Tests of ByHeart infant formula tied to a botulism outbreak that has sickened dozens of babies showed that all of the company’s products may have been contaminated.

Laboratory tests of 36 samples of formula from three different lots showed that five samples contained the type of bacteria that can lead to the rare and potentially deadly illness, the company said Monday on its website.

“Based on these results, we cannot rule out the risk that all ByHeart formula across all product lots may have been contaminated,” the company wrote.

At least 31 babies in

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