While a large proportion of people who come down with a food-borne illness will blame the last restaurant they ate at (regardless of where or when that was), in reality, many cases come from home kitchens. Whether people fail to properly clean and sanitize their food contact surfaces, or they undercook their potentially hazardous food items, there are more risks at home to becoming ill than when you eat in a restaurant (unless, of course, you've developed HACCP plans for your home recipes, in which case: kudos).
Having a food-borne illness is not a fun time. It's exceedingly unpleasant. So once people have gone through that misery, do they learn anything from it? In other words, will they continue to make the same mistakes, or will they practice exceptional food handling procedures to ensure it never, ever, ever happens to them again. A study in volume 41 of Food Control looked to answer that very question, by looking at the food handling and kitchen hygiene of individuals who had previously suffered from Campylobacter infections.
The case control study used a survey to identify behaviors and perceptions about food safety, and followed up with a "kitchen sampling programme" among a sub-set of the cases and controls. Cases were identified as adults who had lab-confirmed campylobacteriosis, and were age/gender/geography matched to controls. The survey asked some general questions about food practices, as well as some questions that were specifically included to identify optimistic bias (e.g. asking what risk of illness came from their kitchen, vs. the risk in the average home kitchen). The kitchen sampling was done with environmental swabs on counters and cutting boards, and an analysis of the dish towel for bacterial growth.
In identifying optimistic bias, the researchers found that everybody thinks their kitchen is safer than the average home. Whether it was cases or controls, nearly 60% of respondents indicated that the average person is "at a significantly greater risk of getting food poisoning" than themselves. Interestingly, when the same question was asked 6 months in the future (i.e. after the campylobacteriosis was a distant memory), the cases had less of an increase in optimistic bias than the controls. Perhaps, with time to reflect on their illness, they were less convinced that they were as amazing at kitchen hygiene as they had originally thought. It's also noted that controls, who have not yet become ill, likely have increased confidence as time goes on and they continue to remain healthy.
In the "kitchen behavior" part of the survey, cases were found to be more likely to state that they wash their raw chicken pieces and their pre-washed bagged salads. These actions are not recommended, as washing your raw chicken increases the chance of cross-contamination, and your bagged salad is already washed much more thoroughly than you'd be able to achieve. Cases over the age of 60 were much more likely to state that they washed their chicken and their bagged salad.
While the survey part of the study relies on people's honesty and memory in answering questions, the kitchen sampling programme cannot be faked. Based on the responses above and the fact that the cases actually had food poisoning, one would expect their kitchen hygiene to be marginally worse than the controls. In reality, however, there was no difference between the two groups whatsoever. It was noted that the participants were warned that the samplers were coming ahead of time, which could have allowed them to clean beforehand, but they weren't made aware of where the samplers would swab.
The bottom line is that there is still work to be done in convincing the public that kitchen hygiene behaviors at home are an important part of reducing cases of food poisoning. The fact that the controls became more optimistic about their behaviors over time, and that the >60 year old age cohort was practicing unsafe food handling procedures shows that the education is not sinking in. As mentioned in the opening paragraph, people generally like to blame the last restaurant they ate at for their illness, a fact reflected in the optimistic bias. Ensuring that people are aware that their home-cooked meals can cause illness is the first step to reducing the burden on the health care system.
Source: Millman, C., Riby, D., Edward-Jones, G., Lighton, L., & Jones, D. (2014). Perceptions, behaviours and kitchen hygiene of people who have and have not suffered campylobacteriosis: A case control study. Food Control, 41, 82-90.