In a recent issue of Gut, van Beurden et al showed the usefulness of ultrasound in the diagnosis of intestinal worms in a case of human taeniasis (Gut 2008;57:515 and 524). The examination was even more sensitive than the stool analysis, which remained negative. However, and specifically in the case of human taeniasis, ultrasound techniques might have a double diagnostic advantage: the detection of the intestinal adult tapeworm as well as the search of the presence of extraintestinal Taenia larval stages in the same patient.

Human taeniasis caused by pig (Taenia solium) or cattle (T saginata) tapeworms arises after eating pork or beef contaminated with cysticerci, the larval stage of these parasites. Due to the frequently asymptomatic and benign course of the intestinal parasitation, the main risk of these parasites is that taeniasis caused by T solium can lead to another dangerous disorder: cysticercosis. This disease is acquired through the ingestion of eggs shed by a carrier of the adult tapeworm. These seemingly asymptomatic patients place themselves, as well as other people (who accidentally ingest the eggs), at risk. The brain is most often affected (neurocysticercosis), and other common locations for the cysticerci include subcutaneous tissue, skeletal or heart muscle and the eye.

Up to 40% of patients harbouring intestinal T solium also show some type of cysticercosis, therefore it would be advisable to look for cysticerci in those patients who harbour T solium. Ultrasonographic techniques are particularly accurate in the diagnosis of cysticercosis.1 2

In the case reported by van Beurden et al, the species was identified as T saginata, which does not cause human cysticercosis. However, there is another pig tapeworm affecting humans, T asiatica, found in the majority of Asian countries, although its definitive geographical distribution is still unknown. The morphology of T asiatica overlaps with that of T saginata, so its specific diagnosis is only possible by using molecular methods.

The main uncertainty concerning T asiatica is whether the parasite is able to cause human cysticercosis, and this question should be addressed urgently in order to prevent this disorder.3

As no immunological method is available for the diagnosis of T asiatica cysticercosis, we believe that one important tool for the investigation of the presence of cysticerci, at least in patients harbouring the adult stage of T asiatica, is by using liver ultrasonography since T asiatica cysticercus shows a clear liver tropism in pigs, its natural intermediate host.4

We do not know if the patient treated by van Beurden et al had visited any Asian country, but due to his origin (Morocco), he would probably not eat pork, so he was likely to have harboured T saginata. But in any other case, and if no molecular technique is applied in the diagnostic process of the adult stage, it would be very useful to investigate the presence of cysticerci in the liver of all those patients harbouring T saginata-like adults.