PCR for enteric pathogens is starting to take hold, both locally and internationally.

One area where there is a significant difference between traditional methods and PCR is in the area of enteric parasites.

PCR is much more sensitive than microscopy at picking up faecal parasites. This has shown great benefit when trying to diagnose conditions like Entamoeba histolytica, (not only in faeces, but also in liver abscesses as well)

So far, so good,

but there are downsides as well….

PCR for Blastocystis hominis and Dientamoeba fragilis are generally much more sensitive methods than their microscopical counterparts. This leads to high numbers of “positives” being reported, particularly in children. However these two parasites are putative pathogens at best, potentially causing symptoms in a small and select number of patients only. Most of the time they are probably just there for the ride.

Using such a sensitive assay for parasites of uncertain significance like this can thus lead to misdiagnosis, over treatment and undue anxiety. More is not always better.

Sometimes ignorance is bliss…

Michael