The number of babies hospitalised in the United States following an outbreak linked to contaminated milk formula has skyrocketed to 51.

Back in November, representatives of the organic infant formula maker ByHeart announced a recall of its Whole Nutrition Infant Formula – including all sized cans and single-serve packets – after being instructed to by the Food and Drug Administration (FDA).

“The safety and well-being of every infant who uses our formula is, and always will be, our highest priority,” the firm claimed at the time.

It came amid an investigation into an apparent botulism outbreak in children, which began in August, with ByHeart finding clostridium botulinum in some samples of its formula.

Four major retailers – including Walmart and Target – were also forced to make the same announcement after receiving major warning letters, with inspectors having discovered recalled formula still on shelves weeks after the initial news had broken.

The condition could prove fatal if left untreated (Getty Stock Images)

“Epidemiologic and laboratory data show that ByHeart Whole Nutrition infant formula might be contaminated with Clostridium botulinum, [the bacteria that causes botulism] which is causing infant illness in multiple regions of the country,” the FDA announced in a statement last month.

“These warning letters highlight a concerning problem with recall effectiveness at the retail level.”

According to the Centre for Disease Control and Prevention (CDC), swallowed clostridium botulinum causes botulism in babies, by which spores ‘grow in the gut and make toxin’.

Early symptoms include constipation, problems when feeding, a weak or altered cry, decreased facial expression, and poor head control.

The CDC added that botulism can prove fatal if left untreated, with infants potentially enduring ‘progressive, flaccid paralysis that can lead to breathing difficulties and require weeks of hospitalisation’.

A total of 51 infants have been hospitalised, as of 10 December (Getty Stock Images)

A total of 51 infants across 19 states have been hospitalised as of 10 December – the states being Arizona, California, Idaho, Illinois, Kentucky, Massachusetts, Maine, Michigan, Minnesota, North Carolina, New Jersey, Ohio, Oregon, Pennsylvania, Rhode Island, Texas, Virginia, Washington and Wisconsin.

No deaths have yet been reported in relation to the outbreak.

In an update given by ByHeart to Fox News Digital on Friday, the firm claimed it was aware of health officials’ expanded review, insisting it’d remain committed to seeking ‘the root cause of the contamination’.

“This is an ongoing investigation and we remain committed to transparency and cooperating with federal and state agencies,” they added.

LADbible Media Group reached out to ByHeart for comment.