Are Campylobacter cases low risk for public health follow-up?

Most Campylobacter cases are treated as low risk enterics (LRE) and receive a mailed letter from Toronto Public Health (TPH) with a questionnaire to gather basic risk information. This study sought to identify reasons why Campylobacter cases who were sent this questionnaire did not respond to the letter and to determine whether any of these cases were working in a high-risk occupation.

Cases reported to TPH between June 11, 2012 and December 6, 2012 who had not returned the questionnaire within 30 days were telephoned. Participants were asked about awareness of the original letter, reasons for not responding, and whether they worked in a high-risk occupation.

Of the 226 cases identified as not responding to the letter, 172 (76.1%) were reached, and 162 (71.7%) answered the survey questions. The most frequent reason chosen for not responding to the original letter was "forgot" (54.4%). The most common suggestion chosen for ways to encourage response to the original letter was "more information on importance of returning questionnaire" (19.1%). Of the 119 cases with a known occupation, 3 (2.4%) were employed in a sensitive occupation - these include a family physician, a food server, and a line cook. None worked while ill. When prompted with a list of reasons for not returning the questionnaire, the majority of respondents indicated that they "forgot" (54.4%); the next most frequent response was "recovered by illness no longer considered it relevant" (21.5%).

To increase response rates in the future, a cover letter should more clearly explain why the response is being solicited by Public Health, even after recovery from the illness, and the form should be simplified for mail return. A very small number of clients originally not reached through the course of the routine LRE program were working in sensitive occupations. Since none reported working while ill, the likelihood of direct or indirect transmission of Campylobacter from these three individuals was low. Using a LRE system to monitor a widespread mostly low-morbidity gastroenteric illness can be an effective public health strategy.