Utilising Virtual Microscopy for Parasitology EQA: Standardising the Gold Standard

Intestinal parasites pose a significant global public health burden. Approximately 3.5 billion people are affected by intestinal parasitic infections globally, with more than 200,000 deaths reported annually. While diagnostic methods such as PCR and serology have their advantages, they may not be as sensitive or specific as microscopy, which remains the gold standard for identifying parasitic micro-organisms in biological samples. The foundation of this statement remains true, as long as the proficiency of the laboratory technician performing the analysis is maintained to a high standard. In this regard, external quality assurance (EQA) programs are essential for medical laboratories as they help ensure the accuracy and reliability of laboratory testing results and assess the proficiency of the operator.Providing EQA material for parasitology proficiency testing programs (PTPs) has historically presented many challenges. Sourcing samples of sufficient quality and quantity to satisfy the requirements of a parasitology PTP is often a major difficulty. Once a suitable sample has been sourced, additional challenges arise in maintaining sample stability and homogeneity to ensure all participants receive a sample representative of the desired final interpretation. The Royal College of Pathology of Australasia Quality Assurance Programs (RCPAQAP) has begun a pilot study to assess the feasibility of using virtual microscopy to resolve some common problems encountered while procuring and planning parasitology PTPs.Virtual microscopy allows digitisation of parasitology microscope slides for viewing and analysis on a computer or other digital device. RCPAQAP uses the MetaSystems VSlide slide scanner paired with the Zeiss Axio Imager Z2 for virtual slide scanning. This apparatus can capture over 200,000 images per slide across 17 individual focal planes, stitched together into a final ultra-high resolution virtual slide image using Metasystems Metafer software. The final product is a virtual slide that effectively emulates visual microscopy of a physical sample while ensuring each participant is assessed equally. This technology is perfectly suited for this type of sample. It provides solutions to issues related to standardisation across all PTP participants and the transport and storage of EQA materials.