Triple faeces test: An effective tool for detection of intestinal parasites in routine clinical practice

Microscopic examination of stool specimens is the cornerstone of detection of intestinal parasites in parasitology laboratories. In Europe, fresh, nonpreserved stool specimens are generally used for examination. Because intestinal parasites are shed intermittently, patients are asked to deliver multiple stool samples for examination. The limitation of this diagnostic approach is that detection of the vegetative stages of protozoa may be missed because of delays in processing and/or low compliance with the request to submit multiple stool samples. To overcome this limitation, a diagnostic test that combines multiple sampling (on 3 consecutive days), a fixative (SAF; sodium acetate acetic acid formalin), a concentration method and an easy-to-use permanent stain (chlorazol black dye) was developed for use in routine clinical practice. The results of the test, called the Triple Faeces Test (TFT), were compared with those of the conventional diagnostic method, i.e. ether sedimentation of a single fresh stool specimen. Stool samples from 544 patients were examined. Vials from the TFT-sets were filled by patients precisely according to instructions in 462 of 544 (85%) of the cases. Using the conventional method and the TFT, 106 and 209 patients, respectively, were diagnosed with infection by one or more parasitic species (P<0.005). Pathogenic species were detected by the conventional method and by the TFT in 39 and 94 cases, respectively, and nonpathogenic species were detected in 124 and 288 cases, respectively (P<0.05). Additional costs for the sampling device, laboratory reagents and handling of the TFT were acceptable. The results of this study suggest that the TFT is an effective method for detection of intestinal parasites in stool samples in routine clinical practice.