Giardia is a parasite which is very common in freshwater lakes, for instance, and can be present on unwashed vegetables. Simple precautions when travelling are important but as the parasite can reside in the gut of children and adults for months if not years it is important to think of this in any child presenting with faltering growth, weight loss, diarrhoea, abdominal distension, etc. Giardia is difficult to detect and is only picked up by normal stool examination in about 20% of cases. Often we will treat with Metronidazole and if your child gets better then we can presume that this has been the case as it can be missed by the faeces test.