Kato technique

Kato technique is a diagnostic method used in parasitology to detect the presence of intestinal parasites, specifically helminths and protozoa, in fecal samples. This technique is widely utilized in the field of public health for the screening and diagnosis of parasitic infections in populations. The Kato technique is named after its developer and has been a fundamental tool in epidemiological studies and control programs for parasitic diseases.

Overview

The Kato technique involves the use of a thick smear preparation from a fecal sample on a microscope slide. A specific amount of fecal matter is placed on a slide and covered with a cellophane strip that has been soaked in glycerin and malachite green. The glycerin clears the fecal sample, making the parasitic elements more visible under a microscope, while malachite green stains the eggs, enhancing their visibility. This method allows for the quantification of eggs per gram of feces, which is crucial for assessing the intensity of infection.

Procedure

The procedure for the Kato technique involves several steps:

1. A small, standardized amount of feces (usually 41.7 mg) is placed on a specially designed template on a microscope slide.
2. The fecal sample is then flattened and covered with a piece of cellophane that has been soaked in a solution of glycerin and malachite green.
3. After a short waiting period, during which the glycerin clears the fecal matter, the slide is ready for examination under a microscope.

Applications

The Kato technique is primarily used for the diagnosis of infections caused by helminths such as Schistosoma spp., Ascaris lumbricoides, Trichuris trichiura, and hookworms. It is particularly valuable in epidemiological surveys and control programs for schistosomiasis and soil-transmitted helminthiases due to its simplicity, cost-effectiveness, and the quantitative data it provides.

Advantages and Limitations

Advantages:

• Cost-effective and simple to perform
• Requires minimal laboratory equipment
• Provides quantitative results (eggs per gram of feces), which are useful for assessing infection intensity and monitoring treatment efficacy

Limitations:

• Less sensitive for detecting low-intensity infections compared to some other diagnostic methods
• The technique's effectiveness can vary depending on the operator's skill and experience
• Not suitable for the detection of all types of intestinal parasites

Comparison with Other Techniques

The Kato technique is often compared to other diagnostic methods such as the Kato-Katz technique, which is a modification that provides improved sensitivity for certain parasites, and the formalin-ether concentration technique, which is more sensitive but also more complex and time-consuming. The choice of diagnostic method depends on the specific objectives of the study or control program, available resources, and the types of parasites of interest.

Conclusion

The Kato technique remains an important tool in the field of parasitology for the diagnosis and epidemiological assessment of helminthic infections. Despite its limitations, its simplicity, cost-effectiveness, and ability to provide quantitative data make it a valuable method for public health programs aimed at controlling and eliminating parasitic diseases.