The Kato technique (also called the Kato–Katz technique) is a laboratory method for preparing human stool samples prior to searching for parasite eggs.

Indications

The Kato technique is now most commonly used for detecting

schistosome ''Schistosoma'' is a genus of trematodes, commonly known as blood flukes. They are parasitic flatworms responsible for a highly significant group of infections in humans termed ''schistosomiasis'', which is considered by the World Health Organ ...

eggs. It has in the past been used for other

helminth Parasitic worms, also known as helminths, are a polyphyletic group of large macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted and infect the gastrointestinal tract. Other par ...

eggs as well. It cannot be used to identify

hookworm Hookworms are Gastrointestinal tract, intestinal, Hematophagy, blood-feeding, parasitic Nematode, roundworms that cause types of infection known as helminthiases. Hookworm infection is found in many parts of the world, and is common in areas with ...

eggs because they collapse within 30 to 60 minutes of preparation using this method. One study of 299 subjects infected with ''

Schistosoma mansoni A paired couple of ''Schistosoma mansoni''. ''Schistosoma mansoni'' is a water-borne parasite of humans, and belongs to the group of blood flukes (''Schistosoma''). The adult lives in the blood vessels ( mesenteric veins) near the human inte ...

'' 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 ''S. mansoni ''tend to clump together which means that even slides prepared from the same specimen may contain widely different egg counts. A comparison with the point-of-care circulating cathodic antigen (POC-CCA) method showed that the Kato technique was less sensitive. 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, but generally involves a standardized amount of sieved feces being examined under

light microscopy Microscopy is the technical field of using microscopes to view subjects too small to be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical, el ...

, and subsequently get a standardized count of the amount of eggs therein, in terms of number of eggs per gram. It can possibly involve staining the fecal sample.

History

It was developed in 1954 by Japanese medical laboratory scientist Dr. Katsuya Kato (1912–1991). 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), and this modification was adopted by the

WHO The World Health Organization (WHO) is a specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Geneva, Switzerland, and has 6 regional offices and 15 ...

as a gold standard for multiple helminth infections.

Indications

Method

History

See also

References

Further reading