Helminths or worms are classified into three groups: nematodes (Ascaris, Trichuris), cestodes (Taenia) and trematodes (Schistosoma). Antihelminthic treatment requires specific drug and dose for each group.
Schistosomes do NOT occur in the Netherlands, but are imported from tropical regions.
A carrier of worms always needs antihelmintic treatment.
Extra info: A helmintic infections might not cause symptoms.