MRCP2-2584

A 32-year-old woman presented to the Emergency Department with a 3-day history of loose stools. She had recently returned from a trip to Thailand.
Upon examination, her temperature was 37.1°C, blood pressure 120/80 mmHg, and pulse rate 92 bpm. Her abdomen was soft with tenderness in the lower quadrants. No rashes were present.
Based on the following lab results, what is the most probable cause of her diarrhoea?

s
Haemoglobin (Hb) 129 g/l 120 – 160 g/l
White cell count (WCC) 10.2 × 109/l 4.0 – 11.0 × 109/l
Sodium (Na+) 142 mmol/l 135 – 145 mmol/l
Potassium (K+) 3.6 mmol/l 3.5 – 5.0 mmol/l
Creatinine (Cr) 98 µmol/l 50 – 120 µmol/l
Urea 7.8 mmol/l (2.5–7.0) 2.5 – 6.5 mmol/l
Bilirubin 12.0 µmol/l 1 – 22 µmol/l
Alanine aminotransferase (ALT) 33 u/l 7 – 55 u/l
Alkaline phosphatase (ALP) 85 u/l 30 – 150 u/l
Gamma glutamyl-transferase (GGT) 28 u/l < 50 u/l