Guest guest Posted February 1, 2008 Report Share Posted February 1, 2008 Difficulties in Detection Parasites have complex life cycles and are often not shed at regular intervals. In fact, three of the major parasites in the United States and worldwide (amoebas, Giardia, and Cyclospora) tend to be shed at irregular intervals. This means that the parasite may be present in the stool for two, three, or four days a week, but not the rest of the week. Entamoeba histolytica is active for one or two days, and then is not typically active or detectable the next day or two. When E. histolytica migrates to the liver it disappears from the gut and becomes undetectable in fecal specimens. If the stool sample is collected from a patient with one of these cyclical parasites on a day when the pathogen is not active, it won¢t be in the stool and obviously won¢t be detected by testing. However this doesn¢t mean that there¢s no infection present. At the current time this is a limitation for which no modern technology can compensate. Consequently repeated samples are very important. Generally, to make testing practical, we recommend at least two or three samples be taken on different days. Quote Link to comment Share on other sites More sharing options...
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