Entamoeba histolytica and Giardia lamblia infections: current diagnostic strategies

Entamoeba histolytica and Giardia lamblia constitute, in a world context, the two commonest intestinal protozoan parasites to affect man. Therefore accurate diagnosis is of paramount importance if resultant infections are to be adequately managed. Demonstration of the cyst or trophozoite stage in a faecal sample(s) (several newer techniques are available) remains the lynch-pin of diagnostic strategies; however, excretion of cysts, especially, is intermittent and evidence of infection is not always manifest in a single examination. A limited range of other techniques is also available for a 'parasitological diagnosis'. Within the last decade, serological techniques (largely dependent on invasive properties of the organism) have attained levels of diagnostic competence. Therefore, a very high index of suspicion now ensues from indirect evidence of infection.