Rapid cytologic diagnosis of respiratory cryptosporidiosis in chickens.

A method is presented for the rapid cytologic detection of cryptosporidial oocysts in Diff-Quik and modified Kinyoun acid-fast-stained tracheal imprints. On Diff-Quik-stained preparations, cryptosporidial oocysts were observed attached to the apical ends of respiratory epithelial cells or scattered throughout the imprint. These oocysts were round to oval, measured approximately 6 to 7 micron in diameter, and appeared faintly blue with fine pink granules. In modified Kinyoun acid-fast-stained tracheal imprints, the oocysts usually were pink to bright red against a blue background. Cytologic examination of tracheal imprints following Diff-Quik and modified Kinyoun acid-fast staining provides a rapid, reliable, and economical method for diagnosis of respiratory cryptosporidiosis in poultry.