Follow-up of sporadic cases of food-borne infection

Abstract

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) of questionnaires were issued within one week of notification, only 16% of replies to the questionnaire were received within this period. The information provided on the returned questionnaires was found by environmental health staff to be generally as useful as that obtained by visiting.