Giardiasis--a cause of travellers' diarrhoea.

A surveillance programme using postal questionnaires was set up to monitor giardiasis in Bristol. Ninety-seven questionnaires were returned from 117 index cases in the first year. Cases appeared to fall into one of three main groups, namely, pre-school children (23 cases), those who travel abroad (22 cases had travelled in the month prior to the onset of their symptoms), and those who engaged in recreational water use prior to the onset of their illness (44 out of 66 cases aged 10 years or more). Routine surveillance data can indicate important routes of transmission of giardiasis in the local community.