8][9] and this modification was adopted by the WHO as a gold standard for multiple helminth infections.