An Upgrade for the Kato Katz Method

Abstract

The kato katz method was, and still is, an invaluable tool to diagnose schistosomiasis mansoni en masse in high and medium intensity infection areas that are economically backward. Due to the current sensitivity capabilities of 24 EPG, the standard kato katz method is unable to diagnose very low intensity infections. And even though alternatives are sought, none are as affordable, cost-effective and easy to use as kato katz in the context of LMICs.
As the goals of the world health organization shift from disease mapping and treatment, to post treatment surveillance and eradication of S. Mansoni, more sensitive means of egg detection are necessary. The lack of a cost effective diagnostic tool will mean a rebound in the prevalence and intensity of infection, as medication cannot be given without a diagnosis. An accurate, cost effective, and easy to use method such as the currently used kato katz thus becomes a necessity. In this light, it was thought to be prudent to explore the idea of improving the kato katz process itself, in terms of sensitivity, ease of use and sustainability.
The context of this project was strictly limited to the sample preparation process only, and the seven steps recomended by WHO were classified into filtration and smearing phases. Three concepts were generated for each phase, and evaluated relatively using the harris profile. The template filter and the draw down smearing method were chosen to be the most desirable, and were finalized for prototyping and evaluation.
Material selection was based on their ability to withstand multiple cycles of cleaning using water and regular soap. Silicone strips with a stainless steel mesh insert and PLA for draw down smearer were chosen for their resistance to soap as well as economical value. Preliminary testing with synthetic feces showed that silicone strips were too flexible during the filtration process and did not allow for consistent deposit of fecal sample onto the glass slide. Hence the material was changed to a more rigid polycarbonate.
The components were taken to Nigeria to be tested on field by one of the stakeholders, Mr. Prosper Oyibo. He let two experienced lab technicians test the components using actual feces, and took notes of their feedback, based on a questionnaire prepared before hand. Overall, the lab technicians found the improved kato katz method to have potential for on field use, given that a certain amount of changes were made, such as reduction in the amount of fecal sample, and changing the template so that feces do not collect at the corners. It may be concluded that with certain steps taken in the future, the improved kato katz method will certainly be useful.