Enhancing the Yield of a Lab-on-a-Disk-Based Single-Image Parasite Quantification Device

Abstract

The recently proposed single-image parasite quantification (SIMPAQ) platform based on a Lab-on-a-Disc (LOD) device was previously successfully tested in field conditions, demonstrating its efficiency in soil-transmitted helminth (STH) egg detection and analysis on the level delivered by the current state-of-the-art methods. Furthermore, the SIMPAQ provides relatively quick diagnostics and requires small amounts of sample and materials. On the other hand, in a recent related study, it was revealed that the performance of the SIMPAQ method can be limited due to the action of the tangential Euler and Coriolis forces, and the interaction of the moving eggs with the walls of the LOD chamber. Here, we propose a new improved design that allows us to overcome these limitations and enhance the yield of the SIMPAQ LOD device, as demonstrated in experiments with a synthetic particle model system and real parasite eggs. Despite the simplicity, the proposed design modification is demonstrated to allow a substantial improvement in the yield of the SIMPAQ device, i.e., above 90% of parasite eggs and 98% of synthetic model particles were transported to the field of view. The new design proposed here will be further examined in the new generation of SIMPAQ devices within ongoing research on STH egg detection in field conditions.

High Specificity but Low Sensitivity of Lab-on-a-Disk Technique in Detecting Soil-Transmitted Helminth Eggs among Pre- and School-Aged Children in North-Western Tanzania

“…This microfluidic tool uses simple and cheap optical components, which are assembled in a robust tool that is portable. The technique has demonstrated excellent sensitivity to detect parasites in animal stool, as well as STH eggs in human samples with low intensity infection during preliminary field tests [ 14 , 15 ]. The technique can handle as much as 1 g of stool.…”

“…A recently adopted Lab-on-a-disk (LOD) technique [ 13 ] is designed for diagnosis of STH infections, using the floatation–dilution principle and centrifugal forces to concentrate eggs, which can be viewed in one field of view (FOV). An image can then be captured and shared via cloud servers, and analysed by different individuals worldwide at different times [ 14 , 15 ]. The innovation in this technique is the separation of eggs from other faecal matter.…”

“…It is based on a combined gravitational and centrifugal flotation, with the eggs guided to a packed monolayer enabling quantitation and identification of egg species present in a single FOV, which can be viewed using a microscope eye piece connected to a regular camera. Images of the samples can be saved and uploaded to internet cloud servers [ 14 , 15 ]).…”

“…The objective of the current study was to evaluate the performance of the purification method as a part of single-image parasite quantification (SIMPAQ) [ 13 , 14 ]), based on the LOD technique, by quantifying all the STH eggs within the entire separation disk. In the present work, we therefore do not only count the eggs that are accumulated in the FOV, but also those that are visible within the entire disk outside the FOV.…”