[Improvement in the diagnosis of opisthorchiasis by fecal egg count]

Chemical sedimentation method of coproovoscopic diagnosis of trematodoses was modified: sodium nitrate was replaced by sodium nitrite (this increased the helminthic egg membrane hydrophilia) and the optimal ratio of sodium nitrite to acetic acid solution volumes was experimentally selected. This improved the method sensitivity twofold (p less than 0.001). Three series of investigations of the sensitivities of the modified chemical sedimentation method, microscopy of the native smear, Kato's, Hein's, Kalantaryan's, Stoll's methods, and ether-formalin sedimentation of helminthic eggs were carried out with the material from opisthorchiasis patients with invasion of low intensity. The modified technique proved to be the most sensitive (p less than 0.01) and productive (p less than 0.001). It is recommended for screening the population at endemic regions and for control analyses after etiotropic therapy of trematodosis patients.