Visualization of hydatid elements: Comparison of several techniques

Some techniques available at our laboratory were tested for their ability t o aid in the morphological diagnosis of hydatid elements (Echinococcus gran ulosus ["Taenia echinococcus"]) isolated from cysts in humans and sheep, Un stained, methanol-fixed hooklets were fluorescent, most starkly so under vi olet light (excitation filter wavelength, 405 nm; long-pass filter waveleng th, 495 mn), Auramine-rhodamine and Gram procedures failed to stain hooklet s, Ziehl-Neelsen stain yielded indifferent results when organisms were view ed under transmitted light but resulted in a surprisingly intense red fluor escence when organisms Here viewed under green light (excitation, 546 nm; l ong pass, 590 nm), Wheatley trichrome stain gave better and more uniform re sults than fuchsin, Ryan trichrome blue stain was the best under transmitte d Light; hooklets stained uniformly and intensely and were easily distingui shable from the background. Very satisfactory results were also obtained wi th a much simpler procedure (modified Baxby technique: no fixation, steamin g hot 1% safranin for 2 min, and malachite green for 30 s), Therefore, Ryan and modified Baxby stains are recommended for the examination of E. granul osus under transmitted light. For fluorescence microscopy, Ziehl-Neelsen st ain under green excitation light, or violet light with no staining, is also very useful. Epifluorescence microscopy is especially convenient for exami ning samples concentrated by filtration, as it renders the filter pores inc onspicuous.