Foodborne illness outbreaks are usually detected through one of three ways: pathogen-specific surveillance of reportable diseases, reports of illnesses by healthcare providers or institutions, or consumer complaints of suspected foodborne illness. In Minnesota, foodborne illness outbreak detection and investigation is largely centralized at the Minnesota Department of Health (MDH).
MDH has operated a foodborne illness complaint system since 1998. This system was recently described and evaluated by Li et al. (2010) and is described in more detail here. Residents of Minnesota are encouraged to call a toll-free number (1-877-FOOD-ILL) when they suspect they have a food-related illness. The availability of this service is advertised through distribution of refrigerator magnets and brochures with the hotline number at a variety of venues, including the state fair, health fairs, and health care provider conferences. Larger poster versions of the magnet have also been mailed to emergency rooms and family practiceand pediatric clinics in the state. The hotline is also advertised through the MDH website. Individuals can also submit a complaint electronically to the MDH via a REDCap survey. Since the public often calls their local health department with foodborne illness complaints, these local health departments are asked to either forward complaint callers to the MDH or fax a completed intake form. Complaints also are occasionally forwarded to the MDH from food establishments. The hotline is staffed from 8:00 a.m. to 4:30 p.m. Monday through Friday (not including holidays). Voice-mails can be left during non-business hours.
The complaint system is managed by a single experienced MDH employee in the Health Program Representative Classification series. This person receives complaint calls during business hours, and calls back people who have left voice-mails or e-mails. This person completes a standard intake form to record complainant information. Questions cover demographics of the caller, detailed illness information (including exact time of symptom onset and recovery), suspected food product or establishment, names and contact information for other members of the dining party (if applicable), and a small number of non-foodborne exposures. When illness is limited to a single person or members of a single household, a 4-day food history is obtained, focused on meals eaten outside of the home. When illness is reported among members of multiple households, information is taken only for meals in common to members of the different households. Hotline staff also attempt to contact and interview ill meal companions reported by the original caller about symptoms and food consumption. All information collected about the caller’s illness is kept private and names are not released to anyone outside of the public health system without the caller’s permission. All information collected is entered into the MDH complaint database.
Complaints involving multiple households, instances of multiple independent complaints about the same restaurant, reports of clusters of illness, and occasionally complaints involving multiple people in the same household (if compelling), are evaluated by the MDH foodborne illness supervisor as complaints are received, and outbreak investigations are initiated with the appropriate state or local health agencies as deemed warranted by this supervisor. The decision to initiate an outbreak investigation is influenced by a number of factors including the number of reported ill persons, reported symptoms and incubations from exposures of interest, whether or not illness was reported in multiple households, the presence/absence of other shared exposures, and whether other independent complaints were received. No automatic detection algorithm is used to detect multiple complaints about the same restaurant; rather, the MDH staff must review incoming data regularly to find common complaints. In practice, temporally associated reports about the same restaurant are easily noticed because one person manages the system.
After a complaint call, MDH faxes the complaint to the environmental health staff responsible for inspecting the restaurants, delis, and grocery stores that the caller mentions (whether or not the establishments are a suspected source of the complainant’s illness). If MDH determines that investigation of a particular establishment is warranted, the appropriate environmental health agency is contacted immediately by telephone. Otherwise, an environmental health specialist to whom a complaint is faxed can respond to that complaint however they choose (i.e., there is no expectation by MDH about what the environmental health agency should or should not do). Note – this arrangement required considerable discussion and reminders on the faxed complaints until everyone was on the same page regarding response to illness complaints.
Other MDH staff conduct standard interviews for all foodborne illness cases detected through pathogen-specific surveillance for a variety of reportable pathogens, including Salmonella, Shiga toxin–producing E. coli, Shigella, Campylobacter, Listeria monocytogenes, Vibrio spp., Yersinia spp., Cryptosporidium, and Cyclospora. All restaurants that affected persons reported eating at within the 7 days prior to illness onset (14 days for Cryptosporidium and Cyclospora) also are entered into the MDH complaint database. Twice a week, the manager of the complaint system examines a list of restaurants from both surveillance streams to search for common establishments (sample complaint report).
From 2000 through 2012, we have received a median of 777 complaints per year (range, 676 to 991) (see Figure 1 below). In the evaluation by Li et al. (2010), which covered the years 2000-2006, the complaint system was responsible for detection of 261 (79%) of the 332 confirmed foodborne outbreaks that were identified in Minnesota during that time frame (62% of those 261 outbreaks occurred at food establishments whereas the other 38% occurred at an event). An additional 8% of outbreaks were detected through a combination of complaints and other surveillance methods. The remaining outbreaks were detected through pathogen-specific surveillance, health care provider reports of clusters of illnesses due to nonreportable pathogens, and reports from institutions, which includes places such as schools and long-term care facilities. Not surprisingly, the complaint system detected almost all of the outbreaks caused by non-reportable pathogens (e.g., norovirus, Clostridium perfringens, Bacillus cereus, Staphylococcus aureus, scombroid toxin). More surprisingly, though, was that five (14%) of foodborne Salmonella outbreaks were detected solely through the complaint system, and complaints contributed to detection of another four (11%) Salmonella outbreaks.
The Li et al. (2010) evaluation also showed that 70% of foodborne outbreaks detected solely through the complaint system were detected through a single complaint. Of outbreaks detected through a single complaint, 87% of complainants reported illness in multiple households, and 13% of complainants reported illness in a single household. 20% of foodborne outbreaks detected solely through the complaint system were detected through 2 independent complaints, 5% through 3 independent complaints, and 5% through more than 3 independent complaints. Complaints that resulted in identification of an outbreak had a median of 3 people ill reported in the complaint – this was significantly higher than in complaints not associated with outbreaks (median, 1 person reported ill; p<0.001)
We recently updated the Li et al. (2010) by adding data from the years 2007-2012. Results from 2007-2012 (Tables 1 and 2 below) generally support the findings of the Li et al. (2010) publication. During the entire time period of 2000-2012, 662 confirmed foodborne outbreaks were reported in Minnesota; of these, 488 (74%) were detected solely by or with the assistance of consumer complaints. Among outbreaks caused by non-reportable pathogens, 456 (94%) were detected solely through the complaint system or through a combination of complaints and another detection method.
Our data reveal that consumer complaint systems are an effective surveillance tool for detection of foodborne illnesses caused by various agents, including reportable pathogens. Complaint systems can be used to enhance pathogen-specific surveillance and provide the primary means of outbreak detection for non-reportable and emerging pathogens for which clinical laboratory diagnosis is not available. The use of a complaint based surveillance system can also speed up investigations; investigators do not have to wait for cases to be reported through pathogen-specific surveillance. When complaint systems are in place, the lag time between illness and reporting to the health department is decreased, which can lead to more timely investigations and follow-up by health departments.
Our data also indicate that high priority should be placed on callers reporting multiple illnesses. The number of ill persons was significantly correlated with an outbreak associated complaint. This issue is related to the ability of the caller to determine a common exposure for their illness when more people are involved and the response of the health departments in targeting investigation of calls with clear common exposures. These types of calls represent events that are highly likely to have been outbreak associated and can easily be detected through a complaint system that collects the proper information to allow timely follow-up.