Multiple choice The causative agent of travellers diarrhoea is Naegleria fowleri Giardia lamblia Rhinosporidium seeberi Toxoplasma gondii Dientamoeba fragilis Reveal answer Fill a bubble to check yourself E Correct answer Explanation Dientamoeba fragilis is a single-celled parasite found in the gastrointestinal tract of humans, pigs and gorillas. It is an important cause of travellers diarrhoea, chronic diarrhoea, fatigue and, in children, failure to thrive.