BRUSSELS Belgian authorities said Monday that they are investigating cases of babies who may have fallen ill after consuming contaminated Nestle baby formula, following a nationwide recall of several products. The Flemish Department of Healthcare said the number of affected infants in the Flanders region could be underestimated, as doctors are not required to test for the cereulide toxin, the bacterial contaminant at the center of the recall. Cereulide is a bacterial toxin that can cause nausea,