STANDARD advice on preventing diarrhoea when abroad does not always work, a doctor from Newcastle University says. In the British Medical Journal he describes the case of a professional couple who obsessively followed the usual advice on food during a 15-month journey around the world. They boiled all drinking water, avoided dairy products and uncooked vegetables and used their own cloth to wipe restaurant plates and cutlery.

Unsurprisingly, the couple often went thirsty and hungry. But between them they also developed two types of dysentery (one life threatening) as well as hepatitis, diarrhoea and giardiasis, an infection of the small intestine. One of the patients still had loose stools 30 months after returning to Britain.