Cereulide is an emetic toxin produced by certain strains of the bacterium Bacillus cereus; it is heat- and acid-stable, so it can survive processing and cause rapid-onset vomiting and, in rare cases, more severe illness. Because infants are especially vulnerable, detection of cereulide in formula typically triggers recalls — if your product is affected, stop using it, keep the packaging for batch information and contact a pediatrician if your baby shows vomiting, fever or signs of dehydration.