These last years, a fall in consumer's confidence in food safety encouraged false alerts which sometimes led to actual crisis. This paper studies a crisis due to an alert concerning a risk of listeria on a raw milk camembert brand. The investigation relies on individual data. Two results of risk economy are confirmed. Firstly, information has asymmetric effects, according its positive or negative aspects. Secondly, punctual alerts have only temporary effects on consumption. In this crisis, education and consumer's habits did not pay any role.