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, vomiting, and diarrhea.

"When babies present to a doctor with symptoms of a cereulide infection, the doctor is not required to take a stool sample and test for the infection," Joris Moonens, spokesperson for the department, told Flemish-speaking broadcaster VRT on Monday.

The first confirmed case of cereulide contamination in Flanders was reported on Jan. 23. Since then, authorities have urged doctors to report any baby who consumed recalled formula and shows related symptoms.

Moonens said if testing is not mandatory, the confirmed cases are likely an "underestimation."

The Federal Agency for the Safety of the Food Chain (FAVV) is currently investigating about 20 reports from parents whose babies showed symptoms after consuming recalled products.

"In that case, the FAVV can also come by to collect any remaining residue of the powder and have it analyzed in the lab," spokesperson Helene Bonte said.

Nestle initially collected some recalled products from households in Belgium, but later stopped. The recall has spread internationally, with French companies Danone and Lactalis removing products after cereulide was detected in ingredients from a shared supplier.

The company said the affected products have been distributed in more than 50 countries across Europe, the Americas, Asia, Oceania, and Africa.

In a video message, Nestle CEO Philipp Navratil apologized to parents and caregivers, describing the situation as "the largest preventive recall in Nestle’s history."