Follow-up of sporadic cases of food-borne infection: comparison of a postal questionnaire with a personal visit.

The aim of the study was to evaluate the follow-up of sporadic cases of suspected food-borne illness by either a postal questionnaire or a personal visit by environmental health staff. This was achieved by comparing the practice in two authority areas within the West Pennine Health Authority in the north west of England. We included all identified cases of suspected food poisoning, campylobacteriosis, cryptosporidiosis, salmonellosis and dysentery occurring in the district between 1 July and 30 September 1996. The main outcome measures were: (1) the proportion of all cases which were successfully followed-up by each method; (2) the timeliness of follow-ups; (3) qualitative estimation by environmental health staff of the data obtained. Visiting by environmental health staff was successful in obtaining information from 76.3% (106/139) of cases, while the postal questionnaires elicited a 52% (50/96) response rate. We found that 70.5% of visits occurred within one week of notification. Although 69.8% (67/96) ...