A previously fit and well 15-year-old Caucasian boy presented with a week of intermittent pyrexia, non-bloody, non-mucoid diarrhoea and bilious vomiting. He also presented with persistent headache, general myalgia, and had episodes of rigours. He had returned 48 hours previously from a family holiday touring Thailand for three weeks with no travel towards the Vietnamese and Laos borders. All recommended pretravel immunisations had been given; antimalarial prophylaxis was not considered necessary in the areas of travel. He had travelled with both parents and his younger brother; during the trip all had engaged in open-water swimming, and eaten partly cooked meat. All family members experienced mild diarrhoea but got better. He seemed to improve but then had recurrence of large volume watery diarrhoea and …