Web-based virtual microscopy for parasitology: a novel tool for education and quality assurance

Abstract

Background: The basis for correctly assessing the burden of parasitic infections and the effects of interventions relies on a somewhat shaky foundation as long as we do not know how reliable the reported laboratory findings are. Thus virtual microscopy, successfully introduced as a histopathology tool, has been adapted for medical parasitology.

Methodology/principal findings: Specimens containing parasites in tissues, stools, and blood have been digitized and made accessible as a "webmicroscope for parasitology" (WMP) on the Internet (http://www.webmicroscope.net/parasitology).These digitized specimens can be viewed ("navigated" both in the x-axis and the y-axis) at the desired magnification by an unrestricted number of individuals simultaneously. For virtual microscopy of specimens containing stool parasites, it was necessary to develop the technique further in order to enable navigation in the z plane (i.e., "focusing"). Specimens were therefore scanned and photographed in two or more focal planes. The resulting digitized specimens consist of stacks of laterally "stiched" individual images covering the entire area of the sample photographed at high magnification. The digitized image information (approximately 10 GB uncompressed data per specimen) is accessible at data transfer speeds from 2 to 10 Mb/s via a network of five image servers located in different parts of Europe. Image streaming and rapid data transfer to an ordinary personal computer makes web-based virtual microscopy similar to conventional microscopy.

Conclusion/significance: The potential of this novel technique in the field of medical parasitology to share identical parasitological specimens means that we can provide a "gold standard", which can overcome several problems encountered in quality control of diagnostic parasitology. Thus, the WMP may have an impact on the reliability of data, which constitute the basis for our understanding of the vast problem of neglected tropical diseases. The WMP can be used also in the absence of a fast Internet communication. An ordinary PC, or even a laptop, may function as a local image server, e.g., in health centers in tropical endemic areas.

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Figure 1. Part of the website for parasitology (www.webmicroscope.net/parasitology), showing “thumbnails” of currently available parasitological specimens (marked as Sample), which have been digitized for viewing at different magnification and freely navigable in the x and y plane.

Focusing (navigation) in the z plane is possible in pictures made up of several layers as indicated for stool samples.

Figure 2. Smear from skin lesion containing Leishmania amastigotes in annotated area (ROI number 3).

(A). Numerous plasmodia in thin blood film from patient with Plasmodium falciparum malaria of Malaria Sample 2 (B). Giemsa-stained specimens at highest magnification (40× objective) as seen on the monitor screen.

Figure 3. Two diagnostic staining patterns in the indirect IF test for antischistosoma antibodies using sections of adult S. mansoni worms as antigen.

Antibodies (anti-GAA) react with “gut associated antigens” of male and female parasites (A). Antibodies (anti-SA) react with interstitial parenchymal “somatic” structures (B). The former pattern is typical for recently acquired infection whereas the latter pattern is seen in chronic infection. Magnification in A 5× objective, B 10×.

Figure 4. Helminth eggs and Entamoeba spp. cyst in “stool sample 1” at the website for parasitology (www.webmicroscope.net/parasitology).

Arrows at the overview panes indicate the area of the samples, which are seen on the screen at the desired magnification. The size of any object can be measured using the ruler as seen in (C). The figures D to E show the appearance of a 3-dimensional object, a Taenia spp. egg, scanned at 4 different focal planes. The composite picture, which consists of 5 different layers, can be navigated in the z-plane which gives the illusion of smooth focusing. For further legends to this Figure 4 see Table 1.